The Cuckoo's Egg
    by Clifford Stoll    

(PDF Version)


o     0     0    How do you spread the word when a computer has a secu-
rity hole? Some say nothing, fearing that telling people how to mix explo-
sives will encourage them to make bombs. In this book I've explicitly
described some of these security problems, realizing that people in black hats
are already aware of them.
      I've tried to reconstruct this incident as I experienced it. My main
sources are my logbooks and diaries, cross-checked by contacting others
involved in this affair and comparing reports from others. A few people
appear under aliases, several phone numbers are changed, and some conver-
sations have been recounted from memory, but there's no fictionalizing.
      For supporting me throughout the investigation and writing, thanks to
my friends, colleagues, and family. Regina Wiggen has been my editorial
mainstay; thanks also to Jochen Sperber, Jon Rochlis, Dean Chacon, Donald
Alvarez, Laurie McPherson, Rich Muller, Gene Spafford, Andy Goldstein,
and Guy Consolmagno. Thanks also to Bill Stott, for Write to the Point, a
book that changed my way of writing.
      I posted a notice to several computer networks, asking for title sugges-
tions. Several hundred people from around the world replied with zany


ideas. My thanks to Karen Anderson in San Francisco and Nigel Roberts in
Munich for the title and subtitle.
      Doubleday's editors, David Gernert and Scott Ferguson, have helped
me throughout. To them, as well as my agent, John Brockman, thanks for
your continued encouragement and wise advice.
      To each of these people, I'm indebted; lowe most of them boxes of
cookies as well.
      Lawrence Berkeley Laboratory supported me throughout this quest;
the people of Smithsonian Astrophysical Observatory-especially Joe
Schwarz and Steve Murray-have been most gracious and supportive while
I've been writing this book. My deep thanks go to my friends at both
institutes, and my hopes that I'll now be able to return to astronomy.
       I was ten years old when Ernst Both of the Buffalo Museum of
Science invited me to look through a telescope, opening up a universe of
astronomy. I wonder if I'll ever be able to thank him properly.
       I needn't thank my sweetheart and wife, Martha Matthews. She's been
as much a part of writing this book as she was in the story.

                                  -Cliff Stoll
                                    Electronic mail addresses:
                                    Compuserve: 71660,3013
                                    Genie:         Cliff-Stoll

o     0    0       Me, a wizard? Until a week ago, I was an astronomer,
contentedly designing telescope optics. Looking back on it, I'd lived in an
academic dreamland. All these years, never planning for the future, right up
to the day my grant money ran out.
       Lucky for me that my laboratory recycled used astronomers. Instead of
standing in the unemployment line, I found myself transferred from the
Keck Observatory at the Lawrence Berkeley Lab, down to the computer
center in the basement of the same building.
       Well, hell, I could fake enough computing to impress astronomers, and
maybe pick it up fast enough that my co-workers wouldn't catch on. Still, a
computer wizard? Not me-I'm an astronomer.
       Now what? As I apathetically stared at my computer terminal, I still
thought of planetary orbits and astrophysics. As new kid on the block, I had
my choice of a cubicle with a window facing the Golden Gate Bridge, or an
unventilated office with a wall of bookshelves. Swallowing my claustropho-
bia, I picked the office, hoping that nobody would notice when I slept under
the desk. On either side were offices of two systems people, Wayne Graves

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and Dave Cleveland, the old hands of the system. I soon got to know my
neighbors through their bickering.
     Viewing everyone as incompetent or lazy, Wayne was crossthreaded
with the rest of the staff. Yet he knew the system thoroughly, from the disk
driver software up to the microwave antennas. Wayne was weaned on
Digital Equipment company's Vax computers and would tolerate nothing
less: not IBM, not Unix, not Macintoshes.
      Dave Cleveland, our serene Unix buddha, patiently listened to
Wayne's running stream of computer comparisons. A rare meeting didn't
have Wayne's pitch, "Vaxes are the choice of scientists everywhere and helps
build strong programs twelve ways." Dave retorted, "Look, you keep your
Vax addicts happy and I'll handle the rest of the world." Dave never gave
him the satisfaction of getting riled, and Wayne's complaints eventually
trailed off to a mutter.
      Great. First day on the job, sandwiched between two characters who
were already ruining my daydreams with their periodic disputes.
      At least nobody could complain about my appearance. I wore the
standard Berkeley corporate uniform: grubby shirt, faded jeans, long hair,
and cheap sneakers. Managers occasionally wore ties, but productivity went
down on the days they did.
      Together, Wayne, Dave, and I were to run the computers as a lab-wide
utility. We managed a dozen mainframe computers-giant workhorses for
solving physics problems, together worth around six million dollars. The
scientists using the computers were supposed to see a simple, powerful
computing system, as reliable as the electric company. This meant keeping
the machines running full time, around the clock. And just like the electric
company, we charged for every cycle of computing that was used.
      Of four thousand laboratory employees, perhaps a quarter used the
main computers. Each of these one thousand accounts were tallied daily, and
ledgers kept inside the computer. With an hour of computing costing three
hundred dollars, our bookkeeping had to be accurate, so we kept track of
every page printed, every block of disk space, and every minute of processor
time. A separate computer gathered these statistics and sent monthly bills to
laboratory departments.
      And so it happened that on my second day at work, Dave wandered
into my office, mumbling about a hiccup in the Unix accounting system.
Someone must have used a few seconds of computing time without paying

                  THE CUCKOO'S EGG

for it. The computer's books didn't quite balance; last month's bills of
$2,387 showed a 75-cent shortfall.
       Now, an error of a few thousand dollars is obvious and isn't hard to
find. But errors in the pennies column arise from deeply buried problems, so
finding these bugs is a natural test for a budding software wizard. Dave said
that I ought to think about it.
       "First-degree robbery, huh?" I responded.
       "Figure it out, Cliff, and you'll amaze everyone," Dave said.
       Well, this seemed like a fun toy, so I dug into the accounting program.
I discovered our accounting software to be a patchwork of programs writ-
ten by long-departed summer students. Somehow, the hodgepodge worked
well enough to be ignored. Looking at the mixture of programs, I found
the software in Assembler, Fortran, and Cobol, the most ancient of com-
puter languages. Might as well have been classical Greek, Latin, and San-
       As with most home-brew software, nobody had bothered to document
our accounting system. Only a fool would poke around such a labyrinth
without a map.
       Still, here was a plaything for the afternoon and a chance to explore
the system. Dave showed me how the system recorded each time someone
connected to the computer, logging the user's name, and terminal. It time-
stamped each connection, recording which tasks the user executed, how
many seconds of processor time he used, and when he disconnected.
       Dave explained that we had two independent accounting systems. The
ordinary Unix accounting software just stored the timestamped records into
a file. But to satisfy some bureaucrat, Dave had built a second accounting
system which kept more detailed records of who was using the computer.
       Over the years, a succession of bored summer students had written
programs to analyze all this accounting information. One program collected
the data and stashed it into a file. A second program read that file and
figured how much to charge for that session. Yet a third program collected
all these charges and printed out bills to be mailed to each department. The
last program added up all user charges and compared that total to the result
from the computer's internal accounting program. Two accounting files,
kept in parallel by different programs, ought to give the same answer.
       For a year, these programs had run without a glitch, but weren't quite
perfect this week. The obvious suspect was round-off error. Probably each
accounting entry was correct, but when added together, tenths of a penny

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differences built up until an error of 75 cents accumulated. I ought to be
able to prove this either by analyzing how the programs worked, or by
testing them with different data.
       Rather than trying to understand the code for each program, I wrote a
short program to verify the data files. In a few minutes, I had checked the
first program: indeed, it properly collected the accounting data. No problem
with the first.
       The second program took me longer to figure out. In an hour I had
slapped together enough makeshift code to prove that it actually worked. It
just added up time intervals, then multiplied by how much we charge for
computer time. So the 75-cent error didn't come from this program.
       And the third program worked perfectly. It looked at a list of autho-
rized users, found their laboratory accounts, and then printed out a bill.
Round-off error? No, all of the programs kept track of money down to the
hundredths of a penny. Strange. Where's this 75-cent error coming from?
       Well, I'd invested a couple hours in trying to understand a trivial
problem. I got stubborn: dammit, I'd stay there till midnight, if I had to.
       Several test programs later, I began actually to have confidence in the
 mishmash of locally built accounting programs. No question that the ac-
 counts didn't balance, but the programs, though not bulletproof, weren't
 dropping pennies. By now, I'd found the lists of authorized users, and
 figured out how the programs used the data structures to bill different
 departments. Around 7 P.M. my eye caught one user, Hunter. This guy
 didn't have a valid billing address.
       Ha! Hunter used 75 cents of time in the past month, but nobody had
 paid for him.
       Here's the source of our imbalance. Someone had screwed up when
 adding a user to our system. A trivial problem caused by a trivial error.
       Time to celebrate. While writing this first small triumph into the
 beginning pages of my notebook, Martha, my sweetheart, stopped by and
 we celebrated with late-night cappuccinos at Berkeley's Cafe Roma.
       A real wizard would have solved the problem in a few minutes. For
 me, it was unknown territory, and finding my way around hadn't been easy.
 As a consolation, I'd learned the accounting system and practiced a couple
 obsolete languages. Next day, I sent an electronic mail message to Dave,
 preening my feathers by pointing out the problem to him.
       Around noon, Dave stopped by to drop off a pile of manuals, and
 casually mentioned that he had never added a user named Hunter-it must

                 THE CUCKOO'S EGG

have been one of the other system managers. Wayne's curt response: "It
wasn't me. RTFM." Most of his sentences ended with acronyms, this one
meaning, "Read the fucking manual."
       But I'd read the manuals. Operators weren't supposed to add a new
user without an account. At other computer centers, you just log into a
privileged account and tell the system to add a new user. Since we also had
to make several bookkeeping entries, we couldn't run such a vanilla system.
Ours was complex enough that we had special programs which automati-
cally did the paperwork and the systems juggling.
       Checking around, I found that everyone agreed the automatic system
was so superior that nobody would have manually added a new user. And
the automatic system wouldn't make this mistake.
       Well, I couldn't figure out who had made this goof. Nobody knew
Hunter, and there wasn't an account set for him. So I erased the name from
the system-when he complained, we could set him up properly.
       A day later, an obscure computer named Dockmaster sent us an elec-
tronic mail message. Its system manager claimed that someone from our
laboratory had tried to break into his computer over the weekend.
       Dockrnaster's return address might have been anywhere, but signs
pointed to Maryland. The e-mail had passed through a dozen other com-
puters, and each had left a postmark.
       Dave answered the message with a noncommittal "We'll look into it."
Uh, sure. We'd look when all our other problems disappeared.
       Our laboratory's computers connect to thousands of other systems
over a dozen networks. Any of our scientists can log into our computer, and
then connect to a distant computer. Once connected, they can log into the
distant computer by entering an account name and password. In principle,
 the only thing protecting the networked computer is the password, since
account names are easy to figure out. (How do you find account names?Just
use a phone book-most people use their names on computers.)
       Dockmaster's electronic mail message was a curiosity, and Dave passed
 it to Wayne, attaching a question, "Who's Dockrnaster?" Wayne forwarded
 it to me with his guess-"Probably some bank."
       Eventually, Wayne bounced the message to me. I guessed Dockmaster
 was some Navy shipyard. It wasn't important, but it seemed worth spending
a few minutes looking into.
       The message gave the date and time when someone on our Unix
 computer tried to log into Dockmaster's computer. Since I'd just mucked

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around the accounting system, scrabbled around the files, looking for
records from Saturday morning at 8:46. Again, the two accounting systems
disagreed. The stock Unix accounting file showed a user, Sventek, logging
in at 8:25, doing nothing for half an hour, and then disconnecting. No
timestamped activity in between. Our home-brew software also recorded
Sventek's activity, but it showed him using the networks from 8:31 until
9:01   A.M.

     Jeez. Another accounting problem. The time stamps didn't agree. One
showed activity when the other account said everything was dormant.
      Other things seemed more pressing, so I dropped the problem. After
wasting an afternoon chasing after some operator's mistake, I wasn't about
to touch the accounting system again.
      Over lunch with Dave, I mentioned that Sventek was the only one
connected when Dockmaster reported the break-in. He stared and said, 'Joe
Sventek? He's in Cambridge. Cambridge, England. What's he doing back?'
Turned out that Joe Sventek had been the laboratory's Unix guru, a soft-
ware wizard who built a dozen major programs over the past decade. Joe
had left for England a year ago, leaving behind a glowing reputation
throughout the California computer community.
      Dave couldn't believe Joe was back in town, since none of Joe's other
friends had heard from him. 'He must have entered our computer from
some network,' Dave said.
      'So you think Joe's responsible for this problem?' I asked Dave.
      "No way," Dave replied. "Joe's a hacker of the old school. A smart,
quick, capable programmer. Not one of those punks that have tarnished the
word 'hacker.' In any case, Sventek wouldn't try to break into some Mary-
land computer. And if he did try, he'd succeed, without leaving any trace."
      Curious: Joe Sventek's been in England a year, yet he shows up early
Saturday morning, tries to break into a Maryland computer, disconnects,
and leaves behind an unbalanced accounting system. In the hallway I men-
tion this to Wayne, who's heard that Joe's on vacation in England; he's
hiding out in the backwoods, far away from any computers. "Forget that
message from Dockmaster. Sventek's due to visit Berkeley RSN and he'll
clear it up."
      RSN? Real Soon Now. Wayne's way of saying, "I'm not sure when."
      My worry wasn't Sventek. It was the unbalanced accounts. Why were
the two accounting systems keeping different times? And why was some
activity logged in one file without showing up in the other?

                  THE CUCKOO'S EGG

    Back to the accounting system for an afternoon. I found that the five
minute time difference between the time stamps came from our various
computers' clocks drifting over the months. One of our computer's clocks
lost a few seconds every day.
      But all of Sventek's activities should have appeared in both tallies. Was
this related to last week's accounting problem? Had I screwed things up
when I poked around last week? Or was there some other explanation?

o     0     0    That afternoon, I sat through an impressively boring lecture
on the structure of galaxies. The learned professor not only spoke in a
monotone, but filled the chalkboard with a snake's nest of mathematical
      Trying to stay awake, I tossed around the problems I'd bumped into.
Someone screwed up when adding a new account. A week later, Sventek
logs in and tries to break into some computer in Maryland. The accounting
record for that event seems garbled. Sventek's unavailable. Something's
amiss. It's almost as if someone's avoiding the accounting program.
    What would it take, I wondered, to use our computers for free? Could
someone have found a way around our accounting system?
     Big computers have two types of software: user programs and systems
software. Programs that you write or install yourself are user programs-
for example, my astronomy routines which analyze a planet's atmosphere.
     Alone, user programs can't do much. They don't talk directly to the
computer; rather, they call upon the operating system to manipulate the
computer. When my astronomy program wants to write something, it
doesn't just slap a word on my screen. Instead, it passes the word to the
operating system, which, in turn, tells the hardware to write a word.
     The operating system, along with the editors, software libraries, and
language interpreters, make up the systems software. You don't write these
programs-they come with the computer. Once they're set up, nobody
should tamper with them.
     The accounting program is systems software. To modify or bypass it,

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you have to either be system manager, or somehow have acquired a privi-
leged position within the operating system.
       OK, how do you become privileged? The obvious way is to log onto
our computer with the system manager's password. We hadn't changed our
password in months, but nobody would have leaked it. And an outsider
would never guess our secret password, "wyvern"-how many people
would think of a mythological winged dragon when guessing our pass-
       But even if you became system manager, you wouldn't fool with the
accounting software. It's too obscure, too poorly documented. Anyway, I'd
seen that it worked.
       Wait-our home-brew software worked properly. Someone had
added a new account without using it. Perhaps they didn't know about it. If
someone had come in from the cold, they'd be unaware of our local wrin-
kles. Our system managers and operators knew this. Joe Sventek, even in
England, surely would know.
       But what about someone from the outside-a hacker?
       The word hacker has two very different meanings. The people I knew
who called themselves hackers were software wizards who managed to
creatively program their way out of tight corners. They knew all the nooks
and crannies of the operating system. Not dull software engineers who put
in forty hours a week, but creative programmers who can't leave the com-
puter until the machine's satisfied. A hacker identifies with the computer,
knowing it like a friend.
       Astronomers saw me that way. "Cliff, he's not much of an astronomer,
but what a computer hacker!" (The computer folks, of course, had a differ-
 ent view: "Cliff's not much of a programmer, but what an astronomer!" At
best, graduate school had taught me to keep both sides fooled.)
       But in common usage, a hacker is someone who breaks into com-
puters. * In 1982, after a group of students used terminals, modems, and long
 distance telephone lines to break into computers in Los Alamos and the
 Columbia Medical Center, the computing people suddenly became aware of
 the vulnerability of our networked systems.

* What word describes someone who breaks into computers? Old style software wizards are proud to be
called hackers, and resent the scoffiaws who have appropriated the word. On the networks, wizards refer
to these hoodlums of our electronic age as "crackers" or "cyberpunks." In the Netherlands, there's the
term "computervrcdebreuk"-literally, computer peace disturbance. Me' The idea of a vandal breaking
into my conlputcr makes me think of words like "varmint," "reprobate," and "swine."

                                                  1   a
                  THE CUCKOO'S EGG

     Every few months, I'd hear a rumor about someone else's system being
invaded; usually this was at universities, and it was often blamed on students
or teenagers. "Brilliant high school student cracks into top security com-
puter center." Usually it was harmless and written off as some hacker's
     Could the movie War Games actually happen-might some teenage
hacker break into a Pentagon computer and start a war?
     I doubted it. Sure, it's easy to muck around computers at universities
where no security was needed. After all, colleges seldom even lock the doors
to their buildings. I imagined that military computers were a whole differ-
ent story-they'd be as tightly secured as a military base. And even if you
did get into a military computer, it's absurd to think you could start a war.
Those things just aren't controlled by computers, I thought.
      Our computers at Lawrence Berkeley Laboratory weren't especially
secure, but we were required to keep outsiders away from them and make
an effort to prevent their misuse. We weren't worried about someone hurt-
ing our computers, we just wanted to keep our funding agency, the Depart-
ment of Energy, off our backs. If they wanted our computers painted green,
then we'd order paintbrushes.
      But to make visiting scientists happy, we had several computer ac-
counts for guests. With an account name of "guest" and a password of
"guest," anyone could use the system to solve their problems, as long as they
didn't use more than a few dollars of computing time. A hacker would have
an easy time breaking into that account-it was wide open. This would
hardly be much of a break-in, with time limited to one minute. But from
that account, you could look around the system, read any public files, and
see who was logged in. We felt the minor security risk was well worth the
     Mulling over the situation, I kept doubting that a hacker was fooling
around in my system. Nobody's interested in particle physics. Hell, most of
our scientists would be delighted if anyone would read their papers. There's
nothing special here to tempt a hacker-no snazzy supercomputer, no sexy
trade secrets, no classified data. Indeed, the best part of working at Lawrence
Berkeley Labs was the open, academic atmosphere.
      Fifty miles away, Lawrence Livermore Labs did classified work, devel-
oping nuclear bombs and Star Wars projects. Now, that might be a target
for some hacker to break into. But with no connections to the outside,

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Livermore's computers can't be dialed into. Their classified data's protected
by brute force: isolation.
     If someone did break into our system, what could they accomplish?
They could read any public files. Most of our scientists set their data this
way, so their collaborators can read it. Some of the systems software was
public as well.
      Though we call this data public, an outsider shouldn't wander through
it. Some of it's proprietary or copyrighted, like our software libraries and
word processing programs. Other databases aren't for everyone's consump-
tion-lists of our employees' addresses and incomplete reports on work in
progress. Still, these hardly qualify as sensitive material, and it's a long way
from classified.
     No, I wasn't worried about someone entering our computer as a guest
and walking off with somebody's telephone number. My real concern cen-
tered on a much bigger problem: could a stranger become a super-user?
      To satisfy a hundred users at once, the computer's operating system
splits the hardware resources much as an apartment house splits a building
into many apartments. Each apartment works independently of the others.
While one resident may be watching TV, another talks on the phone, and a
third washes dishes. Utilities-electricity, phone service, and water-are
supplied by the apartment complex. Every resident complains about slow
service and the exorbitant rents.
     Within the computer, one user might be solving a math problem,
another sending electronic mail to Toronto, yet a third writing a letter. The
computer utilities are supplied by the systems software and operating sys-
tem; each user grumbles about the unreliable software, obscure documenta-
tion, and the exorbitant costs.
      Privacy within the apartment house is regulated by locks and keys.
One resident can't enter another's apartment without a key, and (if the walls
are sturdy), one resident's activity won't bother another. Within the com-
puter, it's the operating system that ensures user privacy. You can't get into
someone's area without the right password, and (if the operating system is
fair about handing out resources), one user's programs won't interfere with
      But apartment walls are never sturdy enough, and my neighbor's par-
ties thunder into my bedroom. And my computer still slows down when
there's more than one hundred people using it at one time. So our apartment

                  THE CUCKOO'S EGG

houses need superintendents, and our computers need system managers, or
      With a passkey, the apartment house superintendent can enter any
room. From a privileged account, the system manager can read or modify
any program or data on the computer. Privileged users bypass the operating
system protections and have the full run of the computer. They need this
power to maintain the systems software ("Fix the editor!"), to tune the
operating system's performance ("Things are too slow today!"), and to let
people use the computer ("Hey, give Barbara an account.")
      Privileged users learn to tread lightly. They can't do much damage if
they're only privileged to read files. But the super-user's license lets you
change any part of the system-there's no protections against the super-
user's mistakes.
      Truly, the super-user is all-powerful: she controls the horizontal, she
controls the vertical. When daylight savings time comes around, she resets
the system clock. A new disk drive? She's the only one who can graft the
necessary software into the system. Different operating systems have various
names for privileged accounts-super-user, root, system manager-but
these accounts must always be jealously guarded against outsiders.
      What if an outside hacker became privileged on our system? For one
thing, he could add new user accounts.
      A hacker with super-user privileges would hold the computer hostage.
With the master key to our system, he could shut it down whenever he
wishes, and could make the system as unreliable as he wishes. He could read,
write, or modify any information in the computer. No user's file would be
protected from him when he operates from this privileged high ground. The
system files, too, would be at his disposal-he could read electronic mail
before it's delivered.
      He could even modify the accounting files to erase his own tracks.
      The lecturer on galactic structure droned on about gravitational waves.
I was suddenly awake, aware of what was happening in our computer. I
waited around for the question period, asked one token question, then
grabbed my bike and started up the hill to Lawrence Berkeley Labs.
      A super-user hacker. Someone breaks into our system, finds the master
keys, grants himself privileges, and becomes a super-user hacker. Who?
How? From where? And, mostly, why?

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o      0 0 It's only a quarter mile from the University of California to
Lawrence Berkeley Labs, but Cyclotron Road is steep enough to make it a
fifteen-minute bike ride. The old ten-speed didn't quite have a low enough
gear, so my knees felt the last few hundred feet. Our computer center's
nestled between three particle accelerators: the 184-inch cyclotron, where
Ernest Lawrence first purified a milligram of fissionable uranium; the Beva-
tron, where the anti-proton was discovered; and the Hilac, the birthplace of
a half-dozen new elements.
      Today, these accelerators are obsolete-their mega-electron volt ener-
gies long surpassed by giga-electron volt particle colliders. They're no
longer winning Nobel prizes, but physicists and graduate students still wait
six months for time on an accelerator beamline. After all, our accelerators
are fine for studying exotic nuclear particles and searching out new forms of
matter, with esoteric names like quark-gluon plasmas or pion condensates.
And when the physicists aren't using them, the beams are used for biomedi-
cal research, including cancer therapy.
      Back in the heyday of World War II's Manhattan project, Lawrence's
cyclotron was the only way to measure the cross sections of nuclear reac-
tions and uranium atoms. Naturally, the lab was shrouded in secrecy; it
served as the model for building atomic bomb plants.
      During the 1950s, Lawrence Berkeley Laboratory's research remained
classified, until Edward Teller formed the Lawrence Livermore Laboratory
an hour's drive away. All the classified work went to Livermore, while the
unclassified science remained in Berkeley.
      Perhaps to spread confusion, both laboratories are named after
California's first Nobel Laureate, both are centers for atomic physics, and
both are funded by the Atomic Energy Commission's offspring, the Depart-
ment of Energy. That's about the end of the similarity.
      I needed no security clearance to work in the Berkeley Lab-there's
no classified research, not a military contract in sight. Livermore, on the
other hand, is a center for designing nuclear bombs and Star Wars laser
beams. Hardly the place for a long-haired ex-hippie. While my Berkeley

                      THE CUCKOO'S EGG

    Lab survived on meager scientific grants and unreliable university funding,
    Livermore constantly expanded. Ever since Teller designed the H-bomb,
    Livermore's classified research has never been short of funds.
          Berkeley no longer has huge military contracts, yet openness has its
    rewards. As pure scientists, we're encouraged to research any curious phe-
    nomena, and can always publish our results. Our accelerators might be
    peashooters compared to the behemoths at CERN in Switzerland, or Fermi-
    lab in Illinois; still, they generate huge amounts of data, and we run some
    respectable computers to analyze it. In fact, it's a source of local pride to
    find physicists recording their data at other accelerators, then visiting LBL
    to analyze their results on our computers.
          In raw number-crunching power, Livermore's computers dwarfed
    ours. They regularly bought the biggest, fastest, and most expensive Crays.
    They need 'em to figure out what happens in the first few nanoseconds of a
    thermonuclear explosion.
          Because of their classified research, most of Livermore's computers are
    isolated. Of course, they have some unclassified systems too, doing ordinary
    science. But for their secret work-well, it's not for ordinary mortal eyes.
    These classified computers have no connections to the outside world.
          It's just as impossible to import data into Livermore from the outside.
    Someone designing nuclear bomb triggers using Livermore's classified com-
    puters has to visit the lab in person, bringing his data in on magnetic tape.
    He can't use the dozens of networks crossing the country, and can't log in
    from home, to see how his program is running. Since their computers are
    often the first ones off the production line, Livermore usually has to write
    their own operating systems, forming a bizarre software ecology, unseen
    outside of their laboratory. Such are the costs of living in a classified world.
          While we didn't have the number-crunching power of Livermore, our
    computers were no slouches. Our Vax computers were speedy, easy to use,
    and popular among physicists. We didn't have to invent our own operating
    systems, since we bought Digital's VMS operating system, and grabbed
    Unix from campus. As an open lab, our computers could be networked
    anywhere, and we supported scientists from around the world. When prob-
    lems developed in the middle of the night, I just dialed the LBL computer
    from my home-no need to bicycle into work when a phone call might
    solve it.
          But there I was, bicycling up to work, wondering if some hacker was
     in our system. This just might explain some of my accounting problems. If

                                ST 0 L L

some outsider had picked the locks on our Unix operating system and
acquired super-user privileges, he'd have the power to selectively erase the
accounting records. And, worse, he could use our network connections to
attack other computers.
      I ducked my bike into a corner and jogged over to the cubicle maze.
By now it was well past five, and the ordinary folks were at home. How
could I tell if someone was hacking inside our system? Well, we could just
send an electronic mail message to the suspicious account, saying something
like, "Hey, are you the real Joe Sventek?" Or we could disable Joe's ac-
count, and see if our troubles ended.
      My thoughts about the hacker were sidetracked when I found a note
in my office: the astronomy group needed to know how the quality of the
telescope's images degraded if they loosened the specifications for the mir-
rors. This meant an evening of model building, all inside the computer. I
wasn't officially working for them anymore, but blood's thicker than water
. . . by midnight, I'd plotted the graphs for them.
      The next morning, I eagerly explained my suspicions about a hacker to
Dave Cleveland, "I'll bet you cookies to doughnuts it's a hacker."
      Dave sat back, closed his eyes, and whispered, "Yep, cookies for sure."
      His mental acrobatics were almost palpable. Dave managed his Unix
system with a laid-back style. Since he competed for scientists with the
VMS systems, he had never screwed down the security bolts on his system,
figuring that the physicists would object and take their business elsewhere.
By trusting his users, he ran an open system and devoted his time to im-
proving their software, instead of building locks.
      Was someone betraying his trust?
      Marv Atchley was my new boss. Quiet and sensitive, Marv ran a loose
group that somehow managed to keep the computers running. Marv stood
in contrast to our division head, Roy Kerth. At fifty-five, Roy looked like
Rodney Dangerfield as a college professor. He did physics in the grand style
of Lawrence Laboratory, bouncing protons and antiprotons together, look-
ing at the jetsam from these collisions.
      Roy treated his students and staff much as his subatomic particles: keep
them in line, energize them, then shoot them into immovable objects. His
research demanded heavy number crunching, since his lab generated millions
of events each time the accelerator was turned on. Years of delays and
excuses had-soured him on computer professionals, so when I knocked on

                  THE CUCKOO'S EGG

his door, I made sure we talked about relativistic physics and ignored com-
      Now, Dave and I could guess Roy's reaction to our problem: "Why
the hell did you leave our doors wide open?"
      Our boss's reaction might be predictable, but how should we react?
Dave's first thought was to disable the suspect account and forget about it. I
felt we ought to send a nastygram to whoever was breaking in, telling him
to stay away or we'd call his parents. After all, if someone was breaking in,
it was bound to be some student from down on campus.
      But we weren't certain that someone was breaking into our system. It
might explain some of our accounting problems-someone learns the sys-
tem manager's password, connects to our machine, creates a new account,
and tampers with the accounting system. But why would someone use a
new account if they already had access to the system manager account?
      Our boss never wanted to hear bad news, but we swallowed hard and
called a lunchtime meeting. We had no clear proof of a hacker, just circum-
stantial pointers, extrapolated from trivial accounting errors. If there was a
break-in, we didn't know how far it extended, nor who was doing it. Roy
Kerth blasted us. "Why are you wasting my time? You don't know any-
thing and you haven't proven a whit. Go back and find out. Show me
      So how do you find a hacker? I figured it was simple: just watch for
anyone using Sventek's accounts, and try to trace their connection.
      I spent Thursday watching people log into the computer. I wrote a
program to beep my terminal whenever someone connected to the Unix
computer. I couldn't see what each user was doing, but I could see their
names. Every couple minutes my terminal beeped, and I'd see who had
logged in. A few were friends, astronomers working on research papers or
graduate students plugging away on dissertations. Most accounts belonged
to strangers, and I wondered how I could tell which connection might be a
      At 12:33 on Thursday afternoon, Sventek logged in. I felt a rush of
adrenaline and then a complete letdown when he disappeared within a
minute. Where was he? The only pointer left for me was the identifier of
his terminal: he had used terminal port tt23.
      Sitting behind a computer terminal, fingers resting on his keyboard,
someone was connecting into our lab. My Unix computer gave him the
address of port tt23.

                                      J   7
                                 ST 0 L L

      Well, that's a start. My problem was to figure out which physical wires
corresponded to the logical name tt23.
      Terminals from our laboratory and modems from dial-in telephones
are all assigned "tt" labels, while network connections show up as "nt." I
figured that the guy must be either from our laboratory or dialing in on a
phone line over a modem.
      For a few seconds, I'd sensed a hesitant feeler into our computer.
Theoretically, it must be possible to trace the path from computer to hu-
man. Someone must be at the far end of that connection.
      It would take six months to track that path, but my first step was to
trace the connection out of the building. I suspected a dial-in modem,
connected from some telephone line, but it conceivably might be someone
at the laboratory. Over the years, well over five hundred terminals had been
wired in, and only Paul Murray kept track. With luck, our homegrown
hardware connections were documented better than the home-brew ac-
counting software.
      Paul's a reclusive hardware technician who hides in thickets of tele-
phone wire. I found him behind a panel of electronics, connecting some
particle detector to the lab-wide ethernet system. Ethernets are electronic
pipelines connecting hundreds of small computers. A few miles of orange
ethernet cable snaked through our lab, and Paul knew every inch of it.
      Cursing me for surprising him in the middle of soldering a wire, he
refused to give me any help until I proved that I had a legitimate need to
know. Aw, hell. Hardware technicians don't understand software problems,
and software jockeys know nothing about hardware.
      Years of ham radio had taught me to solder, so Paul and I had at least
one common denominator. I picked up his spare soldering iron and earned
his grudging respect after a few minutes of burning my fingers and squint-
ing. Finally, he disentangled himself from the ethernet cables and showed
me around the LBL communications switchyard.
      In this roomful of wires, the telephones, intercoms, radios, and com-
puters were all interconnected by a tangle of cables, wires, optical fibers, and
patch panels. The suspicious port tt23 entered this room and a secondary
computer switched it to one of a thousand possible terminals. Anyone dial-
ing into the lab would be randomly assigned to a Unix port. The next time
I saw a suspicious character, I'd have to run over to the switchyard and
unwind the connection by probing the switching computer. If he disap-
peared before I disentangled the connection, well, tough. And even if I did

                  THE CUCKOO'S EGG

succeed, 1'd only be able to point to a pair of wires entering the laboratory.
I'd still be a long way from the hacker.
      By lucky accident, though, the noontime connection had left some
footprints behind. Paul had been collecting statistics on how many people
used the switchyard. By chance he had recorded the port numbers of each
connection for the past month. Since I knew the time when Sventek was
active on port tt23, we could figure out where he came from. The printout
of the statistics showed a one-minute 1200-baud connection had taken place
at 12:33.
       1200 baud, huh? That says something. The baud rate measures the
speed that data flows through a line. And 1,200 baud means 120 characters
per second-a few pages of text every minute.
      Dial-up modems over telephone lines run at 1200 baud. Any lab em-
ployee here on the hill would run at high speed: 9600 or 19,200 baud. Only
someone calling through a modem would let their data dribble out a 1200-
baud soda straw. And the anonymity and convenience of these dial-in lines
are most inviting to strangers. So pieces were beginning to fit together. I
couldn't prove that we had a hacker in the system, but someone dialed into
our lab and used Sventek's account.
       Still, the 1200-baud connection was hardly proof that a hacker entered
our system. An incomplete trace, especially one that went no farther than
my building, would never convince my boss that something was up, some-
thing weird. I needed to find incontrovertible evidence of a hacker. But
       Roy Kerth had shown me the high-energy particle detectors attached
to the Bevatron: they find jillions of subatomic interactions, and 99.99
percent are explainable by the laws of physics. Spending your time explor-
ing each particle trail will lead you to conclude that all the particles obey
known physics, and there's nothing left to discover. Alternatively, you
could throwaway all the explainable interactions, and only worry about
those that don't quite satisfy the canonical rules.
       Astronomers, distant cousins of high-energy physicists, work along
similar lines. Most stars are boring. Advances come from studying the
weirdies-the quasars, the pulsars, the gravitational lenses-that don't seem
to fit into the models that you've grown up with. Knowing cratering
statistics on the planet Mercury tells you how often the planet was bom-
barded in the early solar system. But study the few craters intersected by
scarps and ridges and you'll learn how the planet shrank as it cooled during

                                S TaL L

its first billion years. Collect raw data and throwaway the expected. What
remains challenges your theories.
      Well, let's apply this way of thinking to watching someone visiting
my computer. I've got a terminal on my desk, and can borrow a couple
others. Suppose I just watched the traffic coming into the computer center.
There's about five hundred lines entering the system. Most of these lines run
at 9600 baud, or around one hundred fifty words per second. If half the lines
are used at any time, I'd have to read well over ten thousand pages every
minute. Right. No way could I monitor that kind of traffic on my terminal.
      But the high speed lines come from people at LBL. We'd already
traced one suspicious connection to a 1200-baud line. There are fewer of
them (we can't afford too many incoming phone lines), and they're slower.
Fifty lines at 1200 baud might generate a hundred pages a minute, still far
too fast to watch on the screen of my terminal. I might not be able to watch
fifty people running at once, but maybe I could print out all their interac-
tive sessions, and read the piles of paper at my leisure. A paper printout
would provide hard proof of someone messing around; if we found nothing
suspicious, we could drop the whole project.
       I'd record everything that happened during each 1200-baud connec-
tion. This would be technically challenging-since I didn't know which
line the hacker was calling, I'd have to monitor four dozen. More worri-
some was the ethical problem of monitoring our communications. Did we
have the right to watch the traffic running through our lines?
       My sweetheart, Martha, was just finishing law school. Over a deep-
dish pizza, we talked about the implications of someone breaking into a
computer. I wondered how much trouble I'd be in by listening to incoming
       "Look," she mumbled, burning the roof of her mouth on the vulcan-
ized mozzarella. "You're not the government, so you don't need a search
warrant. The worst it would be is invasion of privacy. And people dialing
up a computer probably have no right to insist that the system's owner not
look over their shoulder. So I don't see why you can't."
      So with a clear conscience, I started building a monitoring system. We
had fifty 1200-baud lines, and a hacker might be using any of them. I had no
equipment designed to record the traffic.
      But there's an easy way to record a hacker's activity. Modify the Unix
operating system so that whenever a suspicious person logged in, the system

                  THE CUCKOO'S EGG

records all the keystrokes. This was tempting, because I only had to add
some lines of code to the Unix daemon software.
       The daemons themselves are just programs that copy data from the
outside world into the operating system-the eyes and ears of Unix. (The
ancient Greek daemons were inferior divinities, midway between gods and
men. In that sense, my daemons are midway between the god-like operating
system and the world of terminals and disks.)
       I could split the daemon's output like aT-joint in a pipe, so the
hacker's keystrokes would simultaneously go to both the operating system
and a printer. Software solutions are simple and elegant.
       "Muck with the daemons at your own risk," Dave Cleveland said.
"Just respect their timing needs."
       Wayne also warned me, "Look, if you goof up, you'll break the
system for sure. It will turn the system into molasses, and there's no way
you'll follow everything that happens. Just wait till you see the system
console print out 'Panic kernel mode interrupt'-don't come crying on my
       Dave chipped in, "Hey, if your hacker has any Unix experience, he's
bound to notice a change in the daemons."
       That convinced me. A sharp systems person would notice that we'd
changed the operating system. The moment the hacker knew someone was
watching him, he'd trash our databases and scram. Our wiretaps had to be
completely undetectable, even to an omnipotent super-user. Silent, invisible
monitors to trap the hacker's activity.
       Maybe just tape recording the telephone lines would werk, but tape
recorders didn't feel right, too much of a kludge. We'd have to play them
back, and couldn't watch the keystrokes until long after a hacker had dis-
connected. Finally, where would I find fifty tape recorders?
       About the only other place to watch our traffic was in between the
modems and the computers. The modems converted the tones of a telephone
into electronic pulses, palatable to our computers and the daemons in their
operating systems. These modem lines appeared as flat, twenty-five conduc-
tor wires, snaking underneath the switchyard's false floor. A printer or
personal computer could be wired to each of these lines, recording every
keystroke that came through.
       A kludge? Yes. Workable? Maybe.
       All we'd need are fifty teletypes, printers, and portable computers. The
first few were easy to get-just ask at the lab's supplies desk. Dave, Wayne,

                                ST 0 L L

and the rest of the systems group grudgingly lent their portable terminals.
By late Friday afternoon, we'd hooked up a dozen monitors down in the
switchyard. The other thirty or forty monitors would show up after the
laboratory was deserted. I walked from office to office, liberating personal
computers from secretaries' desks. There'd be hell to pay on Monday, but
it's easier to give an apology than get permission.
       Strewn with four dozen obsolete teletypes and portable terminals, the
floor looked like a computer engineer's nightmare. I slept in the middle,
nursing the printers and computers. Each was grabbing data from a different
line, and whenever someone dialed our system, I'd wake up to the chatter of
typing. Every half hour, one of the monitors would run out of paper or
disk space, so I'd have to roll over and reload.
       Saturday morning, Roy Kerth shook me awake. "Well, where's your
       Still in my sleeping bag, I must have smelled like a goat. I blinked
stupidly and mumbled something about looking at the fifty piles of paper.
       He snorted, "Well, before you start poking around those printouts,
return those printers. You've been running around here like a maniac swip-
ing equipment used by people who are getting work done. You've pissed off
a dozen astronomers. Are you getting work done? No. Whaddya think this
place is, your own personal sandbox?"
       Bleary-eyed, I dragged each printer back to its rightful owner. The
first forty-nine showed nothing interesting. From the fiftieth trailed eighty
feet of printout. During the night, someone had sneaked in through a hole
in the operating system.

o     0 0 For three hours, a hacker had strolled through my system,
reading whatever he wished. Unknown to him, my 1200-baud Decwriter
had saved his session on eighty feet of single-spaced computer paper. Here
was every command he issued, every typing mistake, and every response
from the computer.
     This printer monitored the line from Tymnet. I didn't realize it, but a
few of our 1200-baud lines weren't dial-in modem lines. Rather, they came

                  THE CUCKOO'S EGG

from Tymnet, a communications company that interconnected computers
around the world.
      Back before divestment, the Bell system monopolized communica-
tions. AT&T was the only way to connect New York to Chicago. By using
modems, the phone system could handle data, but the noise and expense of
the long distance service made it unsuitable for computers. By the late '70s,
a few other companies dipped their toes in the water, offering specialized
services like data phones. Tymnet created a network to interconnect com-
puters in major cities.
      Tymnet's idea was simple and elegant: create a digital communications
backbone, let anyone connect to the backbone by making a local telephone
call, then send the data to any computer on the network. Tymnet would
compress dozens of users' data into a few packets, and economically send
these around the country. The system was immune to noise, and each user
could run as fast as he wished. Customers saved money because they could
access a distant computer by making a local call.
      To satisfy scientists around the country, LBL subscribed to Tymnet.
When a researcher in Stonybrook, New York, wanted to connect to our
computer, he dialed his local Tymnet number. Once his modem was con-
nected to Tymnet, he just asked for LBL and worked as if he were in
Berkeley. Physicists from far away loved the service, and we were delighted
to find them spending their research dollars on our computers, rather than
their home machines.
       Someone was breaking in, using the Tymnet line. Since Tymnet inter-
connected the whole country, our hacker might be anywhere.
       For the moment, though, I was fascinated not by where the hacker
came from, but what he had done in three hours. My guess was right:
Sventek's account was being used to break into our Unix computer.
       Not just break in. This hacker was a super-user.
      The hacker had sneaked through a hole in our system to become a
super-user-he'd never even logged into the system manager's account. He
was like a cuckoo bird.
      The cuckoo lays her eggs in other birds' nests. She is a nesting parasite:
some other bird will raise her young cuckoos. The survival of cuckoo chicks
depends on the ignorance of other species.
       Our mysterious visitor laid an egg-program into our computer, letting
the system hatch it and feed it privileges.
       That morning, the hacker wrote a short program to grab privileges.

                                ST 0 L L

Normally, Unix won't allow such a program to run, since it never gives
privileges beyond what a user is assigned. But run this program from a
privileged account, and he'll become privileged. His problem was to mas-
querade this special program-the cuckoo's egg-so that it would be
hatched by the system.
      Every five minutes, the Unix system executes its own program named
atrun. In turn, atrun schedules other jobs and does routine housecleaning
tasks. It runs in a privileged mode, with the full power and trust of the
operating system behind it. Were a bogus atrun program substituted, it
would be executed within five minutes, with full system privileges. For this
reason, atrun sits in a protected area of the system, available only to the
system manager. Nobody but the system manager has the license to tamper
with atrun.
      Here was the Cuckoo's nest: for five minutes, he would swap his egg
for the system's atrun program.
      For this attack, he needed to find a way to move his egg-program into
the protected systems nest. The operating system's barriers are built specifi-
cally to prevent this. Normal copy programs can't bypass them; you can't
issue a command to "copy my program into systems space."
      But there was a wildcard that we'd never noticed. Richard Stallman, a
free-lance computer programmer, loudly proclaimed that information
should be free. His software, which he gives away for free, is brilliantly
conceived, elegantly written, and addictive.
      Over the past decade Stallman created a powerful editing program
called Gnu-Emacs. But Gnu's much more than just a text editor. It's easy to
customize to your personal preferences. It's a foundation upon which other
programs can be built. It even has its own mail facility built in. Naturally,
our physicists demanded Gnu; with an eye to selling more computing cy-
cles, we installed it happily.
      Just one problem: there's a bug in that software.
      In the way it was installed on our Unix computer, the Gnu-Emacs
editor lets you forward a mail file from your own directory to anyone else
in an unusual way. It doesn't check to see who's receiving it, or even
whether they want the file. It just renames the file and changes its ownership
label. You've just transferred ownership of the file from you to me.
      No problem to send a file from your area to mine. But you'd better
not be able to move a file into the protected systems area: only the system

                  THE CUCKOO'S EGG

manager is allowed there. Stallman's software had better make sure this can't
      Gnu didn't check. It let anyone move a file into protected systems
space. The hacker knew this; we didn't.
      The hacker used Gnu to swap his special atrun file for the system's
legitimate version. Five minutes later, the system hatched his egg, and he
held the keys to my computer.
      He had used this technique to fool the computer into giving him
power. He planted his phony program where the system expected to find a
valid one. The instant that Unix executed his bogus atrun program, he
became super-user. The whole operation depended on his being able to
move a file anywhere he wished.
      Gnu was the hole in our system's security. A subtle bug in an obscure
section of some popular software. Installed blindly by our systems program-
mers, we'd never thought that it might destroy our whole system's security.
      Now I understood. Our friend must have entered a guest account,
leveraged his privileges using Gnu's hole, and then added a new account to
the computer's files.
       In front of me, the first few feet of the printout showed the cuckoo
preparing the nest, laying the egg, and waiting for it to hatch. The next
seventy feet showed the fledgling cuckoo testing its wings.
      As super-user, he had the run of our system. First thing he did was
erase his tracks: he switched the good copy of atrun back where it belonged.
Then he listed the electronic mail of all our users, reading news, gossip, and
love letters. He learned of the past month's computer changes, grant propos-
als, and new hires. He searched for changes in the system managers' files, and
discovered that 1'd just started work. He checked my salary and resume.
More worrisome, he realized that I was a system manager, and my account
       Why me? What did I do? At any rate, from now on, I'd better use a
different name.
       Every ten minutes, the hacker issued the command, "who," to list
everyone logged onto the computer. Apparently, he worried that someone
might see him connected, or might be watching. Later, he searched for any
changes in the operating system-had I modified the daemons to record his
session, as I'd first planned to do, he would surely have discovered it. I felt
like a kid playing hide-and-seek, when the seeker passes within inches of his
hiding place.

                                  ST 0 L L

     Within the first hour, he wrote a program to scan everyone's mail
messages for any mention of his activity. He searched for the word,
"hacker," and "security."
     One scientist had started a program that assembled data from an exper-
iment over the weekend. Running under the name "gather," this program
innocuously collected information every few minutes and wrote it to a file.
The hacker saw this program, spent ten minutes trying to understand what
it did, and killed it.
      Yow! Here's someone looking over his shoulder every few minutes,
checking to see if anyone's around. He kills any jobs that he thinks might
monitor him. He opens my mail, checking to see if anyone's written about
hackers. Wayne was right: if you stay in the open, he'll know you're watch-
ing. From now on, we'd have to be subtle and invisible.
     When he wasn't looking back over his shoulder, the hacker was read-
ing files. By studying several scientists' command files and scripts, he discov-
ered pathways into other lab computers. Every night, our computer auto-
matically calls twenty others, to exchange mail and network news. When
the hacker read these phone numbers, he learned twenty new targets.
     From the mail file of an engineer:

     "Hi, Edl
     I'll be on vacation for the next couple weeks. If you need to get any of
     my data,just log into my accounton the Vax computer. Accountname is
     Wilson, password is Maryanne (mars my wife's name). Have funl"

     The hacker had fun, even if Ed didn't. He connected through our local
area network into that Vax, and had no problem logging into Wilson's
account. Wilson wouldn't notice the hacker reading his files, and probably
wouldn't care. They contained numerical data, meaningless to anyone but
another nuclear physicist.
     Our visitor knew about our lab's internal networks. Our dozen big
computers were tied to a hundred laboratory computers using ethernets,
serial lines, and chewing gum. When physicists wanted to get data from a
computer at the cyclotron into our big computer, elegance meant nothing.
They'd use any port, any line, any network. Over the years technicians had
woven a web of cables around the lab, interconnecting most of the com-
puters with whatever seemed to work. This local area network reached into

                  THE CUCKOO'S EGG

every office, connecting PC's, Macintoshes, and terminals to our mainframe
      Often, these networked computers had been arranged to trust each
other. If you're OK on that computer, then you're OK on this one. This
saved a bit of time: people wouldn't need to present more than one pass-
word when using several computers.
      The hacker exploited that trust to enter a half dozen computers. As
super-user on our main Unix computer, he disguised himself under someone
else's account name. Then he just knocked on the door of another
networked machine, and he was admitted without even whispering the
password. Our visitor couldn't know what these systems were used for; still,
he felt his way around the net, searching for connections into unexplored
      By the end of the session, the printer's ribbon had run out of ink. By
rubbing a pencil lightly over the paper, I could just make out the impres-
sions left from the printhead: the hacker had copied our password file, then
      A bass guitar note took my attention from the hacker's trail. The
Grateful Dead were playing outdoors at the Berkeley Greek Theater, only a
hundred yards downhill from the lab. The police couldn't keep people from
sitting in the field overlooking the concert, so I skipped over there,
mingling with a thousand others in tie-dyed shirts. Burnt-out panhandlers,
left over from the sixties, walked the crowd, begging tickets and selling
posters, buttons, and grass. The drum solo in the second set echoed from
Strawberry Canyon, adding a weird backbeat appreciated only by us cheap-
skates in the fields. Life was full: no hacker is worth missing a Dead concert

o     0     0   Monday morning marked my second week on the job. I
was an uneasy computer jockey: surrounded by overworked experts, yet not
knowing what tasks I ought to be doing. Something fun would turn up, in
the meantime, I might as well finish this hacker project.
     Like a freshman in physics lab, I wrote about the weekend's activity in


                                ST 0 L L

a logbook. Not that I planned to use this logbook: it was a chance to learn a
word processor on my Macintosh. The astronomer's rule of thumb: if you
don't write it down, it didn't happen.
      I passed the results to the gang, hoping nobody would notice that  ra
slept overnight in the machine room.
      The boss wanted to see me as soon as he arrived.
      I suspected he was mad about my grabbing all those terminals. Man-
agement might be loose, but computer jocks still weren't supposed to bor-
row piles of lab equipment without telling anyone.
      But Roy didn't even grinch about the terminals. He wanted to know
about the hacker.
      "When did he show up?"
      "Sunday morning at five for three hours."
      "Delete any files?"
      "Killed one program that he thought was monitoring him."
      "Are we in danger?"
      "He's super-user. He can wipe out all our files."
      "Can we shut him down?"
      "Probably. We know the one hole, it's a quick patch."
      "Think that'll stop him?"
      I could sense where his thoughts were leading. Roy wasn't concerned
about slamming the door. He knew we could easily deactivate the stolen
Sventek account. And now that we understood it, fixing the Gnu-Emacs
hole wasn't difficult: just add a couple lines of code to check the target
      Should we close our doors or remain open? Closing up shop was the
obvious reaction. We knew how this hacker entered our system and knew
how to kick him out.
      But what else was wrong? What other gifts had our mysterious visitor
left for us? How many other accounts did he access? What other computers
did he break into?
      There was the worry. The printout showed the hacker to be a compe-
tent systems programmer, able to exploit obscure bugs that we'd never seen
before. What else had he done?
      When you're super-user, you can modify any file in the system. Did
the hacker modify a system program to open a backdoor entrance? Had he
patched our system to recognize a magic password?
      Did he plant a computer virus? On home computers, viruses spread by

                  THE CUCKOO'S EGG

copying themselves into other pieces of software. When you give an in-
fected piece of software to someone else, the virus copies itself into other
software, spreading from disk to disk.
      If the virus is benign, it'll be hard to detect and probably won't do
much damage. But it's easy to build malicious viruses which duplicate
themselves and then erase data files. Just as easy to create a virus that lies
dormant for months and then erupts some day in the future.
      Viruses are the creatures that haunt programmers' nightmares.
      As super-user, the hacker could infect our system in a way that would
be almost impossible to eradicate. His virus could copy itself into systems
software and hide in obscure areas of the computer. By copying itself from
program to program, it would defy our efforts to erase it.
      Unlike a home computer, where you can rebuild the operating system
from scratch, we had extensively modified our operating system. We
couldn't go to a manufacturer and say, "Give us an original copy." Once
infected, we could only rebuild our system from backup tapes. If he'd
planted a virus six months ago, our tapes would be infected as well.
      Maybe he'd planted a logic bomb-a program timed to blow up
sometime in the future. Or perhaps this intruder had only rifled our files,
killed a couple jobs, and screwed up our accounting. But how could we tell
that he hadn't done much worse? For a week, our computer was wide open
to this hacker. Could we prove that he hadn't tampered with our databases?
      How could we again trust our programs and data?
      We couldn't. Trying to shut him out wouldn't work, as he'd only find
another way in. We needed to find out what he had done and what he was
      Most of all, we needed to know who was at the other end of the line.
      "It's gotta be some student on the Berkeley campus," I said to Roy.
"They're the Unix wizards, and they think of us as bozos."
      "I wouldn't be too sure." Roy leaned back in his chair. "Why would
someone from Berkeley come in through Tymnet, when they could more
easily have dialed our system over the telephone lines?"
      "Maybe Tymnet is just a cover," I said. "A place to hide. If he dialed
the lab directly, we'd trace him. But now, we've got to trace both Tymnet
and a telephone call."
      My hand waving didn't convince the boss. Perhaps from his scientific
experience or maybe as a cynical ploy, Roy kept an open mind: it's not a
student until he's dragged in. Sure, the weekend's printouts showed a good

                                ST 0 L L

programmer, but we might be watching any competent computer jockey,
anywhere. Tracking the guy meant tracing telephone lines. The price of
hard evidence was hard work.
       Confronted with traces of a mysterious visitor, Roy only saw foot-
prints. I saw an intruder.
      Roy decided not to decide. "Let's close down all network connections
for the day. Tomorrow morning, I'll talk to the lab director, and get a sense
of what to do." We could delay, but sooner or later we'd have to either start
tracing, or lock the guy out.
      Did I want to track someone through the city? It would keep me from
scientific computing. It had nothing to do with astronomy or physics. And
it sounded like cops and robbers-or a game of hide-and-seek.
      On the plus side, though, I might learn about phone traces and net-
works. Best of all was imagining the look on some kid's face when we
barged into his dorm room, shouting, "Freeze! Drop that keyboard!"
      Tuesday afternoon, Roy called. "The director says, 'This is electronic
terrorism. Use all the resources you need to catch the bastard. Take all the
time you want. Spend three weeks, if you have to. Nail the bastard.' "
      If I wanted to hunt the hacker, management backed me.

o     0 0 I biked home, thinking of devious hacker-trapping schemes.
As I came closer to home, though, my thoughts turned to dinner. So great
to have someone to come home to.
     Martha Matthews and I had lived together for a few years now, and
been friends for almost ten. We'd known each other so well that it was hard
to remember a time before I knew her.
     Old friends shook their heads. They'd never seen me stay with one
woman this long. I'd fall in love, hang around for a couple years, and then
we'd grow tired of each other and move on. I was still good friends with
several former lovers, but the romance never seemed to last. I'd always been
cynical and sarcastic, protecting myself from getting too close to anyone.
     But life with Martha felt different. Barrier after barrier came down,
slowly, over time. She insisted on talking out our differences, demanded to

                  THE CUCKOO'S EGG

know the reasons for my moods and tempers, demanded that we think of
ways to get along better. It was unbearable sometimes-I hated to talk
when I was mad-but it usually seemed to work.
      I found myself feeling nesting instincts. The perfect afternoon was to
tinker around the house, rewiring a switch, planting some bulbs, or solder-
ing a stained glass window. We spent many a quiet evening, sewing or
reading or playing scrabble. I began to feel . . .
      Married? Who, me? No. Definitely not. Marriage was stultifying, a
trap for the conventional. You married someone and they expected you to
stay the same forever, never changing, never doing anything new. There'd
be fights and you couldn't leave, you'd get tired of the same person every
evening, every morning. Limiting, dreary, artificial, and conventional.
      Living together was different. We were both free. We freely chose to
share each day, and either of us could leave if the relationship was no longer
good for us. It was better this way, and Martha seemed content.
      Uh, right.
      I wondered if she'd remain cheerful if I spent the next few weeks
sleeping at work.
      Three weeks to catch a hacker. How long should this take? Perhaps a
couple days to set up traces, another few days to track him through the
networks, and then bust him. Probably we'd need the cooperation of the
police, so add a day or two. We could wrap it up in two weeks, then I'd be
back to managing a computer, and maybe a bit of astronomy on the side.
      We needed to weave a net fine enough to catch the hacker, but coarse
enough to let our scientists through. I'd have to detect the hacker as soon as
he came on line and call Tymnet's technicians to trace the call.
      Detecting the hacker was easy: 1'd just camp out in my office alongside
two terminals. One terminal for working, another to watch the system.
Each time someone logged onto the computer, two beeps would tell me to
check out the new user. As soon as a stranger showed up, I'd run down to
the switchyard and see what they were doing.
      Theoretically foolproof. Impossible in practice. From a thousand users,
I knew about twenty. The other 980? Well, I had to check each one. So
every two minutes I'd jog down the hall, thinking that I'd caught someone.
And since I'd miss the signal if I went home, I ignored Martha and slept
under the desk.
      The rug smelled like a seat on a crosstown bus and whenever the
terminal beeped, I'd sit up and gouge my head on the bottom of a drawer.

                                 ST 0 L L

A couple nights of slicing my forehead convinced me that there had to be
an easier way.
     If I knew the stolen account names, it would be easy to write a
program that watched for the bad guy to show up. No need to check out
every person using the computer; just ring a bell when a stolen account was
in use. But I also remembered Wayne Graves' warning-stay invisible.
    That meant no jobs running on the main computer. But I could watch
from another computer. We'd just installed a new Unix computer, our
Unix-8 system. Nobody had used it yet, so it might not be secure, but it
surely wasn't contaminated. I could connect it to our local area network,
secure it against all possible attacks, and let it watch the Unix-4 and Unix-S
      I'd protect my Unix-8 castle with a one-way moat. Information could
come into the computer, but nothing could go out. Dave Cleveland, hardly
excited about chasing a hacker, smiled slightly and told me how to set
Unix-8 to reject all log-in attempts, yet covertly scan the other Unix ma-
chines for signs of bad guys.
      The program wasn't hard-just a few dozen lines of code to get a
status block from each of the local computers. From long tradition, astrono-
mers have programmed in Fortran, so I wasn't surprised when Dave gave
me the hairy eyeball for using such an antiquated language. He challenged
me to use the C language; in a few minutes he'd reduced it to twenty lines
of tightly written code.
     We fired up Dave's watchdog program on the Unix-8 computer. From
the outside, it looked like just one more laboratory system. Anyone inquir-
ing about its status received an invitation to log in. But you couldn't log on,
since that computer rejected everyone except Dave and me. The hacker
shouldn't be suspicious, since that computer didn't appear to be hooked up.
    From this high ground, a network messenger asked each of the other
Unix computers, "Hey, who's logged on?" Each minute, the Unix-8 pro-
gram analyzed these reports, and searched for Sventek's name. When
Sventek showed up, my terminal beeped, and it was forehead-gouging time.
     But alarms alone wouldn't catch the hacker. We needed to track him
through our system, and back to his lair. And to protect ourselves, we had
to know what he was doing.
     There was no way to grab fifty printers again to monitor all the traffic
through our system, so I had to watch only those lines that he'd be likely to

                  THE CUCKOO'S EGG

use. Saturday morning, he'd entered through one of our four Tymnet con-
nections, so that seemed like a good place to start.
      I couldn't buy, steal, or borrow four printers for a few weeks, so I
went out begging. One physics professor gave me a beat-up old Decwriter,
delighted that someone would take the ten-year-old heap off his hands. A
secretary donated a spare IBM PC in exchange for my teaching her how to
use spreadsheet programs. A combination of cookies, coaxing, and conniv-
ing led to two more obsolete printers. We were back in business, recording
all our Tymnet traffic.
      Wednesday afternoon marked a week since we'd first detected the
hacker. Berkeley was sunny, though I could barely see the windows from
across the maze of cubicles. Dave's watchdog was awake, the printers busy
chattering with every keystroke, and I was absentmindedly thinking of
infrared emissions from the Pleiades star cluster. Suddenly, the terminal
beeped twice: Sventek's account was active. My adrenaline pumped as I ran
to the switchyard; the top of the ream of paper showed the hacker had
logged in at 2:26 and was still active.
      Letter by letter, the printer spat out the hacker's keystrokes.
      Logged into the Unix-4 computer as Sventek, he first listed the names
of everyone connected. Lucky-there was nobody but the usual gang of
physicists and astronomers; my watchdog program was well concealed
within the Unix-8 computer. "Looking over your shoulder again," I
thought. "Sorry, nobody here but us astrophysicists," I whispered to the
      All the same, he scanned all the processes running. The Unix com-
mand, ps prints the status of other processes. Habitually, I usually typed in ps
-axu, the last three characters telling mother Unix to tell everyone's status.
The intruder, however, entered ps -eafj;. Strange. I'd never seen anyone use
the g flag. Not that he discovered much: just a few scientific analysis pro-
grams, and a cranky typesetting program-and a network link to the
Unix-8 system.
      It'd taken him just three minutes to discover the Unix-8 computer,
loosely linked to the Unix-4 system. But could he get in? With the Unix
rlogin command he tried a half-dozen times, knocking on the door of the
Unix-8 machine with Sventek's account name and password. No luck. Dave
had nailed that door closed.
      Apparently satisfied that nobody was watching him, he listed the sys-
tem password file, There wasn't much for him to see there: all the passwords

                                 ST 0 L L

are encrypted and then stored. An encrypted password looks like gibberish;
without solving an extremely difficult cipher, the password file gave the
hacker little more than a dream.
      He didn't become super-user; rather he checked that the Gnu-Emacs
file hadn't been modified. This ended any doubts about whether the same
hacker was connected: nobody else would search out the security hole in our
system. At 2:37, eleven minutes after he logged in, he abruptly logged off
the Unix-4 computer. But not before we'd started the trace.
      Tymnet! I'd forgotten to warn their network operations center that
they'd have to trace some connections. I hadn't even asked whether they
could trace their own network. Now, watching the printer copy every key
that the hacker pressed, there were only minutes to get the trace.
      Ron Vivier traces Tymnet's network within North America. While I
talked to him on the phone, I could hear him punching keys on his terminal.
In a staccato voice, he asked for our node's address. At least I'd prepared that
much. In a couple minutes, Ron had traced the connection from LBL's
Tymnet port into an Oakland Tymnet office, where someone had dialed in
from a telephone.
      According to Ron, the hacker had called Tymnet's modem in Oak-
land, just three miles from our lab.
      It's easier to call straight into our Berkeley lab than to go through
Oakland's Tymnet office. Why call through Tymnet when you can dial
directly into our system? Calling direct would eliminate Tymnet's interme-
diate connections and might be a tad more reliable. But calling via Tymnet
added one more layer to trace.
      The hacker had called the local Tymnet access number instead of our
lab. It was like taking the interstate to drive three blocks. Whoever was at
the other end of the line knew how to hide. Ron Vivier gave his condo-
lences-I hadn't wanted just some Tymnet telephone number; I was hunting
for a person.
      Well, we were on the trail, but there were bends in the road. Some-
how, we'd have to trace the phone call, and phone traces meant court
orders. Phooey.
      When the hacker logged off, I looked up from the printout. Like a
firehouse dog, Roy Kerth had picked up the news and made it down to the
switchyard. So had Dave and Wayne.
      When Ron hung up, I announced, "He's calling Oakland Tymnet. So

                  THE CUCKOO'S EGG

he must be from around here. If he were in Peoria, he'd save his nickel and
call the Peoria Tymnet modem."
      "Yeah, you're probably right." Roy didn't look forward to losing a
      Dave wasn't thinking about the phone trace. "This ps -eafi command
bothers me," he said. "I can't say why, it just doesn't taste right. Maybe it's
just paranoia, but I'm sure that I've seen that combination before."
      "To hell with Unix. Serves us right for running such a dog operating
system." Wayne saw a chance to bait Dave. "Hey, that password file isn't
much use to him, is it?"
      "Only if he owns a supercomputer. You'd need one to unravel the
encryption. Unix isn't VMS-it's got the tightest cypher locks around,"
 Dave countered.
      Roy had heard it before; he saw himself as above the war of the
operating systems. "Looks like you need some phone traces, Cliff."
      I didn't like his choice of pronoun, but, yes, that was the point. "Any
ideas on where to start?"
      "Let your fingers do the walking."

o     0 0 The morning after we watched the hacker break into our
computer, the boss met with Aletha Owens, the lab's attorney. Aletha didn't
care about computers, but had a wary eye for problems on the horizon. She
wasted no time in calling the FBI.
      Our local FBI office didn't raise an eyebrow. Fred Wyniken, special
agent with the Oakland resident agency, asked incredulously, "You're call-
ing us because you've lost seventy-five cents in computer time?" Aletha
tried explaining information security, and the value of our data. Wyniken
interrupted and said, "Look, if you can demonstrate a loss of more than a
million dollars, or that someone's prying through classified data, then we'll
open an investigation. Until then, leave us alone."
      Right. Depending on how you looked at it, our data was worth either
nothing or zillions of dollars. How much is the structure of an enzyme
worth? What's the value of a high-temperature superconductor? The FBI

                                ST 0 L L

thought in terms of bank embezzlement; we lived in a world of research.
Classified data? We weren't a military base or an atomic weapons lab.
      Yet we needed the FBI's cooperation. When the hacker next popped
his periscope above the water, we'd probably track him to the Tymnet's
Oakland telephone access number. From there, I hoped a phone trace would
lead to him. But I'd heard that the phone company wouldn't trace a line
without a search warrant. And we needed the FBI to get that warrant.
      After hitting the FBI's brick wall, Aletha called our local District
Attorney. The Oakland DA didn't fool around: "Someone's breaking into
your computer? Hell, let's get a warrant and trace them lines." The FBI
might not give a damn, but our local prosecutors took us seriously. Still,
they would have to convince a judge. Our warrant was at least a week
      Just after five, Dave stopped by and started talking about the break-in.
      "Cliff, the hacker's not from Berkeley."
      "How do you know?"
      "You saw that guy typing in the ps -eqJg command, right?"
      "Yeah, here's the printout," I replied. "It's just an ordinary Unix com-
mand to list all the active processes-'ps' means print status, and the four
letters modify the display. In a sense, they're like switches on a stereo-they
change the way the command works."
       "Cliff, I can tell you're used to Berkeley Unix. Ever since Berkeley
Unix was invented, we've mechanically typed 'ps' to see what's happening
on the system. But tell me, what do those four letters modify?"
       Dave knew my ignorance of obscure Unix commands. I put up the
best front I could: "Well, the e flag means list both the process name and
environment, and the a flag lists everyone's process-not just your process.
 So the hacker wanted to see everything that was running on the system."
       "OK, you got half of 'em. So what are the g andf flags for?"
       "I dunno." Dave let me flounder until I admitted ignorance.
       "You ask for a g listing when you want both interesting and uninter-
esting processes. All the unimportant jobs, like accounting will show up. As
will any hidden processes."
       "And we know he's diddling with the accounting program."
       Dave smiled. "So that leaves us with the f flag. And it's not in any
 Berkeley Unix. It's the AT&T Unix way to list each process's files. Berkeley
 Unix does this automatically, and doesn't need the f flag. Our friend doesn't
 know Berkeley Unix. He's from the school of old-fashioned Unix."

                  THE CUCKOO'S EGG

     The Unix operating system was invented in the early 1970s at AT&T's
Bell Laboratories in New Jersey. In the late '70s, Unix zealots from Bell
Labs visited the Berkeley campus, and a new, richer version of Unix was
developed. Along with hot tubs, leftist politics, and the free speech move-
ment, Berkeley is known for its Unix implementation.
      A schism developed between advocates of the small, compact AT&T
Unix and the more elaborate Berkeley implementation. Despite conferences,
standards, and promises, no consensus has appeared, and the world is left
with two competing Unix operating systems.
      Of course, our lab used Berkeley Unix, as do all right-thinking folks.
East Coast people were said to be biased towards AT&T Unix, but then,
they hadn't discovered hot tubs either.
      From a single letter, Dave ruled out the entire computing population
of the West Coast. Conceivably, a Berkeley hacker might use an old-
fashioned command, but Dave discounted this. "We're watching someone
who's never used Berkeley Unix." He sucked in his breath and whispered,
"A heathen."
     Wayne didn't give a damn about Unix. As a VMS junkie, Wayne was
an infidel. Moreover, he felt the hacker couldn't learn anything from our
password file: "Look, there's no way that anyone can decrypt those pass-
words. About all he's learned is our names. Why bother?"
      I'd rolled this around in my mind. Passwords are at the heart of
security on a big computer. Home computers don't need passwords: there's
only one user. Anyone at the keyboard can access any program. But when
there's ten or twenty people using a single system, the computer must be
certain that the person behind the terminal isn't an imposter.
      Like an electronic signature, passwords verify the authenticity of a
transaction. Automatic teller machines, telephone credit cards, electronic
funds transfer networks, even some home telephone-answering machines
depend on passwords. By filching or forging passwords, a hacker can create
counterfeit wealth, steal services, or cover bounced checks. When money
was stored in vaults, safecrackers attacked the combination locks. Now that
securities are just bits in a computer's memory, thieves go after the pass-
     When your computer has fifty or a hundred users, you might just store
each person's password in a file. When the user tries to log on, ask for her
password and compare that to what's in your file. In a friendly environ-

                                ST 0 L L

ment, no problem. But how do you keep someone from sneaking a peek at
that password file? Well, protect the password file so that only the system
can read it.
      Even if you protect the password file, every now and then all the files
will be copied onto backup tapes. Even a novice programmer could read
those tapes on another computer and list the contents of the password file.
File protection alone isn't enough.
      In 1975, Bob Morris and Fred Grampp of Bell Laboratories developed
a way to protect passwords, even when files weren't secure. They would
rely on encryption, rather than file protection. If you chose the password
"cradle," the computer doesn't simply store your choice into a file of pass-
words. Instead, Unix scrambles the letters into an encrypted word, say,
"pn6yywersyq." Your encrypted password is stored, not the plain text.
      So a Unix password file might look something like this:

     Aaron: fnqs241kcvs
     Blacker: anvpqwOxcsr
     Blatz: pn6yywersyq
     Goldman: mwe785jcy12
     Henderson: rp2d9cl49b7

      Following each account name is the encrypted password. Like Wayne
said, stealing the password file just gives you a list of people.
      The computer program that encrypts "cradle" into "pn6yywersyq" is
built upon a trapdoor algorithm: a process that's easy to do, but difficult to
undo. When Sally Blatz logs in, she types in her account name, Blatz, and
then her password, cradle. The system encrypts the password into
pn6yywersyq, and compares that to the entry in the password file. If the
encrypted entries don't match, Sally is booted off the machine. The plain
text password itself isn't compared, its encryption is. Password security
depends on the trapdoor function.
      Trapdoor functions are mathematical ratchets: you can turn them for-
wards, but not backwards. They quickly translate text into ciphers. To make
these locks pickproof, it's got to be impossible to reverse the algorithm.
      Our trapdoors were built upon the Data Encryption Standard (DES),
created by IBM and the National Security Agency. We'd heard rumors that
the electronic spooks of NSA weakened the DES. They hobbled it just
enough to be crackable by NSA, but kept it strong enough to resist the

                 THE CUCKOO'S EGG

efforts of ordinary mortals. The grapevine said that this way NSA could
crack the code and read messages, but nobody else could.
       The cryptographic DES program within our Unix computer was pub-
lic. Anyone could study it. NSA had analyzed its strengths and weaknesses,
but these reports were secret. Occasionally, we'd heard rumors of someone
cracking this cipher, but none of these panned out. Until NSA published its
analyses of the DES, we'd have no choice but to trust that our encryption
was strong enough.
       Wayne and I had watched the hacker break in and steal our password
file. The hacker now knew the names of a few hundred scientists. He might
as well have asked for our telephone book-at least that included addresses.
Unless he owned a Cray supercomputer, he couldn't invert the trapdoor
function, and our passwords remained safe.
       Wayne was still worried. "Maybe this guy's stumbled on some brilliant
way to reverse the trapdoor function. Let's be a tad careful and change our
important passwords."
       I could hardly object. The system password hadn't been changed for a
couple years, and outlasted people who had been hired and fired. I didn't
mind changing my password; to make sure, I used a different password on
each computer. If the hacker managed to figure out my password from the
Unix-4 computer, he'd still have no way to guess it on the others.
       Before pedaling home, I again studied the printout of the previous
day's session. Buried in the ten pages were clues to the hacker's persona,
location, and intentions. But too much conflicted: we traced him through
Tymnet into Oakland, California. But Dave didn't believe he was from
Berkeley. He copied our password file, yet our encryption made those
passwords into gibberish. What was he doing with our encrypted pass-
       In some ways, this was like astronomy. We passively observed a phe-
nomenon, and from a few clues tried to explain the event and find the
location of the source. Astronomers are accustomed to quietly gathering
data, usually by freezing behind a telescope on a mountaintop. Here the data
appeared sporadically, from an unknown source. Instead of thermodynamics
and optics, I needed to understand cryptography and operating systems.
Somehow, a physical connection existed between our system and a distant
terminal. By applying ordinary physics, it must be possible to understand
what was happening.
       Physics: there was the key. Record your observations. Apply physical

                                ST 0 L L

principles. Speculate, but only trust proven conclusions. If I were to make
any progress, I'd have to treat the task as a freshman physics problem. Time
to update my notebook.

o     0     0    And just in time. Wednesday, September 10, at 7:51 A.M.,
the hacker appeared in our system for six minutes. Long enough to ring the
alarm on my terminal, but not enough time to do anything about it. I had
stayed at home that night: "Five days at the lab are enough," Martha said.
      I wasn't at the lab to watch, but the printer saved three pages of the
hacker's trail. He had logged into our Unix-4 computer as Sventek. Well, I
understand that-he had Sventek's password, and had entered from Tyrnnet,
      But he didn't hang around my Unix-4 computer. Instead he leap-
frogged through it and landed in the Milnet. Now it was no news flash that
the Milnet existed-it's a part of the Internet, a computer network that
cross-links a hundred other networks. From our Unix computer, we can
reach the Internet, and from there, the Milner,
      The Milnet belongs to the Department of Defense.
      My hacker connected to Milnet address, logged in there as
"Hunter," and checked that he had a copy of Gnu-Emacs, then disappeared.
      When I biked in around noon, there was no trace to follow upstream.
But the hacker left an indelible trail downstream. Where was that Milnet
address? The Network Information Center decoded it for me: the U.S.
Army Depot, in Anniston, Alabama. The home of the Army's Redstone
missile complex, two thousand miles away from Berkeley.
      In a couple minutes, he'd connected through our lab and into some
Army base. The printout left little doubt that this was the hacker. Nobody
but the hacker would use Sventek's account. And who else would check for
the Gnu-Emacs security hole on some computer in Alabama?
      Nobody was around to tell me to ignore it, so I called Anniston
information. Sure enough, the Anniston Army Depot had a computer cen-
ter, and eventually I found Chuck McNatt, the Anniston Unix wizard.
      "Hi, Chuck. You don't know me but I think we found someone
screwing around with your computer."

                 THE CUCKOO'S EGG

      "Who are you? How do I know you're not trying to break in?"
      After a few minutes of disbelief, he asked for my phone number, hung
up, and called me back. Here's someone that doesn't trust strangers. Or did
he call me back on a secure phone line?
      "Bad news," I said. "I think I saw someone breaking into your sys-
      "Aw, hell-that son of a bitch, Hunter?"
      "Yeah. How'd you know?"
      "I've seen his ass before."
      Chuck McNatt explained through a thick Alabama drawl that the
Army's Redstone Missile Arsenal kept track of its supplies on a couple of
Unix computers. To get orders processed quickly, they'd hooked up to
Chuck's computer at the Anniston Depot. Most of their traffic was news
updates-not many people logged in remotely.
      One Saturday morning, to escape the August heat, Chuck had gone
into work and checked the users on his system. Someone named Hunter was
using up an enormous amount of computing time. Surprised to see anyone
on a Saturday, Chuck had flashed a message on Hunter's screen, saying
"Hey! Identify yourself!"
      The mysterious Hunter typed back, "Who do you think I am?"
      Chuck wasn't that gullible. He sent another message, "Identify your-
self now or I'll knock you off the system!"
      Back came Hunter's reply, "I cannot answer."
      "So I bumped him off the machine," Chuck said. "We called the FBI,
but they didn't give a damn. So we talked CID into tracing every damn
connection coming in on our phone lines."
      "What's the CID-Chestnut Inspection Department?"
      "Be serious," Chuck said. "The CID's the Army's cops. The criminal
investigation division. But they're not doin' much."
      "No classified material lost, huh?"
      The FBI in Montgomery, Alabama, told Chuck about the same story
as Oakland had told me. They'd investigate when a million dollars disap-
peared. Until then, don't bother 'em. Computer crimes weren't sexy.
      "Who'd you find?"
      "The weirdest thing," Chuck continued. "I caught Hunter sneaking
into my computer two or three more times, but my telephone recorders
didn't show a thing."
      "Betcha I know why. He's been coming in through your back door.

                                ST 0 L L

Your Milnet connection. Some hacker's been breaking into our system, and
he got into your computer this morning."
       Chuck cursed-he'd missed the three-minute connection. He had set
traps on all his telephone lines, but hadn't thought to watch his network
       "We're trying to find out who's hacking our system," I said. "We
figure he's a student here in Berkeley, and we're gearing up to track him
down. Our first trace points to Oakland or Berkeley."
       "Well, I know how you feel. We all suspect it's a student here in
Alabama," Chuck said. "We thought about closing up, but we're out to git
him. I'd rather see him behind bars than behind a terminal."
       For the first time, I worried for this hacker's welfare. If the Army
caught the guy, he'd have a rough time.
       "Hey, Chuck, have I got a kicker for you. Betcha this guy's super-user
on your system."
     "Naw, He might have stolen an account, but no way he'd get to be
super-user. We're an Army base, not some goofball college."
     I let the swipe at Berkeley pass. "He went looking for your Gnu-
Emacs move-mail file."
     "Yeah. So what?"
     "What do you know about the nesting habits of cuckoos?" I explained
the workings of the Gnu-Emacs security hole.
     Chuck was taken aback. "You mean we've had this hole since White
Sands sent us this Gnu file?" Chuck whistled. "I wonder how long he's been
poking around." He understood the hole and the implications.
     The hacker listed files at the Anniston system. Judging from the dates
of these files, he'd been in Anniston's computers since early June. For four
months, an illegitimate system manager used an Alabama Army computer.
Yet he'd been discovered by accident, not through some logic bomb or lost
     No obvious damage.
     Looking closely at the morning's printout, I saw that the hacker had
executed the change password command. On the Anniston computer, he
had changed Hunter's password to be "Hedges." A clue at last: of zillions of
possible passwords, he'd chosen Hedges. Hedges Hunter? Hunter Hedges? A
hedge hunter? Time to flip through the H's in the Berkeley telephone book.
     Three phone calls to H. Hunter turned up Harold, Heidi, and Hilda

                  THE CUCKOO'S EGG

Hunter. "Hi, are you interested in a free subscription to Computer Reviews?"
No dice. None of them said they cared about computers.
      What does a physics lab in Berkeley have in common with an army
depot in Anniston, Alabama? You couldn't find more politically opposite
locations: a good-old-boy Army base and a radical hippie town. Yet techni-
cally, we shared quite a bit. Both our computers ran Unix and connected
through the Milnet network.
      But wait-Anniston's system ran AT&T Unix, not the Berkeley dia-
lect. If I believed Dave Cleveland, then the hacker was at home on Annis-
ton's system. Might it be a Southern hacker?

o      0 0 I couldn't stand the sterile, fluorescent lighted halls of the
lab anymore, so I went outside to look at the panoramic view of the Bay
Area below me. The Berkeley campus lay directly beneath my laboratory.
Once the home of the free speech movement and antiwar protests, the
campus is still known for its wild politics and ethnic diversity. If I were a
little closer, I could probably hear the Young Republicans baiting the So-
cialist Workers, while the Chinese Club looked on in amazement.
       Smoky coffeehouses crowded next to the campus, where haggard grad
students scribbled their theses, fueled by espresso. At nearby ice cream shops,
giggling sorority girls mingled with punks in black leather and spiked hair.
Best of all-Berkeley's bookstores.
       From the front of the lab, I could look farther south, to the pleasant
streets of north Oakland, where we lived. There I shared an old bungalow
with an assortment of zany roommates. Across the bay, shrouded by fog,
was San Francisco-Oz.
       Three years ago, Martha had moved here to study law and I'd tagged
along. She'd been worth crossing the country for. She was a damned good
hiking partner and caver. I first met her when I fell thirty feet inside a cave;
she came to the rescue, rapelling down to where I lay incapacitated by a bad
sprain and utter infatuation. My injuries healed, thanks to her chicken soup;
my affection for the smart-aleck kid who climbed rocks so fearlessly ripened
into love.

                                S TaL L

      Now we lived together. She actually enjoyed studying law. She didn't
want to be a lawyer, but a legal philosopher. She was obsessed with aikido,
a Japanese martial art, and often came home bruised but grinning. She
cooked, gardened, pieced quilts, did carpentry, and made stained glass win-
dows. For all our zaniness, we wallowed in disgustingly wholesome domes-
tic bliss.
      I bicycled home and told Martha about the Alabama break-in, specu-
lating about who might be behind it.
      "So there's technocratic vandals," she said. "What else is new?"
      "That's news in itself. Technicians now have incredible power to con-
trol information and communication," I said.
      "So what? Somebody's always had control over information, and oth-
ers have always tried to steal it. Read Machiavelli. As technology changes,
sneakiness finds new expressions."
      Martha was still giving me a history lesson when Claudia bustled in,
complaining about her fifth graders. Life in Berkeley usually includes a
roommate or two. Claudia was ours, and a perfect one at that. She was
generous and cheerful, eager to share her life, her music, and her kitchen
gadgets with us. She was a professional violinist eking out a living by
playing in two symphony orchestras and a chamber music trio, and giving
lessons to kids.
      Claudia was seldom still or quiet. In her few moments between jobs,
she simultaneously cooked meals, talked on the phone, and played with her
      At first I listened, but soon her voice became like the background chirp
of a parakeet while I worried about how malicious this hacker might be.
While I'm at home, how do I know what he's up to?
      Claudia knew how to take my mind off the hacker: she brought home
a video, Plan 9 from Outer Space-aliens in tinfoil flying saucers drag vam-
pires from graves.
      Wednesday, September 17, was a drizzly Berkeley day. As the only
California couple without a car, Martha and I had to bicycle through the
rain. On my way into the lab, I visited the switchyard, to check for any
visits by the hacker. Water dripped off my sopping hair onto the printout,
smudging the ink on the paper.
       Sometime during the night, someone had connected to our computer,
and methodically tried to log into the Unix-4 computer. First they tried to
log into the Guest account, using the password "Guest." Then they tried the

                  THE CUCKOO'S EGG

Visitor account, with password "Visitor"; then accounts Root, System,
Manager, Service, and Sysop. After a couple of minutes, the attacker left.
      Could this be a different hacker? This guy didn't even try valid ac-
counts like Sventek or Stoll. He simply tried obvious account names and
simple passwords. I wondered how often such an attack might succeed.
      Not often-with six-letter passwords a hacker had a better chance of
winning the lottery than randomly guessing a particular password. Since the
computer hangs up after a few log-in failures, the attacker would need all
night to try even a few hundred possible passwords. No, a hacker couldn't
magically enter my system. He'd need to know at least one password.
      By 12:29, most of my clothes had dried off, though my sneakers still
squished. I was part way into a soggy bagel, and most of the way through
an astronomy article about physics of the icy satellites ofJupiter. My termi-
nal beeped. Trouble in the switchyard. A quick (though squeaky) trot down
the hallway let me watch the hacker connect into our system as Sventek.
      Again the adrenaline rush: I called Tymnet and quickly found Ron
Vivier. Ron started the trace, and I huddled over the Decwriter, which now
tapped out the hacker's commands.
      The hacker wasted no time. He issued commands to show all the active
users and any background jobs running. He then fired up Kermit.
      Named after the Muppet hero, Kermit is the universal language for
connecting computers together. In 1980, Frank da Cruz of Columbia Uni-
versity needed to send data to a number of different computers. Instead of
writing five different, incompatible programs, he created a single standard to
exchange files between any systems. Kermit's become the Esperanto of com-
      Absentmindedly chewing on a bagel, I watched as the hacker used
Kermit to transfer a short program into our Unix computer. Line by line,
faithful Kermit reassembled it, and soon I could read the following pro-

     echo -n "PLEASE LOG IN NOW'
     echo -n "LOGIN:"
     read accounLname
     echo -n "ENTER YOUR PASSWORD:"
     (stty -echo; \
     read password; \
     stty echo; \

                                ST 0 L L
     echo" ": \
     echo SaccounLname Spassword >> /tmp/.pub)
     echo "SORRY, TRY AGAIN."

      Yikes! Now here was a strange program! This program, when in-
stalled in our computer, would prompt a user to enter his name and pass-
word. An ordinary user who ran this program would see on his screen:


     His terminal would then wait until he entered his account name. After
he typed his name, the system responds:


     And he'd naturally type in his password. The program then stashes the
unlucky user's name and password into a file, tells the user,


and then disappears.
     Thinking they've mistyped their passwords, most people will just try
to log in again. By then, their password will already have been stolen.
     Four thousand years ago, the city of Troy fell when Greek soldiers
snuck in, hidden inside the Trojan horse.
     Deliver a gift that looks attractive, yet steals the very key to your
security. Sharpened over the millennia, this technique still works against
everyone except the truly paranoid.
     The hacker's Trojan horse program collected passwords. Our visitor
wanted our passwords badly enough to risk getting caught installing a
program that was bound to be detected.
      Was this program a Trojan horse? Maybe I should call it a mocking-
bird: a false program that sounded like the real thing. I didn't have time to
figure out the difference-within a minute, he was bound to install his
program in the systems area, and start it running. What should I do? To
disable it would show him that I was watching him. Yet doing nothing
would give him a new password every time someone logged in.

                  THE CUCKOO'S EGG

      But legitimate super-users have power, too. Before the hacker could
run his program, I changed one line in it, making it look like he'd made a
trivial error. Then I diddled a couple system parameters to slow down the
system. Slow enough that the hacker would need ten minutes to rebuild his
program. Enough time to let us respond to this new attack.
      I shouted down the hall for Guru Dave.
      "What do you feed a Trojan horse?"
      Dave came running. We shifted the computer into high speed, and
prepared a fodder of bogus accounts and false passwords.
       But our panic wasn't necessary. The hacker rebuilt his Trojan horse,
but didn't install it properly. Dave instantly realized that it had been placed
in the wrong directory. His Trojan horse would be happy in standard
AT&T Unix, but couldn't cavort in the fields of Berkeley Unix.
       Dave grinned. "I won't say, 'I told you so,' but we're watching some-
one who's never been to California. Every Unix jockey on the West Coast
would use Berkeley style commands, yet your hacker's still using AT&T
       Dave descended from his tower to explain what he meant. "The spell-
ing of his commands is different from Berkeley Unix. But so is the very feel
of the program. Kinda like how you can tell that a writer is British rather
than American. Sure, you'll see words like 'colour' and 'defence,' but you
can feel the style difference as well."
       "So what's the difference?" I asked.
       Dave sneered, "The hacker used the command, 'read' to get keyboard
data. Any civilized programmer would use the 'set' command." For Dave,
civilized computers spoke Berkeley Unix. All others were uncouth.
       The hacker didn't realize this. Confident that he'd put his Trojan horse
in the right pasture, he ran it as a background process, and logged off.
Before he disconnected, Ron Vivier had traced the hacker through Tymnet's
network, and into an Oakland, California, telephone line. The dust hadn't
yet settled on our court order, so we couldn't start the phone trace.
       The hacker had left, but his Trojan horse stayed behind, running as a
background task. As Dave predicted, it collected no passwords, for it had
been installed in a place that wasn't referenced during log-in. Sure enough,
twenty minutes later, the hacker reappeared, searched for a collection of
passwords, and must have been disappointed to find his program had failed.
       "Look, Dave, the poor guy needs your help," I said.

                                ST 0 L L

     "Right. Should we send him some electronic mail telling him how to
write a Trojan horse program that works?" Dave replied.
     "He's got the basics right-imitating our log-in sequence, asking for
the username and password, then storing the stolen information. All he
needs is a few lessons in Berkeley Unix."
     Wayne stopped by to watch the hacker flounder. "Aw, what do you
expect? There's just too many varieties of Unix. Next time make it easier on
those inept hackers, and give them Digital's VMS operating system. It might
not be easier to hack, but at least it's standardized. IOTTMCO." Intuitively
obvious to the most casual observer.
     Wayne had a good point. The hacker's Trojan horse attack had failed
because the operating system wasn't exactly what he was accustomed to. If
everyone used the same version of the same operating system, a single
security hole would let hackers into all the computers. Instead, there's a
multitude of operating systems: Berkeley Unix, AT&T Unix, DEC's VMS,
IBM's TSO, VM, DOS, even Macintoshes and Ataris. This variety of soft-
ware meant that no single attack could succeed against all systems. Just like
genetic diversity, which prevents an epidemic from wiping out a whole
species at once, diversity in software is a good thing.
      Dave and Wayne continued bickering as they left the switchyard. I
hung around a few more minutes, reloading paper. At 1:30 P.M., the hacker
reappeared; I was still adjusting the printer when he started typing.
      This second session was predictable. Our visitor looked at his special
file for passwords and found none. He listed his Trojan horse program and
tested it a couple times. It didn't work. Apparently, he didn't have a Dave
Cleveland for help. Obviously frustrated, he erased the file and logged off
in a couple minutes.
      But even though he'd been on for only a few minutes, Tymnet man-
aged to trace him, again into Oakland. Ron Vivier, who'd traced Tyrnnet's
connections, apparently welcomed any emergency that might extricate him
from a meeting, so he jumped when I called. If we could only get the phone
company to continue the trace, we could wrap up everything in a couple
      Dave felt he could exclude anyone coming from the West Coast.
Chuck in Anniston suspected a hacker from Alabama. Tymnet's traces
pointed to Oakland.
      Me? I didn't know.

                  THE CUCKOO'S EGG

o     0 0 Our Tymnet traces reached into Oakland, at various times
the home of Jack London, Ed Meese, and Gertrude Stein. A twenty-minute
bike ride from the Berkeley campus led to the Oakland Paramount Theater,
with its sublime art-deco architecture and eye-popping murals. A few
blocks away, in the basement of an ugly modern building, Tymnet rents
space for fifty dialup modems. Ron Vivier had traced the hacker from our
lab into this bank of modems. Now it was my local telephone company's
      A two-inch-thick cable runs under Broadway, connecting Tymnet's
modems to an unmarked, windowless building. There, Pacific Bell's Frank-
lin office houses an electronic switch to handle ten thousand telephone lines
in area code 415 with the prefix 430. Tymnet leases fifty of these lines.
      From somewhere, the hacker had dialed 415/430-2900. The path to
our mysterious visitor led to Pac Bell's ESS-5 switch.
      Across San Francisco Bay, Lee Cheng's office overlooks a grungy alley
off Market Street. Lee is Pac Bell's bloodhound; from his office or up on a
telephone pole, he traces phone lines.
      Lee's degree is in criminology, and his graduate work is in accident
reconstruction and causation. But eight years of telephone tracing gives him
an engineer's view of the phone company and a cop's view of society. To
him, communities are split by area codes, exchanges, and trunk lines, as well
as precincts and neighborhoods.
      With advance warning, Lee starts a software program in the computer
that runs the telephone exchange. At the switching control center, he logs
onto the ESS maintenance channel, brings up line-condition-monitoring
software, and starts a trap program.
     The automatic trap program monitors the status of an individual tele-
phone line. It records the date, time, how many rings before an answer, and
where the call came from.
     If the call came from a nearby phone-one from the same exchange-
then the trace is complete, and Lee's job is easy. More often, the call comes

                                 ST 0 L L

from another exchange, and Lee has to coordinate traces at perhaps five
different phone exchanges.
      When a technician at an exchange receives a trace call, he drops what
he's doing-Lee's traces take precedence over everything except firefighting.
He logs into the control computer, commands his computer to display the
phone number's status (busy, idle, off-hook), and executes programs to show
where the connection came from (routing index, trunk group number,
adjacent exchange name).
      With luck, the trace might take a few seconds. But a few exchanges,
left over from the 1950s, still use mechanical-stepping switches. When you
dial through these exchanges, you can hear a soft pulsing in the background,
as relays move a lever in tune with your dialing. The old grackles of the
telephone system are proud of these antiques, saying, "They're the only
switches that'll survive a nuclear attack." But they complicate Lee's job: he's
got to find a technician to run from rack to rack tracing these calls.
       Local telephones can only be traced while connected. Once you hang
up, the connection evaporates and can no longer be traced. So Lee races
against time to finish a trace before the connection is lost.
       Phone companies view phone traces as a waste of time. Only their
most skilled technicians know how to trace a phone connection. Worse,
traces are expensive, generate lawsuits, and upset customers.
       Lee, of course, sees things otherwise. "Yesterday was a drug bust,
today, it's an extortion racket, tomorrow we're tracing a burglary ring.
 Obscene phone calls around the full moon. Lately, we've been tracing call
girls' pocket pagers. Slice of life in the big city." Still, the fear of lawyers
keeps him from unofficially helping out.
       Our conversation in September 1986 was curt:
       "Hey, we need a telephone line traced."
       "Got a search warrant?"
       "No, do we need one?"
       "We won't trace without a warrant."
       That was quick. No progress until Aletha Owens got the court order.
       After yesterday's attack, we couldn't wait. My searches through the
 phone book were leading nowhere. A more competent Trojan horse would
 panic my boss into closing down the investigation. And my three-week
 allowance was down to ten days.
       Sandy Merola was Roy Kerth's sidekick. When Roy's acid tongue got
 to one of the staff, Sandy applied balm. On a mission to the Berkeley

                   THE CUCKOO'S EGG

campus, Sandy noticed a set of IBM personal computers in a public section
of the library. Like any computer jock would do, he wandered over and
tried to use them. Just as he suspected, these computers were programmed to
automatically dial Tymnet and log into the Dow Jones Information Service.
      Tymnet? Sandy spent a few minutes diddling on the terminal, and
discovered that he could find the latest stock quotations and financial rumors
from The Wall StreetJournal. More important, when he signed off the Dow
Jones service, the terminal prompted him for, "Tyrnnet username?" Seemed
like nothing to lose by trying, so he entered, "LBL." Sure enough, Sandy
connected to my lab's computers.
      Maybe these public terminals explained things. Anyone could use
them; they dialed the Oakland Tymnet number; and the library was all of a
hundred feet away from Cory Hall, where the Berkeley Unix jockeys hang
       Sandy was a jogger the way some people are Catholics. He trotted up
Cardiac Hill and told the police of his discovery. Here was a way to avoid a
phone trace-the next time the hacker appeared, we'd just duck over to the
library and grab the bastard. We didn't even need a court order.
       Sandy returned from the police station, still sweating. He caught me
 practicing a yo-yo trick.
       "Cut the clowning, Cliff. The police are all set to run over to the
campus and arrest whoever's using those terminals."
       Being more accustomed to parking tickets and medical emergencies,
 the LBL police don't understand computers and are pretty wary of tele-
 phone traces. But they had no problem with busting someone breaking into
 a computer.
       "Hadn't we better make sure that it's the hacker, first?" I had visions of
 some undercover cops staking out a terminal and dragging a librarian into
 the paddy wagon for checking the Dow Jones industrials.
       "It's easy. Call me the next time the hacker shows up. I'll drive down
 to the library with the police, and we'll see what's on the screen. If it's data
 from LBL, then we'll leave it to the police."
       "Are they gonna stake out the terminal? You know, like in 'Dragnet'?
 With one-way mirrors and binoculars?"
       "Huh? Be serious, Cliff." Sandy jogged away. I guess scientists are
 graded in seriousness. It reminded me of when I'd filed a student health
 report, listing under complaints, "Potato Famine." The doctor called me
 aside and lectured me, "Son, we take health seriously around here."

                                ST 0 L L

      We got our chance to test Sandy's theory soon enough. Two days after
his failed Trojan horse, the hacker returned at 12:42 P.M. Lunch hour. The
perfect time for a Berkeley student to wander over to the library and use
their terminals.
      At the alarm, I called Sandy. Five minutes later, he appeared with two
undercover police agents, wearing suits, ties, and winter coats. Nothing
could be more conspicuous on a campus of hippies on a hot summer day. I
glimpsed a large revolver under one of the cop's coats. They were serious.
      For the next twenty-five minutes, the hacker didn't do much. He
became super-user via the Gnu-Emacs hole, listed the day's electronic mail,
and scanned through our processes. Ron Vivier skipped lunch to trace the
Tymnet connection into Oakland. Any minute, I expected to see the printer
suddenly stop, signaling that Sandy and the constabulary had caught their
man. But no, the hacker took his time and logged off at 1:20.
      Sandy returned a few minutes later.
      "No luck, huh?" His face said it all.
      "Nobody was at the library's terminals. Nobody even near them. Are
you sure the hacker was on?"
      "Yeah, here's the printout. And Tymnet traced it into Oakland again."
      Sandy was let down. Our short cut hit a dead end: progress now
depended on a telephone trace.

o      0 0 That evening, Martha was supposed to be studying constitu-
tionallaw, but was actually piecing a calico quilt. I came home discouraged:
the library stakeout had seemed so promising.
      "Forget the hacker. You're home now."
      "But he might be in my system right now." I was obsessing.
      "Well, there's nothing you can do about it, then. Here, thread a needle
and help with this seam." Martha escaped law school by quilting; surely it
would work for me as well. After twenty minutes of silence, while she
studied, my sewing started to get crooked.
      "When we get the warrant, we'll have to wait until the hacker shows
up. For all we know, that'll be at 3 A.M., and nobody will be around."

                  THE CUCKOO'S EGG

      "I said, forget the hacker. You're home now." She didn't even look up
from her book.
      Sure enough, the hacker didn't show up the next day. But the search
warrant did. It was legal now. Of course, I couldn't be trusted to start
anything as important as a phone trace: Roy Kerth was explicit that only he
was to talk to the police.
      We went through a couple dry runs, making sure we knew who to call
and checking that we could unwind our own local network. Then I got
bored and went back to writing some software to analyze optical formulas
for an astronomer.
      In the afternoon, Roy called our systems people and operators to-
gether. He lectured us about the need to keep our traces secret-we didn't
know where the hacker was coming from, so we mustn't mention our work
to anyone outside the lab. I figured that people would talk less if they knew
what was going on, so I gave a chalk talk about what we'd seen and where
we were heading. Dave Cleveland chipped in about the Gnu-Emacs hole,
and Wayne pointed out that we'd better discuss the hacker strictly by voice,
since he regularly read our electronic mail. The meeting broke up with
Boris and Natasha imitations.
      Tuesday, at 12:42 in the afternoon, Sventek's account lit up. Roy
called the laboratory police-they wanted to be in charge of the phone
traces. By the time Tymnet had unwound their network, Roy was shouting
over the phone. I could hear his side of the conversation.
      "We need a number traced. We have the search warrant. Now."
      Silence for a moment. Then he exploded.
      "I don't give a damn about your problems!! Start the trace now!"
      More silence.
      "If you don't get a trace immediately, you'll hear about it from the
Lab director." Roy slammed down the receiver.
      The boss was furious-his face turned purple. "Damn our police!
They've never handled a phone trace, and they don't know who to call at
the phone company!" Sheesh. At least his anger was aimed elsewhere.
      Perhaps it was for the best. The hacker disconnected within a couple
minutes, after just listing the names of the active users. By the time the
phone trace was started, there'd be no connection to trace.
      While the boss cooled off, I took the printout to study. There wasn't
much to summarize in my logbook. The hacker had just logged in, listed
the users, then logged off. Didn't even check the mail.

                                 S TO L L

      Aah! I saw why he logged off so fast. The system operator was around.
The hacker must know the sysops's name. He had raised periscope, seen the
enemy, then disappeared. Sure enough, looking back to other printouts, he
stayed around only when no operators were around. Paranoid.
      I talked with each of our operators, explaining this discovery. From
now on, they would run the system covertly, using pseudonyms.
      September 16 marked the end of the second week on the trail. I tried
working on optics again, but my mind kept drifting to the printouts. Sure
enough, just after noon, my terminal beeped: the hacker had returned.
      I called Tymnet, and then the boss. This time, we set up a conference
call, and I listened to the trace as I watched the hacker walk through our
      "Hi, Ron, it's Cliff. We need another trace on our Tymnet line, LBL,
Tymnet node 128, port 3."
      A minute of fumbling on the other end.
      "Looks like it's the third modem in our block of 1200-baud lines. That
would make it line 2903. That's 415/430-2903."
      "Thanks, Ron." The police heard this, and relayed it to Lee Cheng at
the phone company.
      "That's coming from the Franklin switch. Hold on." I was accustomed
to being put on hold by the phone company.
       I watched the hacker fire up the Gnu-Emacs move-mail file. He was
becoming super-user. He'd be on for at least another ten minutes. Maybe
long enough to complete a trace. Come on, Pac Bell!
      Three minutes passed by. Lee came back on line.
      "The line's active, all right. Connects to a trunk leading into Berkeley.
I've got a technician checking that line right now."
       Another two minutes pass by. The hacker's super-user now. He goes
straight for the system manager's mail files.
       "The Berkeley technician shows the line connecting to AT&T long
lines. Hold on." But Lee doesn't punch hold, and I listen in on his conversa-
tion with the Berkeley office. The guy in Berkeley insists that the line's
coming from far away; Lee's telling him to check it again. Meanwhile the
hacker is working on our password file. Editing it, I think, but I'm trying to
hear what's happening at the phone company.
       "It's our trunk group 369, and damn it, that's routed to 5096MCLN."
The Berkeley technician was speaking in tongues.

                  THE CUCKOO'S EGG

      "OK, I guess we'll have to call New Jersey." Lee seemed dismayed.
"Cliff, are you still there?"
      "Yeah. What's going on?"
      "No matter. Is he going to stay on much longer?"
      I watched the printout. The hacker left our password file and was
cleaning up his temporary files.
      "I can't tell. My guess is-oops, he's logged off."
      "Disconnected from Tymnet." Ron Vivier had been quiet until now.
      "Dropped off the phone line." Lee's trace disappeared.
      Our police officer came on line. "Well, gentlemen, what's the story?"
      Lee Cheng spoke first. "I think the call's coming from the East Coast.
There's a slight chance that it's a local Berkeley call, but . . . no, it's from
AT&T." Lee was thinking out loud, like a graduate student at an oral exam.
"All our Pacific Bell trunk lines are labeled with three digits; only the long-
distance trunks have four-digit identifiers. That line . . . let me look it
      I heard Lee type into his computer.
      Lee came back in a minute. "Hey, Cliff, do you know anyone in
Virginia? Maybe Northern Virginia?"
      "No. There's no particle accelerators near there. Not even a physics
lab. Of course, my sister's there . . ."
      "Think your sister's breaking into your computer?"
      Yeah, sure. My sister was a tech writer for the goddamn Navy. She
even attended night school at the Navy War College.
      "If she is," I replied, "I'm the pope of San Francisco."
      "Well then, we can't go any further today. Next time, I'll make the
trace faster."
       It was hard to imagine a faster trace. I'd taken five minutes getting
everyone on line. Ron Vivier had spent two minutes tracing the call
through Tymnet; it had taken Lee Cheng another seven minutes to snake
through several telephone exchanges. In a shade under a quarter hour, we'd
traced the hacker through a computer and two networks.
      Here was a conundrum. Sandy Merola felt the hacker came from the
Berkeley campus. Dave Cleveland was certain he came from anywhere
except Berkeley. Chuck McNatt from Anniston suspected someone from
Alabama. The Tymnet trace led to Oakland, California. Now Pacific Bell
said Virginia. Or was it New Jersey?
      With each session my logbook grew. It wasn't enough to just summa-

                                ST 0 L L

rize what had happened. I began to annotate each printout and search for
correlations between sessions. I wanted to know my visitor: understand his
wishes, predict his moves, find his address, and learn his name.
      While trying to coordinate the traces, I'd pretty much ignored what
the hacker was actually doing. After the tension died down, I hid in the
library with the printout from his most recent connection.
      Right off, it was obvious that the fifteen minutes which I'd watched
were only the coda of the hacker's work. For two hours, he had been
connected to our system; I'd only noticed him during the last quarter hour.
Damn. If only I'd detected him right away. Two hours would have been
enough to complete a trace.
      More damning, though, was why I hadn't noticed him. I'd been
watching for activity on Sventek's account, but he had used three other
accounts before touching Sventek's account.
      At 11:09 in the morning, some hacker had logged into an account
belonging to a nuclear physicist, Elissa Mark. This account was valid, billed
to the nuclear sciences department, though its owner had been on sabbatical
at Fermilab for the past year. It took just one phone call to find that Elissa
was unaware of anyone using her computer account; she didn't even know
if it still existed. Was this the same hacker that I'd been following? Or
someone else?
      I had no way of knowing in advance that the Mark account had been
hacked. But paging through the printout left little doubt.
      Whoever was using the Mark account had become super-user by
crawling through the Gnu-Emacs hole. As system manager, he searched for
accounts that hadn't been used in a long time. He found three: Mark, Goran
and Whitberg. The latter two belonged to physicists long departed from
our lab.
      He edited the password file and breathed life into the three dead
accounts. Since none of these accounts had been deleted, all their files and
accounting information remained valid. To steal these accounts, the hacker
needed to learn their passwords. But the passwords were protected by en-
cryption: our DES trapdoor functions. No hacker could cut through that
      With his purloined super-user powers, the hacker edited the system-
wide password file. He didn't try to decrypt Goran's encrypted password,
instead, he erased it. Now that the account had no password, the hacker
could log in as Goran.

                  THE CUCKOO'S EGG

       With this he disconnected. What's he up to? He couldn't crack pass-
words, but as super-user, he didn't have to. He just edited the password file.
       He reappeared a minute later as Goran, then chose a new password for
this account-Benson. The next time Rodger Goran tried to use our Unix
computer, he'd be frustrated to find his old password no longer worked.
       Our hacker had stolen another account.
       Aah-here's why the hacker stole old accounts. If he stole active
accounts, people would complain when their familiar passwords no longer
worked. So my adversary stole old accounts that weren't used anymore.
Robbing the dead.
       Even as super-user, he couldn't undo the DES trapdoor. So he couldn't
figure out someone else's password. But he could swipe passwords, with a
Trojan horse, or steal a whole account, by changing the password to a new
       Having stolen the Goran account, he then grabbed the Whitberg ac-
count. The hacker now controlled at least four accounts, Sventek,
Whitberg, Goran, and Mark, on two of our Unix computers. How many
other accounts did he hold? On which other systems?
       While running under Whitberg's pseudonym, the hacker tried to con-
nect through our Milnet link into three Air Force systems. After waiting a
minute for those distant computers to respond, he gave up, and started
listing files belonging to LBL folks. He grew tired of this after reading a
few scientific papers, several boring research proposals, and a detailed de-
scription of how to measure the nuclear cross section of some beryllium
isotope. Yawn. Breaking into computers sure wasn't the key to power, fame,
and the wisdom of the ages.
       Getting into our two Unix systems hadn't satisfied my voracious foe.
He'd tried hurdling the moat around our secured Unix-8 computer, but
failed-Dave had sealed off that machine. Frustrated at this, he printed a list
of remote computers available from our site.
       Nothing secret there, just the names, phone numbers, and electronic
addresses for thirty Berkeley computers.

                                S TaL L

o     0 0 With the full moon, I expected more hacking and planned
on sleeping under the desk. The hacker didn't show up that evening, but
Martha did. Around seven, she biked up, bringing a thermos of minestrone
and some quilting to keep me occupied. There's no shortcut to hand stitch-
ing a quilt. Each triangle, square, and parallelogram must be cut to size,
ironed, assembled, and sewn to its neighbors. Up close, it's hard to tell the
pieces from the scraps. The design becomes visible only after the scraps are
discarded, and you stitch the pieces together. Hmmm. A lot like understand-
ing this hacker.
      Around 11:30, I gave up my watch. If the hacker wanted to show up
at midnight, the printers would catch him anyway.
      The next day, the hacker turned up once. I missed him, preferring to
share lunch with Martha just off campus. It was worth it: on a street corner,
a jazz band played 1930s tunes.
      The singer belted out some '30s ditty, "Everybody loves my baby, but
my baby loves nobody but me."
      "That's absurd," Martha said between tunes. "Logically analyzed, the
singer must be his own baby."
      "Huh?" It sounded fine to me.
      "Look. 'Everybody' includes my baby. Since 'Everybody loves my
baby,' then my baby loves herself. Right?"
      "Uh, yeah." I tried to follow.
      "But then he says, 'My baby loves nobody but me.' So my baby, who
must love herself, cannot love anyone else. Therefore, my baby must be
      She explained it twice before I understood. The singer had never
learned elementary logic. Neither had 1.
      By the time I returned from lunch, the hacker was long gone, leaving
his trail on a paper printout.
      For once, he didn't become super-user. Yes, in his paranoid way, he
 checked for systems people and monitoring processes, but he didn't sneak
 through the hole in the operating system.

                  THE CUCKOO'S EGG

      Instead, he went fishing over the Milnet.
      A single isolated computer, out of communication with the world, is
immune to attack. But a hermit computer has limited value; it can't keep up
with what's happening around it. Computers are of the greatest use when
they interact with people, mechanisms, and other computers. Networks let
people share data, programs, and electronic mail.
      What's on a computer network? What do computers have to say to
each other? Most personal computers satisfy the needs of their owners, and
don't need to talk to other systems. For word processing, accounting spread-
sheets, and games, you really don't need any other computers. But hook up
a modem to your computer, and your telephone will report the latest from
the stock market, news wires, and rumor mills. Connecting to another
computer gives you a powerful way to tune in the latest news.
      Our networks form neighborhoods, each with a sense of community.
The high-energy physics networks transfer lots of data about subatomic
particles, research proposals, as well as gossip about who's pushing for a
Nobel prize. Unclassified military networks probably pass along orders for
shoes, requests for funding, and rumors of who's jockeying for base com-
mander. Somewhere, I'll bet there are classified networks, to exchange secret
military orders and top secret gossip like who's sleeping with the base
      These electronic communities are bounded by the limits of their com-
munications protocols. Simple networks, like public bulletin boards, use the
simplest ways to communicate. Anyone with a personal computer and a
telephone can link into them. Advanced networks require leased telephone
lines and dedicated computers, interconnecting hundreds or thousands of
computers. These physical differences set boundaries between networks. The
networks themselves are linked together by gateway computers, which pass
reformatted messages between different networks.
      Like Einstein's universe, most networks are finite but unbounded.
There's only a certain number of computers attached, yet you never quite
reach the edge of the network. There's always another computer down the
line. Eventually, you'll make a complete circuit and wind up back where
you started. Most networks are so complicated and interwoven that no one
knows where all their connections lead, so most people have to explore to
find their way around.
      Our lab's computers connect to a dozen computer networks. Some of
them are local, like the ethernet that ties computers in one building to a lab

                                ST 0 L L

next door. Other nets reach to an extended community: the Bay Area
Research Net links a dozen northern California universities. Finally, the
national and international networks let our scientists connect to computers
around the world. But the premier network is the Internet.
      In the mid 1950s, the Federal government started building the inter-
state highway system, a twentieth-century marvel of pork-barrel public-
works politics. With memories of wartime transportation shortages, mili-
tary leaders made certain that the interstate system could handle tanks,
military convoys, and troop carriers. Today, few think of interstate high-
ways as a military system, though they're just as capable of sending tanks
across the country as trucks.
      With the same reasoning, the Department of Defense began develop-
ing a network to link military computers together. In 1969, the Defense
Advanced Research Projects Agency's (DARPA) experiments evolved into
the Arpanet and then into the Internet: an electronic highway interconnect-
ing a hundred-thousand computers around the world.
      In the world of computing, the Internet is at least as successful as the
interstate system. Both have been overwhelmed by their success, and every-
day carry traffic far beyond what their designers dreamt. Each regularly
inspires complaints of traffic jams, inadequate routes, shortsighted planning,
and inadequate maintenance. Yet even these complaints reflect the phenome-
nal popularity of what was an uncertain experiment only a few years ago.
      At first, DARPA's network was simply a testbed to prove that com-
puters could be linked together. Since it was seen as an unreliable experi-
ment, universities and laboratories used it, and mainstream military people
ignored it. After eight years, only a few hundred computers connected into
the Arpanet, but gradually, others were attracted by the network's reliability
and simplicity. By 1985 the network directory listed tens of thousands of
computers; today, there must be over one hundred thousand. Taking a
census of networked computers would be like counting the cities and towns
reachable from the interstate system-it's hard to name many places which
can't be reached via some convoluted route.
      The network's growing pains have been reflected in name changes. The
first Arpanet was a backbone connecting random university, military, and
defense contractor computers. As military people grew to depend on the
network for carrying messages and mail, they decided to split the network
into a military portion, the Milnet, and a research section, the Arpanet.
      But there's not much difference between the military and academic

                   THE CUCKOO'S EGG

nets, and gateways let traffic flow between them. Indeed, any Arpanet user
can connect to any Milnet computer without so much as an invitation.
Together, the Arpanet, Milnet, and a hundred other networks make up the
     There are thousands of university, commercial, and military computers
connected through the Internet. Like buildings in a city, each has a unique
address; most of these addresses are registered at the Network Information
Center (NIC) in Menlo Park, California. Anyone computer may have
dozens or hundreds of people using it, so individuals as well as computers
are registered in the NIC.
     The NIC's computers provide a directory: just connect to the NIC and
ask for someone, and it'll tell you where they're located. They don't have
much luck keeping their database up to date (computer people change jobs
often), but the NIC still serves as a good phone directory of computer
     During my lunch break, the hacker ducked into the NIC. Our printer
quietly saved the session as he searched the NIC for the abbreviation,

     LBL> telnet NICARPA The hacker asks for the Network Information Center
     Connected to I.
     Escape character is  'I\r
     + ------------------DDN Network Information Center-----------------------
     I For user and host information, type:                  WHOIS 
     I For NIC information, type:                            NrC 
     @ whois wsmr He searches for WSMR
     White Sands Missile Range WSMR-NET-GW.ARMY.MIL               
     White Sands Missile Range WSMR-TRAPSARMY.MIL                 
     White Sands Missile Range WSMR-AIMS.ARMY.MIL                 
     White Sands Missile Range WSMR-ARMTE-GW.ARMY.MIL                       128.44.4. J
     White Sands Missile Range WSMR-NELARMY.MIL                   

     WSMR? White Sands Missile Range. With two commands and
twenty seconds, he found five computers at White Sands.
     Astronomers know Sunspot, New Mexico, as one of the finest solar
observatories. Clear skies and great telescopes make up for the utter isolation
of Sacramento Peak, a few hundred miles south of Albuquerque. The only

                                   S TaL L

road to the observatory runs through White Sands, where the Army tests
their guided missiles. Once, when I was studying the solar corona, an ob-
serving run took me to Sunspot, past the desolation of White Sands. The
locked gates and guardhouses discourage onlookers; if the sun doesn't fry
you, the electric fences will.
       I'd heard rumors that the Army was designing rockets to shoot down
satellites. Seemed like an SDI/Star Wars project, but civilian astronomers
can only guess. Maybe this hacker knew more about White Sands than I
     No doubt, though, that the hacker wanted to know more about White
Sands. He spent ten minutes trying to log into each of their computers,
connecting to them over the Internet.
     The printer recorded his steps:

     LBL> telnet WSMR-NET-GW.ARMY.MIL connect to a White Sands computer
     Connected to WSMR-NET-GWARMY.MIL

     4.2 BSD UNIX
     Welcome to White Sands Missile Range
     login: guest                                Try the guest account
     Password: guest                             Guesses a password
     Invalid password, try again                 But no luck
     login: visitor                              Try another likely account name
     Password: visitor
     Invalid password, try again                 No luck
     login: root                                 He tries yet another account
     Password: root
     Invalid password, try again                 Still no luck
     login: system                               And a fourth try
     Password: manager
     Invalid password, disconnecting after 4 tries

      For each computer, he tried to log in as guest, visitor, root, and system.
We saw him failing, time after time, as he tried to guess passwords. Perhaps
those accounts were valid; the hacker couldn't enter them because he didn't
know the right passwords.
      I smiled at the printout. No doubt, the hacker wanted to get into
White Sands. But they didn't fool around with security. Between their
electric fences and passwords, neither tourist nor hacker could enter. Some-
one at White Sands had locked their doors.

                  THE CUCKOO'S EGG

      With a snicker, I showed his attempts to the boss, Roy Kerth.
      "Well, what do we do about it?" I asked. "Since he didn't get into
White Sands, should we tell them?"
      "Hell, yes, we'll tell them," Roy responded. "If someone tries to break
into my neighbor's house, I'll tell 'em. I'll call the cops, too."
      I asked what cops were in charge of the Internet.
      "Damned if I know," Roy said. "But here's our policy, from here out:
anyone that's attacked, we tell them. I don't care if the hacker didn't get in,
you call them on the phone and tell them. Remember, keep this out of
electronic mail. And find out who the cops are."
      It took only one phone call to find out that the FBI wasn't policing
the Internet. "Look, kid, did you lose more than a half million dollars?"
      "Uh, no."
      "Any classified information?"
     "Uh, no."
      "Then go away, kid." Another attempt at rousing the feds had failed.
      Maybe the Network Information Center would know who policed
their net. I called Menlo Park and eventually found Nancy Fischer. To her,
the Internet wasn't just a collection of cables and software. It was a living
creature, a brain with neurons extending around the world, into which ten
thousand computer users breathed life every hour. Nancy was fatalistic: "It's
a miniature of the society around us. Sooner or later, some vandal's going to
try to kill it."
      It seemed that there were no network police. Since the Milnet-now
called the Defense Data Network-isn't allowed to carry classified data,
nobody paid much attention to its security.
      "You ought to be talking to the Air Force Office of Special Investiga-
tions," she said. "They're the narcs of the Air Force. Drug busts and
murders. Not exactly white-collar crime, but it can't hurt to talk to them.
I'm sorry I can't help you, but it's really not my bailiwick."
      Three phone calls later, I'm in a conference call with Special Agent Jim
Christy of the AFOSI and Major Steve Rudd of the Defense Communica-
tions Agency.
      Jim Christy made me nervous-he sounded like a narc. "Let me get
this straight. Some hacker broke into your computer, then got into an Army
computer in Alabama, and is now going for White Sands Missile Range?"
      "Yes, that's about what we've seen." I didn't want to explain the Unix

                                  ST 0 L L

Gnu-Emacs security hole. "Our traces aren't complete yet; he might be
from California, Alabama, Virginia, or maybe New Jersey."
      "Oh . . . you're not shutting him out so that you can catch the
bastard." He was ahead of me.
      "And if we close him out, he'll just enter the Internet through some
other hole."
      Steve Rudd, on the other hand, wanted the hacker nailed. "We can't
let this continue. Even without classified information, the Milnet's integrity
demands that spies be kept out."
      Spies? My ears pricked up.
      The narc spoke next. "I don't suppose the FBI has lifted a finger."
      I summarized our five calls to the FBI in one word.
      Almost apologetically, Jim Christy told me, "The FBI isn't required to
investigate every crime. Probably they look at one in five. Computer crimes
aren't easy-not like kidnapping or bank robbery, where there's witnesses
and obvious losses. Don't blame them for shying away from a tough case
with no clear solution."
       Steve pressed Jim, "OK, so the FBI won't do anything. How about
      Jim answered slowly, "We're the Air Force computer crime investiga-
tors. We usually hear about computer crimes only after a loss. This is the
first one that we've come across in progress."
       Steve cut in, "Jim, you're a special agent. The only difference between
you and an FBI agent is your jurisdiction. Doesn't this fall in your court?"
       "It does. It's a strange case that falls in several courts." Over the phone,
I could almost hear Jim think. "We're interested, all right. I can't tell if this
is a serious problem or a red herring, but it's well worth investigating."
      Jim continued, "Look, Cliff. Each agency has thresholds. Our re-
sources are finite so we're forced to choose what we investigate. That's why
the FBI asked you about the dollar loss-they're looking to get the most
bang for their effort. Now if classified stuff gets stolen, it's a different story.
National security doesn't equate to dollars."
       Steve interrupted, "But unclassified information can also equate to
national security. The problem is convincing law enforcement people."
       "So what'll you do?" I asked.
       "Right now, there's really not much we can do. If this hacker's using
 the military networks, though, he's walking on our territory. Keep us in-
formed and we'll sharpen our stingers."

----   -----------------------------------
                         THE CUCKOO'S EGG

             In hopes of encouraging AFOSI, I sent Jim a copy of my logbook, and
       samples of the hacker's printouts.
             After this conversation, Jim Christy explained about the Milnet. What
       I called the Milnet, Jim knew as the unclassified Defense Data Network, run
       by the Defense Communications Agency. "The Department of Defense runs
       the Milnet for all the services-Army, Navy, Air Force, and Marines. That
       way, each service has equal access to the network, and you'll find computers
       from every branch on the net."
             "So why is Steve Rudd in the Air Force?"
             "He's really a purple-suiter-he works for all three branches. Natu-
       rally, when he smelled a problem, he called the Air Force investigators."
             "And you work full time on computer crime?"
             "You betcha. We're watching ten thousand Air Force computers."
             "Then why can't you wrap up this case in a snap?"
             Jim spoke slowly, "We've got to clearly define our territory. Unless
       we do, we step on each other's toes. You, Cliff, have no worries that you'll
       be busted by the OSI-our bailiwick is the Air Force base."
             Bailiwicks always belong to someone else.
             You know, much as I complained about bailiwicks, I realized that they
       protected my own rights: our constitution prevents the military from grub-
       bing around civilian affairs. Jim had put this into a new light-sometimes
       these rights actually do interfere with law enforcement. For the first time, I
       realized that my civil rights actually limit what police can do.
             Whoops. I'd forgotten the boss's instructions to call White Sands.
       Another few minutes on the phone, and I reached Chris McDonald, a
       civilian working for the missile range.
              I outlined the case-Unix, Tymnet, Oakland, Milnet, Anniston,
       AFOSI, FBI.
              Chris interrupted, "Did you say Anniston?"
              "Yes, the hacker was super-user at Anniston Army Depot. It's a little
       place in Alabama, I think."
              "I know Anniston, all right. They're our sister Army base. After we
       test our missiles, we ship 'em off to Anniston," Chris said. "And their
       computers come from White Sands as wel1."
              I wondered if this was just coincidence. Perhaps the hacker had read
       data in the Anniston computers, and realized that the good stuff came from
       White Sands. Maybe the hacker was sampling every site where the Army
       stored missiles.

                                S TaL L

      Or maybe the hacker had a list of computers with security holes. "Say,
Chris, do you have Gnu-Emacs on your computers?"
      Chris didn't know, but he'd ask around. But to exploit that hole, the
hacker had to log in first. And the hacker had failed, after trying four times
on each of five computers.
      White Sands kept their doors locked by forcing everyone on their
computers to use long passwords, and to change them every four months. A
technician wasn't allowed to choose her own password-the computer as-
signed unguessable passwords, like "agnitfom" or "nietoayx." Every ac-
count had a password, and none could be guessed.
      I didn't like the White Sands system. I couldn't remember computer-
generated passwords, so I'd write them in my wallet or next to my terminal.
Much better to allow people to choose their own passwords. Sure, some
people would pick guessable passwords, like their names. But at least they
wouldn't complain about having to memorize some nonsense word like
"tremvonk," and they wouldn't write them down.
      But the hacker got into my system and was rebuffed at White Sands.
Maybe random passwords, obnoxious and dissonant, are more secure. I don't
      I'd followed the boss's orders. The FBI didn't care about us, but the
Air Force sleuths were on the case. And I'd notified White Sands that
someone was trying to break in. Satisfied, I met Martha at a vegetarian pizza
stand. Over slices of thick-crust spinach and pesto, I described the day's
      "Vell, Natasha, we have accomplished mission one."
      "Vonderful, Boris, vhat a victory. Boris . . . vhat is mission one?"
      "We have made rendezvous vith ze secret air force police, Natasha."
      "Yes, Boris?"
      "Ve have alerted ze missile base to ze counter-counter-intelligence
      "Yes, Boris?"
      "And we have ordered ze secret spy pizza."
      "But Boris, ven do we catch ze spy?"
      "Patience, Natasha. Zat is mission two."
      It wasn't until we started walking home that we got to the serious side
 of our game.
      "This thing is getting weirder and weirder," Martha said. "It started
 out as a hobby, chasing some local prankster, and now you're talking to

                  THE CUCKOO'S EGG

these military people who wear suits and have no sense of humor. Cliff,
they're not your type."
      I defended myself stuffily, "This is a harmless and possibly beneficial
project to keep them busy. After all, this is what they're supposed to be
doing-keeping the bad guys out."
      Martha wouldn't let that sit. "Yeah, but what about you, Cliff. What
are you doing hanging out with these people? I understand that you have to
at least talk to them, but how deeply are you getting involved?"
      "Every step makes perfect sense from my point of view," I said. "I'm a
system manager trying to protect my computer. If someone hacks into it, I
have to chase him. To ignore the bastard will let him wreck other systems.
Yes, I'm cooperating with the Air Force police, but that doesn't mean I
approve of everything the military stands for."
      "Yes, but you have to decide how you want to live your life," Martha
said. "Do you want to spend your time being a cop?"
      "A cop? No, I'm an astronomer. But here's someone threatening to
destroy our work."
      "We don't know that," Martha retorted. "Maybe this hacker is closer
to us politically than those security people. What if you're chasing someone
on your own side? Perhaps he's trying to expose problems of military
proliferation. Some sort of electronic civil disobedience."
      My own political views hadn't evolved much from the late 1960s
. . . a sort of fuzzy, mixed bag of the new-left. I'd never thought much
about politics, feeling that I was a harmless non-ideologue, trying to avoid
unpleasant political commitments. I resisted radical left-wing dogma, but I
sure wasn't a conservative. I had no desire to buddy up with the feds. Yet
here I was, walking side by side with the military police.
      "About the only way to find out who's at the other end is to trace the
wires," I said. "These organizations may not be our favorites, but the partic-
ular actions that we're cooperating over aren't bad. It's not like I'm running
guns to the Contras."
      'Just watch your step."

                                ST 0 L L

o     0 0 My three weeks were almost up. If I didn't catch the hacker
within twenty-four hours, the lab would shut down my tracking operation.
I camped out in the switchyard, jumping at every connection. "Come into
my parlor," said the spider to the fly.
     Sure enough, at 2:30 in the afternoon, the printer advanced a page, and
the hacker logged in. Although this time he used the stolen account, Goran,
I didn't doubt that it was the hacker: he immediately checked who was on
the computer. Finding no operator present, he searched out the Gnu-Emacs
security hole, and started his delicate minuet to become super-user.
      I didn't watch. A minute after the hacker connected, I called Ron
Vivier at Tymnet and Lee Cheng at the phone company. I took notes as
Ron mumbled, "He's coming into your port 14, and entering Tymnet from
Oakland. It's our port 322 which is, uh, let me see here." I could hear him
tapping his keyboard. "Yeah, it's 2902. 430-2902. That's the number to
     Lee Cheng popped on the phone line. "Right. I'm tracing it." More
keytaps, this time with a few beeps thrown in. "That line is live, all right.
And it's coming from AT&T. AT&T in Virginia. Hold on, I'll call New
      I listened in as Lee talked with some AT&T guy named Edsel (or was
it Ed Sell?) in Whippany, New Jersey. Apparently, all of AT&T's long-
distance phone lines are traced through New Jersey. Without understanding
the jargon, I transcribed what I heard. "Routing 5095, no that's
     Another technician's voice broke in. "I'll call McLean."
      The New Jersey technician came back. "Yeah. 5096 terminates in 703
       There were suddenly six people on the line. The phone company's
conference calls were crisp and loud. The newest member of the conference
call was a woman with a slight drawl. "Y'all are trunked into McLean, and
it's almost dinnertime here at C and P."

                  THE CUCKOO'S EGG

      Lee's clipped voice interrupted her. "Emergency trace on routing code
5096MCLN, your termination line 427."
      "I copy 5096MCLN line 427. I'm tracing right now."
      Silence for a minute, then she came back on line. "Here it comes, boys.
Hey, it looks like it's from 415 territory."
      "Yeah. Greetings from San Francisco Bay," Lee slid in.
      She spoke to no one in particular. "Trunk group 5096MCLN, routing
427 winds up in 448. Our ESS4 at 448. Is it a PBX?" She answered her own
question: "No, it's a rotary. Frame twenty-four. I'm almost at the tip ring
sleeve. Here we are. Five hundred pair cable, group three number twelve
. . . that's ten, uh, ten sixty. You want me to confirm with a short drop-
      Lee interpreted her jargon. "She's completed the trace. To make sure
that she's traced the right number, she wants to turn off the connection for a
second. If she does that, it'll hang up the line. Is that OK?"
      The hacker was in the midst of reading some electronic mail. I
doubted that he'd miss a few characters. "Sure. Tell her to go ahead, and I'll
see what happens here."
      Lee talked with her a bit, and announced with certainty, "Stand by."
He explained that each telephone line has a set of fuses in the central
switching office; they protect the equipment from lightning and idiots that
plug their phone lines into power outlets. The central office technician can
go to the cable room and pull the line's fuse, forcing it to hang up. It wasn't
necessary, but it double checked their tracing efforts.
      In a minute, the central office tech came onto the line and said, "I'm
popping the fuse . . . now." Sure enough, the hacker dropped off, right in
the middle of a command. They'd traced the right line.
      The woman's voice came on. "It's 1060, all right. That's all, boys. I'll
shuffle some tissues and ship it on upstairs."
       Lee thanked everyone, and I heard the conference call clear. "The trace
is complete and the technician's writing it up. As soon as I get the trace data,
I'll give it to the police."
       I didn't understand. Why didn't he just tell me the owner of the
       Lee explained that the telephone company dealt with the police, not
with individuals. Moreover, he didn't know where the line had been traced
to. The tech that completed the trace would fill out the proper papers (aah!
"shuffiing tissues") and release them to the authorities.

                                ST 0 L L

       I protested, "Can't you just short-circuit the bureaucracy and tell me
who the hacker is?"
       No. First, Lee didn't have the trace information. The technician in
Virginia did. Until the Virginia phone company released it, Lee knew as
little as I did.
       Lee pointed out another problem: my search warrant was only valid in
California. A California court couldn't compel the Virginia telephone com-
pany to turn over evidence. We'd need either a Virginia or Federal court
       I protested, "The FBI's turned us down five times already. And the
guy's probably not breaking any Virginia law. Look, can't you give me the
phone number on the side and just wink?"
       Lee didn't know. He'd call Virginia and try to convince them to give
us the information, but he didn't hold out much hope. Damn. At the other
end of the phone line, someone was breaking into military computers, and
we couldn't even get his phone number, ten seconds after the line was
       The phone trace was complete, though not quite successful. How do
we get a Virginia search warrant? My boss, Roy Kerth, was gone for the
next couple weeks, so I called the lab's lawyer directly. To my surprise,
Aletha paid serious attention to the problem. She'd rattle the FBI again, and
see whether we had a case in Virginia. I warned her that, as a peon, I had no
authority to even be talking to her, let alone asking for legal services. She
reassured me, "Don't be silly. This is more fun than worrying about patent
       The laboratory police wanted to know all about the phone trace. I told
them to prepare to stake out the entire state of Virginia. Despite my cyni-
cism, they were surprisingly sympathetic to my problem with the Virginia
search warrant, and offered to use their old-boy-network to get the infor-
mation through some informal channel. I doubted it would work, but why
not let them try?

                     THE CUCKOO'S EGG

o     0 0 The phone company might conceal the hacker's phone
number, but my printers showed his every move. While I talked to Tymnet
and the telephone techs, the hacker had prowled through my computer. He
wasn't satisfied reading the system manager's mail; he also snooped through
mail for several nuclear physicists.
      After fifteen minutes of reading our mail, he jumped back into Goran's
stolen account, using his new password, Benson. He started a program that
searched our user's files for passwords; while that executed, he called up the
Milnet Network Information Center. Again, he knew who he was looking

    Connected to
     + ------------------DDN Network Information Center---------------------l
    I For TAC news. type:                        TACNEWS 
    I For user and host information, type:       WHOIS 
    I For NIC information, type:                 NIC 
    + -----------------------------------------------------------------------------------l
  SRI-NIC, TOPS-2O Monitor 6.1(7341)-4
   Central Intelligence Agency 1CIA)
     Office of Data Processing
     Washington, DC 20505
     There are 4 known members:
  Fischoff, J. (JF27)                FISHOFF@AISI.EDU                     1703/351-3305
  Gresham, D. L (DLG33)              GRESHAM@AISI.EDU                     (703) 351-2957
  Manning, Edward J. (EM44)          MANNING@88N.ARPA                     (703) 281-6161
  Ziegler, Mary IMZ9j                MARY@NNS.ARPA                        (703) 351-8249

     He had asked for the pathway into the CIA. But instead of their
computer, he found four people who worked at the CIA.
     Whee! I pictured all these CIA spies playing cloak-and-dagger; mean-
while, someone's pushing on their backdoor.
     So I asked myself, "Should I tell them?"

                                 ST 0 L L

      "No. Why waste my time telling them? Let some spy run around in
the CIA's backyard. See if I care. My three weeks of chasing the hacker are
up. It's about time to shut our doors and work on real problems of physics
and astronomy. He's someone else's problem now."
      And yet it didn't feel right. The hacker walked through military
computers, yet nobody noticed. The CIA didn't know. The FBI didn't care.
Who would pick up where we left off?
      I reached for the telephone to call the people listed in the CIA, then
put it down. What's a long-haired hippie doing calling some spooks? What
would Martha say?
      Well, whose side was Ion? Not the CIA's, for sure. But then, I wasn't
rooting for someone to break in there, either. At least I didn't think so.
      Foo. The jerk was trying to slither into sorneone's computer. Nobody
else will warn them, so I'd better. I'm not responsible for the CIA's actions,
only my own.
      Before I could change my mind again, I called the first CIA guy's
phone number. No answer. The second guy was on vacation-his answer-
ing machine said so. The third person . . .
      A business voice answered, "Extension 6161."
      I stammered a bit, "Urn, hello, I'm looking for Ed Manning."
      I didn't know where to begin. How do you introduce yourself to a
spy? "Uh, you don't know me, but I'm a computer manager, and we've
been following a computer hacker."
      "Well, he searched for a pathway to try to get into the CIA's com-
puters. Instead, he found your name and phone number. I'm not sure what
this means, but someone's looking for you. Or maybe they're just looking
for the CIA and stumbled on your name." I'm floundering, scared of the
guy I'm talking to.
      "Who are you?"
      Nervously, I told him, expecting him to send over a gang of hit men
in trench coats. I described our laboratory, making sure he understood that
the People's Republic of Berkeley didn't have official diplomatic relations
with his organization.
      "Can I send someone over tomorrow? No, that's Saturday. How about
Monday afternoon?"
      Uh oh. The hit men were on their way. I tried to backpedal. "This

                  THE CUCKOO'S EGG

probably isn't serious. The guy didn't find anything except four names. You
don't have to worry about him getting into your computer."
      Mr. Manning wasn't convinced. "I know why my name's listed. Last
year I worked on some computers at the Ballistics Research Lab. But we're
professionally interested in this, and we'd appreciate a chance to learn more.
Conceivably, this might be a serious problem."
      Who was I talking to? Weren't these the people who meddle in Cen-
tral American politics and smuggle arms to right-wing thugs? Yet the guy
I'd just talked to didn't sound like a villain. He seemed like an ordinary
person concerned with a problem.
      And why not set them on the trail of someone just as meddlesome and
destructive as I always thought they were? Tracking down a real wrongdoer
would give the CIA something harmless, perhaps even beneficial, to do-
keep them out of trouble.
      It was no use arguing. They needed to know, and I couldn't see a good
reason to avoid telling them. And talking to the CIA wouldn't hurt anyone
-it wasn't like shipping guns to a military dictator. After all, isn't this
what they're legitimately supposed to do: protect us from bad guys? If I
don't tell them what's happening, who will?
      I couldn't help comparing the CIA's immediate reaction with the
response I got from the FBI. Six calls for help, and a half dozen responses,
"Go away, kid."
      Well, I agreed to meet with his agents, provided they didn't wear
trench coats.
      "Now I've put my foot in it," I thought. "Not only am I talking to
the CIA, but I'm inviting them up to Berkeley. What'11 I tell my radical

                                ST 0 L L

o      0 0 Windmill Quarry is just across the Niagara River from
Buffalo, New York, where I grew up. It's a ten-mile bicycle ride, across the
Peace Bridge to Canada and down a few winding roads to the finest swim-
ming hole around. If you dodge the potholes and speak politely to the u.s.
and Canadian customs agents, you'll have no problems.
      High school had just let out in June of 1968 when I biked over to
Windmill Quarry for a Saturday swim. Two other friends and I wore
ourselves out trying to swim to the raft in the middle of the water. Around
six, we ran out of steam, hopped on our bikes, and headed back to Buffalo.
      Three miles shy of the Peace Bridge, we were pedaling along the stony
margins of a country road when a pickup truck crowded us off the roadside.
Someone swore at us and tossed a half-empty can of Genessee beer, hitting
our lead rider. She wasn't hurt but all three of us were furious.
      We were on our bikes. No way to catch up with the SOBs. Even if
we could, what would we do? We were three miles inside of Canada, after
all. We were powerless, unable to retaliate.
      But I'd caught a glimpse of the license plate. From New York State.
Oh . . . they're returning to Buffalo, too. Then it hit me.
      I stopped at the first phone booth-luckily there was a directory-and
called the U.S. customs agents. "There's a green Chevy pickup truck head-
ing for the Peace Bridge," I reported. ''I'm not sure, but I think they're
carrying some drugs." The agent thanked me, and I hung up.
      The three of us biked back at a leisurely pace. We got to the bottom of
the bridge, looked over at the side of the road . . . and my heart sang!
Sure enough, there was that green pickup, hood up, seat pulled out, and two
wheels removed. Customs agents were crawling all over it, searching for
      Aah. The sense of recovered dignity.
      Years ago, I hadn't asked that clown to throw a beer can at us. Nor
today had I asked this hacker to invade my computer. I didn't want to track
him around the networks. I'd rather be doing astronomy.
      But now that I'd evolved a strategy, I could only follow the hacker by

                  THE CUCKOO'S EGG

being sneaky and tenacious. And by informing the few authorities that
seemed to care. Like the CIA.
      Roy was on vacation, so not only couldn't he tell me to drop the
investigation now that my three weeks were up, but he couldn't say any-
thing about the CIA visiting. His stand-in, Dennis Hall, was to greet the
      Dennis is a tranquil, introspective Zen master whose job is to link
small computers to Cray supercomputers. He sees networks as channels to
slosh computing power from laboratories to desktops. Little computers
should talk to people; leave the number crunching to the mainframes. If
your desktop workstation's too slow, then move the hard work into a
bigger computer.
       In a sense, Dennis is the enemy of computer centers. He wants people
to use computers without the mumbo jumbo of programming. As long as
there are software wizards and gurus, Dennis won't be satisfied with the
distribution of computing power.
      His is a world of ethernets, optical fibers, and satellite links. Other
computer folks measure size in megabytes of memory, and speed in
megaflops-millions of floating-point-operations per second. To Dennis,
size is measured by counting computers on your network; speed is measured
in megabytes per second-how fast the computers talk to each other. The
system isn't the computer, it's the network.
       Dennis saw the hacker problem in terms of social morality. "We'll
always find a few dodos poking around our data. I'm worried about how
hackers poison the trust that's built our networks. After years of trying to
hook together a bunch of computers, a few morons can spoil everything."
       I didn't see how trust had anything to do with it. "Networks are little
more than cables and wires," I said.
       "And an interstate highway is just concrete, asphalt, and bridges?"
Dennis replied. "You're seeing the crude physical apparatus-the wires and
communications. The real work isn't laying wires, it's agreeing to link
isolated communities together. It's figuring out who's going to pay for the
maintenance and improvements. It's forging alliances between groups that
don't trust each other."
       "Like the military and universities, huh?" I said, thinking of the In-
       "Yes, and more. The agreements are informal and the networks are
overloaded," Dennis said. "Our software is fragile as well-if people built

                                 ST 0 L L

houses the way we write programs, the first woodpecker would wipe out
      With the CIA due in ten minutes, Dennis and I talked about what to
say. I had no idea what they wanted, other than a listing of last Friday's
activity. I could imagine them: some secret agent looking like James Bond,
or a hit man specializing in rubouts. Of course there'd be Mr. Big behind
them all, pulling the puppet strings. They'd all be in dark glasses and trench
      Dennis gave me instructions. "Cliff, tell them what we know, but
don't speculate. Confine yourself to facts."
      " 'S'all reet. But suppose there's a hit man with 'em, who wants to rub
me out because I found that they're spying on the military?"
      "Be serious." Everyone told me to be serious. "And for once, be
polite. They've got enough problems without a raving Berkeley longhair.
And skip the yo-yo tricks."
     "Yes, Daddy. I'll be good. I promise."
     "Don't worry about them. They're like anyone else around here, ex-
cept a bit more paranoid."
     "And a bit more Republican," I added.
     OK, so they didn't wear trench coats. Not even sunglasses. Instead,
boring suits and ties. I should have warned them to dress like the natives:
beat-up dungarees and flannel shirts.
     Wayne saw the four of them walk up the drive and flashed a message
to my terminal: "All hands on deck. Sales reps approach through starboard
portal. Charcoal-gray suits. Set warp speed to avoid IBM sales pitch." If
only he knew.
     The four spooks introduced themselves. One guy in his fifties said he
was there as a driver, and didn't give his name-he just sat there quietly the
whole time. The second spy, Greg Fennel, I guessed to be a computer
jockey, because he seemed uncomfortable in a suit.
     The third agent was built like a halfback. Teejay didn't give his last
name-or did he conceal his first name? If anyone was the hit man, Teejay
was. The fourth guy must be the bigwig: everyone shut up when he talked.
Together, they looked more like bureaucrats than spies.
     The four of them sat quietly while Dennis gave them an overview of
what we'd seen. No questions. I walked to the chalkboard and drew a

                                ST 0 L L

     Greg Fennel wouldn't let me get away with just a drawing. "Prove the
connection from the phone company to Tymnet."
     I described the phone trace and the conference calls to Ron Vivier.
     "Since he's not erasing anything, how did you detect him?"
     "A hiccup in our accounting system, you see, he imbalanced our ac-
counts when he . . ."
     Greg interrupted, "So he's super-user on your Unix system? Bad news,
huh?" Greg seemed to be a sharp systems guy. I figured I might as well go
into detail.
      "It's a bug in the Gnu-Emacs editor. Its mail utility runs with root
privilege." Technical questions were easy.
      We talked Unix for a bit, and Mr. Big started playing with his pencil.
"Can you give us a profile of this guy? How old is he? What's his level of
      Tougher question. "Well, we've only watched him for three weeks, so
it's hard to say. He's accustomed to AT&T Unix, so he's not from around
Berkeley. Perhaps he's a high school student. He's paranoid, always looking
over his shoulder, yet patient, and not very creative."
      "Does he know English?"
     "Well, we think that he once sent mail to our system manager, saying,
'Hello.' After sending that message, he never again used that account."
     Teejay, silent until now, asked "Is he recording his sessions?"
     "I can't tell for certain, but I think that he's keeping a notebook. At
the very least, he's got a good memory."
     Mr. Big nodded and asked, "What keywords has he scanned for?"
     "He looks for words like password, nuclear, SDI, and Norad. He's
picked some curious passwords-lblhack, hedges, jaeger, hunter, and benson.
The accounts he stole, Goran, Sventek, Whitberg, and Mark don't say much
about him because they are names of people here at the laboratory."
     Teejay suddenly lit up. He passed a note to Greg. Greg passed it on to
Mr. Big, who nodded and asked, "Tell me what did he do at Anniston?"
     "I don't have much of a printout there," I said. "He was into their
system for several months, perhaps as long as a year. Now, since he knows
they've detected him, he logs in only for a moment."
     Mr. Big fidgeted a bit, meaning that the meeting was about to break
up. Greg asked one more question, "What machines has he attacked?"
     "Ours, of course, and the Army base in Anniston. He's tried   to   get into

                  THE CUCKOO'S EGG

White Sands Missile Range, and some Navy shipyard in Maryland. I think
it's called Dockmaster."
       "Shit!" Greg and Teejay simultaneously exclaimed. Mr. Big looked at
them quizzically. Greg said, "How do you know he hit Dockmaster?"
       "About the same time he screwed up our accounting, this Dockmaster
place sent us a message saying that someone had tried to break in there." I
didn't know what the big deal was.
       "Did he succeed?"
       "I don't think so. What is this Dockmaster place, anyway? Aren't they
some Navy shipyard?"
        They whispered among themselves, and Mr. Big nodded. Greg ex-
plained, "Dockmaster isn't a Navy shipyard. It's run by the National Secu-
rity Agency."
       A hacker breaking into NSA? Bizarre. This guy wanted to get into the
CIA, the NSA, Army missile bases, and the North American Air Defense
       I knew a little about the NSA. They're the secret electronics spooks
that listen in on foreign radio broadcasts. They launch satellites to listen to
Soviet telephone calls. I'd heard (and didn't believe) rumors that they record
every overseas phone call and telegram.
       Greg explained from his standpoint. "Most of NSA works on collect-
ing and analyzing signals from abroad. One section, however, works on
protecting information belonging to the United States."
       "Yeah," I said, "like making ciphers that you think the Commies can't
break." Dennis shot me a glance and silently mouthed the word, "Polite."
       "Uh, yeah," Greg said, "that group worries about computer security.
They run the Dockmaster computer."
       "Sounds like Janus, the two-faced god," I said. "One side tries to crack
ciphers of foreign countries; the other side tries to make unbreakable codes.
Always pulling in opposite directions."
       "Sorta like our own agency," Greg looked around nervously. "We're
known for dirty tricks, but we're fundamentally a news organization. Most
of our work is just gathering and analyzing information, yet try saying that
on campus." Greg rolled his eyes. He'd paid his dues as a college recruiter.
Hard to say why, but this spy seemed reasonable. Not arrogant, but sensitive
and aware. If we must poke around in dark corners, I'd be more comfort-
able with him in charge.
       "Well then, why can I reach NSA's computers from my unclassified

                                ST 0 L L

and obviously insecure computer?" If I could reach out and touch NSA,
then they could touch me.
      "Dockmaster is NSA's only unclassified computer," Greg said. "It be-
longs to their computer security group, which is actually public."
      Mr. Big started talking slowly. "There's not much we can do about
this affair. I think there's no evidence of foreign espionage. Agents on
assignment don't send notes to adversaries."
      "Well, who should be working on this case?" I asked.
      "The FBI. I'm sorry, but this isn't our bailiwick. Our entire involve-
ment has been the exposure of four names-names that are already in the
public domain, I might add."
      On the way out, I showed our Vax computers to Greg and Teejay.
Between rows of disk drives, Greg said, "This is the most serious hacker
problem I've heard of. Despite what the boss says, could you keep me
      I decided to trust this guy. "Sure. Want a copy of my logbook?"
      "Yes. Send me anything. Even if the agency can't do anything, we
need to become aware of this type of threat."
      "Why? Do spooks have computers?"
      Greg looked at Teejay and laughed. "We've lost count. Our building
floats on computers."
      "What would the CIA use computers for? Can you overthrow foreign
governments with software?" Dennis wasn't around to tell me to be polite.
      "Stop thinking that we're arch villains and think of us instead as
information gatherers. The information's worthless until its correlated, ana-
lyzed, and summarized. That alone is a lot of word processing."
      "Personal computer stuff, I'll bet."
      "No, not if you want to do it right. We're trying to avoid the next
Pearl Harbor, and that means getting information to the right person fast.
 Right off, that says networks and computers. To analyze and predict the
actions of foreign governments, we use computer-based models. Again, big
computers. Nowadays, everything from economic forecasts to image pro-
cessing requires powerful number crunchers."
      I'd never thought of the CIA as needing really major computers.
"How do you keep your systems secure?"
      "Strict isolation. There's no wires connecting to the outside."
      "Can any CIA agent read anyone else's files?"
      Greg laughed, but Teejay didn't. "No way. In our world, everyone's

                  THE CUCKOO'S EGG

compartmentalized. So if one person turns out to be, how should I say, less
than trustworthy, the amount of damage is limited."
     "Then how do you keep people from reading each other's files?"
      "We use trusted operating systems. Computers with thick walls be-
tween each individual's data. If you want to read someone else's files, then
you've got to get permission. Teejay can tell you some horror stories."
      Teejay looked sideways at Greg. Greg said, "Go ahead, Teejay. It's
already public."
      "Two years ago, one of our contractors built a centralized terminal
switchbox," Teejay said. "We needed to interconnect a few thousand termi-
nals to some of our computers."
     "Oh, like my lab's switchyard."
     "Multiply your switchyard by fifty, and you have some idea."
      Teejay continued, "Each employee of this contractor had to pass the
same tests as our regular employees-compartmentalized top secret.
      "Well, one of our secretaries went on vacation for a month. When she
returned and logged onto her computer, she noticed that her account had
been accessed a week earlier. You see, every time you sign onto our com-
puters, it shows the date when you last logged on."
      "We started sniffing around. The SOB that had connected the termi-
nals wiretapped them from our computer room. He'd capture passwords and
text, and then pry into our password disks."
      I knew how easy it was to watch the traffic in the LBL switchyard.
"Did you bump him offi" I asked, imagining some midnight action with a
silenced gun.
     Teejay looked at me strangely. "Be serious. Where we come from, it's
'In God we trust, all others we polygraph.' "
     Greg finished the story. "We wired him to a lie detector for a week,
and the FBI indicted him. It'll be a long time before he sees sunlight."
     Walking out of the lab, I asked Teejay, "Looks like the CIA's not
going to do much for me, huh?"
     "If my superior doesn't think it's serious, there's not much we can do.
Ed Manning has the power to make something happen."
     "Huh? I thought Ed Manning was a programmer?"
     "Hardly. He's director of information technology. When you called
him, you hit a central nerve."
     A director who knew his way around the networks? Now that's a rare

                                 S TaL L

organization. No wonder they flew four people out here. There's a bigger
Mr. Big back at the headquarters.
     "So when you report that there's nothing shaking here, you'll drop

      "Well, there's not much that we can do," Greg said. "It's the FBI's
      "Any chance you can rattle their cages and ask them to investigate?"
      "I'll try, but don't expect much. The FBI likes to chase bank robbers
and kidnappers. Computer crime, well, let's say they've got other worries."
      "What I hear you saying is, 'Stop watching and zipper things up.' "
      "Not quite. You're watching an extensive attack on our networks.
Someone's going after the very heart of our information systems. We've
expected minor attacks for several years, but I've never heard of anything
this far reaching. The convoluted connections, the singleminded search for
sensitive targets . . . it points to an adversary who's determined to get into
our computers. If you close your doors, he'll just find another way in."
      "So you're saying, 'Stay open and keep monitoring' even though the
FBI ignores us."
      Greg looked at Teejay. "I can't buck my management. But you're
doing an important piece of, well, research. The FBI will eventually wake
up. Until then, keep at it."
        I was astonished-these guys saw the severity of the situation but
couldn't do anything. Or were they just saying that?
      Encouraging words from the CIA.

o     0 0 It would have been a fun show for the spooks if the hacker
appeared while they were visiting. Instead he showed up the next morning
at 9:10. Once again we started the traces through Tymnet and the phone
company; once again we struck a brick wall somewhere in Virginia. If only
our California search warrant were good in Virginia . . .
      That day the hacker seemed confident, even arrogant. He performed
his usual tricks: checking who's on the system, sneaking through the hole in
our operating system, listing electronic mail. In the past he made occasional

                  THE CUCKOO'S EGG

mistakes as he tried new commands. Today he used no new commands. He
was smooth, determined. No mistakes.
       As if he were showing off.
       He went straight for the Anniston Army Depot and printed out a short
file about the combat readiness of Army missiles. He then tried the Army's
Ballistic Research Lab's computers in Aberdeen, Maryland. The Milnet took
only a second to connect, but BRL's passwords defeated him: he couldn't
get through.
       He wasted the rest of my morning by raking through my scientists'
files, searching for passwords. In a physicist's area, he found one: an old file
that described the way to get into a Cray supercomputer at Lawrence
Livermore Labs.
       To keep people from guessing passwords into their supercomputer,
Livermore also used random computer-generated passwords, like agniifOm or
ngagk. Naturally, nobody can remember these passwords. Result? Some
people save their passwords in computer files. What good is a combination
lock when the combination's scribbled on the wall?
       Dave Cleveland, our Unix Guru, watched the hacker. "At least he
can't get into the classified computers at Livermore," Dave said.
       "Why not?"
       "Their classified system is completely off net. It's isolated."
       "Then what's the password lead to?"
       "Livermore has a few unclassified computers, where they research fu-
sion energy."
       "Sounds like bomb making to me," I said. Any kind of fusion seemed
like bomb making.
       "They're trying to build fusion energy reactors to generate cheap
electricity. You know, fusion reactions inside donut-shaped magnetic fields."
       "Sure. I played with one when I was a kid."
       "I thought so. Since it's not weapons research, that computer's accessi-
ble from networks."
       "We'd better warn Livermore to disable that account."
       "Just wait. You can't reach the Magnetic Fusion Energy computer
 from here. Your hacker friend's going to wear himself out trying."
       "Uh, the ranger's not gonna like this, Yogi . . ."
       "Trust me."
        The hacker stayed around for a few more minutes, then disconnected.
 Never even tried to get into Livermore.

                                 ST 0 L L

     "So much for that theory," Dave shrugged.
      In hopes that they might be used as evidence, Dave and I signed the
printouts. We left the printers in the switch yard and I wandered back to my
office. Within an hour my terminal beeped: the hacker was back.
      But none of the printers showed him. Checking the Unix systems, I
saw him, logged in as Sventek. But he wasn't entering through our Tymnet
     Quickly, I scanned the dial-in modems. Two scientists editing pro-
grams, a bureaucrat listing boilerplate from a contract, and a student writing
a love letter. No obvious hacking.
     I ran back to my office and glanced at the Unix computer's status.
Sventek, all right. But coming from where?
     There: the hacker's port wasn't an ordinary 1200-baud line. That's why
he didn't show up in the switchyard. No, he was coming from our local
network. Our ethernet. The green cable that interconnected a hundred ter-
minals and workstations around our laboratory.
     I ran to Wayne's office. "Look-the hacker's on our local area net-
      "Slow down, Cliff. Lemme see." Wayne kept five terminals in his
office, each watching a different system. "Yeah, there's Sventek, on the
Unix-4 computer. Whatcha wanna do?"
      "But he's the hacker. And he's coming from our lab-wide ethernet."
      "Big deal. There's a dozen ways to get there." Wayne turned to an-
other terminal. "I'll just switch on my friendly ethernet analyzer, and see
who's doing what."
      As Wayne typed in the parameters, I thought about the implications of
finding the hacker on our local network. Our ethernet was a party line that
snaked through every office. That he found a way into the ether was bad
news: it meant that the hacker could attack even personal computers at-
tached to the ethernet.
      But maybe this would prove to be good news. Perhaps the hacker
lived here in Berkeley and worked at our laboratory. If so, we were closing
in on him quickly. Wayne would trace the ethernet to within a few feet of
the source.
      "Here's your connection. He's coming from . . . from the computer
that controls the MFE net."
      "You mean the hacker is entering our lab through the MFE network?"

                     THE CUCKOO'S EGG

        "Yeah. He's coming from Lawrence Livermore Laboratory. The Mag-
  netic Fusion Energy Network."
       I called down the hallway, "Hey, Dave! Guess who's visiting
       Dave ambled over to Wayne's office. "How'd he get there? There's no
  connection from there into our Unix system."
      "I don't know how he got into Livermore, but he's in our ethernet,
  coming from Livermore."
       Dave raised his eyebrows. "I didn't know you could do that. Your
  hacker found a path to the Unix system that I didn't know about."
       Wayne launched into Dave with his usual tirade against Unix. I left
  the two bosom enemies and called Livermore.
       It took three calls to find the system manager of the MFE network.
 "Hi, you don't know me, but you've got a hacker in your system."
      A woman answered, "Huh? Who are you?"
      "I work at LBL. Someone's messing around in my computer and he's
 coming in from the MFE network. It looks like he's logged in from
      "Oh, hell. I'll scan our users. . . . There's only one job that's con-
 nected from Livermore to Berkeley. Account 1674 . . . it belongs to
 someone named Cromwell."
      "That's him," I said. "The hacker found the password a couple hours
 ago. Got the password from a command file here in Berkeley."
      "I'll kill that account. Cromwell can use our system, when he learns to
keep his passwords secret." She saw the problem as ignorant users, not
unfriendly systems that forced people to use bizarre passwords like agniifom.
     "Can you trace the connection?" I wanted Livermore to keep the
hacker on line, at least long enough to trace the line.
     "No, we're not authorized to make any traces. You'll have to talk to
our management first."
     "But by the time anyone decides, the hacker will be gone."
     "We run a secure installation," she said. "If anyone finds out there's a
hacker at Livermore, heads will roll."
      "Unless you trace where the hacker's coming from, you'll never know
if he's out of your system."
     "My job is to run a computer. Not to catch criminals. Leave me out of
your wild goose chase."

                                ST 0 L L

     She decided to chop off all access and disable the stolen account. The
hacker disappeared from Livermore's computer, and from ours.
      Maybe it was just as well. Even if she had started a trace, I couldn't
monitor what the hacker was doing. I could detect that he was in my
computer, all right. But the MFE network connected directly into my
computer, without going through the switchyard. My printers wouldn't
capture what the hacker typed.
      Depressed, I shuffled to lunch. At the LBL cafeteria, Luis Alvarez sat
down across from me. Inventor, physicist, and Nobel Laureate, Luie was the
twentieth-century Renaissance man. He didn't waste time on bureaucracy;
he demanded results.
      "How's astronomy?" Even from the stratosphere, Alvarez still found
time to talk to pipsqueaks like me. "Still building that telescope?"
      "Naw, I'm working at the computer center now. I ought to be
writing programs, but I've been spending all my time chasing a hacker."
      "Any luck?"
      "It's playing hide-and-seek over the wires. First I think he's coming
from Berkeley, then Oakland, then Alabama, then Virginia. Lately I've
traced him to Livermore."
      "Called the FBI?"
      "Six times. They've got better things to do. The frustrating part is the
complete lack of support." I told him about the morning's activity at
      "Yes, they've got their jobs to worry about."
      "But I'm trying to help them, damn it. They don't care that their
neighbor's being burglarized."
      "Stop acting like a crusader, Cliff. Why don't you look at this as
research. Nobody else is interested-not Livermore, not the FBI. Hell, in a
week or two, probably not even our lab's administration."
      "They gave me three weeks. It's already up."
      "That's what I mean. When you're doing real research, you never
know what it'll cost, how much time it'll take, or what you'll find. You just
know there's unexplored territory and a chance to discover what's out
      "That's easy for you to say. But I've got to keep three managers off
my back. There are programs to write and systems to manage."
      "So what? You're following a fascinating scent. You're an explorer.
Think of who might be behind it. Some international spy, perhaps."

                  THE CUCKOO'S EGG

      "More likely some bored high school kid."
      "Well then, forget who's causing the problems," Luie said. "Don't try
to be a cop, be a scientist. Research the connections, the techniques, the
holes. Apply physical principles. Find new methods to solve problems.
Compile statistics, publish your results, and only trust what you can prove.
But don't exclude improbable solutions-keep your mind open."
      "But what do I do when I hit a brick wall?"
      "Like Livermore's system manager?" asked Luie.
      "Or the telephone company withholding a phone trace. Or the FBI
refusing a court order. Or our laboratory shutting me down in a couple
      "Dead ends are illusory. When did you ever let a 'Do Not Enter' sign
keep you away from anything? Go around the brick walls. When you can't
go around, climb over or dig under. Just don't give up."
      "But who's going to pay my salary?"
      "Permission, bah. Funding, forget it. Nobody will pay for research;
they're only interested in results," Luie said. "Sure, you could write a
detailed proposal to chase this hacker. In fifty pages, you'll describe what
you knew, what you expected, how much money it would take. Include the
names of three qualified referees, cost benefit ratios, and what papers you've
written before. Oh, and don't forget the theoretical justification.
      "Or you could just chase the bastard. Run faster than him. Faster than
the lab's management. Don't wait for someone else, do it yourself. Keep
your boss happy, but don't let him tie you down. Don't give them a
standing target."
      That's why Luie won a Nobel Prize. It wasn't what he did, so much as
how he went about it. He was interested in everything. From a few rocks
slightly enriched in the element iridium, he'd inferred that meteorites (a
source of iridium) must have struck the earth some sixty-five million years
ago. Despite skepticism from paleontologists, he recognized those meteors
to be the death knell of the dinosaurs.
      Luis Alvarez never saw the subatomic fragments that won his Nobel
prize. Instead, he photographed their trails inside bubble chambers. He ana-
lyzed those trails-from their length, he calculated the particles' lifetimes;
from their curvature, their charge and mass.
      My research was a far cry from his, but what have I got to lose?
Maybe his techniques would work for me. How do you scientifically re-
search a hacker?

                                 ST 0 L L

      At 6:19 that evening, the hacker returned. This time, he came through
Tymnet. I didn't bother tracing it-no use rousting everyone from dinner
when they wouldn't give me the phone number.
      Instead, I sat and watched the hacker deliberately connect to the MX
computer, a PDP-10 at the MIT artificial intelligence labs in Cambridge,
Massachusetts. He logged in as user Litwin, and spent almost an hour learn-
ing how to operate that computer. He seemed quite unaccustomed to the
MIT system, and he'd frequently ask for the automated help facility. In an
hour, he'd learned little more than how to list files.
      Perhaps because artificial intelligence research is so arcane, he didn't
find much. Certainly, the antique operating system didn't provide much
protection-any user could read anyone else's files. But the hacker didn't
realize this. The sheer impossibility of understanding this system protected
their information.
      I worried about how the hacker might abuse our network connections
over the weekend. Rather than camping out in the computer room, I pulled
the plugs to all the networks. To cover my tracks, I posted a greeting for
every user logging in: "Due to building construction, all networks are down
until Monday." It would surely isolate the hacker from the Milnet. By
counting complaints, I could take a census of how many people relied on
this network.
      Quite a few, it turned out. Enough to get me in trouble.
      Roy Kerth was first. "Cliff, we're taking a lot of heat for the network
being down. A couple dozen people are bitching that they haven't received
electronic mail. Can you look into it?"
      He must have believed the greeting! "Uh, sure. I'll see if I can get it
working right away."
      It took five minutes to patch the network through. The boss thought
I'd done magic. I kept my mouth shut.
      But while the network was down, the hacker had appeared. My only
record was a printout from the monitor, but that was enough. He had
shown up at 5:15 A.M. and tried to connect into a Milnet site in Omaha,
Nebraska. Disappeared two minutes later. From the network directory, I
found he tried to get into a defense contractor there, SRI Inc.
      I called Ken Crepea of SRI, and he hadn't noticed anyone trying to
get in. "But I'll call you back if I see anything strange."
      Ken called back two hours later. "Cliff, you won't believe this, but I
checked our accounting logs, and someone's broken into my computer."

                 THE CUCKOO'S EGG

     I believed him. "How do you know?"
     "There's weekend connections from several places, on accounts that
ought to be dead."
     "From where?"
     "From Anniston, Alabama, and from Livermore, California. Someone
used our old account, SAC. It used to be used for the Strategic Air Com-
mand, here in Omaha."
     "Any idea how it was invaded?"
     "Well, it never had much password protection," Ken said. "The pass-
word was SAC. Guess we screwed up, huh?"
     "What was he up to?"
     "My accounting records don't say what he did. I can only tell the
times he connected."
     He told me the times, and I entered them into my log book. To
protect his system, Ken would change all passwords to all accounts, and
make each person show up in person to get a new password.
     The hacker was on the Milnet through at least two other computers,
Anniston and Livermore. And probably MIT.
     MIT. 1'd forgotten to warn them. I called Karen Sollins of their
computer department and told her about Friday night's intrusion. "Don't
worry," she said, "there's not much on that computer, and we're throwing it
away in a few weeks."
     "That's good to know. Can you tell me who owned the Litwin ac-
count?" I wanted to know where the hacker got Litwin's password.
     "He's a plasma physicist from the University of Wisconsin," she said.
"He uses Livermore's big computers, and ships his results to our system."
Doubtless, he left his MIT passwords on the Livermore computer.
     This hacker silently followed scientists from one computer to another,
picking up the crumbs they left. What he didn't know was that someone
was also picking up the crumbs he was leaving.

                                ST 0 L L

o 0         0     The hacker knew his way around the Milnet. Now I could
see the futility of closing him out of our computers. He'd just come in
through some other door. Perhaps I could nail my own doors shut, but he'd
still climb into other systems.
       Nobody detected him. Unmolested, he had sneaked into Livermore,
SRI, Anniston, and MIT.
       Nobody chased him. The FBI certainly didn't. The CIA and the Air
Force Office of Special Investigations couldn't or wouldn't do anything.
       Well, almost nobody. I followed him, but I couldn't figure out a way
to catch him. The telephone traces wouldn't pan out. And since he used
several networks, how was I to know where he came from? Today, he
might enter through my lab and break into a computer in Massachusetts, but
tomorrow, he might just as well enter the nets in Peoria and break into
Podunk. I could monitor him only when he touched my system.
       It was time to give up and go back to astronomy and programming, or
make my site so inviting that he preferred to use Berkeley as a jumping-off
       Giving up seemed best. My three weeks had expired, and I heard
grumblings about "Cliff's quest for the Holy Grail." So long as it looked
like my chase might bear fruit, the lab would tolerate me, but I had to show
progress. For the past week, only the hacker had made progress.
       "Do research," Luis Alvarez had said. Well, OK, I'd watch this guy
and call it science. See what I can learn about networks, computer security,
and maybe the hacker himself.
       So I reopened our doors and sure enough, the hacker entered and
poked around the system. He found one interesting file, describing new
techniques to design integrated circuits. I watched as he fired up Kermit, the
universal file-transfer program, to ship our file back to his computer.
       The Kermit program doesn't just copy a file from one computer to
another. It constantly checks to make sure there haven't been any mistakes in
 transmission. So when the hacker launched our Kermit program, I knew he
was starting the same program on his own computer. I didn't know where

                  THE CUCKOO'S EGG

the hacker was, but he certainly used a computer, not just a simple terminal.
This, in turn, meant that the hacker could save all his sessions on a printout
or floppy disk. He didn't have to keep notes in longhand.
      Kermit copies files from one system to another. The two computers
must cooperate-one sends a file, and the other receives it. Kermit runs on
both computers: one Kermit does the talking, the other Kermit listens.
      To make sure it doesn't make mistakes, the sending Kermit pauses after
each line, giving the listener a chance to say, "I got that line OK, go on to
the next one." The sending Kermit waits for that OK, and goes on to send
the next line. If there's a problem, the sending Kermit tries again, until it
hears an OK. Much like a phone conversation where one person says "Dh
huh" every few phrases.
       My monitoring post sat between my system's Kermit and the hacker's.
Well, not exactly in the middle. My printer recorded their dialogue, but
was perched at the Berkeley end of a long connection. I watched the hack-
er's computer grab our data and respond with acknowledgements.
       Suddenly it hit me. It was like sitting next to someone shouting mes-
sages across a canyon. The echoes tell you how far the sound traveled. To
find the distance to the canyon wall, just multiply the echo delay by half the
speed of sound. Simple physics.
       Quickly, I called our electronic technicians. Right away, Lloyd Bell-
knap knew the way to time the echoes. "You just need an oscilloscope. And
maybe a counter." In a minute, he scrounged up an antique oscilloscope
from the Middle Ages, built when vacuum tubes were the rage.
       But that's all we needed to see these pulses. Watching the trace, we
timed the echoes. Three seconds. Three and a half seconds. Three and a
quarter seconds.
       Three seconds for a round trip? If the signals traveled at the speed of
light (not a bad assumption), this meant the hacker was 279,000 miles away.
       With appropriate pomp, I announced to Lloyd, "From basic physics, I
 conclude that the hacker lives on the moon."
       Lloyd knew his communications. "I'll give you three reasons why
you're wrong."
       "OK, I know one of them," I said. "The hacker's signals might be
 traveling through a satellite link. It takes a quarter second for microwaves to
 travel from earth to the satellite and back." Communications satellites orbit
 twenty-three thousand miles over the equator.
       "Yeah, that's one reason," Lloyd said. "But you'd need twelve satellite

                                 ST 0 L L

hops to account for that three-second delay. What's the real reason for the
     "Maybe the hacker has a slow computer."
      "Not that slow. Though maybe the hacker has programmed his Kermit
to respond slowly. That's reason two."
      "Aah! I know the third delay. The hacker's using networks that move
his data inside of packets. His packets are constantly being rerouted, assem-
bled, and disassembled. Every time they pass through another node, it slows
him down."
       "Exactly. Unless you can count the number of nodes, you can't tell
how far away he is. In other words, 'You lose.' " Lloyd yawned and re-
turned to repairing a terminal.
       But there was still a way to find the hacker's distance. After the hacker
left, I called a friend in Los Angeles and told him to connect to my com-
puter through AT&T and Tymnet. He started Kermit running, and I timed
his echoes. Real short, maybe a tenth of a second.
      Another friend, this time in Houston, Texas. His echoes were around
0.15 seconds. Three other people from Baltimore, New York, and Chicago
each had echo delays of less than a second.
     New York to Berkeley is about two thousand miles. It had a delay of
around a second. So a three-second delay means six thousand miles. Give or
take a few thousand miles.
      Weird. The path to the hacker must be more convoluted than I sus-
      I bounced this new evidence off Dave Cleveland. "Suppose the hacker
lives in California, calls the East Coast, then connects to Berkeley. That
could explain the long delays."
     "The hacker's not from California," my guru replied. "I tell you, he
just doesn't know Berkeley Unix."
      "Then he's using a very slow computer."
      "Not likely, since he's no slouch at Unix."
      "He's purposely slowed down his Kermit parameters?"
      "Nobody does that-it wastes their time when they transfer files."
     I thought about the meaning of this measurement. My friends' samples
told me how much delay Tymnet and AT&T introduced. Less than a sec-
ond. Leaving two seconds of delay unaccounted for.
     Maybe my method was wrong. Maybe the hacker used a slow com-

                  THE CUCKOO'S EGG

puter. Or maybe he was coming through another network beyond the
AT&T phone lines. A network I didn't know about.
     Every new piece of data pointed in a different direction. Tymnet had
said Oakland. The phone company had said Virginia. His echoes said four
thousand miles beyond Virginia.

o     0     0      By the end of September, the hacker was appearing every
other day. Often, he'd pop up his periscope, look around, and disappear in a
few minutes. Not enough time to trace, and hardly worth getting excited
       I was tense and a little guilty. I often passed up dinner at home to
sneak in some extra hacker watching.
       The only way I could keep following the hacker was by disguising my
efforts as real work. I'd muck around with computer graphics to satisfy the
astronomers and physicists, then fool with the network connections to sat-
isfy my own curiosity. Some of our network software actually needed my
attention, but usually I was just tinkering to learn how it worked. I called
other computer centers ostensibly to clear up network problems. But when
I'd talk to them, I'd cautiously bring up the subject of hackers-who else
had hacker problems?
        Dan Kolkowitz at Stanford University was quite aware of hackers in
his computer. He was an hour's drive away from Berkeley, but that was an
all-day bicycle ride. So we compared notes on the phone, and wondered if
we were watching the same rodent gnawing at our systems.
        Since I'd started watching my monitors, I'd seen an occasional inter-
loper trying to get onto my computer. Every few days, someone would dial
into the system and try to log on as system or guest. These inevitably failed,
so I didn't bother following them. Dan had it much worse.
        "Seems like every kid in Silicon Valley tries to break into Stanford,"
Dan moaned. "They find out passwords to legitimate student accounts, then
waste computing and connect time. An annoyance, but something we'll
have to tolerate so long as Stanford's going to run a reasonably open sys-
tern. "


                                    ST 0 L L

          "Have you thought about clamping down?"
          "To really tighten up security would make everyone unhappy," Dan
    said. "People want to share information, so they make most of the files
    readable to everyone on their computer. They complain if we force them to
    change their passwords. Yet they demand that their data be private."
          People paid more attention to locking their cars than securing their
          One hacker in particular annoyed Dan. "Bad enough that he found a
    hole in Stanford's Unix system. But he had the nerve to call me on the
    phone. He talked for two hours, at the same time pawing through my
    systems files."
          "Did you trace him?"
          "I tried. While he was talking on the phone, I called the Stanford
    police and the phone company. He was on for two hours, and they couldn't
    trace it."
          I thought of Lee Cheng at Pacific Bell. He needed just ten minutes to
    trace clear across the country. And Tymnet unwound their network in less
    than a minute.
          We compared the two hackers. "My guy's not wrecking anything," I
    said. 'Just scanning files and using my network connections."
          "Precisely what I see. I changed my operating system so that I can
    watch what he's doing."
          My monitors were IBM PC's, not modified software, but the principle
    was the same. "Do you see him stealing password files and system utilities?"
          "Yes. He uses the pseudonym of 'Pfloyd' . . . I bet he's a Pink Floyd
    fan. He's only active late at night."
          This was a difference. I often watched my hacker at noon. As I
    thought about it, Stanford was following different people. If anything, the
    Berkeley hacker seemed to prefer the name, "Hunter," though I knew him
    by the several different account names he stole.
          Three days later, the headlines of the October 3 San Francisco Examiner
    blared, "Computer Sleuths Hunt A Brilliant Hacker." Reporter John Mark-
    off had sniffed out the Stanford story. On the side, the newspaper men-
    tioned that this hacker had also gotten into the LBL computers. Could this
    be true?
          The story described Dan's snares and his inability to catch Stanford's
    Pfloyd hacker. But the reporter got the pseudonym wrong-the newspaper
     reported "a crafty hacker using the name 'Pink Floyd.' "

                  THE CUCKOO'S EGG

     Cursing whoever leaked the story, I prepared to close things up. Bruce
Bauer of our lab's police department called and asked if I'd seen the day's
     "Yeah. What a disaster. The hacker won't show up again."
     "Don't be so sure," Bruce said. "This may be just the break we're
looking for."
     "But he'll never show up, now that he knows that we know there's a
hacker in our system."
      "Maybe. But he'll want to see if you shut him out of the computer.
And he's probably confident that if he can outwit the Stanford people, he
can sneak past us as well."
      "Yes, but we're nowhere near tracing him."
      "That's actually what I called about. It'll be a couple weeks before we
get the search warrant, but I'd like you to stay open until then."
      After he hung up, I wondered about his sudden interest. Could it be
the newspaper story? Or had the FBI finally taken an interest?
      The next day, doubtless thanks to Bruce Bauer, Roy Kerth told me to
keep working on following the hacker, though he pointedly said that my
regular duties should take precedence.
      That was my problem. Every time the hacker showed up, I'd spend an
hour figuring out what he did and how it related to his other sessions. Then
a few more hours calling people, spreading the bad news. Then I'd record
what happened in my logbook. By the time I'd finished, the day was pretty
much wasted. Following our visitor was turning into a full-time job.
      In my case, Bruce Bauer's intuition was right. The hacker returned a
week after the article appeared. On Sunday, October 12, at 1:41, I was
beating my head against some astronomy problem-something about or-
thogonal polynomials-when my hacker alarm went off.
      I ran down the hallway and found him logged into Sventek's old
account. For twelve minutes, he used my computer to connect to the
Milner, From there, he went to the Anniston Army base, where he had no
trouble logging in as Hunt. He just checked his files and then disconnected.
      On Monday, Chuck McNatt from Anniston called.
      "I dumped this weekend's accounting logs and found the hacker
      "Yes, he was on your system for a few minutes. Just long enough to see
if anyone was watching." My printouts told the whole story.
      "I think I'd better close my doors to him," Chuck said. "There's too

                                 ST 0 L L

much at risk here, and we don't seem to be making headway in tracking
hi "
     "Can't you stay open a bit longer?"
     "It's already been a month, and I'm afraid of him erasing my files."
Chuck knew the dangers.
     "Well, OK. Just be sure that you really eliminate him."
     "I know. I'll change all the passwords and check for any holes in the
operating system."
     Oh well. Others didn't quite have the patience to remain open to this
hacker. Or was it foolishness?
     Ten days later, the hacker reappeared. I got to the switchyard just as he
was trying Anniston.

    tEL> Telnet ANAD.ARPA
    Connecting to
    Welcome To Anniston Army Depot
    login: Hunt
    Bad login. Try again.
    login: Bin
    password: jabber
    Welcome to Anniston Army Depot
    TigerTeams Bewarel
    Watch out for any unknovvn users
    Challenge all strangers using this computer

    Chuck had disabled the Hunt account, but hadn't changed the pass-
word on the system account, Bin.
    The greeting message warned the hacker that someone had noticed
him. He quickly checked his Gnu-Emacs files, and found they had been
erased. He looked around the Anniston system and found one file that had
been created July 3. A file that gave him super-user privileges. It was hidden
in the public directory /usr/lib. An area that anyone could write into. He'd
named the file, ".d". The same name he used to hide his files on our LBL
      But he didn't execute that program. Instead he logged off the Anniston
system and disconnected from LBL.
      Chuck hadn't noticed this special file. On the phone, he said he'd
changed every user's password-all two hundred. But he hadn't changed
any of the system passwords like Bin, since he assumed he was the only one

                  THE CUCKOO'S EGG

who knew them. He'd thought that he'd thoroughly eradicated any danger-
ous files, but he'd missed a few.
      That .d file at Anniston was a useful benchmark. The hacker had laid
this egg on July 3, yet remembered exactly where he'd hidden it three
months later.
      He didn't guess or hunt around for the .d file. No, he went straight for
      After three months, I can't remember where I stash a file. At least not
without a notebook.
      This hacker must be keeping track of what he's done.
      I glanced at my own logbook. Somewhere, someone was keeping a
mirror-image notebook.
      A kid on a weekend lark doesn't keep detailed notes. A college joker
won't patiently wait three months before checking his prank. No, we were
watching a deliberate, methodical attack, from someone who knew exactly
what he was doing.

o      0 0 Even though you have to coast slowly by the guardhouse,
you can reach thirty miles an hour by pedaling down the LBL hill. Tuesday
evening I was in no hurry, but pedaled anyway: it's a kicker to feel the
wind. A mile downhill, then a rendezvous at the Berkeley Bowl.
      The old bowling alley was now a huge fruit and vegetable market, the
cheapest place for kiwis and guavas. Year 'round, it smelled of mangoes-
even in the fish section. Next to a pyramid of watermelons, I saw Martha
knocking some pumpkins, hunting for the filling to our Halloween pie.
      "Vell, Boris, ze secret microfilm is hidden in ze pumpkin patch." Ever
since I met the CIA, I was a spy in Martha's eyes.
      We decided on a dozen little pumpkins for a carving party, and one
fresh big one for the pie. After stuffing them in our backpacks, we biked
      Three blocks from the fruit market, at the corner of Fulton and Ward,
there's a four-way stop. With a can of spray paint, someone's changed one
stop sign to read, "Stop the CIA." Another, "Stop the NSA."

                                 ST 0 L L

     Martha grinned. I felt uneasy, and pretended to adjust my backpack. I
didn't need another reminder of Berkeley politics.
      At home, she tossed pumpkins to me, and I stashed them in a box.
"What you're missing is a flag," she said, throwing the last one low and
inside, "some sort of pennant for chasing hackers."
      She ducked into a closet. "I had a bit left over from my costume, so I
stitched this together." She unrolled a shirt-sized banner, with a snake coiled
around a computer. Underneath, it said, "Don't Tread on Me."
     In the weeks before Halloween, both of us sewed furiously to make
costumes. I'd made a pope's outfit, complete with miter, scepter and chalice.
Martha, of course, kept her costume hidden-you can't be too careful when
your roommate uses the same sewing machine.
      Next day, I hoisted my hacker-hunter flag just above the four
monitors that watched the incoming Tymnet lines. I'd bought a cheap
Radio Shack telephone dialer, and connected it to an expensive but obsolete
logic analyzer. Together, these waited patiently for the hacker to type in his
password, and then silently called my telephone.
     Naturally, the flag fell down and got caught in the printer, just as the
hacker showed up. I quickly unsnarled the shreds of paper and cloth, just in
time to see the hacker change his passwords.
     The hacker apparently didn't like his old passwords-hedges, jaeger,
hunter and benson. He replaced them, one by one, with a single new pass-
word, lblhack.
     Well, at least he and I agreed on what he was doing.
     He picked the same password for four different accounts. If there were
four different people involved, they'd each have a separate account and
password. But here in one session, all four accounts were changed.
      I had to be following a single person. Someone persistent enough to
return over and over to my computer. Patient enough to hide a poisonous
file in the Anniston Army base and return to it three months later. And
peculiar in aiming at military targets.
      He chose his own passwords. "Lblhack" was obvious. I'd searched the
Berkeley phone book for Jaegers and Bensons; maybe I ought to try Stan-
ford. I stopped by the library. Maggie Morley, our forty-five-year-old
documentmeister, plays rough and tumble Scrabble. Posted on her door is a
list of all legal three-letter Scrabble words. To get in, you have to ask her
one. "Keeps 'em fresh in my mind," she says.

                  THE CUCKOO'S EGG

       "Bog," I said.
       "You may enter."
       "I need a Stanford telephone book," I said. "I'm looking for everyone
in Silicon Valley named Jaeger or Benson."
       Maggie didn't have to search the card catalog. "You need directories
for Palo Alto and San Jose. Sorry, but we don't have either. It'll take a week
or so to order 'em."
       A week wouldn't slow things down, at the rate I was going.
       "Jaeger. A word that's been kind to me," Maggie smiled. "Worth
sixteen points, but I once won a game with it, when the T landed on a
 triple-letter score. Turned into seventy-five points."
       "Yeah, but I need it because it's the hacker's password. Hey, I didn't
know names were legal in Scrabble."
       "Jaeger's not a name. Well, maybe it's a name-Ellsworth Jaeger, the
 famous ornithologist, for instance-but it's a type of bird. Gets its name
 from the German word meaning hunter."
       "Huh? Did you say, 'Hunter'?"
       "Yes.Jaegers are hunting birds that badger other birds with full beaks.
 They harass weaker birds until they drop their prey."
       "Hot ziggity! You answered my question. I don't need the phone
       "Well, what else can I do for you?"
       "How about explaining the relationship between the words hedges,
jaeger, hunter and benson?"
       "Well, Jaeger and Hunter is obvious to anyone who knows German.
 And smokers know Benson and Hedges."
       Omigod-my hacker smokes Benson and Hedges. Maggie had won
 on a triple-word score.

o     0 0 I was all set on Halloween morning. I'd finished my pope's
costume, even the miter. Tonight's party would be a gas: pasta with a dozen
lunatics, followed by Martha's fantastic pumpkin pie, and an excursion into
San Francisco's Castro district.

                                ST 0 L L

      But first I had to dodge my bosses at the lab. The physicists were
ganging up on the computer center, refusing to pay our salaries. Supporting
central computing was expensive. The scientists figured that they could buy
their own small machines, and avoid the overhead of paying our program-
ming staff.
      Sandy Merola tried to convince them otherwise. "You can hitch a
thousand chickens to your plow or one horse. Central computing is expen-
sive because we deliver results, not hardware."
     To placate them, Sandy sent me to write a few graphics programs.
"You're a scientist. If you can't make 'em happy, at least listen to their
     So I spent the morning sitting in the back row of a physics seminar. A
professor droned on about the quark function of the proton-something
about how each proton has three quarks. I wasn't tired enough to sleep, so I
pretended to take notes while thinking about the hacker.
      Returning from the seminar, Sandy asked if I'd learned anything.
      "Sure." I glanced at my notes. "The distribution function of quarks
isn't quantized over the proton. Happy?"
      "Be serious, Cliff. What did the physicists say about computing?"
      "Not much. They know they need us, but don't want to pay."
     "Same as the Air Force," Sandy smiled. "I just got off the phone with
one Jim Christy of their Office of Special Investigations."
     "Hey, isn't he the narc with the military spooks?"
     "Be serious. He's a detective working for the Air Force, please."
     "OK, he's an all-American good guy. So what did he say?"
     "He says the same thing as our physicists. They can't support us, but
they don't want us to go away."
     "Did he make any progress with the Virginia phone company?"
     "Naw, He called around, and they won't budge without a Virginia
search warrant. He checked out the Virginia state law, and the hacker's
committing no crime there."
     "Breaking into our computer isn't a crime?" I couldn't believe it.
     "Breaking into a California computer isn't a crime in Virginia."
     "I don't suppose the Air Force can lean on the FBI to get a warrant?"
     "Nope. But they want us to keep monitoring, at least until the Air
Force decides it's a dead end."
     "Did they cough up any dimes?" My time was funded through the

                  THE CUCKOO'S EGG

grants of astronomers and physicists. They weren't pleased to watch me
spend their money chasing some ghost.
      "No bucks, nothing but an unofficial request. When I asked for sup-
port, Jim gave me the bailiwick story."
      Sandy wasn't going to give in. "It's been two months since we started,
and nobody's listened to us. Let's stay open for another week, then call it
       By five o'clock, I was ready for the Halloween party. On my way out,
I checked the floppy disks on the monitors. The printer suddenly started up.
There was the hacker. I glanced at the time-17:43:11 PST.
       No. Not now. I've got a party to go to. A costume party no less. Can't
he choose any other time?
       The hacker logged into the old Sventek account, and checked who was
on our system. Dave Cleveland was there, running under the alias of Sam
Rubarb, but the hacker couldn't know.
       He moved over to our accounting files, and collected the past month's
files in one place. He scanned that long file, searching for the word, "Pink
       Hmmmm. Interesting. He didn't search for the word "Pfloyd," which
was the Stanford hacker's pseudonym. Rather, he searched for the pseud-
onym that was reported in the newspaper.
       My hacker wasn't the same guy as Stanford's. If he were, he wouldn't
have to search for "Pink Floyd"-he'd know when he had been active.
       In fact, my hacker wasn't even in contact with Stanford's. If the two
had met, or even written to each other, my hacker would know to search
for "Pfloyd," not "Pink Floyd."
      The hacker must have read the news. But it had been almost a month
since the article was published. Dave Cleveland must be right: the hacker
wasn't from the West Coast.
      At 6 P.M., the hacker gave up searching our accounting logs. Instead,
he went through our computer onto the Milner. From there, he went
straight for the Anniston army base in Alabama. "Which hole will he sneak
into this time?" I wondered.

    LBL> Telnet
    Welcome to Anniston Computer Center
    Login: Hunter
    Password: Jaeger
    Incorrect login. try again.


                                         ST 0 L L

         Login: Bin
         Password: Jabber
         Incorrect login, try again.
         Login: Bin
         Password: Anadhack
         Incorrect login, 3 tries and you're out.

           Chuck McNatt had finally locked him out. By changing all his pass-
     words, Chuck had nailed his door shut. He still might have holes in his
     system, but this hacker couldn't exploit them.
           The hacker didn't give up. He reached over into the building design
           Some scientists at Lawrence Berkeley Lab worry about how to design
     energy efficient homes. Most other physicists look down on them-"Yech,
     applied physics." Protons and quarks are sexy. Saving ten dollars on your
     monthly heating bill isn't.
           The building design group searchesfor new glasses that let light in, but
     block the infra-red. They build new insulators to prevent heat leaks through
     walls. They'd just started analyzing basements and chimneys for thermal
           The hacker learned this because he dumped all their files. Page after
     page of thermal emissivity data. Memos about paint absorption in the ultra-
     violet. And a note saying, "You can move to the Elxsi computer next
           He didn't need to see that note twice. He interrupted his listing, and
     commanded my Unix computer to connect him to the Elxsi system.
           I'd never heard of this computer. But my computer had. Within ten
     seconds, he'd made the connection and the Elxsi prompted him for an
     account name and password. I watched him try to get in:

         LBL> Telnet Elxsi
         Elxsi at LBL
         login: root
         password: root
         incorrect password, try again.
         login: guest
         password: guest
         incorrect password, try again.
         login: uucp
         password: uucp

                 THE CUCKOO'S EGG

     He got into the UUCP account. No password protection. Wide open.
      UUCP is the account for Unix to Unix copying. When one Unix
computer wants to copy a file from another, it logs into the UUCP account
and gets the file, People should never be able to connect to this special
account. The system manager should disable it from human log-ins.
      Worse, this Elxsi had its UUCP account set up with system privileges.
It took the hacker only a minute to realize that he'd stumbled into a
privileged account.
     He didn't lose any time. He edited the password file, and added a new
account, one with system manager privileges. Named it Mark. "Keep it
bland," I thought.
    But he didn't know much about this computer. He spent an hour
dumping its fIles, and learned about designing energy efficient buildings.
Nothing about the computer itself.
     So he wrote a program to time the Elxsi computer. A short C
program that measured its speed and reported its word length.
     He needed three tries to get his program to work, but finally it flew.
He found the Elxsi to have thirty-two bit words, and he measured it at
about ten million instructions per second.
      Eight-bit and sixteen-bit computers are diddlysquat machines; the
thirty-two-bit systems are the biggies. Thirty-two bits meant a big machine,
ten MIPS meant fast. He'd entered a super-minicomputer. One of the fastest
in Berkeley. One of the most mismanaged.
      As I watched him walk through the Elxsi, I talked to Tymnet. While
the hacker tried to understand the new computer, Ron Vivier searched out
the needle that pointed where the hacker came from.
      "No news. He's coming in from Oakland again." Ron knew that
meant a phone trace.
     "No use calling the phone company. They'll just tell me       to   get a
Virginia search warrant."
      I hung up, disappointed. A long connection like this was perfect for
tracing him. I couldn't shut him out of our system when he was into
computers I'd never even heard of. When he fmally signed off at 7:30, he'd
pretty much mapped out our lab's major computers. He might not be able
to get into each of them, but he knew where they were.
      7:30. Damn, I'd forgotten the party. I ran down to my bike and
pedaled home. This hacker wasn't wrecking my computer, he was destroy-

                                 S TaL L

ing my life. Being late for a Halloween party-that's a capital crime in
Martha's book.
       Not only was I late, but I'd shown up without a costume. I slinked
guiltily through the kitchen door. What a scene! Princess Diana, tastefully
attired in a tailored dress, pillbox hat and white gloves, shuddered as she
removed a dripping handful of seeds from a pumpkin. Alice and the mad
hatter were serving the last of the lasagna. Charlie Chaplin was dipping
apples in caramel. In the midst of this swirl of activity stood a small but
fierce samurai warrior in full battle gear, shouting orders. "You're late," the
samurai scowled. "Where's your costume?"
       Buried in the back of the closet, I found my white velvet robe. Worn
over Martha's nightgown, with a sheet pinned around my shoulders and a
tall, jeweled miter of construction paper and sequins, I suddenly became
. . . Pope Cliff the First. I went around blessing the guests. Martha's friend
Laurie, who usually wore a crew cut, jeans, and hiking boots, sidled up in a
short black cocktail dress and long pearl necklace. "Come on, your holiness,
let's go forth and bless the Castro."
       We piled into the Mad Hatter's car (Laurie rode her motorcycle) and
crossed the bridge to Babylon. Halloween is San Francisco's favorite holi-
day. Five blocks along Castro Street are cordoned off, and thousands of
elaborately costumed revelers jostle up and down, looking at each other and
at the drag queens in sequined gowns who lip-sync to Ethel Merman on the
fire escapes overlooking the street.
       This year's costumes were incredible: a person dressed as a giant bag of
groceries, complete with giant paper replicas of vegetables and cans; various
creatures from outer space; and several rival samurai' whom Martha fought
off with her plastic sword. White-faced draculas mingled with witches,
kangaroos, and butterflies. Over near the trolley stop, an assortment of
ghouls harmonized with a three-legged pickle.
       I offered benedictions left and right-to demons and angels, gorillas
and leopards. Medieval knights knelt to me, and nuns (some with mus-
taches) rushed up to greet me. A trio of sturdy, cheerful fellows in pink
tutus and size-thirteen ballet shoes bowed gracefully to receive my blessings.
       Despite layoffs at the factories, rent payments due, drugs, and AIDS,
somehow San Francisco celebrated life.
       Next Monday I showed up late, expecting to find a message from the
manager of the Elxsi computer. No such luck. I called around the building
design group, and talked with the physicist in charge of the Elxsi computer.

                 THE CUCKOO'S EGG

     "Noticed anything strange on your Elxsi?"
     "No, we've only had it a month. Anything wrong?"
     "Who set up your accounts?"
     "I did. I just signed on as system manager, then added users."
     "Do you run accounting?"
     "No. I didn't know you could."
     "Someone broke into your computer through the UUCP account. He
became system manager and added a new account."
     "I'll be damned. What's the UUCP account?"
     Here's the problem. This guy's a physicist, bored by computers. He
didn't know about managing his machine. Probably didn't care.
     This guy wasn't the problem. Elxsi was. They sold their computers
with the security features disabled. After you buy their machine, it's up to
you to secure it. Just plow through a dozen manuals to find a paragraph
saying how to modify the permissions granted to the UUCP account. If
you know that account exists.
     The same thing must be happening all over. The hacker didn't succeed
through sophistication. Rather he poked at obvious places, trying to enter
through unlocked doors. Persistence, not wizardry, let him through.
      Well, he wasn't going to get into our Elxsi anymore. Knowing my
adversary, I could easily lock him out in a way that would mystify him. I
built a trap door into our Elxsi: whenever the hacker touched the purloined
accounts on that machine, it notified me and pretended to be too busy to
accept another user. The Elxsi didn't say, "Go away"; rather, it slowed
down to a crawl whenever the hacker showed up. The hacker wouldn't
realize that we were on to him, yet the Elxsi was protected against him.
      Still, we were treading water. Without search warrants, our phone
traces went nowhere. Sure, we read every word he typed into our com-
puter, but how much did we miss? He might be using a dozen other
computers to get onto the Milnet.
      This much is for sure: I was now dedicated to catching this hacker.
The only way to snag this guy was to watch every minute of the day. I had
to be ready all the time-noon or midnight.
     That was the problem. Sure, I could sleep under my desk and rely on
my terminal to wake me up. But at the cost of the domestic tranquility:
Martha wasn't pleased at my office campouts.

                                ST 0 L L

      If only my computer would call me whenever the hacker appeared,
then the rest of the time would be my own. Like a doctor on call.
      Of course. A pocket pager. I had a bank of personal computers watch-
ing for the hacker to appear. I'd just program them to dial my pocket pager.
I'd have to rent a pager, but it'd be worth the $20 a month.
      It took an evening to write the programs-no big deal. From now on,
wherever I went, I'd know within seconds of the hacker's arrival. I'd be-
come an extension of my computer.
      It was him against me now. For real.

o     0     0    Lawrence Berkeley Labs is funded by the Department of
Energy, the successor to the Atomic Energy Commission. Perhaps nuclear
bombs and atomic power plants are fading into the mists of history, or
maybe splitting atoms isn't as sexy as it used to be. For whatever reason, the
DOE isn't the same animated team that started atomic energy plants two
decades ago. I'd heard rumors that over the years, the organization had silted
up like the Mississippi.
      The DOE may not be the most nimble of our many Governmental
agencies, but they did pay our bills. For over a month, we'd kept silent
about our problem, worrying that the hacker might find out we were
tracking him. Now that our trace led far from Berkeley, it seemed safe to
tell our funding agency about the hacker.
      On November 12, I called around the DOE, trying to find out who I
should talk to about a computer break-in. It took a half dozen calls to find
out that nobody really wanted to listen. Eventually I reached the DOE
manager of computer security for unclassified computers.
      Rick Carr listened patiently as I told him about the hacker, occasion-
ally interrupting with questions. "Is he still active in your computer?"
      "Yes, and we're homing in on him every time he shows up."
      He didn't seem especially excited. "Well when you catch him, let us
      "Want a copy of my logbook?" I asked.
      "No. Keep it quiet until you're through."

                  THE CUCKOO'S EGG

      I explained our need for search warrants and the FBI's lack of interest.
"Any chance you might be able to get the FBI to open a case?"
      "No, I wish they did, but the FBI doesn't listen to us," Rick said. "I'd
like to help, but it's just not my bailiwick."
      Bailiwicks again. I mumbled my thanks, and was about to hang up
when Rick said, "You might want to call the National Computer Security
Center, though."
      "Who are they?" Seemed like a group that I should have heard of.
      Rick explained, "The NCSC is a sidekick of the National Security
Agency. They're supposed to make standards for securing computers." From
his emphasis on the word "supposed," it sounded like they weren't.
      "Since when does the NSA talk to the public?" I'd always thought that
the NSA was the most secret of all government agencies.
      "The computer security section of NSA is the only part of NSA that's
unclassified," Rick said. "Because of this, they're treated as ugly ducklings
within NSA. Nobody from the secret side of the house will talk to them."
      "And since they're a part of the NSA, nobody from the public trusts
them either," I realized where he was leading.
      "Right. They take flack from both sides. But you ought to tell them
about your hacker. They're certain to be interested, and they might just
rattle the right cages in the bureaucracy."
      Next call: the National Computer Security Center. Zeke Hanson was
their desk officer. His voice was cheerful and he seemed fascinated by the
idea of silently watching a hacker. He wanted all the technical details of our
monitors and alarms.
      "You're an intercept operator," Zeke informed me.
      "What's that?" I'd never heard of it.
      He stammered a bit, as if he wanted to unsay his last sentence. I figured
out what he meant on my own. NSA must have thousands of people
watching teletypes around the world. Intercept operators, huh?
      Zeke asked about my computer. I explained, "A couple of Vaxes
running Unix. Lots of networks." For the next twenty minutes, I told him
about the holes that the hacker exploited-Gnu-Emacs, passwords, Trojan
horses. It hit him where he lived.
      But when I asked if there was any way that he could finagle a search
warrant, he clammed up tight.
      "I'll have to talk to my colleagues about this."
      Well, what did I expect? Ideally, I'd call an electronic spy on the

                                 ST 0 L L

phone, explain my need for a search warrant, and he'd kick the FBI into
acting. Right. How would I react to someone calling my observatory,
reporting an invader from some unknown planet?
      Still, I might as well explain our problem. "Look, we're about to call
it quits. If someone doesn't help out, we're giving up on this monitoring.
I've had it with being a volunteer intercept operator."
      Not a dent. "Cliff, I'd like to take over, but our charter prevents it.
NSA can't engage in domestic monitoring, even if we're asked. That's
prison term stuff."
      He took this seriously. NCSC or NSA, whichever he worked for,
wouldn't monitor my hacker. They'd advise me on how to protect my
computers and serve as a liaison to the FBI, but they wouldn't take over my
      Getting a search warrant? Zeke would look into it, but didn't offer
much help. "If you can't interest the FBI, I doubt that they'll listen to us.
We're here to make computers more secure, not to catch criminals."
      Another bailiwick problem.
      I hung up, discouraged. Five minutes later, I walked down the hallway
and asked myself what I was doing talking to the NSA.
      Maybe Martha was right. She'd said I was on a slippery slope that led
into deep water. First you call the FBI, then the CIA, now the NSA.
      But it wasn't the spooks that bothered me. It was their inaction. Sure,
they all listened to my troubles, but not one would lift a finger.
      Frustrating. Every agency seemed to have a good reason to do noth-
ing. Disgusted, I paced the halls.
      The hallways at Lawrence Berkeley Labs look like a plumber's night-
mare. There's no suspended ceiling tiles to hide the pipes, cables, and ducts.
Looking up, I recognized the steam pipes, and the orange ethernet cables.
The steam runs at about one hundred pounds per square inch, the ethernet at
around ten million bits per second.
      My networks were as essential to the lab as steam, water, or electricity.
      Did I say, "my networks?" The networks were no more mine than the
steam pipes belonged to the plumbers. But someone had to treat them as his
own, and fix the leaks.
      Something strange was happening to me. In a daze, I sat down on the
hallway floor, still staring up at the pipes. For the first time in my life,
something important was entirely up to me. My attitude at work had
always been like my days as an astronomer-I'd write proposals, observe at

                  THE CUCKOO'S EGG

the telescope, publish papers, and stand cynically apart from the struggles
and triumphs of the world around me. I didn't care if my research led
      Now, nobody was telling me what to do, yet I had a choice: should I
quietly let things drop? Or do I take arms against this sea of troubles?
      Staring at the pipes and cables, I realized that I could no longer fool
around behind the scenes, an irreverent, zany kid. I was serious. I cared. The
network community depended on me, without even knowing it. Was I
becoming (oh, no!) responsible?

o     0      0 That evening, Martha studied criminal procedure at Boalt
Hall Law Library. I stopped by to deliver some bagels and cream cheese, the
high-octane fuel of law students. We necked and pecked among the books,
occasionally dodging a zombie cramming for the bar exam. Aah, Boalt
library, where the law never sleeps.
      In a back room, she showed me the law school's Lexis computer.
"Hey, want to play with a fun toy while I study?" she asked.
      Without waiting for a reply, she switched on the Lexis terminal. She
pointed to the sign giving instructions on how to log into the document
search system. She dived back into her books, leaving me with some un-
known computer.
      The instructions couldn't be plainer. Just press a couple buttons, type
the account name, a password, and begin searching judicial records for
whatever seems interesting. Next to the instructions were scribbled five
account names and passwords, so I picked a pair and logged in. Nobody had
thought to protect its passwords. I wondered how many former law stu-
dents were still freeloading from the library.
      So I logged into the law computer and searched on the keywords
telephone trace. It took a while to understand the legal jargon, but eventually
I stumbled on the law regulating telephone traces. It turned out that a
search warrant wasn't necessary to trace a phone call made to your own
telephone, so long as you wanted the trace made.
      This made sense. You shouldn't need a court order to find out who was

                                 ST 0 L L

calling you. Indeed, some telephone companies now sell phones that display
the digits of the calling telephone as your phone is ringing.
      But if we didn't legally need a search warrant, why were the phone
companies so insistent? Monday morning, clutching a xerox of 18 USCA
§3121, I called Lee Cheng at the phone company. "Why do you make us
get search warrants, when the law doesn't require it?"
      "It's partly to protect ourselves from lawsuits and partly to filter out
worthless traces," Lee said.
      "Well, if the warrant isn't required, why won't the Virginia phone
company release the information?"
      "I dunno. But they won't. I've spent half an hour talking to them, and
 they won't budge." If they wouldn't release the number to another phone
company, there wasn't much chance they'd tell my lab. Looked like the
phone trace was a dead end after all.
      Aletha Owens, our lawyer, called. "The FBI won't give us the time of
day, let alone a search warrant."
      Same story with our lab police. They'd called around and got no-
where. Dead end.
      Over lunch at the lab cafeteria, I described the past week's adventures
to two astronomer pals, Jerry Nelson and Terry Mast.
      "You mean to say that they traced the call and won't tell you the
number?" Jerry asked incredulously.
      "That's about the size of it. No tickee, no laundry."
      Between sandwiches, I showed them my logbook. A couple weeks
ago, while the phone technician was tracing the line, I'd copied all her
jargon into my logbook. Now, Jerry started interpreting like a palm reader.
      "Hey, look, Cliff-the phone technician said 703," Jerry said. "Area
code 703 is in Virginia. And C and P . . . I bet that's Chesapeake and
Potomac. Yeah. They're the phone company for northern and western Vir-
      Terry Mast is an experimentalist. "You copied those numbers that the
phone technician said. Why not call every permutation of those numbers in
area code 703, and find out if there's a computer there?"
     Jerry Nelson looked at my notes. "Yeah, that oughta work. The tech-
nician said 1060 and 427 and 448. Try calling 703/427-1060. Or maybe
448-1060. There's only a few combinations."
      It was worth a try. But I'd be slightly more devious.
      I called my local telephone business office and said, "I have a couple

                  THE CUCKOO'S EGG

calls on my bill that I don't remember making. Could you tell me who I
      The operator was completely cooperative. "Just read me the numbers
and I'll check them for you."
      I told her six possible numbers, all in area code 703. Ten minutes later,
she called back. "I'm very sorry, but five of those numbers are nonexistent
or out of service. I don't know how you got billed for them."
      Five of the six were bad numbers! One might just do it. I said, "Oh
yes, that's all right. Who is the owner of the sixth number?"
      "That's Mitre, Incorporated spelled M-I-T-R-E, at 703/448-1060.
Would you like me to start a refund for those five other calls?"
      "I'm in a hurry right now. I'll take care of it later."
      Nervously, I dialed the phone number, ready to hang up when I heard
a voice. A computer's modem answered with a high-pitched whistle. Far
      Mitre. I knew of a defense contractor, Mitre, in Massachusetts. But not
in Virginia. I'd seen their ads in electronics magazines-they were always
looking for programmers who were U.S. citizens. Digging through the
library, I found that, yes, Mitre did have a branch in Virginia. McLean,
      Strange. Where had I heard of that city? The library's atlas told me.
      The CIA's headquarters are in McLean.

o     0      0 I couldn't believe it. The hacking seemed to be coming
from Mitre in McLean, Virginia-a couple of miles from CIA headquar-
ters. Time to call the boss.
      "Hey, Dennis, the calls are coming from Mitre. It's a defense contrac-
tor just down the road from CIA headquarters. What do you think Teejay
will say to that?"
      "How do you know it's Mitre?"
      "Well, during the phone trace, I copied down all the numbers and
digits that I heard from the technician. I called all combinations of them,
and ended up at a computer modem at Mitre."

                                 ST 0 L L

      "So you're not certain." Dennis saw the hole in my argument. "If we
spread this around and we're wrong, we'll be in hot water."
      "But what are the chances of randomly dialing a telephone and getting
a computer to answer?"
      "I don't care. Until you find some proof, don't act on it. Don't call
Mitre. And don't tell our spooky friends."
      Back to square one. I think I know the phone number of the hacker
but how to prove it?
      Aah! Just wait until the hacker calls back again. Then see if the phone
is busy. If it's busy, then likely I've got the right number.
      There was another way to get the phone number. Less sophisticated,
but more reliable.
      Back in graduate school, I'd learned how to survive without funding,
power, or even office space. Grad students are lowest in the academic hierar-
chy, and so they have to squeeze resources from between the cracks. When
you're last on the list for telescope time, you make your observations by
hanging around the mountaintop, waiting for a slice of time between other
observers. When you need an electronic gizmo in the lab, you borrow it in
the evening, use it all night, and return it before anyone notices. I didn't
learn much about planetary physics, but weaseling came naturally.
      Still, I couldn't finagle a federal search warrant. All I had were the
standard tools of astronomers. Exactly enough to get the information I
      I dialed Chesapeake and Potomac's business office and asked for the
security office. After a few transfers, I recognized the voice of the technician
that had traced last week's call.
      After a few minutes of casual chat, she mentioned that her eleven-year-
old kid was fascinated by astronomy. I saw my opening. "Think he'd like
some star charts and posters of the planets?"
      "Sure! Especially that ringed thing, you know, Saturn."
      One of the few resources that I've plenty of: pictures of planets and
galaxies. We talked a bit about her kid, and I returned to the matter on my
      "By the way, I think the hacker is coming from Mitre, over in
McLean. 448-1060. Does this agree with your trace?"
      "I'm not supposed to release this information, but since you already
know the number. . . ."
      Aah! Grad school comes through.

                  THE CUCKOO'S EGG

      I rolled a dozen posters into a mailing tube. Today, somewhere in
Virginia, a kid's wall sports a collection of planetary and galactic photos.
      McLean, Virginia . . . I knew more about Mars than McLean. I
called my sister, Jeannie, who lived somewhere near there. At least she had
the same area code.
      Jeannie had, indeed, heard of Mitre. They weren't just a defense con-
tractor grabbing secret Pentagon contracts. They also had ties to the CIA
and the NSA. Among thousands of other projects, Mitre tested computers
for security. When someone needed a secure computer, Mitre certified it.
      Odd. The hacker came from a company that certifies secure computers.
Maybe one of their testers was fooling around on the side? Or did Mitre
have some secret contract to explore security on the military networks?
      Time to call Mitre. It took five phone calls to pierce their veil of
secretaries, but eventually I reached a man named Bill Chandler.
      It took fifteen minutes to convince him that there really was a prob-
lem. "Simply impossible. We're running a secure shop, and nobody can
break in." I described my traces, leaving out the missing search warrants.
      "Well, I don't know if sorneone's hacking from our computers, but if
they are, they're sure not coming from the outside."
      It took another ten minutes before he'd accept that it was his problem.
Five more to decide what to do.
      I proposed a simple solution. Simple for me, at least. "The next time
the hacker's connected to Berkeley, just examine Mitre's telephone line.
Find out who's connected to it."
      Bill Chandler agreed. He'd round up some technicians and quietly
watch Mitre's telephone line, 448-1060. As soon as I'd call him, he'd trace
his internal network and find the culprit.
      "I doubt we'll find much," he said. "It's impossible to break into our
secure site, and all our employees have clearances."
      Right. If he wanted to keep his head in the sand, it was all right with
me. Maybe one of Mitre's employees was screwing around the military
networks, just for kicks. But what if this was an organized effort?
      If so, who was behind it? Could some secret agency have hired Mitre?
If so, it had to be someone right around the corner. Someone just a couple
miles away. Time to call the CIA.
      Ten minutes later, I'm on the phone with Teejay. "Dh, I don't know
how to ask this, and you probably can't tell me anyway, but what are the
chances that our hacker is someone from the CIA?"

                                 S TO L L

      Teejay wouldn't consider it. "Absolutely zero. We don't pry into
domestic affairs. Period."
      "Well, I can't say for certain, but it looks like our phone traces lead to
Virginia, and I was just wondering if . . ." I let my voice trail off, hoping
Teejay would pick up.
      "Where in Virginia?" Teejay asked.
      "Northern Virginia. Someplace called McLean."
      "Prove it."
      "We got a telephone trace, but it hasn't been officially released. We
don't have a search warrant, but there's no doubt it's from McLean."
      "How do you know?"
      "Standard techniques I picked up in graduate school," I said. If I told
him how, he wouldn't believe me. Anyway, he'd never reveal his methods
to me.
      "What else do you know about this McLean connection?"
      "A little bit. Know any defense contractors there?" For once I played
cat and mouse.
      "Cut the crap. Who is it?"
      "Come on. Be serious."
      "Would you believe 1820 Dolly Madison Road?"
      "Are you trying to tell me that someone from Mitre is hacking into
military computers?"
      "That's what our phone trace says."
      "Well, I'll be damned. . . . No, it's just not possible." Teejay went
silent for a second. "Mitre's a secure site. . . . Do you know anything
more about this hacker?"
      "I know what brand of cigarettes he smokes."
      Teejay laughed over the phone. "I guessed that last month."
       "Then why didn't you tell me?" Teejay wanted my news, but wasn't
forthcoming with his own. "Look, I've got to know one thing. Mitre's a
mile from you. They work on classified projects. Are you sure the hacker's
not with the CIA?"
       Teejay became suddenly bureaucratic. "I can only say that nobody in
our agency is authorized to observe domestic activities, with or without a
 computer." On the side, he added, "Damned if I know who this guy is, but
 he'd better not be one of us."
       "Can you find out?"

                   THE CUCKOO'S EGG

       "Cliff, this is a domestic problem. I'd love to help, but we can't touch
     Well, the CIA was interested, but not much help. Time to call the FBI.
For the seventh time, the Oakland FBI office didn't raise an eyebrow. The
agent there seemed more interested in how I traced the call than in where it
       Still, there was one more place to call. The Defense Communications
Agency. They seemed to be on good terms with the Air Force Office of
Special Investigations-maybe they could scare up some official interest.
     Despite ten thousand computers on the Milnet, only one person man-
aged security. A month ago, Major Steve Rudd had asked about our prob-
lems. He hadn't promised any action, just wanted to hear any news. Maybe
the word Mitre would wake him up.
     I called him, and mentioned that we'd traced things back to McLean,
Virginia. "I hope you're kidding," Steve said.
     "No kidding. The hacking's coming from a defense contractor in
    "Can't say till I check with my boss." I wondered if he'd play cat and
      Despite his protests, I stood my ground. Maybe by keeping quiet, I
could keep him interested. After a few more minutes on the phone, he gave
up, exasperated. "Look, talk to your boss and see if he'll tell us. We might
be able to help if we know who to lean on. Unless you tell us, though, we
can't do much."
       While it was fresh in my mind, I typed the day's events into my
logbook. The phone rang, and when I picked it up, a recorded message was
playing: "This phone line is not secured. Do not discuss classified informa-
tion." It repeated a couple times, so I hung up. I didn't know anything
classified, and didn't want to.
     Three minutes later, the same message came on my phone. By listening
carefully, you could hear where the tape was spliced. I was just getting into
the rhythm of the mechanical voice when an angry army officer interrupted.
     "Hello, is this Doctor Stol1?" People only used titles on me when I
was in trouble. "This is Jim Christy of the OSI."
     The Air Force narcs were on the phone. The Defense Communications
Agency must have rung their bell.

                                ST 0 L L

     The narc had just one question. "Where did you trace the hacker in
      "Uh, I can't tell you. This line isn't secure."
      "Be serious."
      There wasn't any reason not to tell him. At worst, he'd do nothing. At
best, he might armtwist Mitre into cooperating. So I explained the traces to
Jim Christy, and he seemed surprised, but satisfied.
      "I'll call the Virginia FBI," Jim said. "Maybe we can get some action
from our end."
      "Then you know something I don't. The Oakland office won't lift a
finger unless there's a million dollars involved."
      Jim explained that the FBI offices are pretty much autonomous. What
excites one agent, another won't consider worthwhile. "It's the luck of the
draw. Sometimes you get the elevator . . ."
      ". . . and sometimes you get the shaft." I wished him luck, asked him
to keep me posted, and went back to my logbook. Seemed like the rumors
were true. No police agency trusted another. The only way to solve the
problem was to tell everyone who might be able to help. Sooner or later,
someone might take action.
      None of us, at that time, would have guessed anything close to the
truth. None of us-not the CIA, not the FBI, not the NSA, and certainly
not me-knew where this twisted path would lead.

o      0 0 The next morning I arrived at the lab to find nothing more
than a couple stale phone messages. My boss wanted me to call our funding
agency, the Department of Energy-"Give them a heads-up." And Dan
Kolkowitz called from Stanford.
      "I would have sent you electronic mail," Dan said, "but I'm worried
that someone else might read it." We both had learned that hackers scan
electronic mail. The simple solution was to use the phone.
      In between bites of a cashew-butter sandwich, I told Dan about my
traces to Mitre, omitting any mention of the CIA. No need to start rumors
about someone in Berkeley cooperating with Big Brother.

                   THE CUCKOO'S EGG

      Dan took it all in. "Strange. I called you to say that we've just traced
our hacker into Virginia. McLean."
      My tongue stuck to my mouth-maybe it was cashew-butter-and it
took a moment to talk. "But your hacker's not the same guy that I'm
      "Yeah. Maybe a group of hackers are using the same methods to attack
different computers. In any case, I know the name of the hacker that's
breaking into Stanford."
      "How'd you get that?"
       "Simple. We did the same thing as you: printed out everything the
hacker typed. Well, one night, the hacker logged into our Stanford Unix
computer and tried to solve his homework. It was a simple calculus prob-
lem, solving the area under a curve by counting squares. But the hacker
loaded the entire problem into our computer, including his name and his
instructor's name."
       "Ha! So who is he?"
       "I'm not sure. I know his name is Knute Sears. He's in the fourth
period math class, taught by a Mr. Maher. But I haven't any idea where he
is. I've searched the phone books in Stanford, and I can't find him."
       Dan and I both realized that his hacker must be a high school student.
Finding the area under a curve is introductory calculus.
       "So how do you find a high school student named Sears?" Dan asked.
"Ever heard of a directory of all kids in high school?"
       "No, but maybe there's a directory of high school math teachers."
There's a directory of everyone else, I figured.
       We compared our logs, and again decided that we were following two
different people. Perhaps Knute Sears did know the hacker that was break-
ing into my system, but they certainly weren't the same guy.
       After I hung up, I hopped on my bike and coasted down to campus.
Surely the University library would have a directory of high school teach-
ers. No luck. Finding an individual isn't easy when you know their name
but not their city.
       As a last straw, I could call my sister, Jeannie, in Virginia. Life was a
little zooey for her. What was it like, from my sister's perspective, to be
sucked into this ever-widening vortex of compute-crud?
       All I needed at first was a little telephone work. I'd be most apprecia-
tive if she could call around the McLean area high schools to try and locate
the mystery math teacher, Mr. Maher. Compared to the FBI's foot-drag-

                                S TaL L

ging, any help on the East Coast, no matter how minor, would amount to a
substantial dragnet. Furthermore, Jeannie had experience with the Depart-
ment of Defense-well, anyone was more experienced with the military
than me. I trusted Jeannie's discretion; even if she did no more than just
listen, it would be a service.
      I phoned Jeannie at work and launched into the requisite background
explanation, but as soon as I dropped the words, "hacker" and "Milner," she
said, "Okay, what do you want from me?" It turned out that the Navy
research and development center she worked for had warned its support staff
about the risks of leaky computers.
      Jeannie did attach one thin string to her offer of help. "It would be
real sweet if you could get someone to write me a nice, official thank-you
note. Say, from the OSI or the FBI, or whoever."
      When I next spoke to the OSI, I relayed Jeannie's request. They
assured me that this was easy for them. . . . "We're really good at writing
notes." (Hardly. Despite abundant promises in the next year, from majors,
colonels and generals, my sister was never to receive her official pat on the
back. Eventually, we concluded that it's just not possible for someone in one
part of the federal bureaucracy to officially thank someone in another.)
     At any rate, Jeannie decided to start her investigation during her lunch
break. And she called back with something to report within an hour.
      "The public high school that's closest to Mitre is McLean High School,
so I started there," she said. "I asked to talk to a math teacher named Mr.
Maher. They repeated the name, said, 'One moment please,' and connected
me to someone. At that point, I hung up."
     Could it have been that my sister, in one phone call, had gotten more
done than the FBI? Gee, maybe I should impose on her further. "How
about dropping by that school and see if you can spot any computers-most
schools have 'em. Also, see if you can find Knute Sears in their yearbook.
But be careful. The way I've got him scoped, he's extremely skittish. Don't
spook the guy."
     "Okey doke, I'll take a long lunch tomorrow."
     The next day, while I pedaled the verdant hills of Berkeley, my sister
circumnavigated the Washington, D.C. beltway, feeling alternately exhila-
rated and foolish.
      It turns out that McLean is the home of loads of elected officials,
policymakers, and upper-end military leaders. Jeannie reports that it looks

                  THE CUCKOO'S EGG

like the "apotheosis of the affluent second-ring suburb," though I'm not sure
what that means.
       And on that bright Virginia autumn day, its high school seemed a
distillation of all the myths surrounding the Great American High School.
Classes had just let out. Expensively dressed kids spilled out of the front
door. The student parking lot included Mercedes, BMWs, and an occasional
Volvo. Jeannie's pride and joy, a beat-up '81 Chevy Citation, shrank to the
remote outskirts of the lot in self-conscious mortification.
     Jeannie reported that, like her car, she felt discomfort, not   to   mention
an attack of absurdity, snooping around a suburban school.
     Now, my sister has better reason than most to hate being in a high
school. In her younger and more vulnerable years, she taught eleventh-grade
English. Now, teenagers give her the hives, especially teenagers that don't
belong to her. Really affluent ones are the worst, she reports.
     Under the guise of a concerned parent, Jeannie visited the school office
and sat for half an hour, scanning yearbook listings of the swim team, the
Latin scholars, the debaters, for just one mention of the apocryphal Knute
Sears. No dice.
     Having thoroughly exhausted the resource material and convinced that
there was no Knute at McLean, she turned her attention to the teachers'
mailboxes. Sure enough, one was labeled, "Mr. Maher."
      Abruptly, a clerk appeared and asked what she wanted to see. With a
ditsiness reminiscent of Gracie Allen, my sister burbled, "Gee, I don't know,
dear. . . . Well, well, what do you know? Here it is, right in front of my
eyes." The clerk smiled patronizingly as Jeannie grabbed a brochure from
the nearest pile on the counter-it turned out to explain how to register for
night school. Half covering a silly-me smirk with her hand, she waved bye-
bye with the other hand and booked out of there.
      Her covert operation complete, Jeannie called me that afternoon.
Stanford's mythical Knute Sears was to remain a myth. He'd never regis-
tered at McLean High School. And their Mr. Maher wasn't a math teacher.
He taught history, part time.
     Another dead end. Even today,.I can't talk to my sister without feeling
acute embarrassment for sending her on a wild goose chase.
     I called Dan at Stanford with the bad news. He wasn't surprised. "It'll
take a long investigation. We're giving up on the FBI. The Secret Service
has a computer crime division that's eager to work on the case."

                                 ST 0 L L

      The Secret Service was helping Stanford? Weren't they the people that
caught counterfeiters and protected the president?
      "Yes," Dan said, "but they also investigate computer crimes. The De-
partment of the Treasury tries to protect banks from computer fraud, and
the Secret Service is a branch of the Treasury Department."
      Dan had found a way around a recalcitrant FBI. "They don't know
much about computers, but they've got moxie. We'll provide the computer
expertise, and they'll get the warrants." Moxie?
      It was too late for me, though. Our local FBI still didn't care, but the
FBI office in Alexandria, Virginia, had noticed. Someone-Mitre, the Air
Force, or the CIA-had leaned on them, and Special Agent Mike Gibbons
      In a couple minutes, I realized that at last, I was speaking to an FBI
agent who knew computers. He'd written Unix programs, used modems,
and wasn't scared by databases and word processors. His latest hobby was
playing Dungeons and Dragons on his Atari computer. J. Edgar Hoover
must be rolling in his grave.
      Better yet, Mike didn't mind communicating by electronic mail, al-
though since anyone might intercept our traffic we used an encryption
scheme to keep our conversations private.
      From his voice, I guessed Mike wasn't over thirty, but he knew com-
puter law thoroughly. "There's at least a violation of U.S. Code Section
1030. Probably breaking and entering as well. When we find him, he'll be
looking at five years or $50,000." I liked how Mike said "when" rather than
      I explained my agreement with Mitre. "When the hacker next shows
up in Berkeley, Bill Chandler will trace Mitre's network from the inside.
We'll find him then."
      Mike wasn't so sure, but at least he didn't object to my plan. The only
missing piece was the hacker: he hadn't shown up since Halloween-a two-
week hiatus. Each morning, I'd check the recorders. Day and night, 1'd wear
my beeper, waiting for the hacker to step on our invisible tripwire. But not
a peep.
      Finally, on November 18, my hacker returned to his Sventek account.
He entered at 8:11 in the morning and stayed around for half an hour.
Immediately, I called Mitre in McLean. Bill Chandler wasn't in, and a stuffy
manager told me that only Bill Chandler was authorized to trace Mitre's
internal network. He talked about "strict guidelines" and "certified secure

                  THE CUCKOO'S EGG

networks." I cut him off. With the hacker live on my system, I didn't need
to listen to some big-shot manager. Where were the technicians, the people
who actually knew how Mitre's system worked?
     Another chance to catch the hacker-foiled.
      He showed up again in the afternoon. This time I got through to Bill
Chandler, and he ran over to check his outbound modems. Sure enough,
someone had dialed out through Mitre's modem, and it looked like a long-
distance call. But where was the connection originating?
      Bill explained, "Our network within Mitre is complex, and it's not
easy to trace. We don't have individual wires connecting one computer to
another. Instead, a lot of signals travel on a single wire, and connections
have to be traced by decoding the addresses of each packet on our ethernet."
      In other words, Mitre couldn't trace the calls.
    Damn. Someone was calling out from Mitre, but they couldn't fmd
where the hacker was coming from. We still didn't know if it was a Mitre
employee or someone from the outside.
      Furious, I looked over the printout from the hacker. Nothing new
there. He tried once again to slip into the Army base in Anniston but was
turned away. The rest of the time he spent searching my Berkeley computer
for words like "nuclear bomb," and "SDI."
       Bill promised to get his best technicians on the problem. A few days
later, when the hacker showed up, I heard the same story. No doubt that
someone was dialing out from Mitre's computer system. But they couldn't
trace it. They were baffled. Who was behind it? And where was he hiding?
       On Saturday, Martha dragged me on a day's outing to Calistoga,
where the geysers and hot springs attract butterflies, geologists, and hedo-
nists. For the latter, there are mud baths, said to be the height of Northern
California decadence. For twenty dollars, you can be parboiled in an ooze
of volcanic ash, peat, and mineral water.
       "It'll take your mind off your work," Martha said. "You've been all
twisted up over this hacker-a break will do you good." Mired in an
oversized bathtub didn't sound like a recipe for rejuvenation, but I'll try
anything once.
     Wallowing in this private swamp, my mind drifted off to thoughts of
Mitre. My hacker used Mitre's outgoing telephone lines to cross the coun-
try. Stanford had traced one hacker to McLean; likely he came through
Mitre. Maybe Mitre provided a central point for hackers, a sort of switch-

                                  S TaL L

board to place their calls. That would mean the hackers weren't Mitre
employees, but were from outside the company.
      How could this happen? Mitre would have to make three mistakes.
They'd have to create a way for anyone to connect freely to their local
network. Then, they'd have to allow a stranger to log onto their computer.
Finally, they'd have to provide unaudited outgoing long-distance telephone
     They'd met the third condition: the modems connected to their inter-
nal network could call all over the country. We'd traced our troubles into
those very lines.
      But how could someone connect into Mitre? Surely they wouldn't
allow just anyone to dial into their network. As Bill Chandler had said,
they're running a secure shop. Military secrets and stuff like that.
     What other ways could you get into Mitre? Over some network,
perhaps? Could a hacker get there through Tymnet? If Mitre paid for
Tymnet service and didn't protect it with passwords, you could call them
from anywhere for free. Once connected, Mitre's internal network might let
you turn around and call out. Then you could dial anywhere, with Mitre
picking up the tab.
     It would be easy to test my hypothesis: I'd become a hacker. I'd go
home and try to use Tymnet to connect to Mitre, trying to break into a
place I wasn't supposed to be.
       The mud smelled of sulfur and peat moss, and felt like a hot primor-
dial ooze. I enjoyed the mud bath and the sauna that came afterward, but I
still couldn't wait to get out of the mud and return home. I had a lead. Or
at least a hunch.

o     0      0      Logbook, Sunday, November 23, 1986
     10:30 A.M. Oakland Tymnet access number is 415/430-2900. Called
from my Macintosh at home. 1200 baud, no parity. Tymnet asked for a
username. I entered MITRE. Response: Welcome to Mitre-Bedford.
     10:40   A.M.   Mitre has an internal network which gives a menu. Four-

                  THE CUCKOO'S EGG

teen choices, apparently different computers within Mitre. I try each in
      10:52 A.M. One choice, MWCC leads to another menu. That menu has
twelve choices. One choice is DIAL. I try:
      DIAL 415486 2984 no effect
      DIAL 1 415486 2984 no effect
      DIAL 9 1 415486 2984 Connected into Berkeley computer.
      Conclusion: An outsider can connect into Mitre through Tymnet. No
password necessary. Once in Mitre, they can dial out, either locally or long
      MWCC means, "Mitre Washington Computing Center"; Bedford
means "Bedford Massachusetts." 1'd entered Mitre in Bedford, and popped
out five hundred miles away in McLean.
      11:03 A.M. Disconnect from Berkeley computer, but remain at Mitre. I
request connection into system AEROVAX. It prompts for username. I
enter "Guest." It accepts and logs me in, without any password. Explore
Aerovax computer.
      Aerovax has programs for some sort of airport flight safety. Program
to find allowable landing angles for high-speed and low-speed aircraft ap-
proaches. Presumably funded by government contracts.
      Aerovax connects to several other computers over Mitre's network.
These are password protected. "Guest" is not a valid username on these
other Mitre computers. (I'm not sure they're even at Mitre.)
      Wait-something's wrong here. The network controlling software
doesn't seem normal-its greeting message shows up too quickly, but it
completes its connection too slowly. I wonder what's in that program. . . .
      Aha! It's been modified. Someone has set a Trojan horse in the Aer-
ovax network software. It copies network passwords into a secret file for
later use.
      Conclusion: someone's been tampering with Mitre's software, success-
fully stealing passwords.
      11:35 A.M. Disconnect from Mitre and update logbook.
      Today, reading my logbook, I remember an hour of poking around
Mitre's internal network. At once it felt exciting and forbidden. Any min-
ute, I expected someone to send a message on my computer screen, "We
caught you. Come out with your hands up."
      No doubt Mitre had left a gaping hole in their system. Anyone could
make a local telephone call, tell Tymnet to connect to Mitre, and spend an

                                 S TaL L

afternoon fooling around with Mitre's computers. Most of their machines
were protected with passwords, but at least one was pretty much wide open.
       I remembered Mitre's pious disclaimer, "We're running a secure shop,
and nobody can break in." Right.
       The "Guest" account on their Aerovax let anyone on. But the Trojan
horse was deadly. Someone had tampered with their network program to
copy passwords into a special area. Every time a legitimate employee used
the Aerovax computer, her password was stolen. This gave the hacker keys
to other Mitre computers. Once the hacker penetrated their armor, he could
roam anywhere.
       How deeply was Mitre's system infested? By listing their directory, I
saw that the Trojan horse was dated June 17. For six months, someone had
silently booby-trapped their computers.
       I couldn't prove that it was the same hacker that I was dealing with.
But this morning's exercises showed that anyone could enter Mitre's system
and dial into my Berkeley computers. So the hacker wasn't necessarily at
Mitre. He might be anywhere.
       In all likelihood, Mitre served as a way station, a stepping stone on the
way to breaking into other computers.
       The McLean connection became clear. Someone dialed into Mitre,
and turned around and dialed out from them. This way, Mitre paid the bills
both ways: the incoming Tymnet connection and the outgoing long-dis-
tance telephone call. Even nicer, Mitre served as a hiding place, a hole in the
wall that couldn't be traced.
        Mitre, the high-security defense contractor-I'd been told that you
can't get past their lobby without showing picture ID. Their guards wear
 guns, and their fences are barbed. Yet all it takes is a home computer and a
 telephone to prowl through their databases.
        Monday morning, I called Bill Chandler at Mitre and told him the
news. I didn't expect him to believe me, so I wasn't disappointed to hear
him insist that his company was "highly secured and sensitive to any secu-
 rity problems."
        I'd heard it before. "If you're so concerned about security, why isn't
 anyone auditing your computers?"
        "We do. We keep detailed records of how each computer's used," Bill
 said. "But that's for accounting, not to detect hackers." I wondered what his
 people would do about a 75 cent accounting error.
        "Ever hear about a system called the Aerovax?"

                  THE CUCKOO'S EGG

     "Yeah, what about it?"
     "Just wondering. Hold any classified data?"
     "Not that I know. It's for an airport control system. Why?"
     "Oh, just wondering. You ought to check it over, though." I couldn't
admit that I'd danced through his system yesterday, discovering the Trojan
horse. "Know any way for a hacker to enter your system?"
     "It had better be impossible."
       "You might check out your public access dial in ports. While you're at
it, try accessing Mitre's computers over Tymnet. Anyone can connect to
your system, from anywhere."
     This latest news woke him up to some serious problems in his system.
Mitre wasn't inept. Just semi-ept,
     Bill wasn't sure how to react, but he wouldn't keep his system open
any longer. I couldn't blame him. His computers were naked.
      Mostly, he wanted me to keep my mouth shut.
      I'd shut up, all right, on one condition. For months, Mitre's computers
had called around the country, using expensive, AT&T long-distance tele-
phone lines. There must be phone bills for those calls.
      In Berkeley, five of us shared a house. We had a monthly dinner party
when the phone bill arrived. With poker faces, each of us would deny
making any of the calls. But somehow, eventually, every call was accounted
for, and the bill paid.
     If the five of us could haggle through a phone bill, Mitre must be able
to as well. I asked Bill Chandler, "Who pays the phone bills for your
     "I'm not sure," he replied. "Probably central accounting. I never see
      That's how the hacker got away with it for so long. The people
paying the phone bills never talked to the managers of the computers.
Strange. Or was it typical? The computer's modems run up a long-distance
phone bill. The phone company sends the bill to Mitre, and some faceless
accountant signs a check. Nobody closes the loop. Nobody asks about the
legitimacy of those dozens of calls to Berkeley.
      Bill wanted me to be quiet about these problems. Well, yes, but I had a
price. "Say, Bill, could you send me copies of your computer's phone bills?"
      "What for?"
     "It might be fun to see where else this hacker got into."

                                            ST 0 L L

      Two weeks later, a thick envelope arrived, stuffed with long-distance
bills from Chesapeake and Potomac.
       At home, my housemates and I haggled over a twenty-dollar phone
bill. But I'd never seen thousand-dollar bills. Every month, Mitre had paid
for hundreds of long-distance calls, all over North America.
       But these weren't people reaching out to touch each other. These bills
showed Mitre's computer dialing hundreds of other computers. (I proved
this to myself by calling a few. Sure enough, in each case, I heard a modem
answer with a whistle.)
       Now here's some useful information. Mitre might not be interested in
analyzing it, but together with my logbook, I might be able to understand
how far the hacker had penetrated. I'd just have to somehow separate the
hacker's calls from the normal calls.
       Plenty of the calls were obvious hacking. On the list were lots of calls
to Anniston, Alabama. And there were the calls to Tymnet in Oakland-
they'd cost me a galaxy to trace.
       But some of the calls on the bills must be legitimate. After all, Mitre's
employees must call computers to transfer data or copy the latest software
from the West Coast. How could I separate the hacker's calls?
       Back home, when our phone bill arrived, Martha cooked up dinner,
Claudia did the salad, and I baked cookies. * Afterward, stuffed on chocolate
chips, we'd divvy up the phone bill.
       Sitting around the dining table, my housemates and I had no problem
figuring out who'd made which long-distance calls on our bill. If I had
made a call to Buffalo from 9:30 until 9:35 and another to Baltimore from
9:35 to 9:45, then it was likely that I'd made the call to New York from
9:46 to 9:52.
       Looking at Mitre's phone bills, I knew that only the hacker would call
the Army base in Anniston, Alabama. Pretty likely that a phone call made a
minute after calling Anniston belonged to the hacker. Same for a call that
ended just before dialing Alabama.
       In physics, this is correlation analysis. If you see a solar flare today and
tonight there's a bright aurora, chances are that these are correlated. You

* Two eggs, 1 cup brown sugar, 1/2 cup regular sugar, 2 sticks softened butter. Fold in 2 1/4 cups flour,
1/2 teaspoon salt, 1 teaspoon baking soda, and a couple tablespoons of vanilla. For an extra chocolate jag,
toss in 3 tablespoons of cocoa. Oh, don't forget 2 cups of chocolate chips. Bake'em at 375 degrees for 10

                   THE CUCKOO'S EGG

look at things that occur close together in time, and try to find the probabil-
ity that they're somehow connected.
      Correlation analysis in physics is simply common sense.
      Well, here were six months of phone bills. Dates, times, phone num-
bers, and cities. Probably five thousand in all. Enough that I couldn't ana-
lyze it by hand. Perfect for analyzing on a computer-there's plenty of
software written to search out correlations. All I had to do was enter them
into my Macintosh computer and run a few programs.
      Ever type five thousand phone numbers? It's as boring as it sounds.
And I had to do it twice, to make sure I didn't make any mistakes. Took me
two days.
      Two days to enter the data, and an hour to analyze it. I told my
program to assume that the hacker made all calls to the Anniston Army base.
Find all calls that immediately preceded or trailed those calls. It took a
minute, and showed me that the hacker had called Oakland's Tymnet many
times. Aah, the program behaved reasonably.
      I spent the afternoon tinkering with the program, refining its statistical
techniques and watching the effect of different algorithms on the output. It
determined the probability that each call was made by the hacker. Cute-
just the thing to settle arguments at home.
      It wasn't until the evening that I realized what the program was telling
me: this hacker hadn't just broken into my computer. He was into more
 than six, and possibly a dozen.
      From Mitre, the hacker had made long-distance connections to Nor-
folk, Oak Ridge, Omaha, San Diego, Pasadena, Livermore, and Atlanta.
      At least as interesting: he had made hundreds of one-minute-long
phone calls, all across the country, to Air Force bases, Navy shipyards,
aircraft builders, and defense contractors. What can you learn from a one-
 minute phone call to an Army proving ground?
      For six months, this hacker broke into Air Force bases and computers
all across the country. Nobody knew it. He was out there, alone, silent,
 anonymous, persistent, and apparently successful-but why? What's he af-
 ter? What's he already learned? And what's he doing with this information?


                                   ST 0 L L

   o     0     0     Mitre's phone bills showed hundreds of telephone calls all
   around the country, most of them a minute or two long. But no human
   voice spoke over that line-it was one computer dialing another.
         My boss's voice, though, was singularly human. Around the end of
   November, Roy Kerth stopped in my office, and found me asleep under my
         "Whacha been doing for the past month?"
         I could hardly say, "Oh, typing in phone bills from some East Coast
   defense contractor." Reminding him of my chase would jog his memory of
   a three-week limit. Quickly, I thought of our department's new graphics
   terminal-a spiffy new toy that displays three-dimensional images of me-
   chanical devices. I'd fiddled with it for an hour, just long enough to learn
   how difficult it was to use. But it was an excuse to get the boss off my back,
   and I told him, "Oh, I'm helping some astronomers design their telescope
   with our new display terminal." This wasn't a total lie, since we'd talked
   about doing this. For all of five minutes.
          My maneuver backfired. Roy smiled slyly and said, "OK. Next week
   show us some pretty pictures."
          By never showing up before noon, I'd managed to avoid half of the
   department's meetings. If I didn't have something by next week, no doubt
   my wings would get clipped.
          Time to slide the hacker onto the back burner-and just as the trail
   was heating up.
          One week to learn how to program the beast, figure out what the
   astronomers needed, and get something on the screen. I knew zero about
   computerized design. And the programming language was from the twenty-
   first century: it claimed to be "an object-oriented language with graphical
   inheritance." Whatever that meant.
          So I wandered over to the telescope design team, where Jerry Nelson
   and Terry Mast were arguing over how much their telescope would bend
   due to gravity. When looking at stars straight overhead, gravity wouldn't
   bend the telescope tube. But when pointing near the horizon, the tube

                  THE CUCKOO'S EGG

would bow slightly. Just enough to upset the delicate optical alignment.
They wanted to know how much, and could I show the effect on the
      This seemed like fun-at least more fun than figuring out what
"graphical inheritance" meant. We talked for a while, and Jerry mentioned
that Professor Erik Antonsson had written a program to display the tele-
scope on a graphics display terminal. The same type as I was supposed to
      "You mean that someone has already written the program to solve
your problem and display a picture on the screen?" I asked.
      "Yes," the astronomer explained. "But it's down at Caltech in Pasa-
dena. Doesn't do us much good four hundred miles away. We need the
results now."
      I just had to get the Cal tech program up to Berkeley and fit it into my
Vax computer. No need to even figure out how to program the beast.
       I called Professor Antonsson at Caltech. He'd be happy if we used his
program, but how would he send it to us? Mail would take a week. Faster
to send it electronically. Aah-when you need a program, don't mail a tape.
Just ship it over the network. In twenty minutes, the program percolated
across the wires, and settled into my computer.
       Well, Professor Antonsson had done a super job of programming the
problem. By nine that evening, 1'd customized his program for my system
and the new telescope data.
       Amazingly, the damn thing worked, though not quite the first time.
By 2 A.M., I got it to draw a multicolored picture of the Keck Telescope,
complete with struts, bearings, and mirrors. You could see where the tube
bent, where the stresses built up, and which sections needed reinforcing.
Technology comes through again.
       One evening of real work, and I was off the hook. The hacker was
back on the front burner.
       But not a peep from him. My alarms were set, the monitors active, but
 he'd been invisible for two weeks. On my way home, I wondered if he too
might have an urgent project that kept him away from my computer. Or
 had he found a new way to enter the Milnet, completely bypassing my
       As usual, I slept late the next morning. (No need to work early when
Thanksgiving weekend was coming up.) At 11:30, I pedaled up the hill and
ducked into work, ready to show off my zero-work computer display. But

                                S TaL L

once in my office, I went back to wondering why the hacker wasn't show-
ing up. Time to call Mitre, and find out what they'd done.
      Bill Chandler's voice crackled through a noisy long-distance connec-
tion. Yes, a week ago, he'd disconnected their outgoing modems. The hacker
could no longer leapfrog through Mitre's local network.
      The gig was up. We didn't know where he came from, and we'd never
find out. Since Mitre had corked up their hole, the hacker would have to
find another path into my system.
      Not likely. If someone had bolted my door shut, I'd be suspicious that
they were about to bust me. And I knew this hacker was paranoid. He'd
disappear for sure.
      So all my traps had been set in vain. The hacker was gone, and I'd
never find out who he was. Three months of searching, with only a fuzzy
question mark at the end.
      Not that I should complain. Without a hacker to occupy my time,
there was plenty of worthwhile work waiting. Like designing a telescope.
Or managing a computer. And building scientific software. Jeez-I might
even do something useful.
      But I'd miss the excitement. Running down the hallway and jumping
to a printer. Crowding around a computer screen, trying to trace connec-
tions through my computer out somewhere across the country.
      And I'd miss the satisfaction of building tools with which to follow
him. By now, my programs were almost instant. Seconds after the hacker
touched my computer, my pocket pager beeped. It didn't just tell me that
the hacker was around. I'd programmed my pager to beep in Morse code,
telling me the hacker's target computer, his account name (usually Sventek),
and which line the hacker had entered from. Backup alarms and monitors
made the system fail-safe.
      Somewhere out there, a stranger had come close to getting nailed. If
only I'd been able to make one more trace.
      Just one more trace.
      The hacker was gone, but I had a few loose ends. Mitre's long-distance
phone bills showed dozens of calls to a number in Norfolk, Virginia. By
calling around (standard graduate school technique: keep pestering), I even-
tually found that the hacker had been dialing the Navy Regional Auto-
mated Data Center.
      Well, nobody's stopping me, so I called the Navy data center and
talked to their system manager, Ray Lynch. Ray seemed to be an outgoing,

                   THE CUCKOO'S EGG

competent guy who took his job very seriously. He ran an electronic
mailbox system-pigeonholes for electronic mail.
      Ray reported that back on July 23, from 3:44 until 6:26 P.M., someone
had broken into his Vax computer, using the account belonging to the field
service engineers. Once inside his system, the hacker had created a new
account named Hunter.
      There's that name again. Same guy, no doubt.
      The episode normally would have escaped Ray's attention. With three
hundred Navy officers using his computers, he'd never have noticed some-
one illegally adding a new account.
      But the next day, he received a phone call from Jet Propulsion Labora-
tory in Pasadena, California; the same people that run interplanetary space-
craft. An alert JPL operator had detected a new system manager at their mail
management computer. This new user had entered from the Milnet, coming
in from Virginia.
      JPL called Ray Lynch, and asked him why his field service people had
been fooling with their computer. Ray didn't wait around to ask questions.
He shut down his computer and changed all its passwords. The next day, he
reregistered each of his users.
       So my hacker had broken into JPL and a Navy computer. Months
before I'd detected him in Berkeley, he had been fooling around the Milnet.
      These targets were news to me. Were they a clue to where the hacker
was? Well, if you live in California, there's no reason to go through Vir-
ginia to reach a computer in Pasadena. And why would someone in Vir-
ginia go through Mitre to dial another Virginia phone?
       Suppose this hacker had used Mitre to dial all his calls, except for local
ones. That meant that any state that showed up on Mitre's phone bills was
not the hacker's home. Ruled out Virginia, California, Alabama, Texas,
Nebraska, and a dozen others. This didn't lead anywhere, and hardly seemed
       I called some of the other places listed on Mitre's phone bills. The
hacker had hit a college in Atlanta, Georgia. The system manager there
hadn't detected it, but he wasn't likely to, either. "We run a pretty open
system. Lots of students know the system password. The whole thing de-
pends on trust."
       That was one way to run a computer. Leave all the doors open. Like
one of my physics profs: anyone could wander into his office. Didn't do
much good, though. He kept his notes in Chinese.

                                      13 I
                                S TaL L

      From talking to Ray, I learned one new wrinkle about the hacker. Up
until now, I'd watched him exploit Unix systems. But Ray's system was a
Vax computer running the VMS operating system. The hacker might not
know the Berkeley variant of Unix, but he certainly knew how to break
into Vax VMS systems.
      Since 1978, Digital Equipment Corporation had been making Vaxes,
their first thirty-two-bit computers. They couldn't make them fast enough:
by 1985, over fifty thousand had been sold, at $200,000 each. Most of them
used the versatile, friendly VMS operating system, although some contrary
cusses threw away the VMS system, preferring the power of Unix.
      Both Unix and VMS divide up the computer's resources to give a
separate area for every user. There's space reserved for the system and com-
mon space that can be shared by everyone.
      Somehow, when you uncrate the machine and first switch it on,
you've got to be able to create places for your users. If the machine comes
to you protected with passwords, you won't be able to log on the first time.
      Digital Equipment Company answered this problem by packaging
every Vax-VMS computer with three accounts, each with its own password.
There's the SYSTEM account, with the password, "MANAGER." An ac-
count named FIELD, password "SERVICE." And an account USER with
the password "USER."
      The instructions say to start the system running, create new accounts
for your users, and then change these passwords. Starting up a computer is a
bit tricky, and well, some system managers have never changed these pass-
words. Despite Digital's best efforts to make the system managers change
those passwords, some never do. The result? Today, on some systems, you
can still log in as SYSTEM, with the password "MANAGER."
      That system account is completely privileged. From it, you can read
any file, run any program, and change any data. Seems nutty to leave it
      The hacker either knew about these backdoor passwords, or else he
knew some very subtle bug in the VMS operating system. Either way, there
was little doubt that he was skilled in two operating systems: Unix and
      Some high school students are impressive computer jockeys. But it's a
rare high school student who's both deeply skilled and versatile-experi-
enced in several computers. That takes time. Years, usually. Yes, most Unix
systems folks could exploit the Gnu-Emacs hole, once they realized its

                   THE CUCKOO'S EGG

 weakness. And most VMS system managers knew about the not-so-secret
 default passwords. But each operating system took a couple years to become
 proficient in, and the skills weren't very portable.
      My hacker had a couple of years of Unix experience, and a couple of
 years in VMS. Probably had been system manager or administrator along
 the way.
      Not a high school student.
       But not an experienced wizard, either. He didn't know Berkeley Unix.
       I had been following someone in his twenties who smoked Benson and
 Hedges cigarettes. And broke into military computers, searching for classi-
 fied information.
      But was I following him anymore? No, not really. He wouldn't show
 up agam.
      Teejay called from the CIA. "I'm just checking to hear what's new
 about our boy."
      "No, nothing really. I think I know how old he is, but not a whole
lot." I started explaining about the Navy data center and the backdoor
passwords, but then the CIA agent interrupted.
      "Got printouts of those sessions?"
     "Well, no, my direct evidence is Mitre's phone bills. If that's not
convincing, there's other pointers. He created an account with the name
Hunter. Same as at Anniston."
     "Did you write this in your logbook?"
     "Sure. I put everything there."
     "Could you send me a copy?"
      "Well, it's kinda private. . . ." Teejay wouldn't send me copies of his
      "Come on, be serious. If we're ever going to light a fire under the 'F'
entity, I've got to know what's happening."
     The "F" entity? I searched my memory. Fourier transform? Fossils?
Finger painting?
     "What's the 'F' entity?" I asked, somewhat humiliated.
     "You know, the entity in Washington," Teejay replied with a touch of
annoyance. 'j. Edgar's boys. The Bureau."
     Why not just say the FBI?
     "Oh, I get it, you want my logbook to convince the 'F' entity to do
something." Entity, indeed. Spooktalk.
     "Yeah. Just send it to me."

                                  ST 0 L L

     "What's your address?"
     "Just mail it to Teejay, Zip Code 20505. It'll reach me."
     Now there's status. No last name, no street, no city, no state. I won-
dered if he ever got junk mail.
     With the CIA off my neck, I might as well go back to real work. I
played around with Professor Antonsson's graphics program for a while,
and found that it was amazingly simple to understand. All this hype about
object-oriented programming just meant that you didn't write programs
using variables and data structures; instead, you told the computer about
things. To describe a robot, you'd detail its feet, legs, joints, torso, and head.
No need to talk about X's and y's. And "graphical inheritance" just meant
that when the robot moved its leg, the feet and toes moved automatically.
You didn't have to write a separate program to move each object.
      Neat. After a day or two of fooling with the Caltech program, its
simplicity and elegance came shining through. What seemed a hairy pro-
gramming challenge turned out to be easy. So I spiffed up the display,
adding colors and titles. The boss wanted me to jump through hoops; 1'd
put up a three-ring circus.

o     0      0 Thanksgiving would be a corker. With her bicycle and
backpack, Martha had hauled home forty pounds of groceries. She made
only a few sarcastic comments about roommates who sleep late, and set me
to putting stuff away and cleaning the house.
      "Put away the veggies, honey," she said. "I'm going to the Safeway."
How could there possibly be more food to get? Seeing my amazement, she
explained that this was just the fresh stuff, and she still had to get the goose,
flour, butter, cream, and eggs. A corker, for sure.
      I put the food away and climbed back in bed. I woke up to the smell
of biscuits and goose wafting through the house. We expected Martha's grad
school friends who couldn't go home (or preferred Martha's cooking to
mom's), a couple of law professors, a few hungry warriors from her aikido
dojo, and her zany friend Laurie. My conscience finally responded to all
Martha's bustling, and I revved up our 250-horsepower Hoover.

                  THE CUCKOO'S EGG

      As I vacuumed the room, our roommate Claudia returned from a
violin rehearsal. "Oh, don't do that," she exclaimed, "that's my job." Imag-
ine-a roommate that enjoyed doing housework. Her only fault was play-
ing late-night Mozart.
      Thanksgiving passed by idyllically, with friends wandering in, helping
in the kitchen, talking, and lounging around. It was an all-day feed, starting
with fresh oysters from the San Francisco wharf, moving on leisurely to
Martha's wild mushroom soup, then the goose. Then we lay around like
beached whales until we worked up the energy to take a short walk. Over
pie and herbal tea, the talk turned to law, and Martha's friend Vicky held
forth on environmental regulation while a couple of professors argued over
affirmative action.
      Finally, too full and contented for intelligent conversation, we lay in
front of the fire and roasted chestnuts. Vicky and Claudia played piano
duets; Laurie sang a ballad, and I thought about planets and galaxies. Wor-
ries about computer networks and spies seemed unreal in this warm world
of friends, food, and music. A down-home Thanksgiving in Berkeley.
      At the lab, I forgot about the hacker. He'd been gone for almost a
month. Why? I didn't know.
   The astronomers fiddled with their new graphics display, studying ways
to strengthen their telescope. By now, I'd figured out how to animate the
display, so they could zoom in on interesting parts, and rotate it on the
screen. Object-oriented programming-by accident, I'd learned a new
buzzword. The astronomers didn't care, but I had to give a talk to computer
      On Wednesday, I was all set to dazzle the other systems folks. I'd
memorized all the jargon and set up the display so that it wouldn't foul up
at the last minute.
       A dozen computer whizzes showed up at three o'clock. The display
system worked flawlessly, and the Caltech software loaded without a hitch.
Computer people are accustomed to boring talks on databases and structured
programming, so this three-dimensional color graphics display amazed them
      Twenty-five minutes into the show, I was answering a question about
the programming language ("It's object oriented, whatever that
means. . .") when my pocket pager beeped.
      Three beeps. Morse code for the letter S. S for Sventek. The hacker
had connected to our system on the Sventek account.

                                 ST 0 L L

     Damn. A month of quiet, and the SOB shows up now.
     Well, the show must go on. I couldn't acknowledge that I was still
chasing the hacker-my three-week allowance had long ago been used up.
But I had to get over to the monitoring post and watch what he was doing.
     Of course. I stopped showing pretty pictures and began describing an
obscure area of galactic astronomy. It took five minutes, but people began
to squirm and yawn. My boss looked at his watch, and ended the meeting.
Another application for advanced astronomy.
     I dodged the gang in the hallway, and slipped into the switchyard. The
hacker wasn't active on any of my monitors.
      He'd left his footprints though. The printer showed him here for two
minutes. Long enough to check out our system. He checked that the system
manager wasn't around, then looked for the Gnu-Emacs hole-it still hadn't
been patched. And he listed his four stolen accounts-no change there.
Then, poof, gone.
      No way to trace him after the fact. But the monitor that caught him
was on the Tymnet line. So he was coming in on the same line. Was his path
from Mitre to AT&T to Pacific Bell to Tymnet?
      Time to call Mitre. Bill Chandler answered. "No, he couldn't have
used our modems. They're all turned off."
      Really? Easy to check. I called Mitre through Tymnet, I could still
reach into Mitre's network, but Bill had indeed shut off his modems. A
hacker could fool with his computers, but couldn't get out. My hacker had
come from somewhere else.
      Should I feel elated or despondent? The varmint was back with super-
user privileges. But maybe this time I'd nail the bastard. If he kept returning
to his roost, I'd trace him for sure.
      I suppressed my vindictive feelings towards my unseen adversary. Re-
search was the answer. The question wasn't, "Who's doing it?" I'd get no
satisfaction if a postcard showed up saying, ''Joe Blatz is breaking into your
      No, the problem was to build the tools to find who was there. What if
I traced the whole connection, and it turned out to be a red herring? At
least, I'd understand the phenomenon. Not all research yields exactly the
results you expect.
      My tools were sharp. The alarms triggered as soon as he entered his
stolen account names. If they failed, a backup program, hidden behind my

                 THE CUCKOO'S EGG

Unix-8 computer would detect him within a minute. When the hacker
touched the tripwire, my beeper told me about it instantly.
      The hacker could hide, but he couldn't violate physics. Every connec-
tion had to start somewhere. Whenever he showed up, he exposed himself. I
just had to be alert.
      The fox was back. This hound was ready for the chase.

o     0     0  After a month's disappearance, the hacker was back on my
system. Martha wasn't happy about this; she began to see a mechanical rival
in my pocket pager. "How long before you're free from that electronic
    "just a couple more weeks. It'll be over by New Year's Day, for sure."
Even after three months of chasing, I still thought I was close to the end.
     I was sure I'd catch him: since the hacker couldn't hide behind Mitre
anymore, the next trace would move us one step closer. He didn't know it,
but he was running out of space. In a few more weeks he'd be mine.
     Friday, December 5, the hacker showed up again at 1:21 in the after-
noon. He raised periscope, looking for our system manager and then listed
our password file.
     This was the second time he'd ripped off my password file. What for?
There's no key to unlock these encrypted passwords: they're just goulash
until they're decrypted. And our encryption software is a one-way trapdoor:
its mathematical scrambling is precise, repeatable, and irreversible.
     Did he know something that I didn't? Did this hacker have a magic
decryption formula? Unlikely. If you turn the crank of a sausage machine
backwards, pigs won't come out the other end.
     Four months from now, I'd realize what he was doing, but for now, I
had my hands full trying to trace him.
      Nine minutes after he showed up, he disappeared. Enough time for me
to trace the connection to Tymnet. But their network sorcerer, Ron Vivier,
was taking a long lunch. So Tymnet couldn't make the trace. Another
chance lost.

---------   -------------------------------

                                       ST 0 L L

            Ron returned my call an Hour later. "It was an office party," he said. "I
      thought you'd given up on chasing this guy."
            I explained the month-long hiatus. "We tracked him into Mitre, and
      they plugged the hole he was using. Stopped him for a month, but now he's
            "Why don't you cork up your hole, too?"
            "Guess I ought to," I said, "but we've sunk three months into this
      project. We can't be far from solving it."
            Ron had been in the middle of every trace. He'd invested plenty of
      time, all voluntary. We didn't pay Tymnet to trace hackers.
            "Hey, Cliff, how come you never call me at night?" Ron had given
      me his home number, but I only called him at his office.
            "Guess the hacker doesn't show up at night. I wonder why." He
      started me thinking. My logbook recorded every time the hacker had shown
      up. On the average, when was he active?
            I'd remembered him on at 6 A.M. and at 7 P.M. But never at midnight.
      Isn't midnight operation the very image of a hacker?
            As of December 6, the hacker had connected to us one-hundred-thirty-
      five times. Enough times for a statistical analysis of his work habits. In a
      couple of hours, I'd entered all the dates and times into a program. Now just
      average them.
            Well, not exactly a simple average. What's the average of 6 A.M. and 6
      P.M.? Is it noon or midnight? But this is bread and butter for statistics folks.
      Dave Cleveland showed me the right program, and I spent the rest of the
      day making all sorts of averages.
            On the average, the hacker showed up at noon, Pacific time. Because
      of daylight savings time, 1 could stretch this to 12:30 or even 1 P.M., but
      there was no way that he was-an evening person. Though sometimes he
      showed up in the morning, and occasionally at night (I still resented him
      spoiling Halloween for me!), he generally worked in the early afternoon.
      On the average, he stayed connected twenty minutes. A lot of two- or
      three-minute connections, and a few two-hour runs.
              So what does this mean? Suppose he lives in California. Then he's
      hacking during the day. If he's on the East Coast, he's three hours ahead of
      us, so he works around three or four in the afternoon.
            This doesn't make sense. He'd work at night to save on long-distance
      telephone fees. To avoid network congestion. And to avoid detection. Yet
      he brazenly breaks in during the day. Why?

                  THE CUCKOO'S EGG

      Confidence? Perhaps. After he made certain that no system operator
was present, he roamed the insides of my computer without hesitation.
Arrogance? Possibly. He was shameless in reading others' mail and copying
their data. But this hardly could account for his showing up during mid-
      Maybe he felt he was less likely to be noticed when dozens of others
were using our computer. Although lots of programs ran at night, most of
these were batch jobs, submitted during the day and postponed until eve-
ning. By midnight, only a couple of night owls were logged in.
      Whatever his reason, this peculiar habit made life slightly easier for
me. Fewer interruptions when sleeping with Martha. Less need to call the
police at night. And a greater chance that I'd be around when he showed up.
      As we chopped onions at the kitchen table, I told Martha about my
results. "I'm tailing a hacker that avoids the dark."
      She wasn't impressed. "This doesn't make sense. If the guy's an ama-
teur, then he'd be breaking in during off-hours."
      "So you say he's a professional, keeping regular office hours?" I could
picture someone punching a time card in the morning, spending eight hours
breaking into computers, then punching out.
      "No," Martha said, "even professional burglars keep odd hours. What
I want to know is whether his hours change on weekends."
      I couldn't answer that one. I'd have to go back to the lab, cull out all
the weekend times, and average them separately.
      "But suppose the hacker really only shows up around noon," Martha
continued. "It might be nighttime where he lives."
      When it's noon in California, where is it evening? Even astronomers
get confused by time changes, but I know it gets later as you move east.
We're eight hours behind Greenwich, so lunchtime in Berkeley is bedtime
in Europe. Is the hacker coming from Europe?
      Improbable, but worth thinking about. A month or two ago, I'd
measured the distance to the hacker by timing echos when the hacker ran
Kermit. What I found didn't make much sense: the hacker seemed to be
around six thousand miles away.
      Made sense now. It's five thousand miles to London. Small world.
      But how do you get from Europe into our networks? Phoning across
the Atlantic would cost a fortune. And why go through Mitre?
      I had to keep reminding myself that these were just weak pointers.

                                 S TaL L

Nothing conclusive. But it was hard to fall asleep that evening. Tomorrow
1'd go up to the lab and reread my logbook with a new hypothesis: the
hacker might be coming in from abroad.

o     0     0    Saturday morning I woke up nestled in Martha's arms. We
fooled around for a while, and I made a batch of my quasi-stellar waffies-
the ones that are advertised all over the Andromeda galaxy.
      Despite the early hour, I couldn't resist heading over to the lab. I
bicycled along side streets, scanning for yard sales. Right along the way,
someone was selling their household, well preserved from the 1960s. Rock
posters, bell-bottom jeans, even a Nehru jacket. I picked up a Captain
Midnight Secret Decoder Ring for two dollars. It still had an endorsement
for Ovaltine.
      At the lab, I started analyzing the hacker's log-in times, separating out
his weekend sessions. It took a while, but I managed to show that on
weekdays he showed up from noon to three P.M.; on weekends he'd show up
as early as six A.M.
      Suppose this sneak lived in Europe. He might break in at any hour on
the weekend, but confine himself to evenings during the week. The log-in
times agreed with this, but agreement is hardly proof. A dozen other theo-
ries could satisfy the data.
      I'd ignored one source of information. The Usenet is a nationwide
network of thousands of computers, tied together by telephone links. It's a
wide-area electronic bulletin board, a sort of networked classified newspa-
per. Anyone can post notes; every hour, dozens of new messages show up,
divided into categories like Unix Bugs, Macintosh Programs, and Science
Fiction Discussions. There's nobody in charge: any Unix computer can link
to Usenet, and post messages to the rest. Anarchy in action.
      System managers post a lot of the messages, so you'll find notes like,
"We have a Foobar model 37 computer, and we're trying to hook up a
Yoyodyne tape to it. Can anyone help?" Often someone will respond,
solving the problem in minutes. Other times, it's a lone voice in an elec-
tronic wilderness.

                  THE CUCKOO'S EGG

       I couldn't post a note saying, "Hackers are breaking into my com-
puter. Any idea where they're coming from?" Since most systems folks read
these bulletin boards, the hacker would find out right away.
       But I could scan for information. I started a text search, hunting for
the word, "Hack." Any messages with that keyword would pop out.
       Oops. Bad choice of keyword. The word hacker is ambiguous. Com-
puter people use it as a complement to a creative programmer; the public
uses it to describe a skunk that breaks into computers. My search turned up
lots of the former usage and not many of the latter.
       A few useful notes turned up, though. A guy in Toronto reported that
his computer had been attacked by a group from Germany. They called
themselves the Chaos Computer Club and seemed to be technocratic van-
dals. Another note talked about hackers in Finland trying to extort money
from a corporation by holding their computers hostage. A third mentioned
that a hacker in London ran a credit card scam, where he sold credit card
information over the telephone lines.
       None of these seemed to describe what my hacker was doing. Nor was
it much comfort to realize that others face similar varmints.
       I walked out on the roof of the building and looked out over the bay.
Below me, Berkeley and Oakland. Across the water, San Francisco and the
Golden Gate Bridge. For all I knew, someone within a few blocks was
playing an elaborate practical joke on me. I was fiddling with my secret
decoder ring when my beeper went off. Three dots. Sventek again, and on
my Unix machine.
       I ran down the staircase and into the switchyard. The hacker was just
logging in. Quickly I called Ron Vivier at Tymnet. No answer. Of course,
dummy, it's a Saturday. Another call to his home. A woman answered.
       "I need to talk to Ron right away. He's got to make a panic network
 trace right now." I was out of breath and panting. Five flights of stairs.
       She was taken aback. "He's in the yard washing the van. I'll get him."
A few centuries later, Ron showed up. There were a couple kids screaming
 in the background.
       "I've got a live one for you," I gasped. 'Just trace my port 14."
       "Right. It'll take a minute. Good thing I've got two phone lines here."
 I hadn't realized that he didn't have a whole switchboard at his fingertips.
He must be dialing into his computer.
        Another couple eons passed, and Ron came back on the line. "Hey
 Cliff, are you certain that it's the same guy?"

                                ST 0 L L

      I watched him searching for the word SDI on our computer. "Yes, it's
him." I was still wheezing.
      "He's coming in from a gateway that I've never heard of. I'm locked
onto his network address, so it doesn't matter if he hangs up. But the guy's
coming from somewhere strange."
      "Where's that?"
      "I don't know. It's Tymnet node 3513, which is a strange one. I'll have
to look it up in our directory." In the background, Ron's keyboard clicked.
"Here it is. That node connects to ITT node DNIC 3106. He's coming from
the ITT IRe."
      "Huh? What's that mean to me?" His ante was beyond my purse.
      "Oh, I'm sorry," Ron said. "I keep thinking that I'm talking to an-
other Tymnet guy. Your hacker is coming from outside the Tymnet system.
He's entering Tymnet from a communications line operated by the Interna-
tional Telephone and Telegraph company."
      "So what?"
      "Tyrnnet moves data between countries using International Record
Carriers, or IRC's. Once, international agreements forced us to use IRCs,
now we choose the cheapest carrier around. The IRCs are the go-betweens
that link countries together."
      "Are you saying that the hacker is coming from abroad?"
      "No doubt. ITT takes a Westar downlink. . . ." Ron spoke quickly
and used plenty of acronyms.
      "Huh? What's that mean?" I interrupted.
      "You know," Ron said, "Westar 3." I didn't know, but I was learning
by listening.
      He continued, "The communications satellite over the Atlantic. It
handles ten or twenty thousand phone calls at once.".
      "So my hacker is coming from Europe?"
      "For sure."
      "That's the part I don't know, and I probably can't find out. But hold
on, and I'll see what's there." More keyboard clicks.
      Ron came back to the phone. "Well, ITT identifies the line as DSEA
744031. That's their line number. It can connect to either Spain, France,
Germany, or Britain."
      "Well, which is it?"
      "Sorry, I don't know. You'll have to call ITT. In three days, they'll

                  THE CUCKOO'S EGG

send us billing information, and then I can find out. Meantime, I can't tell
you much more than that."
       From twenty-three thousand miles over Brazil, the Westar-3 satellite
watches Europe and America at the same time. It relays microwave signals
between the continents, each signal in its own channel. ITT, the multina-
 tional giant, leases a few thousand of Westar's channels.
        Ron went back to washing his car and I crossed the room to the
monitoring printer. Twenty minutes had passed, and my hacker hadn't
wasted a moment. Everything he typed was saved on my printer and dis-
played on my computer's screen. If he started to wreck our system, I could
pull his plug by just reaching behind the table.
       But he wasn't interested in my lab's computer. He first made sure that
nobody was watching him by seeing who was logged on, and listing their
jobs. Good thing my monitors were concealed.
       Then, he went directly to our network links and logged into the
Network Information Center. This time, he searched for keywords like
 CIA, ICBM, ICBMCOM, NORAD, and WSMR. After picking up a few
computer names, he methodically tried to log into each of them, using
 default account names like Guest and Visitor. He didn't get far. Five systems
bumped him off with bad passwords.
       Like a month ago, when he spent a while trying to get into the Army's
 White Sands Missile Range. Over and over, he tried to log onto their
 computers. He had no problem fmding the names of people working there
-he just scanned the network directory. But he couldn't guess their pass-
       The Milnet connects to thousands of computers. Yet he wanted to get
 into White Sands. Why bother?
       Why's this guy only interested in military stuff? There's a whole
world of computers, yet he's targeting Army bases. Something serious is
 going on-it would be a long time before I found out what.
       After half an hour, he gave up on White Sands and tried to get back
 into our Elxsi computer. On Halloween, he'd sneaked in there and added a
new account.
       Along with the physicist that managed the Elxsi, 1'd planted a trap
 there. The computer looked like it was still wide open, but when the hacker
 touched it, it slowed down. The more the hacker tried to use it, the slower
 it went.
       Our electronic tar baby worked like an ace. The hacker tried to log


                                    ST 0 L L

    into the Elxsi, and the machine coasted slower and slower. Not quite halt-
    ing; he could see that he was making progress, but at an appalling rate.
    Elxsi, Inc. would have been ashamed-theirs is the zippiest of all minicom-
          Took him ten minutes to throw in the towel. But he came right back
    to our Unix machines, and right out onto the Milnet. This time, he spent an
    hour trying to break into forty-two military computers, literally around the
          With a single command, telnet, he'd connect to a military system, and
    spend one minute trying default account names and passwords. If he
    couldn't guess his way in with four tries, he'd go on to the next computer.
          He knew how to guess. When greeted by the Unix response login:
    he'd try default accounts like guest, root, who, and visitor. The Vax-VMS
    operating system greets you with Username., on those systems he tried the
    defaults system, field, service, and user. He'd done this before, and I'm sure
    that hackers will do it again.
          If the Milnet was a roadway, connecting thousands of computers to-
    gether, then he was a burglar, patiently visiting each house. He'd twist the
    front doorknob to see if it was unlocked, then walk around and try the
    backdoor. Maybe try lifting a window or two.
          Most of the time, he found the doors and windows locked. After a
    minute pushing them, he'd move on to the next place. Nothing sophisti-
    cated: he wasn't picking locks or digging under foundations. Just taking
    advantage of people who left their doors open.
          One after another, he tried military computers: Army Ballistics Re-
    search Lab; U.S. Naval Academy; Naval Research Lab; Air Force Informa-
    tion Services Group; and places with bizarre acronyms, like WWMCCS
    and Cincusnaveur. (Cincus? Or was it Circus? I never found out.)
          Today wasn't lucky for him. None of his guesses panned out. Forty-
    two at-bats, forty-two outs.
          Clearly, he was going to be on a long time. I reached into my pocket
    for a Milky Way candy bar-what else, for an astronomer?-and sat back
    to watch the hacker on my green monitor. I could imagine the far end of
    that long connection. The hacker sitting behind his monitor, watching the
    same green characters on his screen. Probably chewing on his own Milky
    Way bar. Or smoking a Benson and Hedges.
          It was Saturday, but I figured I'd try to call the Air Force Office of
    Special Investigations. They'd told me to call if anything bubbled up, and

                  THE CUCKOO'S EGG

the cauldron was boiling now. But no answer. Anyway, there wasn't much
they could do. I needed to know who was at the other end of ITT's satellite
     Only two people knew where I was-Ron Vivier and Martha. Ron
was washing his car. So when the phone rang in the switchyard, I answered,
"Hello, sweetie!"
      Silence, then, "Aah, I've probably got the wrong number. I'm looking
for Cliff Stoll." A man's voice with a profound English accent. Had some
British spies found me? Or was the hacker in London? What a mindgame.
      Turned out to be nothing so subtle. Ron Vivier had called Tymnet's
international department, where their experts in transatlantic communica-
tions took over. One of Tymnet's international specialists, Steve White,
started tracing.
       Steve works in Vienna, Virginia, making certain that Tymnet's cus-
tomers can communicate worldwide. He grew up in Dorset, England, and
first learned to program a computer by mail: he'd write a program at
school, send it to a computer center, and receive the printout a week later.
Steve claims that this makes you write good programs the first time, since
each mistake wastes a week of your time.
       Steve had studied zoology at the University of London, and found it
just like astronomy: fascinating but impoverishing. So he moved to the
states, and began working in his other specialty: digital communications.
Steve troubleshoots international communications systems.
       There's a dozen ways to tie computers together-telephones, optical
fibers, satellite links, and microwave links. At my laboratory, I didn't care
how my data moved, so long as a scientist in Podunk could reach my
computer in Berkeley. It was Steve's job to make sure that data funnelled in
one end of Tymnet reached me at the far end.
      Every communications company has someone like Steve White, or at
least the successful ones do. To him, the network is a gossamer web of
connections: invisible threads that appear and disappear every few seconds.
Each of his three thousand nodes have to be able to instantly talk to each
      You could build a network by stringing a wire to every computer, and
then connecting them together in one big switch. With a thousand terminals
at our lab, that's exactly how we did things; a zillion wires in the switch-
yard. Local phone companies still work that way: they route all the neigh-

                                            S TaL L

borhood telephone WIres to a single building, where mechanical switches
make connections.
       With thousands of computers spread around the country, Tymnet
couldn't have a central exchange. Mechanical switches were out of the
question: too slow and unreliable. Instead, Tymnet creates virtual circuits
between computers. Across the country, Tymnet's switching computers,
called nodes, communicate with each other over leased cables.
      When your computer sends a message to mine, Tymnet treats it like a
piece of mail: it squeezes your data into a envelope and sends it to one of
Tymnet's nodes. There, Tymnet's computers stamp the envelope with the
forwarding address, along with your own calling address. Like a post office
running at the speed of light, special software grabs each envelope and tosses
it to a node nearer its destination. When the envelope finally reaches my
computer, Tymnet removes the address, opens the envelope, and delivers the
     There's not one giant switch hooking your computer to mine. Instead,
each network node knows where to toss every data packet-a central com-
puter tells it the shortest path.* In crossing the country, a dozen Tymnet
nodes may forward an envelope.
      When your computer's silent, the network sits back and handles other
envelopes, but each Tymnet node still remembers where to send your pack-
ets. Every node has a thousand pigeonholes, and is constantly sorting enve-
     There's no wire to trace; rather, there's a thread of addresses between
your computer and mine. Ron and Steve, the Tymnet guys, could trace the
hacker's connections by untangling this thread. The tail of the thread origi-
nated at an ITT earth station. Beyond there, who could tell?

* The Internet, too, doesn't have one central switch, but instead has many local switches, all around the
country. The lowest-level switches (really, computers) are tied together, forming local networks. These,
in turn, ate grouped together into regional networks, which connect to national backbones. The Internet,
then, connects networks together-like the Arpanet, the Milnet, and its hundred other networks.
   While Tymnet (and its many cousins) builds virtual circuits from one point to another, the Internet is
hierarchical. An Internet message moves from local roads, to state roads, onto the highways, and then
down through state roads to a specific street address.
  Envelopes for messages on Tymnet can be simple-once the virtual circuit is established, each node
knows where to toss the message. Internet messages, however, have envelopes with complete destination
and return addresses, so that each network can figure out how to send it one step closer to the ultimate
destination. Those more complex envelopes let Internet packets get through even when the system's
  Which is better' Don't ask me.

                    THE CUCKOO'S EGG

 o     0     0   So after months of tracking, the hacker's coming from Eu-
 rope. He was still on my computer, trying to chisel into the Navy Research
 Labs, when Steve White called.
      "Tymnet's connection begins at ITT," Steve said.
      "Yes, Ron Vivier already told me that. But he says that it could be
 from any of four countries."
      "Ron can't trace any farther," Steve said, typing on his terminal. "I'll
 do the trace myself."
      "You can trace ITT's lines?"
      "Sure. The international record carriers give Tymnet permission to
trace their links, in case of problems. I'll just log into ITT's switch and see
who's calling." Steve made it sound simple.
     I kept watching the hacker on my screen, hoping that he wouldn't
hang up while Steve made the trace.
     Steve came back on the line. In his modulated, almost theatric British
accent, he said, "Your hacker has the calling address DNIC dash 2624 dash
      I'd grown accustomed to not understanding the jargon, but on princi-
ple, I dutifully wrote it down in my logbook. Fortunately, Steve translated
for me.
       "You see, as far as Tymnet's concerned, the hacker's coming from
ITT's satellite. But from inside of ITT's computers, I can see past their
satellite link and trace the connection all the way back."
      Steve had X-ray vision. Satellites didn't stop him.
      "That DNIC number is the data network identifier code. It's just like a
telephone number-the area code tells where the call originates."
      "So where's the hacker coming from?"
      "East or West?"
     "West Germany. The German Datex network."
     "What's that?" Steve lived in a universe of networks.
     "Datex is the German equivalent of Tymnet. It's their national net-

                                 S TaL L

work to connect computers together," Steve explained. "We'll have to call
the Bundespost to find out more."
      I forgot about the hacker on my computer, and listened to Steve. "You
see, the DNIC completely identifies the computer that's making the call.
The first four digits tell me that it's from the German Datex network. The
Bundespost can look up that number in their catalog, and tell us exactly
where it's located."
      "Who's the Bundespost?" It sounded vaguely German.
      "They're the German national postal service. The government commu-
nications monopoly."
      "Why's the post office running networks?" I wondered out loud.
Here, the post office delivers letters, not data.
      "In a lot of countries, the post office owns the phone service. An
historical outgrowth of government regulation. Germany's probably the
most centralized of all. You can't get a telephone answering machine with-
out government approval."
      "So the hacker is coming from a government computer?"
      "No, it's a private computer, probably. But the communications link is
operated by the Bundespost. And that's our next step. We'll ring up the
Bundespost in the morning."
      I liked how he said "we" rather than "you."
      Steve and I talked for a solid hour. Listening to his descriptions of the
network was far more interesting than watching the hacker scan my com-
puter for keywords like SDI. Steve wasn't a technician, but a craftsperson;
no, an artist who expressed himself through an invisible tapestry of elec-
tronic threads.
      To hear Steve speak of it, the network is a living, growing organism.
It senses trouble and responds to its environment. To him, the network's
elegance lay in its simplicity. "Each node just passes the data on       to   the
      "Every time your visitor types a key," Steve said, "a character bounces
from Datex to ITT to Tymnet and into your system. And between key-
strokes, our network wastes no time on him."
      With thousands of conversations threaded through his system and mil-
lions of bits of data, not one dialogue was lost, and not a byte of data spilled
out. The network kept track of the connections, and you couldn't slip
through the cracks.
      All the same, Steve seemed pessimistic about completing a successful

                  THE CUCKOO'S EGG

trace. "We know where he connects into the system. But there's a couple
possibilities there. The hacker might be at a computer in Germany, simply
connected over the German Datex network. If that's the case, then we've
got him cold. We know his address, the address points to his computer, and
the computer points to him."
      "Seems unlikely," I said, thinking of my trace to Mitre.
      "It is unlikely. More likely, the hacker is coming into the German
Datex network through a dial-in modem."
      Just like Tymnet, Datex lets anyone dial into their system, and connect
to computers on the network. Perfect for business people and scientists. And
      "The real problem is in German law," Steve said. "I don't think they
recognize hacking as a crime."
      "You're kidding, of course."
      "No," he said, "a lot of countries have outdated laws. In Canada, a
hacker that broke into a computer was convicted of stealing electricity,
rather than trespassing. He was prosecuted only because the connection had
used a microwatt of power from the computer."
      "But breaking into a computer is a crime in the USA."
      "Yes, but do you think the hacker will be extradited for that?" Steve
asked. "Look at the support you got from the FBI. Be serious, Cliff."
      Steve's pessimism was contagious. But his trace jagged my spirits: so
what if we couldn't nail the hacker-our circle was closing around him.
      This hacker, though, knew nothing of our trace. He finally discon-
nected at 5:22, after two hours of twisting doorknobs and scanning files. My
printer captured everything, but the real news was Steve White's work.
       Germany. I ran over to the library and dug out an atlas. Germany's
nine hours ahead of us. The hacker showed up around noon or 1 P.M.; for
him, it's 9 or 10 P.M. He's probably taking advantage of cheap rates.
       Poring over the atlas, I remembered Maggie Morley recognizing the
hacker's password. 'Jaeger-it's a German word meaning Hunter." The
answer had been right in front of me, but I'd been blind.
      This explained the timing of the acknowledgement echos when the
hacker used the Kermit file transfers. I'd measured 6000 miles to the hacker,
though I'd never relied much on that figure. I should have. Germany was
5200 miles from Berkeley.
       Not just blind. Deaf as well.
       I'd been gathering facts. Not interpreting them.

                                 ST 0 L L

       Sitting alone in the library, I was suddenly deeply embarrassed over
sending my sister on a wild goose chase, searching for a high school kid in
Virginia; and the Berkeley detectives, running around campus with revolv-
       I'd messed up. For months, I'd scoured North America, searching for
the hacker. Dave Cleveland kept telling me, "The hacker's not from the
West Coast." No, not by 5200 miles.
       Some details were still fuzzy, but I understood how he operated.
Somewhere in Europe, the hacker called into the German Datex network.
He asked for Tymnet, and the Bundespost made the connection through the
international record carrier. Once he reached the States, he connected to my
laboratory and hacked his way around the Milnet.
       Mitre must have been his stopover point. I could see how he made the
connection. He'd entered the German Datex system, asked for Tymnet, and
then logged into Mitre. Once there, he could explore their computers at his
leisure. When he grew tired of reading the defense contractor's reports, he
could dial out from Mitre, connecting anywhere in North America-with
Mitre picking up the tab.
       But who paid for his transatlantic connections? According to Steve, his
sessions cost fifty or one hundred dollars an hour. Walking back to the
computer room, I realized that I was following a well-heeled hacker. Or a
clever thief.
    Now I realized why Mitre paid for a thousand one-minute-Iong phone
calls. The hacker would connect to Mitre, and instruct their system to phone
another computer. When it answered, he would try to log in with a default
name and password. Usually he failed, and went on to another phone
number. He'd been scanning computers, with Mitre picking up the tab.
       But he'd left a trail. On Mitre's phone bills.
       The path lead back to Germany, but it might not end there. Conceiv-
ably, someone in Berkeley had called Berlin, connected to the Datex net-
work, connected through Tymnet and came back to Berkeley. Maybe the
start of the path was in Mongolia. Or Moscow. I couldn't tell. For the
present, my working hypothesis would be Germany.
       And he scanned for military secrets. Could I be following a spy? A real
spy, working for them-but who's them? . . . Jeez-I didn't even know
who spies work for.
       Three months ago, I'd seen some mouse droppings in my accounting
files. Quietly, we watched this mouse, seeing him sneak through our com-

                  THE CUCKOO'S EGG

puter, and out through a hole and into the military networks and com-
     At last I knew what this rodent was after. And where he was from. I'd
been mistaken.
     This wasn't a mouse. It was a rat.

o     0     0  I spent Saturday evening filling in my logbook. Now I
could tie up loose ends. Anniston's search wouldn't turn up a hacker in
Alabama: they were off by five thousand miles. Stanford's hacker was cer-
tainly a different guy . . . my hacker would have homework in German,
not English. And there wasn't much use in calling around Berkeley, looking
for someone named Hedges.
      Probably the wrong name. Certainly the wrong continent.
      Our stack of printouts was a foot thick. I'd carefully sorted and dated
each listing, but I'd never combed through all the listings at one sitting.
Most of it was dreary file listings and one-at-a-time guesses at passwords.
      Is it easy to break into computers?
     Elementary, my dear Watson. Elementary, and tediously dull.
     I didn't return home until 2 A.M. Martha waited up, piecing a quilt.
     "Out with a hussy?"
     "Yeah," I replied. "Spent the day with a mysterious foreigner."
     "So the hacker's from Europe after all." She'd guessed what I'd been
     "He might live anywhere in the world," I said, "but my bets are on
    I wanted to sleep late Sunday morning, curled up with Martha. But,
dammit, my pager sounded at 10:44, a harsh, insistent squeal followed by a
Morse code greeting. The hacker was at it again. In my Unix-5 computer.'
      I jumped into the dining room and dialed Steve White at his home.
While his phone was ringing, I fired up my Macintosh computer. On the
fifth ring, Steve answered.
      "The hacker is live again, Steve," I told him.

                                 ST 0 L L

     "OK, Cliff. I'll start the trace and call you back."
     As soon as I hung up, I reached for my Macintosh. The beast acted like
a remote terminal, thanks to a modem and a stellar software program called
Red Ryder. Red automagically dialed my lab's computer, logged onto the
Vax, and showed me what was up. There was my hacker, traipsing through
the Milnet,
     Logged on like that, I appeared like an ordinary user, so the hacker
could see me if he looked. So I disconnected quickly. Ten seconds was
enough to see what my visitor was up to.
     Steve called back in a couple minutes. The line didn't come from the
ITT international record carrier; today it was from RCA.
     "RCA doesn't use the Westar satellite," Steve said. "They talk through
the Comsat satellite." Yesterday he used Westar, today Comsat. One elusive
hacker-switching communications satellites from day to day.
      But I had my facts wrong, and Steve set me straight.
      "Your hacker doesn't have any choice in the matter," Steve explained.
"To provide redundant service, we use a variety of international routes."
      With every call, Tymnet's traffic takes a different route across the
Atlantic. As a customer I would never notice, but traffic is spread across four
or five satellites and cables.
      "Oh, like interstate trucking, before deregulation."
      "Don't get me started," Steve said angrily. "You wouldn't believe the
international communications laws."
      "So where's the hacker coming from today?"
      "Germany. Same address. Same place."
      There wasn't much more to do. I couldn't monitor the hacker from
home, and Steve had finished the trace. I sat shivering next to the Macin-
tosh. Where do I go next?
     To the lab. And quick. I scribbled a note for Martha ("The game is
afoot"), threw on some jeans, and hopped on my bike.
      I wasn't fast enough. The hacker disappeared five minutes before I
arrived. I should have stayed in bed.
      Well, I paged through Sunday morning's listing-Sunday evening for
him-and saw him up to his old tricks. One by one, trying to break into
military computers by guessing obvious passwords. Tedious. About as inter-
esting as guessing locker combinations.
     Since he'd shown up in the morning, I might as well wait around and

                  THE CUCKOO'S EGG

see if he'd return. Based on my statistics, he'd be back within an hour or
      Sure enough, he returned at 1:16 in the afternoon. My pager sounded
off, and I ran to the switchyard. There he was, logging into the stolen
Sventek account.
      As usual, he looked around for others on the computer. Had I been
connected from my home, he'd have noticed me. But from my high ground
in the switchyard, I was undetectable. He couldn't pierce my electronic veil.
     Confident that nobody was watching him, he headed straight out
through our Milnet port. With a few commands, he searched the Milnet
directory for any locations with the acronym "COC." Huh? I'd never seen
such a word. Did he misspell something?
     I needn't have wondered. The network information computer cranked
for a minute or two, and then returned a half dozen military Command
Operations Centers. He kept searching for other keywords: "Cheyenne,"
"icbm," "combat," "kh11," "Pentagon," and "Colorado."
      Sitting there watching him paw through the Milnet directory, I felt
like I was watching someone thumbing through the yellow pages. Which
numbers would he dial?
       All of them. Every keyword brought up a few computer addresses,
and after he'd found thirty of them, he closed his connection to the Milnet
directory. Then, once again, he methodically tried to break into each of the
sites; the Air Force Data Services Center in Arlington, Virginia, the Army
Ballistics Research Lab, an Air Force training center in Colorado Springs,
the Navy Pacific Monitoring Center in Hawaii, and thirty other places.
     But again, he had no luck. By chance, he'd picked places which didn't
have obvious passwords. It must have been a frustrating evening for him.
       Finally, he tried to break into his old haunt, the Anniston Army base.
Five times. No luck.
       So he gave up on the Milner and returned to messing with my Unix
computer. I watched the cuckoo lay its egg: once again, he manipulated the
files in my computer to make himself super-user. His same old trick: use the
Gnu-Emacs move-mail to substitute his tainted program for the system's
atrun file. Five minutes later, shazam! He was system manager.
       Now I had to watch him carefully. With his illicit privileges, he could
destroy my system, either by accident or on purpose. And it would only
take one command, like rm*-erase all files.

                                  ST 0 L L

    For now, though, he restrained himself. He just printed out phone
numbers of different computers, and logged off.
     Uh oh. He took a list of telephone numbers that our computer often
connects to.
     But Mitre had cut off their outbound telephone service. He must have
discovered this by now. Yet he still collected phone numbers. So he must
have some other way to make phone calls. Mitre wasn't his only stepping
stone to the telephone system.
     He came back to my system after fifteen minutes. Wherever he'd gone,
none of his calls had panned out. Bad passwords, I'll bet.
      As soon as he returned, he started Kermit running. He was going to
copy a file back to his computer. My password file again? No, he wanted
my network software. He tried to export the source code to two programs:
telnet and r1ogin.
      Whenever one of my scientists connects through the Milnet, they use
telnet or r1ogin. Both of them let someone remotely log into a foreign
computer. Each of them transfers commands from a user over to a foreign
computer. Either is a perfect place to plant a Trojan horse.
     By changing a couple lines of code in our telnet program, he could
make a password grabber. Whenever my scientists connected to a distant
system, his insidious program would stash their passwords into a secret file.
Oh, they'd log in successfully. But the next time the hacker came into my
Berkeley computer, there'd be a list of passwords waiting to be picked up.
     Line by line, I watched Kermit shovel the program over to the hacker.
No need to time the transfer-I now knew those long delays were caused
by satellites and the long hop into Germany.
     Watching him, I got annoyed. No, pissed off. He was stealing my
software. Sensitive software at that. If he wanted it, he'd have to swipe it
from someone else.
     But I couldn't just kill Kermit. He'd notice that right away. Now that
I was closing in on him, I especially didn't want to tip my hand.
     I had to act fast. How do I stop a burglar without letting on that I'm
     I found my key chain and reached over to the wires connected to the
hacker's line. Jangling the keys across the connector, I shorted out his circuit
for an instant. This added just enough noise to confuse the computer, but
not enough to kill the connection. To him, it would look like some charac-

                   THE CUCKOO'S EGG

ters had become garbled. Misspelled words and unintelligible text-the
computer equivalent of radio static.
       He'd blame it on network interference. He might try again, but even-
tually, he'd give up. When the connections are lousy, there's no use in
talking long distance.
       It worked like a charm. I'd jangle my keys, he'd see noise, and his
computer would ask for a replay of the last line. I was careful to let a little
data get through. But so slowly that the whole file would take all night.
       The hacker disconnected and tried again. No way. He couldn't make it
 through my fog, and he couldn't figure out where the noise was coming
       He gave up trying to steal our software, and contented himself with
just looking around. He found a pathway into Berkeley's Opal computer,
but didn't explore it.
       Now there's a strange one. The Berkeley Opal computer is the home
 of some real computer research. You don't have to look far to find some of
 the finest communications programs, academic software, and games. Appar-
ently this hacker didn't care for the things students might be interested in.
 But show him something military, and he goes wild.
       It was 5:51 in the afternoon when the hacker finally called it quits. I
 can't say that his every frustration gave me satisfaction. Rather, he re-
sponded the way I expected. My work was slowly yielding a solution.
       Steve White traced the connections throughout the day. Just as in the
morning, they all came from Germany.
       "Any chance that it's someone from another European country?" I
asked, knowing the answer in advance.
       "The hacker could be from anywhere," Steve answered. "My trace
 only proves a connection from Berkeley into Germany."
       "Any idea where in Germany?"
       Steve was as curious as I. "There's no way to tell without a directory.
 Every network has its own way of using the address. The Bundespost will
 tell us tomorrow."
       "So you'll call them in the morning?" I asked, wondering whether he
spoke German.
       "No, it's easier to send electronic mail," Steve said. "I've already sent a
message about yesterday's incident; today's will confirm it, and add a few
more details. Don't worry, they'll hop to it."
       Steve couldn't hang around this Sunday afternoon-he was cooking a

                                ST 0 L L

dinner with his lady friend Lynn-which reminded me of Martha. I hadn't
called home.
      Martha wasn't pleased. She'd left word with Claudia that she'd be out
late. Were it not for this hacker, we'd be hiking in the redwoods. Oops.

o     0      0 Last night was a tense time at home. Martha didn't talk
much. By spending the day watching the hacker, I'd wrecked a fine Sunday
afternoon. Progress with the hacker had cost dearly on the home front.
      Who should I tell about the latest discovery? My boss, for sure. We'd
had a bet on where the hacker came from, and I'd lost. I owed him a box of
      The FBI? Well, they hadn't shown much interest, but this was now out
of the league of my local police. Might as well give them another chance to
19nore us.
      Air Force Office of Special Investigations? They'd asked to be kept
aware. With the hacker's attacks on military computers, I ought to tell
someone from the defense establishment, no matter how politically awk-
ward I felt.
      If it was hard to talk to the military, then calling the CIA was a real
hurdle. A month ago, I'd accepted that they needed to know about someone
trying to break into their computers. I'd done my duty. Now, should I tell
them that it's a foreigner?
      But once again, they seemed like the right people to call. I could
understand the nodes, and networks, but espionage . . . well, they don't
teach you that stuff in grad school.
      Surely my friends among Berkeley's flourishing left wing would tell
me I'd be co-opted by the State. But I didn't exactly feel like a tool of the
ruling class, unless imperialist running-dog puppets breakfasted on stale gra-
nola. I argued with myself as I biked through traffic, but my guts told me
what to do: the CIA should know, and I ought to tell them.
      It had been a constant struggle to get the bureaucracy to move. Maybe
I could get someone to notice by waving this flag in front of all the three-
letter agencies.

                  THE CUCKOO'S EGG

      First I'd call the FBI. Their Oakland office hadn't been interested, but
maybe I could get a rise out of Mike Gibbons in Alexandria, Virginia. But
Mike was on vacation, so I left a message, figuring he'd hear it in a couple
of weeks. "Just tell him that Cliff called. And that my friend has a return
address in Germany." You can't fit much on a yellow while-you-were-out
      My second pitch was to the Air Force OSI-the air force narcs. Two
people got on the line, a woman's voice and a gravelly man's voice.
      The woman, Ann Funk, was a special agent specializing in family
crimes. In a serious tone, she explained, "Wife beating, child abuse. The Air
Force has the same ugly problems as the rest of the world." Not hi-tech
stuff, but even over the phone, her presence inspired respect and sympathy.
Now, she worked with the OSI's computer crime group.
       A month ago, I'd spoken with Jim Christy. Today, his first question to
me was the same as I'd asked Steve: "East or West Germany?"
       "West," I answered. "We'll know more in the next couple days."
       "Where'd did he get into?" Ann asked.
       "Nowhere, it least that I saw. Not that he didn't try." I rattled off
some of the places he tried to sneak into.
       "We'll have to call you back," Jim said. "We have an office in Europe
that might be able to work on this."
       I'd given the Air Force a heads-up warning. Let's see what they'd do.
       Time to call the CIA. Teejay's office answered-he wasn't in. Whew.
Off the hook. I felt like a kid who had to give a report to the class, only to
find that the teacher was sick.
       But having made up my mind to tell the spooks, I called Teejay's
fellow spy, Greg Fennel. Greg was in, all right.
       "Look, I've got a meeting in three minutes. Keep it short." A busy day
at the CIA.
       "In short, we traced the hacker to Germany. Goodbye!"
       "Huh? Wait! How'd you do it? Are you sure it's the same guy?"
       "You've got a meeting now. We can talk tomorrow."
       "Forget the meeting. Just tell me what happened. Don't embellish,
don't interpret."
       Easy to do when you keep a logbook. I read off my weekend's sum-
mary. An hour later, Greg was still asking questions, and had forgotten his
meeting. It hit him where he lived.
       "Fascinating," the spy thought out loud. "Someone in West Germany

                                ST 0 L L

is breaking into our networks. Or at least they're coming through a West
German gateway." He understood that we'd identified one link in the chain.
The hacker still could be anywhere.
      "Any chance that you'll take action?" I asked.
      "That's for someone else to decide. I'll pass it up the chain of com-
mand, but I really don't know what will happen."
      What did I expect? The CIA couldn't do much to solve the problem
-they were information gatherers. I hoped they'd take over the whole
mess, but that seemed unlikely. The hacker wasn't in their machines, he was
m ours.
      Lawrence Berkeley Laboratory was tired of wasting time on the chase.
I hid my hacker work, but everyone could see that I wasn't tending to our
system. Scientific software slowly decayed while I built programs to analyze
what the hacker was doing.
      Fearing my vitriolic boss, I polished up on quantum mechanics before
talking to Roy Kerth. Maybe if we talked physics for a while, he might
overlook my work on the hacker front. After all, he seemed pleased by my
graphics software, even though I thought it was comparatively trivial.
    But no amount of shop talk could deflect Roy's anger. He was irritated
about the time I'd spent tracking this hacker. I wasn't contributing to the
department-nothing that he could show off, nothing he could quantify.
      At least he didn't shut me down. If anything, he seemed more eager
 than ever to nail this eggsucker.
      I spent a few hours searching bulletin boards on the Usenet network
 for news about hackers, and found one note from Canada. I called the
 author on the phone-I didn't trust electronic mail. Bob Orr, a scientist at
 the University of Toronto, told a sad story.
      "We connect to lots of networks, and it's tough to convince funding
 agencies to pay for it. Some hackers from Germany have invaded our
 system, changing programs and damaging our operating system."
      "How'd they get in?" I asked, already suspecting the answer.
      "We collaborate with the Swiss physics lab, CERN. And those vandals
 have thoroughly walked through their computers. They probably stole pass-
 words to our system, and linked directly to us."
      "Did they do any damage?" I asked.
      "Damage! Haven't you been listening?" Bob exploded. "Our net-
 works are delicate things-people connect to us in hope of mutual support.
 When someone breaks into a computer, they destroy that trust. Aside from

                  THE CUCKOO'S EGG

wasting days of my time, and forcing us to disable our network connec-
tions, these hackers undermine the openness that lets us do science together."
      "But did they erase your files?" I asked. "Did they change any pro-
      "Well, they modified my system to give them a backdoor password.
But if you're looking for headlines like, 'Hacker wipes out entire system,'
you won't find them here. These break-ins are far more insidious. They're
technically skilled but ethically bankrupt programmers without any respect
for others' work-or privacy. They're not destroying one or two programs.
They're trying to wreck the cooperation that builds our networks."
      Whew! Here was a guy who took his computing seriously. I hadn't
learned much about hackers from Germany, but at last I'd spoken to some-
one who described them with the same expletives that I used. Bob realized
that damage wasn't measured in dollars ripped off, but rather in trust lost.
He didn't see this as fun and games, but a serious assault on a open society.
      Once, I would have argued with Bob, saying that these were only kids
fooling around. Once, I might have smiled and respected anyone who could
hack around in so many computers. Not any more.
      As an aside, Bob told me the German Chaos Club was attacking the
u.s. Fermilab computer as well. I called Fermilab in Illinois and talked with
their system manager. "Yes, some German hackers have been giving us
headaches. They call themselves the Chaos Computer Club."
       "Were they spying?" I asked.
       "Be serious. There's no classified work here."
       I wondered. Were they vandals or spies? "Can you identify who's
breaking in?"
       "One guy uses the pseudonym Hagbard. Another, Pengo. I don't
know their real names."
       "Have you secured your system since you detected them?"
       "A little. We're trying to do science, so we don't want to shut our
 doors to the world. But these vandals are making it tough to run an open
 computing center. I wish they'd pick on someone else-like the military,
 for instance. Or NSA."
       If only he knew. "I suppose the police haven't been much help?" I
       "Not much. They listen, but they're not doing much."
       I called Stanford and asked one of their system managers, Dan
 Kolkowitz, if he'd heard anything from Germany.

                                 ST 0 L L

     "Come to think of it, someone broke in a few months ago. I moni-
tored what he did, and have a listing of him. It looks German."
     Dan read the listing over the phone. Some hacker with the nom de
guerre of Hagbard was sending a file of passwords to some hackers named
Zombie and Pengo.
     Hagbard and Pengo again. I wrote them in my logbook.
     Still, it seemed like these guys were right. Those hackers were vandals
who wanted to create trouble. They attacked universities and scientific insti-
tutes-easy pickings. They didn't seem interested in military targets, and
didn't seem to know how to navigate the Milnet.
     I realized another difference between my hacker and the Chaos Club
hoodlums. My hacker seemed at home on Unix; not the Berkeley version,
but Unix all the same. The vandals that Bob and Dan described seemed to
only attack Dec's VMS operating systems.
      From now on, I'd watch for any news about the Chaos Computer
Club, but I couldn't assume that all German hackers were in league to-
      One good thing was happening. One by one, I was making contact
with other people who were losing sleep and slugging down Maalox over
the same troubles that obsessed me. It was comforting to learn that I wasn't
completely alone.
    It was time to take my mind off the hacker and return to astronomy.
No such luck-Mike Gibbons of the FBI called.
    "I thought you were on vacation," I said.
    "I am. At my folk's place, in Denver."
      "Then how'd you get my message?" I wondered if the CIA had called.
      "Oh, that's easy," Mike said. "We're on two-hour alert. Day or night,
the office can reach me. Sometimes makes my marriage uncomfortable."
      I understood all too well. My own beeper was an albatross. "Did you
hear about the German connection?"
      "How about telling me what happened over the weekend." Gust the
facts, ma'am.)
     Once again, I read from my logbook. I'd reached the part about the
DNIC numbers, when Mike interrupted.
     "Can you Fed-ex your logbook here?"
     "Sure. I'll print out a copy and ship it to you." Easy to do when you
keep your notes inside a computer.

                  THE CUCKOO'S EGG

      "I'll see if we can open a case. No promises, but this looks interesting."
By now I'd learned that nobody ever promised to do anything.
      I printed out a copy of my logbook and dropped it off at the express
      When I returned, the phone was ringing. It was Teejay.
      "I heard the news," said my CIA contact. "You're sure your friend
lives across the puddle?"
      "Yes, if you mean the Atlantic." Teejay's shorthand might confuse an
eavesdropper, but they threw me for a loop every time. "Almost certainly
he's from Germany, and I'd be amazed if he's from the States."
      "Do you know his exact location?"
      "All I know is the electronic address of a computer. It's a DNIC
number, whatever that means."
      "Who's going to decode it for you?"
      "I expect the Bundespost to tell us who's at the other end. Maybe
tomorrow. "
      "Have you called the, uh, northern entity?"
      Northern entity? Who's that? "You mean the 'F' entity?"
      "No, the entity in the north. You know, Mr. Meade's place."
      Meade. Fort Meade. He must mean the National Security Agency.
"No, I called the 'F' entity, though."
      "Good. Are they moving or sitting on their butts?"
      "I don't know. They might open an investigation, but they wouldn't
      "They never do. I'll get in touch with them and see if we can help
things along. Meanwhile, why don't you call the northern entity, and see if
they'll decode that address."
      Of course. NSA must have lists of every telephone number and elec-
tronic address in the world. I dialed the National Computer Security Cen-
      Zeke Hanson answered my call.
      "Hey, Zeke, remember that you said that NSA can't help me if the
hacker's coming from America?"
      "Yeah, so what?"
      "Well, he's from Europe."
      "You mean that you've been following a foreigner on the Milnet?"
      "You heard right."
      "Let me call you right back."

                                 ST 0 L L

      By now, I'd gotten used to these call backs. The spooks either have
secure telephone lines, or assume that I'm calling from a phone booth.
        For the fifth time, I gave a how-l-spent-my-weekend talk. Zeke
listened intently, obviously taking notes.
      "Think the hacker's on assignment?"
      "I can't say. But I suspect he's saving his printouts."
      "How about sending me a list of keywords that he's searched for."
      "Well, I'd be happy to, but I'm kind a busy today. Mostly, I'm trying
to find the electronic address that belongs to that German DNIC number.
I'd be glad to swap information."
      "You mean you'll send me copies of the traffic in return for looking up
that address?"
      "Sure. Seems like a fair trade to me." If I simply asked for the address
point blank, he'd turn me down.
      It didn't work. Zeke stood his ground. "No possible way. I can't even
confirm that we have such information."
      Stymied. I'd have to decode that address some other way.
      Frustrating, too. All day long, secret agencies were asking details from
me, but nobody ever told me anything.
      The day's flurry left me exhausted, but hopeful. This one trace to
Germany opened several doors. The spooks could no longer wash this away
as a minor domestic disturbance. It still might be minor, but it certainly
wasn't domestic.

o     0     0   I'd kicked over an anthill. For the next few days, I couldn't
get away from my phone. The spooks kept calling back, asking for technical
details-how do you connect from Europe into military computers? Could
I prove that the hacker came from Germany? Where did he pick up pass-
words? How did he become super-user?
     The Air Force OSI, however, worried about how to defend the
Milnet. Did the hacker get into this site or that network? What type of
computers did he attack? Could we contain him by locking him out of
Lawrence Berkeley Labs?

                  THE CUCKOO'S EGG

      Finally, Steve White called. He'd received a terse message from the
manager of the German Datex network:
      "The address belongs to a computer in Bremen. We investigate."
      Our circle was slowly closing.
      I was off to the library again, paging through the atlas. Bremen's a
port city in northern Germany, renowned for its medieval paintings and
town hall. Momentarily, my thoughts flew across the Atlantic . . . these
are places from history books.
      On the heels of Steve's call, Mike Muuss of the Ballistic Research
Laboratory called. In Aberdeen, Maryland, the Army runs a research and
development laboratory; it's one of the last government labs that doesn't
farm out its research to private contractors. Mike's their computer honcho.
      Mike Muuss-he's famous throughout the Unix community as a pio-
neer in networking and as a creator of elegant programs to replace awkward
ones. As Mike puts it, good programs aren't written or built. They're
grown. A six-foot-tall, mustached runner, he's incredibly driven, intense,
and obsessed. Mike's paid his dues on ancient versions of Unix, dating back
to the '70s. When Mike talks, other wizards listen.
      "We detected Joe Sventek probing our system on Sunday," Mike
Muuss said. "I thought he was in England."
      Do all wizards know each other? Is it telepathy?
      "He is," I replied. "You detected a hacker masquerading as Joe."
      "Well, keep him off the network. Boot him out."
      1'd been through that before. "Closing him from my computer proba-
bly won't stop him."
      "Oh, he's in a lot of computers, huh?" Mike understood.
      We chatted about an hour, and I tried to hide my ignorance. Mike
assumed that I knew about the Eniac, the world's first big computer. "Yep,
it was right here at Ballistics Research Lab. Back in 1948. Ten years before I
was born."
      Eniac might have been their first world class computer, but hardly
their last. Now, the Army runs a pair of Cray supercomputers-the fastest
in the world. Without much modesty, Mike said, "If you want to see the
Army in the year 2010, look in my computers today. It's all there."
      Exactly what the hacker wanted.
      Soon after that call, Chris McDonald of White Sands phoned. He'd
also heard someone pounding at his doors and wanted to know what we
intended to do about it.

                               ST 0 L L

      "Nothing," I replied. "Nothing until the bastard's been arrested." A
bluff, considering the chances of even discovering where the hacker lived.
      The hacker had tried to chisel into eighty computers. Two system
managers had detected him.
      Suppose you walked along a city street trying to force doors open.
How long would it take before someone called the cops? Five houses? Ten?
      Well, with the help of the hacker, I knew the answer. On the com-
puter networks, you can bang on forty doors before someone notices. With
this kind of guard our computers are sitting ducks. Almost nobody's watch-
ing for intruders trying to break in.
      My own lab was as blind as anyone else. The hacker had broken in,
become system manager, and had full run of my Unix computer before we
detected him. Even then, we'd stumbled on him by accident.
      It seemed unlikely that computer people could detect hackers in their
systems. Well, maybe they could, but nobody was looking. So it was fruit-
ful to keep combing through Mitre's phone bills. The hacker had clearly
called TRW, Incorporated in Redondo Beach; he'd spent hours hooked into
their computer.
      TRW-they're a defense contractor, working for the Air Force and
      When I called Howard Siegal of TRW's signal processing facility,
he'd never heard a thing.
      "We can't possibly have a hacker here. We're running a secure facil-
      By definition, they were secure. 1'd heard it before. "Just for my
curiosity, could you check your accounting logs for the past couple
      He agreed, though I didn't expect to hear back from him. The next
morning, though, he called back with bad news.
       "You were right," Howard said. "Sorneone's been in our system, but I
can't discuss it. We're closing all access to our computer." He wouldn't
describe what evidence had changed his mind, nor would he say if the
hacker had become super-user.
       I mentioned TRW to my friends at the Keck Observatory. Terry Mast
raised his eyebrows: "Hell, they're the defense contractors that built the
      Wait a second. 1'd seen KH-ll before. The hacker scanned for that
keyword on Saturday. "Say, Terry, what's the KH-ll?"

                   THE CUCKOO'S EGG

     "It's a spy satellite. A secret spy satellite. KH stands for Key Hole. It's
the eleventh in a series. It's obsolete now."
     "Replaced by the KH-12, I suppose."
     "Yes, in fact. Massive cost overruns, the usual. Both of them are ex-
tremely secret projects." Secrecy automatically multiplied the cost of any
     After a while, Steve White of Tymnet called back. The German
Bundespost had determined that the hacker came from the University of
Bremen. The address pointed to a Vax computer, not a telephone line, but
the University knew nothing of any hacker. Apparently, they doubted that
a hacker was on their computer. I wasn't surprised: I'd heard it before. Give
'em a day or two, I thought.
     A Vax computer, at a university. A university pointed to a student. I
wondered if my gut feeling was wrong: could I just be chasing some poor
sophomore prankster?
      When talking to the CIA and NSA, I'd been careful to point out that
possibility. It was bad enough to waste my time on this quest. I didn't want
the spooks to gird up for battle, only to find some kid with a peashooter.
      But the spooks asked me speculative questions. Zeke at the NSA: "Can
you characterize this person's computer experience?" Well, that's easy. Just
list what he's done, and how adept he appears. Then, "How old is he?" and
"Is he paid or is this his hobby?" I could only guess at these: the hacker
never typed in his age, weight, and occupation.
      All my callers wanted to know about the hacker, even if they hadn't
the slightest interest in solving the case. My logbook held the information,
but was well over fifty pages. To get out from under these phone calls, I
wrote a note describing what I knew about him. By bringing together
observations about him, perhaps I could paint a profile of this hacker.
     Some of their questions I could answer directly: he targeted the mili-
tary and defense contractors. He guessed and stole passwords. He'd usually
work at nights, German time.
     Other answers came from indirect observations: he seemed to be in his
twenties-his experience in Unix and VMS told me that. Probably out of
college-he worked even when school was out. And only a smoker would
choose Benson and Hedges as passwords.
     I must be watching only one or two people. I inferred this by know-
ing that he had four purloined accounts on my system, yet he had chosen

                                ST 0 L L

the same password for all of them. Had there more than a couple people in
on the caper, they would have chosen separate passwords.
      In writing this profile, I got an impression of someone methodical and
diligent. He'd been active for well over six months-and some of Mitre's
records indicated almost a year. He didn't mind spending two hours on
Sunday night, slowly trying to guess passwords into military computers.
Tedious and tiresome work.
      The NSA kept pushing at my conclusions. Zeke asked, "If he's so
methodical, how do you know you're not just following some computer
      This one threw me for a loop. Zeke had challenged me on a point I
hadn't thought of before.
       Could I prove that I was following a real person?
       1'd once assumed that computer hackers were brilliant geniuses, cre-
atively searching out ways to build new programs. This guy was patient and
plodding, repeatedly trying the same tricks. The same sort of behavior you'd
expect to find from a computer program.
       Suppose someone had programmed a computer to methodically try to
 log into a hundred other computers. All you'd need would be a home
 computer with a modem: the programming would be fairly easy. It could
 guess passwords (like "visitor" and "guest") about as well as a human. And
 it could run all night long, without anyone nearby.
       A momentary panic. Could I prove that I wasn't following such a
       Sure. My hacker made mistakes. Occasional typing errors.
       I told Zeke, "There's a human behind that keyboard, all right, who's
 not a perfect typist."
       "Can you be sure that the hacker's in the same country as the com-
       Zeke was on top of this, all right. His questions kept me thinking. I
 was watching someone, and my guts said he was in Germany. But there's no
 reason why he couldn't be sitting in Australia, connected into a computer in
       My beeper interrupted my answer. The hacker was back. "Cotta run,
       Down the hall again, into the switchyard. There he was, just logging
 in. I started calling Tymnet, but by the time Steve White answered, the
 hacker had logged off. Total connect time: thirty seconds.

                      THE CUCKOO'S EGG

          Damn. All week long, the hacker had been connecting for a minute or
    two at a time. Every time, he triggered my beeper and siphoned off my
,   adrenaline. But I couldn't trace such short connections. Ten minutes, for
    sure. Five minutes, maybe. But not one minute.
          Fortunately, Steve didn't mind my panic calls, and each time would
    explain a new wrinkle in Tymnet's switching system. Today, however,
    Steve mentioned that the Bundespost had talked with the University of
          After a meticulous search, the systems folks at the University of
    Bremen had discovered a privileged user: "An expert has created an account
    for himself, and had root privileges. He was last active on December 6, and
    erased all accounting traces."
          Sounded familiar. In fact, the more I read it, the more it said. I could
    infer that Bremen used Unix, rather than the VMS operating system: on
    Unix computers, people say "root" access; on VMS, it's "system" privileges.
    Same concept, different jargon.
          Meanwhile, the German Bundespost had determined the account that
    the hacker used to connect across the Atlantic. They set a trap on that
    account: the next time someone used that account, they'd trace the call.
          The man at the Bundespost thought the account might be stolen.
    Instead of asking the account owner if he'd authorized the hacker to call
    America, the Bundespost would quietly watch what was going on.
          The Germans weren't sitting around. The University would monitor
    the suspicious account, and the Bundespost watched the network activity.
    More and more mouse holes were being watched.
          Within an hour, Steve received one more message from Germany: the
    University of Bremen will be shutting down its computers for the next
    three weeks. Christmas break.
          Maybe this was good news. If the hacker didn't show up during the
    break, he was likely from Bremen. But if he continued despite the break,
    he'd have to pick a different route . . . one that might lead directly to
          The hacker wasn't more than a few minutes from Berkeley. Now, we
    were only a couple weeks from him.

                                ST 0 L L

o      0 0 December was time to print greeting cards and my house-
mates got together for our annual ink splash. Martha drew the design and
Claudia and I cut the silk screens. We figured that we'd avoid offending our
zealot friends by keeping the card astronomical: Winter Solstice Greetings!
      "We make cards the way you chase hackers," Martha said.
     "Do it yourself," she observed. "Not the way professionals would do
it, but satisfying anyway."
      I wondered how a real professional would track this hacker. But then,
who were the professionals? Was anyone dedicated to following people
breaking into computers? I hadn't met them. I'd called every agency I could
think of, yet nobody had taken over. Nobody had even offered advice.
      All the same, the FBI, CIA, OSI, and NSA were fascinated. A for-
eigner was siphoning data from U.S. databases. The case was documented-
not just by my logbook, but also by massive printouts, phone traces, and
network addresses. My monitoring station ran full time-the chances for
catching the culprit seemed good.
     But not a dime of support. My salary was skimmed from astronomy
and physics grants, and lab management leaned on me for systems support,
not counterespionage. Eight thousand miles away, a hacker was prying
around our networks. Three thousand miles east, some secret agents were
analyzing my latest reports. But two floors up, my bosses wanted to slam
the door.
     "Cliff, we've decided to call it quits," Roy Kerth said. "I know you're
close to finding the hacker, but we can't afford it anymore."
     "How about another two weeks. Until New Year's Day?"
    "No. Close things up tomorrow. Revoke everyone's passwords tomor-
row afternoon." In other words, slam the door.
    Damn. Three, nearly four months work down the tubes. And just
when the trace seemed promising.

                   THE CUCKOO'S EGG

      Frustrating. The hacker could hide, but he couldn't shake me. My
 management was the only one who could do that. Just as we were zeroing
 in on the bastard.
      Depressing as well. The hacker wouldn't have any trouble returning to
 his haunts. He would still roam the networks, breaking in wherever he
 could. Nobody cared.
      I began planning how to pull every user's password. It's easy to do-
just rebuild the password file. But how do you tell passwords to twelve
hundred scientists? Bring them together in one room? Call everyone on the
phone? Mail them notes?
      I was still bummed out when Mike Gibbons called from the FBI.
      'Just checking to see where the trace has led."
      "Into Bremen," I said. "A university there."
      "So it's a college student, huh?"
      "Not necessarily. But we'll never find out."
      "Why not?"
      "LBL is closing its doors. Tomorrow."
      "You can't do that," the FBI agent said. "We're opening an investiga-
non, "

      "My boss thinks he can."
     "Tell him that we're just making contacts in Europe. Whatever you
do, don't stop now."
     "You're talking to the wrong guy, Mike."
     "OK. What's your boss's phone number?"
     I wasn't about to draw fire from Roy Kerth by asking for another
extension. If the FBI really wanted us to stay open, let them deal with him.
      Anyway, nobody was supporting me. All those fancy three-letter
agencies ever said was, "Gimme." Every agency wanted copies of logs and
printouts. Every time we completed a trace, four or five people demanded
to know where it led.
      These were the facts of life in dealing with a bureaucracy: everyone
wanted to know what we discovered, but nobody would take responsibility.
Nobody volunteered to be the contact point, the center for collecting and
distributing information. I'd started out in the center of the study, and it
seemed like I'd stay there.
    On the other hand, since nobody told me what to do, I could take
chances-like remaining open to a hacker who could wipe out my com-

                                ST 0 L L

puter in a couple seconds. I could be a one-man band, as in grad school: if
it's worth doing, do it for yourself, not to please some funding agency.
      If only I could keep Kerth and company off my back.
      The FBI did that. Mike Gibbons talked to Roy Kerth. I'm not sure
what they said, but half an hour later, Roy told me to remain open for the
next few weeks.
      "They're finally taking us seriously," Roy said.
      "Serious enough to pay our overhead?"
      "Are you kidding?"
      Rescued from the brink. We'd stay open, though only through the
grace of an informal agreement. I had a couple more weeks to catch the
      I might not need much more. Friday, December 19, at 1:38, the hacker
showed up again. Stayed around for two hours, fishing on the Milnet.
      A pleasant Friday afternoon, trying to guess passwords to the Strategic
Air Command, the European Milnet Gateway, the Army's West Point Ge-
ography Department, and seventy other assorted military computers.
      I got to the monitors within a few seconds, and phoned Steve White
at Tymnet. He was getting ready to go home when I called.
      "The hacker's on our computer. Tymnet's logical port number 14."
      "OK," Steve said. The usual keyboard clatter in the background.
Twenty seconds elapsed, and he called out, "Got it!"
      Steve had traced a connection from California to Germany in less than
a minute.
      "How'd you do that?"
      Steve laughed. "Now that I know you're looking for traces, I've
automated my tracing program. I just have to tell it to fly."
      "Where's it point to?"
      "You're getting a call from address 2624 DNIC 4511 dash 049136."
      "What's that mean?"
      "We'll have to ask the Bundespost, but I can tell you a bit about the
address. The first digits, 2624, mean Germany."
      "We already know that."
      "The next four digits, 4511, begin with a 4. That means the hacker's
coming through a public dial-in port."
      "I don't understand. What's different from the last time you traced the
      "Last time, we traced him to a computer at the University of Bremen.

                  THE CUCKOO'S EGG

That time, the digits were 5421. The 5 means that a computer was at the
other end."
      Oh-the address was coded, like American pay telephones, whose
phone numbers always seem to have a fourth digit of 9.
      "So the connection isn't coming from the University of Bremen's
computer?" I asked.
      "That's for certain. But we know more than that. We know that the
hacker's coming into a dial-in port. He's connecting from a local tele-
      "Do you know his phone number?"
      "No, but the Bundespost can determine what telephone number he
      Steve's news brought us one step closer. The hacker couldn't hide
behind the University of Bremen.
      "So when will we find the location of this electronic address?"
      "Should be soon. I asked Wolfgang to look it up."
      "Who's that?"
      "Wolfgang Hoffman. The Datex network manager in Germany."
      "You're on the phone with him?"
      "Of course not," Steve said. "We're sending electronic mail to each
other." I could have guessed.
      "And he hasn't decoded today's address, huh?"
      "That's right. Until the Bundespost decodes the address, we can't do
much . . . hold on, something's showing up . . . it's a message from
Germany." Steve apparently had a direct line to Europe, and passed notes
between countries the way I might dash off an interoffice memo.
      Steve translated the note. "Wolfgang says the hacker came from a dial-
in port. He's dialed in over a telephone line."
      "We knew that already."
      "Yeah, but he's not coming from Bremen. Today, he's dialing from
      "So where is he? In Bremen or Hannover?"
      "Wolfgang doesn't know. For all we know, he could be in Paris,
calling long distance."
      Another dash to the library. Their atlas showed the city of Hannover,
maybe seventy-five miles south of Bremen. Looked like a big city, around
half a million people. Jeez-the stuff that travelogues are made from.
      Was some student in Bremen dialing Hannover? Not likely. Even with

                                    J   7   J
                                 ST 0 L L

the university closed, he could just call Bremen's Datex port. A Bremen
student wouldn't make a long distance call to Hannover.
      Aah, but when the university closed up, students go home.
      Was I following some sophomore, home on vacation?
      But it didn't feel like a student. College students don't have six-month
attention spans. They'd search for games and academic programs, not mili-
tary keywords. And wouldn't a student leave some kind of signature or joke
behind-some way of sticking out his tongue at us?
      If this wasn't a student, then why did he come from two places in
Germany? Maybe he knew some way to call long distance into Hannover-
perhaps from some unprotected computer, or with a stolen credit card.
Yesterday it was Bremen. Today Hannover. Where will he hide tomorrow?
      The only way to find out was to keep watching. Quietly.
      I'd waited four months. I could wait a while longer.

o     0     0 "You need a German search warrant."
      Steve White called back from Tymnet, He'd just received electronic
mail from Wolfgang Hoffman at the German Bundespost. Wolfgang was
hot to pursue the hacker, but needed legal support to trace their lines.
      "How do I get a search warrant in Germany?" I asked Steve.
      "I don't know, but the Bundespost says they're going to the Hannover
courts tomorrow to discuss it."
      This was good news. Somewhere in Germany, Wolfgang Hoffman had
started wheels turning. With luck, they'd get some court orders, make a
couple more traces, and arrest the varmint.
      Steve White was less optimistic. "When the hacker shows up, the
Germans will have to trace the Datex networks, find the phone number that
the hacker is calling, and then trace that telephone line."
      "Foo," I said, remembering my traces in Berkeley and Virginia. Unless
Wolfgang and his team were patient, competent, and clever, the hacker
would evade them.
      Too many things could go wrong. The hacker could be from another
country. He could be using a phone line from another city, disguised

                  THE CUCKOO'S EGG

through a wide-area telephone system. The court might not grant the search
warrants. Or the hacker might sniff the wind and realize that someone was
on his trail.
      Wolfgang sent another message: "Until the search warrant appears, we
will record the name of the Datex user-identifier."
      Steve explained, "Whenever you use Tymnet or Datex, someone pays
for the service. When you use the network, you have to type in your
account number and password. The Germans are going to find out who's
paying for the hacker's connections. When we signal them that the hacker's
around, they'll not only trace their Datex network, but also find the account
name that's paying for the connection."
      I understood. If the hacker had stolen someone else's account number
and password, he could be charged with theft, and getting a search warrant
would be easy. On the other hand, if he was paying for his own connec-
tions, it would be easy to find his name, and a court order wouldn't be
necessary. They might not even have to trace his telephone lines.
     No doubt, this guy Wolfgang was sharp. He was looking for shortcuts
to avoid making telephone traces. At the same time, he was building a case
against the hacker.
      Saturday, December 20, Steve called me at home. Martha glared at me
for letting brunch get cold.
      Steve had just received another message from Germany. The
Bundespost had contacted the Bremen State Prosecutor, Herr Stattsanwalt
Von Vock. ("Now that's a high-class title," I thought.)
      The message from Germany read: "The German State Prosecutor needs
to contact high-level U.S. criminal justice persons so as to execute proper
search warrants. The Bundespost cannot move until officially notified by a
high-level U.S. criminal office."
     What's a high-level U.S. criminal office? The Mafia? Whatever they
meant, I'd better get people moving.
    I called my boss, Roy Kerth, who crustily observed that it'd taken the
Germans six months to discover this problem. "If they were half competent,
the hacker would be behind bars by now."
     To catch this snake, we all had to pull in the same direction. My boss's
flames didn't promote harmony, so how could they promote international
cooperation? Maybe 1'd be better off appealing to our legal counsel.
     Aletha Owens knew what to do. "I'll call Germany and talk to them

                                ST 0 L L

directly. They probably need someone in the FBI, but I'll start things mov-
      "Sprechen Sie Deutsch?"
      "Not in twenty years," Aletha said. "But I'll haul out the old Berlitz
      Sunday morning, Aletha called back. "Hey, my German isn't so bad. A
few problems with the future tense, but not bad. Not bad."
      "Yeah, but what did you learn?"
      "Well, I learned all sorts of things about reflexive verbs and
      "What about the hacker?"
      "Oh, him. Aah, yes." Aletha adopted a mock academic tone. "The
German State Prosecutor is a most kindly gentleman who believes in pro-
tecting both liberty and property. So he needs an official request to open an
      "Who's the official?"
      "The FBI. We've got to ask the FBI to contact their German counter-
parts. Or should I say, 'you,' since I'll be gone next week."
      It was on my shoulders to get the FBI to call the Germans to open an
investigation. Great-another chance for them to say 'go away kid.' I left a
message for Mike Gibbons at the Alexandria, Virginia, FBI office.
      Amazingly, Mike called ten minutes later from Colorado.
      "Hi, Cliff. This had better be important."
      "Sorry to bother you, but the German prosecutor needs to talk to
someone in the FBI. We've traced our troubles into Hannover."
      "Well there's nothing I can do tonight," Mike said. "And I don't have
any documentation here."
      In theory, the FBI's representative in Germany would contact his Ger-
man counterpart, and things would progress from there. Mike said that this
guy, the U.S. Legal Attache, lived in Bonn and handled communications
between the two countries. In a sense, he represents the FBI within Ger-
      Over the next few months, I would often hear about the U.S. Legal
Attache. I never learned his name, though plenty of curses were directed his
      The next day, Mike fished through the crime laws. "It's covered by the
computer fraud act. Open and shut case."
      "But the guy has never set foot in the States," I observed. "How can
you get someone from another country?"

                  THE CUCKOO'S EGG

     "Well, he probably won't be extradited, if that's what you mean. But
we can press charges and get him thrown into a German prison, especially if
the German law is similar to ours."
      "What's the likelihood that the FBI will drop the whole thing?"
      "Not if I can help it," Mike said. "We'll have to work with attorneys
at the Justice Department, but I don't see a problem there."
      I still didn't believe him. The case was obvious to me, but too complex
to describe to a criminal lawyer.
     "Is there anything that I can get that will help you?"
      "Come to think of it, there is. Could you write up a summary of the
hacker? You know, draw up a profile of him and tell us who we're looking
for. Things like when he's active, what he's expert in, any idiosyncrasies.
Don't speculate, but try to identify our man."
     Here was a useful project to keep me from pestering Mike for a few
days. I combed through my logbook and drew together a profile of my
      Compiling this profile should have kept me out of trouble for a few
days. But trouble came from another front.
      Someone at NSA had leaked word of my research to the Department
of Energy. In turn, they were pissed that they hadn't heard earlier-and
more directly.
      Roy Kerth stopped me in the hallway. "DOE is going to reprimand
us for not telling them about this incident."
      "But we did tell them," I objected. "More than two months ago."
      "Prove it."
     "Sure. It's in my logbook."
      Roy wanted to see it, so we walked over to my Macintosh and
brought up the logbook. Sure enough, on November 12th, my logbook said
that I'd informed DOE. I'd written a summary of our conversation and
even included a phone number. DOE couldn't complain-we could prove
that we'd informed them.
     Saved by my logbook.
     Just like observing at a telescope. If you don't document it, you might
as well not have observed it. Sure, you need powerful telescopes and com-
puters. But without a logbook, your observations won't amount to much.
      On December 30, my beeper woke me up around 5 A.M. By reflex, I
called Steve at his house. He wasn't pleased to hear from me.

                                ST 0 L L

     "The hacker's on."
     "Aaw, I was just in the middle of a dream. Are you sure it's him?" His
British accent didn't .hide his annoyance.
      "I'm not sure, but I'll find out in a minute."
      "OK, I'll start a trace." Steve put up with a lot from me.
      From home, I dialed my Unix computer. Damn. No hacker. The
electricians had tripped my alarm by shutting off a nearby computer.
     Sheepishly, I called Steve back.
     "Say, Cliff, I can't find anyone connected to your computer." His
voice was still sleepy.
     "Yeah. It's a false alarm. I'm sorry."
     "No problem. Maybe next time, huh?"
     Now here's a good guy. If someone I'd never met rousted me out of
bed to chase a phantom in a computer. . . .
    Luckily, only Steve had heard me cry wolf. What would happen to
my credibility if I'd passed the word along to Germany or the FBI? From
now on, I'd double-check every alarm.

o      0 0 New Year's Eve found us sitting around the fire with
friends, sipping eggnog and listening to the explosions as neighborhood
idiots set off cherry bombs in the street.
      "Hey," said Martha, "we'd better get moving if we're going to make
it to First Night." San Francisco was throwing a city-wide party to wel-
come in 1987, foster civic pride, and give people an alternative to getting
drunk and smashing into each other. There was music, dance, theater, and
comedy in a dozen locations across town, with cable-car shuttles between
      Seven of us piled into a beat-up Volvo and inched into San Francisco,
trapped in a raucous traffic jam. Instead of honking, people blew party horns
out their car windows. Finally we came to the brightly-lit city, ditched the
car, and headed for a flamenco concert.
      We found our way to the Mission district-the Latin section of town,

                  THE CUCKOO'S EGG

and discovered a packed Catholic church with an impatient audience. A
sheepish face emerged from behind the curtain, explaining, "None of the
lights work so we're delaying the performance."
       Amid the catcalls and boos, Martha stood up and pushed me forward. I
still had my electrician's license, and she'd done tech for many an amateur
theatrical. We snuck backstage. The flamenco dancers in their glittering
costumes smoked and paced the dark stage like caged tigers, tapping their
feet and glancing at us doubtfully. Martha set about untangling the maze of
cables strewn in the wings while I located the blown fuse. A quick swap of
fuses and, shazam, the stage lights lit.
      The dancers stamped and cheered and, as Martha neatly coiled the last
cable and adjusted the lighting board, the emcee dragged us on stage to
thank us. After we escaped the limelight, we enjoyed the flamenco dancing
and.faro singing; the scowling, nervous creatures we'd seen on the dark stage
were transformed into elegant, whirling dancers.
     We ducked outside and found a shuttle bus driven by an old lady who
could have passed for Tugboat Annie, in appearance and language. She
maneuvered the bus gamely through the crowded streets, and we found
ourselves at the Women's Building on Eighteenth Street. There the Wall-
flower Order danced and told stories of feminism and social protest.
     One dance was about the Wu-Shu, a legendary Chinese monkey who
defeated the greedy warlords and gave land back to the people. Sitting in
the balcony, I thought about politically correct monkeys-was I a pawn of
the warlords? Or was I really a clever monkey, on the side of the people? I
couldn't tell, so I forgot about my hacker and enjoyed the dance.
      Finally, we wound up dancing wildly to a rhythm and blues band
with lead singer Maxine Howard, a sensational blues singer and the sexiest
woman in the history of the world. She was picking people out of the
audience to dance with her on the stage, and we soon found ourselves
hoisting a protesting Martha onto the platform. Within a few minutes, she
and her fellow victims overcame their stage fright and formed themselves
into a fairly synchronized chorus line, doing little hand motions like the
Supremes. I was never much for dancing, but by two o'clock or so, I found
myself jumping and spinning around with Martha, lifting her high in the
aIr . . .
      We finally had our fill of high culture and cheap thrills, and went to
sleep at a friend's house in the Mission district. What felt like moments after

                                 S TO L L

my head touched the pillow (though it was actually nine the next morning),
my beeper woke me up.
      Huh? The hacker was at work on New Year's Day? Give me a break.
      There wasn't much I could do. Hacker or not, I wasn't about to call
Steve White on New Year's morning. Anyway, I doubted that the German
Bundespost could do much about it on a holiday. Most of all, I was ten
miles from my laboratory.
      I felt caged in while the hacker had free run. If he wanted to tweak my
nose, he'd found the way. Just show up when I couldn't do anything.
      Well, I couldn't do much beyond worry, so I tried to sleep. With
Martha's arm around me, rest came easily. "C'mon, sweetie," she purred.
"Give the hacker a holiday." I sank into the pillows. Hacker or not, we
would celebrate the New Year. We slept the rest of the morning. Around
noon, we found our way back home. Claudia greeted us with a violin
sonata . . . she'd spent New Year's Eve playing at some millionaire's
      Martha asked about her job. "You should have seen the canapes!"
Claudia answered. "We had to sit and stare at them for hours before they
finally saw us looking pathetic and brought us some. They had a whole
smoked salmon and caviar and strawberries dipped in chocolate and-"
      Martha cut in, "I meant what music you played."
      "Oh, we played that Mozart sonata everyone likes that goes diddle
dum diddle da da da. Then they started making requests for really icky
things like 'My Wild Irish Rose.' I thought I'd get sick but after all it was
$125 for two hours and it was on the way to my Mom's so I could drop the
dog off there, and do some shopping up at Santa Rosa-"
       Martha snuck in a word about brunch. We were all in the kitchen
mixing waffle batter and making fruit salad when my beeper sounded.
       Damn. The hacker again. Martha cursed, but I hardly heard her: I
zipped over to my Macintosh and dialed the lab.
       There was the hacker, all right, logged in as Sventek. It looked like he
was using the Milnet, but I couldn't be sure until I went to the lab. Mean-
while, I'd better call Steve White at Tymnet.
       No time-the hacker disappeared within a minute. He was playing
New Year's games.
       There wasn't much to do but pick up the pieces. I scarfed down the
waffies and biked over to the lab. There, the hacker's New Year's celebration

                   THE CUCKOO'S EGG

was saved on my printers. I scribbled notes on the printouts, next to each of
his commands:

     4.2 BSD UNIX(lbl-ux4)
     login: sventek                     The hacker logs in as Sventek
     Password: Iblhack                  and gives his current password
     Last login: Mon Dec ?7 13:31:43 on ttyi7
     4.2 BSD UNIX #20: Fri Aug 2220:08:16 PDT 1986
     % telnet                            He's going out over the Milnet
     telnet> open optimis                And into the Optimis Army Database
                For user assistance, call 695-5772, (AVj225
     Usemame: ANONYMOUS                He logs in there as
     Password: GUEST                     And uses an obvious password

    Welcome to the Army OPTIMIS database
    If you use these databases and they achieve a savings in
    time spent on a project or money saved to the govemment or both,
    please send a mail message outlining the details to
    Maj Gene leClair, Chief, OPTIMIS

                                 WELCOME TO
                    THE DATA BASE WAS LAST UPDATED
                             ON 861024 AT 102724
                     AND CONTAINS 33 J6 DOCUMENTS
    This data base is an extract of AR 25-400-2, Modem Army Recordkeep-
    ing System (MARKS) to help you identify information for filing.

     Please enter a word or              Looking for SDI dope
    / sdi
    The word "sdi" was not               But there's none there.
    Please enter a word or
    / stealth                            Any word on the Stealth bomber?
    The word "stealth" was not           No such luck

    Please enter a word or
    / sac                                Strategic Air Command?
    The word "sac" was not               Nope

                                  S TO L L

      Whee! The hacker had entered an Army database and searched [or
secret Air Force projects. Even an astronomer would know better. He
caught on quickly, though:

  Please enter a word or 'EXIT'.
  / nuclear
I have found 79 documerqs] containing the phrase 'nuclear'.
ITEM #      MARKS #        TITLE

1         2O-1f          IG Inspections (Headquarters, Department of the Army)
2         SOa            Nuclear, chemical, and biological national security affairs
3         SOb            Nuclear, chemical and biological warfare arms controls
4         SOd            Nuclear and chemical strategy formulations
5         50e            Nuclear and chemical politico-military affairs
6         SOf            Nuclear and chemical requirements
7         50g            Nuclear and chemical capabilities
8         SOh            Theater nuclear force structure developments
9         SOi            Nuclear and chemical warfare budget formulations
10        SOj            Nuclear and chemical progress and statistical reports
II        SOk            Army nuclear, chemical. and biological defense program
12        SOm            Nuclear and chemical cost analyses
13        SOn            Nuclear, chemical warfare, and biological defense
                            scientific and technical information
14        SOp            Nuclear command and control communications
15        SOq            Chemical and nuclear demilitarizations
16        SOr            Chemical and nuclear plans
17        5O-5a          Nuclear accident/incident controls
18        5O-5b          Nuclear manpower allocations
19        50-5c          Nuclear surety files
20        5O-Sd          Nuclear site restorations
21        5O-5-1a        Nuclear site upgrading files
22        5O-115a        Nuclear safety files
23        55-355FRTd     Domestic shipmentcontrols
24        200-1c         Hazardous material management files
25        385-11k        Radiation incident cases
26        385-11m        Radioactive material licensing
27        385-4Oc        Radiation incident cases
28        700-65a        Intemational nuclear logistics files
79        J 125-2-300a   Plant data

      Well, 1'd never come across such things. 1'd always thought that a
theater was somewhere to watch movies, not a place to develop nuclear
forces. This hacker wasn't playing games.
      And he wasn't satisfied with the titles to these documents-he dumped

                          THE CUCKOO'S EGG

    all twenty-nine over the line printer. Page after page was filled with army
    double-talk like:

           TITLE: Nuclear, chemical. and biological national security affairs
           DESCRIPTION: Documents relating to domestic, foreign, and milital)' police for
           application of atomic energy, utilization of nuclear and chemical weapons,
           biological defense relating to national security and national level crises
           management Included are studies, actions, and directives of an related to
           President National Security Council, Assistant to the President for National
           Security Affairs, and interdepartmental groups and committees addressing
           national security affairs regarding nuclear and chemical warfare and

          There, my printer jammed. The old Decwriter had paid its dues for ten
    years, and now needed an adjustment with a sledge hammer. Damn. Right
    where the hacker listed the Army's plans for nuclear bombs in the Central
    European theater, there was only an ink blot.
      I didn't know much about movie theaters in Central Europe, so I gave
Greg Fennel a call at the CIA. Amazingly, he answered his phone on New
Year's Day.
           "Hi, Greg-what brings you in on New Year's?"
           "You know, the world never sleeps."
     "Hey, what do you know about movie houses in Central Europe?" I
asked, playing the fool.
     "Oh, a bit. What's up?"
     "Not much. The hacker just broke into some Army computer at the
      "What's that got to do with movies?"
      "I dunno," I said, "but he seemed especially interested in nuclear force
structure developments in Central European theaters."
      "You dunce! That's Army tactical warfare plans. Jeez. How did he get
.   ,;,"
     "His usual techniques. Guessed the password to the Army Optimis
database in the Pentagon. It looks like a bibliography of Army documents."
     "What else did he get?"
     "I can't tell. My printer jammed. But he searched for keywords like
'SDI,' 'Stealth,' and 'SAC.' "

                                 ST 0 L L

      "Comic book stuff." I wasn't sure if Greg was joking or serious. He
probably thought the same of me.
       Come to think of it, how did the spooks know if I was putting them
on? For all they knew, I might be inventing everything. Greg had no reason
to trust me-I had no clearance, no badge, not even a trench coat. Unless
they were spying behind my back, my credibility remained untested.
       I had only one defense against this quicksand of distrust-the facts.
       But even if they believed me, they weren't likely to do anything. Greg
explained, "We can't just send Teejay overseas and bust down someone's
door, you know."
       "But can't you, well, sorta snoop around there and find out who's
responsible for this?" I imagined spies in trench coats again.
       Greg laughed. "That's not how things work. Trust me~~e're work-
ing on it. And this latest news will add fuel to the fire." So much for the
CIA. I just couldn't tell if they were interested or not.
       On January 2, I called the Alexandria FBI office and tried to leave a
message for Mike Gibbons. The duty agent who answered the phone said in
a dry voice, "Agent Gibbons is no longer working this case. We suggest you
contact the Oakland office."
       Super. The only FBI agent that knows the difference between a net-
work and a nitwit has been pulled off the case. No explanation given.
       And just when we need the FBI. Wolfgang was still waiting for a
warrant from the U.S. Legal Attache in Bonn. A week of waiting, and it
still hadn't come through. Time to knock on another door.
       No doubt the National Security Agency would want to know about
leaks from a Pentagon computer. Zeke Hanson at Fort Meade answered.
     "Did the Army information go directly to Europe?" Zeke asked.
    "Yeah, though I don't know exactly where," I said. "Looks like Ger-
      "Do you know which International Record Carrier they used?"
      "Sorry, I don't. But I can fish it out of my records if it's that impor-
tant." Why would NSA want to know who had carried this traffic?
     Of course. NSA is rumored to tape record every transatlantic tele-
phone conversation. Maybe they'd recorded this session.
     But that's impossible. How much information crosses the Atlantic
everyday? Oh, say there's ten satellites and a half-dozen transatlantic cables.
Each handles ten thousand telephone calls. So the NSA would need several
hundred thousand tape recorders running full time. And that's just to listen

                  THE CUCKOO'S EGG

to the phone traffic-there are computer messages and television as well.
Why, fishing out my particular session would be nearly impossible, even
with supercomputers to help. But there was an easy way to find out. See if
NSA could obtain the missing data.
     "The New Year's Day sessions were interrupted by a paper jam," I told
Zeke, "so I'm missing an hour of the hacker's work. Think you could
recover it?"
      Zeke was cagey. "What's its importance?"
      "Well, I can't quite say, since I haven't seen it. The session started at
8:47 on New Year's Day. Why don't you see if someone in Ft. Meade can
find the rest of the traffic from this session?"
      "Unlikely at best."
      The NSA was always willing to listen but clammed up tight whenever
I asked questions. Still, if they were doing their homework, they'd have to
call me and see if our results were the same. I waited for someone to ask to
see our printout. Nobody did.
      Come to think of it, two weeks ago, I'd asked Zeke Hanson at the
NSA to find out an electronic address. When I first traced a line into
Europe, I passed the address to Zeke. I wondered what he'd done with it.
      "Did you ever find out where that DNIC address comes from?" I
      "Sorry, Cliff, that information is unavailable." Zeke sounded like one
of those Magic-8 balls, the kind that say, "Reply hazy, ask again later."
      Fortunately, Tymnet had already figured out the address . . . it only
took Steve White a couple hours.
      Perhaps NSA has lots of electronics wizards and computer geniuses,
listening to the world's communications. I wonder. Here, I'd presented them
with two fairly easy problems-find an address and replay some traffic.
Maybe they did, but they never told me a whit. I suspect they do nothing,
hiding behind a veil of secrecy.
      Well, there was one more group to inform. The Air Force OSL The
Air Force narcs couldn't do much about the hacker, but at least they could
figure out whose computer was wide open.
     Jim Christy's gravelly voice crackled over the phone lines: "So it's the
Army Optimis system, huh? I'll make a few calls and bang a few heads." I
hoped he was joking.
      So 1987 started on a sour note. The hacker still had the free run of our

                               S TaL L

computers. The only competent FBI agent had been pulled from the case.
The spooks wouldn't say a thing, and NSA seemed uninspired. If we didn't
make some headway soon, 1'd give up too.

o    0     0    Around noon on Sunday, January 4, Martha and I were
stitching a quilt when my beeper sounded. I jumped for the computer,
checked that the hacker was around, then called Steve White. Within a
minute, he'd started the trace.
     I didn't wait while Steve tracked the call. The hacker was on my
computer, so I biked up to the lab and watched from there. Another
twenty-minute race up the hill, but the hacker took his time: he was still
typing when I reached the switchyard.
     Underneath the printer, an inch-thick printout had accumulated. The
hacker hadn't been lazy today. The top line showed him masquerading
behind Sventek's name. After checking that none of our system managers
were around, he went back to the Pentagon's Optimis database. Not today:
"You are not authorized to log in today," was the Army computer's reply.
     Well, hot ziggity! Jim Christy must have bashed the right heads.
     Scanning the printout, I could see the hacker going fishing on the
Milnet. One by one, he tried fifteen Air Force computers, at places like
Eglin, Kirtland, and Bolling Air Force Bases. No luck. He'd connect to each
computer, twist the doorknob once or twice, then go on to the next system.
     Until he tried the Air Force Systems Command, Space Division.
     He first twisted on their doorknob by trying their System account,
with the password of "Manager." No luck.
     Then Guest, password of "Guest." No effect.
     Then Field, password "Service":

    Usemame: FIELD
    Password: SERVICE

     VAX,NMS 4.4

                  THE CUCKOO'S EGG

     Computer System problems should be directed to the Information Systems
     Customer Service Section located in building 130, room 2359.
     Phone 643-21 77/AV 833-2177.

      Last interactive login on Thursday, II-DEC-1986 19: II
      Last non-interactive login on Tuesday, 2-DEC-1986 17:30
    WARNING - Your password has expired; update immediately with SET

    S show process/privilege
    4-JAN-1987 13: 16:37.56      NTY1:          User: FIELD
    Process privileges:
          BYPASS               may bypass all system protections
          CMKRNL               may change mode to kernel
          ACNT                 may suppress accounting messages
          WORLD                may affect other processes
          OPER                 operator prMlege
         VOLPRO                may override volume protection
         GRPPRV                group access via system protection
         READALL               may read anything as the owner
         WRITEALL              may write anything as the owner
         SECURITY              may perform security functions

      Shazam: the door had swung wide open. He'd logged III as Field
Service. Not just an ordinary user. A completely privileged account.
      The hacker couldn't believe his luck. After dozens of attempts, he'd
made the big time. System operator.
      His first command was to show what privileges he'd garnered. The Air
Force computer responded automatically: System Privilege, and a slew of
other rights, including the ability to read, write, or erase any file on the
      He was even authorized to run security audits on the Air Force com-
      I could imagine him sitting behind his terminal in Germany, staring in
disbelief at the screen. He didn't just have free run of the Space Command's
computer; he controlled it.
      Somewhere in Southern California, in EI Segundo, a big Vax com-
puter was being invaded by a hacker halfway around the world.
      His next moves weren't surprising: after showing his privileges, he
disabled the auditing for his jobs. This way, he left no footprints behind; at
least he thought not. How could he know that I was watching from Berke-

                                ST 0 L L

     Confident that he was undetected, he probed the nearby computers. In
a moment, he'd discovered four on the Air Force network, and a pathway
to connect to others. From his high ground, none of these were hidden from
him; if their passwords weren't guessable, he could steal them by setting up
Trojan horses.
     This wasn't a little desktop computer he'd broken into. He found
thousands of files on the system, and hundreds of users. Hundreds of users?
Yep. The hacker listed them all.
     But his greediness got in his way. He commanded the Air Force
computer to list the names of all its files; it went merrily along typing out
names like "Laser-design-plans" and "Shuttle-launch-manifest." But he
didn't know how to shut off the spigot. For two hours, it poured a Niagara
of information onto his terminal.
     Finally, at 2:30, he hung up, figuring that he'd just log back into the
Air Force computer. But he couldn't get back on. The Air Force computer
informed him:

     "Your password has expired. Please contactthe system manager."

    Looking back over the printout, I realized his goof. The air force
computer had expired the "field service" password; he'd received a warning
when he first broke in. Probably, the system automatically expired pass-
words after a few months.
      To stay on the machine, he should have immediately reset his pass-
word. Instead, he ignored the request. Now the system wouldn't let him
      From thousands of miles away, I could sense his frustration. He desper-
ately wanted to get back into that computer, but he'd been foiled by his
own stupid mistake.
      He'd stumbled on the keys to a Buick, and locked them in the car.
      The hacker's mistake solved one problem: what should I tell the Air
Force Space Division? Since it was a Sunday, there was nobody to call
today. And because the hacker had locked himself out, he was no longer a
danger to the Air Force computer. 1'd just report the problem to the Air
Force narcs, and let them handle it.
      While the hacker stepped through the Air Force computer, Steve
White traced Tyrnnet's lines.
      "He's coming through RCA," Steve said. "TAT-6."

                  THE CUCKOO'S EGG

     "Huh? What's that mean in English?"
       "Oh, nothing really. RCA is one of the international record carriers,
and today the hacker is coming across the number six transatlantic cable."
Steve dealt in worldwide communications like a taxi driver in midtown
     "Why isn't he on a satellite link?"
     "Probably because it's a Sunday-the cable channels are less crowded."
     "You mean that people prefer cable to satellite links?"
     "Sure. Every time you connect through a satellite, there's a quarter
second delay. The undersea cables don't slow down your messages so
     "Who would care?"
     "People on the telephone, mostly," Steve said. "Those delays make for
jittery conversations. You know, where each person tries to speak at the
same time, then they both back off."
     "So if the phone companies try to route over the cables, who wants
the satellites?"
     "Television networks, mostly. TV signals can't be squeezed into sub-
marine cables, so they grab the satellites. But fiber optics will change every-
     I'd heard of fiber optics. Running communications signals over strands
of glass, instead of copper wires. But who was running fiber-optic cables
under the ocean?
       "Everyone wants to," Steve explained. "There's a limited number of
satellite channels available-you can crowd only so many satellites over
Equador. And the satellite channels aren't private-anyone can listen in.
Satellites may be fine for television, but cable's the way to go for data."
     My conversations with Steve White began with tracing the hacker,
but inevitably slipped into other topics. A short talk with Steve usually
became a tutorial on communications theory.
      Realizing that the hacker was still connected, I asked Steve for the
details of the trace.
      "Oh yeah. I checked with Wolfgang Hoffman at the Bundespost. Your
visitor is coming from Karlsruhe today. The University of Karlsruhe."
      "Where's that?"
    "I don't know, but I'd guess the Ruhr valley. Isn't that along the

c                                                                                    ___

                                      ST 0 L L

          The hacker was still chipping away at the Air Force computer, but
    after he left, I jogged over to the library. Yes, there's Karlsruhe. Three
    hundred miles south of Hannover.
         Draped across the floor of the Atlantic Ocean, the TAT-6 cable ties
    together Europe and America. The western end of the connection came
    through Tymnet, then Lawrence Berkeley Laboratory, across the Milnet,
    and ended at the Air Force Systems Command Space Division.
         Somewhere in Germany, the hacker tickled the eastern end of the
    connection, unaware that we were zeroing in on him.
         Three different places in Germany. My hacker was moving around. Or
    maybe he was staying in one place, playing a shell game with the telephone
    system. Perhaps he really was a student, visiting different campuses and
    showing off to his friends. Was I certain that there was only one hacker-or
    was I watching several people?
          The solution depended on completing a trace. Not just to a country or
    a city, but all the way to an individual. But how do I get a phone trace
    from six thousand miles away?
          The search warrant! Had the FBI pushed the warrant into Germany?
    For that matter, had they really opened an investigation? Time to call Mike
    Gibbons of the FBI.
          "I hear you've been pulled off the computer case," I told Mike. "Is
    there anything I can do?"
        "Not to worry," Mike said. "Let me handle it. Just lay low, and we'll
    make progress."
        "Well, is there an open investigation or not?"
            "Don't ask me, because I can't say. Just be patient, and we'll work it
          Mike slipped out of every question. Maybe I could pry some informa-
    tion from him by telling him about the Air Force computer.
          "Hey, the hacker broke into an Air Force computer yesterday."
         "Oh, somewhere in Southern California." I didn't say that it was at
    2400 East EI Segundo Boulevard, across from the Los Angeles Airport. He
    wouldn't tell me what was happening, so I'd play coy with him.
         "Who runs it?"
        "Someone in the Air Force. Sounds like some Buck Rogers place. I

                  THE CUCKOO'S EGG

       "You'd better call the Air Force OSI. They'll know what to do."
       "Won't the FBI investigate?"
       "I told you. We are investigating. We are making progress. It's just not
for your ears to hear." So much for extracting information from the FBI.
       The Air Force narcs were a bit more expressive. Jim Christy of the Air
Force OSI put it succinctly.
       "Systems Command? Son of a bitch."
       "Yeah. The guy became system manager there."
       "Systems manager at Systems Command. Amusing. Did he get any-
thing classified?"
       "Not that I can tell. He really didn't get that much, just the names of a
few thousand files."
       "Damn. We told them. Twice." I wasn't sure if I should be listening.
       "If it makes any difference, he's not going to get back on their system.
He's locked himself out." I told him about the password expiration.
       "That's fine for the Systems Command," Jim said, "but how many
other computers are just as wide open? If the Space Division screws up like
that, even after we warn them, then how are we ever going to get the word
       "You warned them?"
       "Damn straight. We've been telling systems operators for six months
to change all their passwords. Don't you think we've been listening to
       Smoley hokes! They'd actually heard my message, and were spreading
the word. It's the first time that anyone had even hinted that I'd had any
       Well, the Air Force OSI in Washington sent the message out to their
agent at Vandenberg Air Force Base. He, in turn, was to knock heads at the
Space Division. They'd make sure that the hole stayed plugged up.
       Two days later, Dave Cleveland and I were sitting in front of his
terminal, playing with some broken software. My beeper went off and
without saying a word, Dave switched the terminal over to the Unix
computer. Sventek was just logging on. We looked at the screen, then
nodded to each other. I jogged over to the switchyard to watch the action
       The hacker didn't bother with my computers, but went straight over
 the Milnet to the Air Force Space Division. I watched him start to log in
 there as Field Service, thinking how he would just be booted off again.

                                 ST 0 L L

      But no! He was welcomed back into their system. Someone at the Air
Force base had re-enabled the Field Service account with the same old
password. The service technician may have noticed that the account had
expired, and asked the system manager to reset the password.
      Stupid. They'd unlocked the doors and left the keys in the ignition.
      The hacker didn't waste a minute. He went straight to the authoriza-
tion software and added a new account. No, not a new account. He searched
for an old, unused account and modified it. Some Air Force officer, Colonel
Abrens, had an account, but hadn't been around this computer in a year.
     The hacker slightly modified Colonel Abrens' account, giving it sys-
tem privileges and a new password: AFHACK.
     AFHACK-what arrogance. He's thumbing his nose at the United
States Air Force.
      From now on, he didn't need the Field Service account. Disguised as
an officer in the Air Force, he had unlimited access to the Space Division's
      Heavy duty. This guy wasn't tinkering around. Air Force OSI had left
for the day. What should I do? Leaving the hacker connected would leak
sensitive information from the Air Force. But disconnecting him would
only cause him to use a different route, bypassing my lab's monitors.
      We'd have to chop him off at the Space Command.
      But first, I wanted him traced. A call to Steve White started things
rolling. Within five minutes, he'd traced the connection to Hannover, and
called the Bundespost.
      A few minutes of silence. "Cliff, does the connection look like it will
be a long one?"
      "I can't tell, but I think so."
     "OK." Steve was on another telephone; I could only hear an occa-
sional shout.
      In a minute, Steve returned to my line. "Wolfgang is tracing the call
in Hannover. It's a local call. They're going to try to trace it all the way."
     Here's news! A local call in Hannover meant that the hacker's some-
where in Hannover.
     Unless there's a computer in Hannover doing his dirty work.
     Steve shouted instructions from Wolfgang: "Whatever you do, don't
disconnect the hacker. Keep him on the line if you can!"
     But he's rifling files at the Air Force base. It was like letting a burglar

                  THE CUCKOO'S EGG

rob your home while you watched. Should I boot him out or let the trace
go ahead? I couldn't decide.
     Well, I ought to call some authority. How about Mike Gibbons of the
FBI? He's not around.
      Hey-the National Computer Security Center might be a good place
to call. Zeke Hanson will know what to do.
      No luck. Zeke wasn't in and the voice at the far end of the line
explained, "I'd like to help you, but we design secure computers. We don't
get involved in the operational aspects." I'd heard that before, thank you.
      Well, there wasn't anyone else to tell but the Air Force. I hooked into
the Milnet Network Information Center and looked up their phone num-
ber. Naturally, they'd changed their phone number. They even listed the
wrong area code. By the time I reached the right person, the hacker had
thoroughly penetrated their computer.
      "Hi, I'm looking for the system manager of the Space Command's Vax
      "This is Sergeant Thomas. I'm the manager."
      "Uh, I don't know how to explain this to you, but there's a hacker in
your computer." (Meanwhile, I'm thinking, "He won't believe me and will
want to know who I am.")
      "Huh? Who are you?" Even over the phone, I could feel him giving
me the hairy eyeball.
      "I'm an astronomer at Lawrence Berkeley Laboratory." (First mistake,
I think, nobody's gonna believe that.)
      "How do you know there's a hacker?"
      "I'm watching him break into your computer over the Milnet."
      "You expect me to believe you?"
      "Just look at your system. List out your users."
      "OK." I hear typing in the background.
      "There's nothing strange here. We've got fifty-seven people logged in,
and the system's behaving normally."
      "Notice anyone new?" I asked.
      "Let's see . . . No, everything's normal." Should I tell him or just
beat around the bush?
      "Do you know someone named Abrens?"
      "Yeah. Colonel Abrens. He's logged in right now. Hey, what are you
getting at?"

                                ST 0 L L

     "Are you sure that Abrens is legit?"
     "Hell, yes. He's a colonel. You don't mess with the brass."
     I was getting nowhere by asking leading questions. Might as well tell
him. "Well, a hacker's stolen Abren's account. He's logged on right now,
and he's dumping your files."
     "How do you know?"
     "I watched him. I've got a printout," I said. "He came in on the Field
Service account, then reset Abrens' password. Right now, he's got system
privileges. "
      "That's impossible. Just yesterday, I reset the password to the Field
Service account. It had expired."
      "Yes, I know. You set the password to 'service.' The same as it's been
for the past year. Hackers know this."
      "Well, I'll be damned. Hold on." Over the phone, I hear Sergeant
Thomas call someone over. A couple minutes later, he's back on the line.
      "What do you want us to do?" he asked. "I can shut off my computer
right now."
      "No, hold off for a bit," I said. "We're tracing the line right now, and
we're closing in on the hacker." This was no fib: Steve White had just
relayed Wolfgang Hoffman's request to keep the hacker on the line as long
as possible. I didn't want Sergeant Thomas to cut the line before the trace
was complete.
      "OK, but we'll call our commanding officer. He'll make the final
decision." I could hardly blame them. A total stranger calls from Berkeley
and tells them that someone's breaking into their system.
      Between these phone calls, I watched the printer punch out the hack-
er's every command. Today, he didn't list the names of every file. Quite the
contrary: he listed individual files. He already knew the names of the files he
was looking for; he didn't need to scramble around searching for their
      Aah. This was an important clue. Three days ago, the hacker listed the
names of a thousand files. Today, he went straight to those files that inter-
ested him. He must have printed out his entire session. Otherwise, he would
have forgotten the names of the files.
      So the hacker's printing out everything he gets. I already knew that he
kept a detailed notebook-otherwise, he'd have forgotten some of the seeds
that he'd planted months ago. I remembered my meeting with the CIA:

                  THE CUCKOO'S EGG

Teejay had wondered if the hacker kept recordings of his sessions. Now I
     At the far end of the connection, somewhere in Germany, sat a deter-
mined and methodical spy. Every printout that came across my monitor was
duplicated in his lair.
     Which files did he list? He skipped over all the programs and ignored
system management guidelines. Instead, he went for operational plans. Doc-
uments describing Air Force payloads for the space shuttle. Test results from
satellite detection systems. SDI research proposals. A description of an astro-
naut-operated camera system.
   None of this information had the comment, "classified" on it. It wasn't
secret, top secret, or even confidential. At least, none of the files carried
those labels.
     Now, no military computer on the Milnet is allowed to carry classified
information. There's another computer network, completely separate, that
handles classified data. So in one sense, the Systems Command's Space Divi-
sion had nothing to lose: its computer is unclassified.
      But there's a deeper problem. Individually, public documents don't
contain classified information. But once you gather many documents to-
gether, they may reveal secrets. An order from an aircraft manufacturer for
a load of titanium sure isn't secret. Nor is the fact that they're building a
new bomber. But taken together, there's a strong indicator that Boeing's
new bomber is made of titanium, and therefore must fly at supersonic speeds
(since ordinary aluminum can't resist high temperatures).
     In the past, to pull together information from diverse sources you'd
spend weeks in a library. Now, with computers and networks, you can
match up data sets in minutes-look at how I manipulated Mitre's long-
distance phone bills to find where the hacker had visited. By analyzing
public data with the help of computers, people can uncover secrets without
ever seeing a classified database.
     Back in 1985 Vice Admiral John Poindexter worried about just this
problem. He tried to create a new classification of information, "Sensitive
but unclassified." Such information fit below the usual levels of Top Secret,
Secret, and Confidential; but access to it was to be denied to certain foreign-
      Poindexter clumsily tried to apply this to academic research-natu-
rally, the universities refused, and the idea died. Now, standing in front of

                                   ST 0 L L

my monitor, watching the hacker prowl through the Space Command's
system, I realized his meaning.    Air Force SDI projects might not be top
secret, but they sure were sensitive.
     What? Me agreeing with Vice Admiral Poindexter? The guy that
shipped arms to Iran? How could I have any common ground with Ollie
North's boss? Yet dancing across my screen was just what he'd described:
sensitive but unclassified data.
     Tymnet came back on the line. "I'm sorry, Cliff, but the trace in
Germany is stymied."
     "Can't they trace the call?" I asked, unsure of who I meant by "they."
     "Well, the hacker's line comes from Hannover, all right," Steve re-
plied. "But Hannover's phone lines connect through mechanical switches-
noisy, complicated widgets-and these can only be traced by people. You
can't trace the call with a computer."
     I started to understand. "You mean that someone has to be in the
telephone exchange to trace the call?"
     "That's it. And since it's after 10 P.M. in Hannover, there's nobody
     "How long will it take to get someone into the exchange?"
     "About three hours."
     To trace the line, a Bundespost telephone technician would have to
visit the telephone exchange and follow the switches and wires. For all I
knew, he might even have to climb telephone poles. Bad news.
     Meanwhile, the hacker was slithering through the Air Force computer.
Sergeant Thomas was still on hold-he'd probably called all sorts of Air
Force brass by now.
      I popped my phone to the Air Force line. "Well, we can't trace things
any further today."
     "Gotcha. We'll cut off the hacker right now."
     "Wait for a second," I said. "Don't make it look like you're just
booting him off your system. Instead, find a way that he won't suspect that
you're on to him."
      "Yeah. We figured out a plan," Sergeant Thomas replied. "We'll
broadcast an announcement to everyone on the system that our computer's
malfunctioning, and will have to be serviced."
      Perfect. The hacker will think the system's going down for repairs.

                  THE CUCKOO'S EGG

      I waited for a minute and in the middle of a page of SDI proposals,
this message interrupted the hacker's screen:

      System going down for maintenance, back up in 2 hours.

     He saw it right away. The hacker immediately logged off and disap-
peared into the void.

o     0     0  Having broken into another military base, the hacker wasn't
about to give up. He returned to our lab, trying over and over to get back
into the Air Force Systems Command. But none of his magic charms
worked. He couldn't get back into their computers.
      They were clever about how they'd locked out the hacker. They didn't
just post a notice saying, "Hackers stay out". Instead, they set the hacker's
stolen account so that it almost worked. When the hacker logged into his
stolen account, Abrens, the Air Force computer appeared to accept it, but
then barfed back an error message-as if the hacker had set up his account
     I wondered if the hacker realized that he was under my thumb. Every
time he succeeded in breaking into a computer, he was detected and booted
     From his viewpoint, everyone except us detected him. In reality, al-
most nobody detected him.
     Except us.
      He couldn't know that he was caged in. My alarms, monitors, and
electronic tripwires were invisible to him. Tymner's traces-through satel-
lites and under the ocean-were totally silent. And the Bundespost was
now on his scent.
     Wolfgang's latest message said that he was arranging to keep a techni-
cian at the Hannover telephone exchange until midnight every night. This
was expensive, so he needed to coordinate this with us. More important, the
Germans had still not heard from the FBI.

                               S TaL L

      Time to call Mike Gibbons. "The Germans haven't received anything
from the FBI," I said. "Any idea why?"
      "We're having, er, internal problems here," Mike replied. "You don't
want to know."
      I did want to know, but there was no use asking. Mike wouldn't say a
      "What should I tell the Bundespost?" I asked. "They're getting antsy
for some kind of official notification."
      "Tell them that the FBI's Legal Attache in Bonn is handling every-
thing. The paperwork will come along."
      "That's what you said two weeks ago."
      "And that's what I'm saying now."
      Zip. I passed the message back to Steve at Tymnet, who forwarded it
to Wolfgang. The bureaucrats might not be able to communicate with each
other, but the technicians sure did.
      Our complaints to the FBI should have been filtered through their
office, sent to the American Legal Attache in Bonn, then passed to the
German FBI, the Bundeskriminalamt. The BKA probably inspires the same
image of truth and justice in Germany as the FBI does in America.
      But someone was plugging up the communications downstream of
Mike Gibbons. About all I could do was keep pestering Mike, and stay in
close touch with Tymnet and the Bundespost. Sooner or later, the FBI
would reach out to the BKA, and the warrants would appear.
      Meanwhile, my astronomer buddies needed help. I spent the day trying
to understand the optics of the Keck Observatory's telescope. Jerry Nelson
needed my programs to predict the telescope's performance; I hadn't made a
whit of progress since I'd started chasing the hacker.
      The other systems programmers were on my case, too. Crusty Wayne
Graves leaned on me to build some disk driver software. ("Screw the
hacker. Write some code, already.") And Dave Cleveland gently reminded
me he needed to hookup ten new desktop computers to our lab-wide net-
      I told each of them that the hacker would be gone "RSN." The
ubiquitous statement of software developers everywhere. Real Soon Now.
      On my way over to the astronomy group, I ducked into the switch-
yard for a moment-just long enough to check my monitors. They showed
someone working on the Bevatron computer, manipulating the password

                  THE CUCKOO'S EGG

      Bizarre. The Bevatron's one of the lab's particle accelerators, and their
programmers all worked at our lab. Only a system manager could manipu-
late the password file. I stood around, watching. Someone was adding sev-
eral new accounts.
      Well, there's one way to find out if this is legit. Call the Bevatron
folks. Chuck McParland answered. "No, I'm the system manager. Ain't
nobody else licensed."
      "Uh, oh. Then you've got a problem. Someone's playing God on your
      Chuck typed a few commands and came back to the phone.
      "Son of a bitch."
      Chuck's Bevatron particle accelerator used magnets the size of houses
to shoot fragments of atoms into thin targets. In the sixties, its ammunition
was protons. Now, fed from a second accelerator, it zipped heavy ions up to
nearly the speed of light.
      After smashing these atomic particles into thin foils, physicists sift
through the debris, looking for fragments which may be the fundamental
building blocks of the universe. Physicists waited months for time on the
beamlines; more important, cancer patients waited as well.
      The Bevatron can accelerate helium ions to a fraction of the speed of
light, where they'll acquire about 160 million electron volts of energy. At
this speed, they travel a few inches and then dump most of their energy.
       If you position a cancer tumor at just the right distance beyond this
accelerator, most of the particles' energy goes into the tumor. The cancer
cells absorb this energy, and the tumor's destroyed without affecting the rest
of the person's body. Unlike X rays, which irradiate everything in their
path, the Bevatron particles deposit the bulk of their energy at one location.
This works especially well on brain tumors, which are often surgically
       Chuck's Bevatron computers calculate that "right distance." They con-
trol the accelerator too, so that the correct energy is used.
       Get either of these wrong, and you'll kill the wrong cells.
       Every few seconds, a burst of ions spills out of the beamline. By
flipping magnets at the right times, Chuck's computers send these to either a
physics experiment or a cancer patient. A bug in the program is bad news
for both.
       The hacker wasn't just poking around a computer. He was playing
with someone's brain stem.

                                ST 0 L L

      Did he know? I doubt it. How could he? To him, the Bevatron's
computer was just another plaything-a system to exploit. Its programs
aren't labeled, "Danger-medical computer. Do not tamper."
      He wasn't innocently looking for information. Having found a way to
become system manager, he was fooling with the operating system itself.
      Our operating systems are delicate creations. They control how the
computer behaves, how their programs will respond. System managers deli-
cately tune their operating systems, trying to squeeze every bit of perfor-
mance from the computer. Is the program too slow because it's competing
with other tasks? Fix it by changing the operating system's scheduler. Or
maybe there's not enough room for twelve programs at once. Then alter the
way the operating system allocates memory. Screw up, though, and the
computer won't work.
      This hacker didn't care if he wrecked someone else's operating system.
He just wanted to introduce a security hole so that he could reenter when-
ever he wished. Did he know that he might kill someone?
      Chuck nailed his system shut by changing all the passwords. Another
door slammed in the hacker's face.
      But another worry. I'd been chasing someone around the world, yet I
couldn't prevent him from breaking into any computer he wished. My only
defense was to watch him and warn people who were attacked.
      Sure, I could still boot him out of my computer, and wash my hands
of the whole mess. My earlier fears seemed unjustified: I now knew what
security holes he exploited, and it didn't look like he'd planted any time
bombs or viruses in my computer.
      Kicking him off my machine would only black out the window that I
used to watch him. He'd continue to attack other computers, using different
networks. I didn't have much choice but to let this SOB wander around
until I could catch him.
      But try explaining that to the FBI. On Thursday, January 8, my local
FBI agent Fred Wyniken stopped over.
      "I'm here only as a representative of the Alexandria, Virginia office,"
Fred said.
      "I don't understand," I said. "Why isn't the case being handled from
the Oakland office?"
      "The FBI's field offices are pretty much independent of one another,"
Fred replied. "What one office thinks is important, another may well ig-
nore." I could sense in which category he thought my case belonged.

                  THE CUCKOO'S EGG

     Fred explained that he didn't know the likelihood of prosecution be-
cause he wasn't handling the case. "But I'd say it's pretty slim. You can't
show any monetary loss. There's no obviously classified data. And your
hacker isn't in the States."
       "So that's why my local office isn't handling this case?"
       "Remember, Cliff, that the FBI only works cases that the Department
of Justice will prosecute. Since no classified information's been compro-
mised, there's no reason to commit the resources that it'll take to resolve
    "But unless you take action, this hacker will keep hammering on our
computers until he pretty much owns them."
     "Look. Every month we get a half-dozen calls saying, 'Help! Some-
one's breaking into my computer.' Ninety-five percent of them have no
records, no audit trails, and no accounting data."
     "Hold on there. I've got records and audit trails. Hell, I've got every
keystroke that this bastard's typed."
      "I'm getting to that. In a few cases, and yours is one of them, there's
good documentation. But that's not enough. The damage must be sufficient
to justify our efforts. How much have you lost? Seventy-five cents?"
     Here we go again. Yes, our computing costs were small change. But I
sensed a larger issue, perhaps one of national importance. My local FBI
agent saw only a six-bit accounting error. No wonder I couldn't get any
interest-let alone support-from him.
     How much longer before someone noticed? Maybe if a classified mili-
tary computer were hit? Or a high-tech medical experiment damaged?
What if a patient in a hospital were injured?
      Well, I gave him printouts from the past couple of weeks (after first
signing the back of each copy-something to do with "rules of evidence")
and a floppy disk with the Mitre telephone logs. He'd send it all to Mike
Gibbons at the Alexandria office. Maybe Mike would find them useful in
convincing the FBI to talk to the German BKA.
     Discouraging. The German telephone technicians still didn't have their
warrants, the FBI wasn't responding, and my boss sent me a curt note asking
when I'd write some software to link up a new printer.
     Martha wasn't happy either. The hacker wasn't just breaking into
computers. By way of the beeper, he was invading our home.
     "Isn't the FBI or the CIA doing something," she asked, "now that

                                ST 0 L L

there's foreigners and spies? I mean, aren't they the G-men-Truth, Justice,
and the American Way?"
      "It's the same old bailiwick problem. The CIA says that the FBI
should work it. The FBI doesn't want to touch it."
      "Is the Air Force Office of Something or Another doing anything?"
      "Same story. The problem starts in Germany, and someone's got to call
Germany to solve it. The Air Force Office of Special Investigations can only
bang on the FBI's door."
      "Then why not punt?" Martha suggested. "Brick up your computer
and let the hacker roam around theirs. Nobody appointed you official
guardian of America's computers."
      "Because I want to know what happened. Who's behind it. What
they're searching for. Research." Luis Alvarez's words still rang, months
      "Then think of a way to solve your problem without the FBI. If they
won't get the Germans to trace a call, then find some other way."
      "How? I can't call the German Bundespost and say, 'Trace this call!' "
      "Why not?"
      "For one, I wouldn't know who to call. And they wouldn't believe me
if I did."
      "Then find some other way to home in on the hacker."
      "Yeah, right. Just ask him to tell me his address."
      "Don't laugh. It might work."

o     0 0 "The FBI's tossing in the towel."
     This was the message Ann Funk of the Air Force Office of Special
Investigations left for me. The day before, I'd called her and she said that
her group was waiting for the FBI to take action. Now this greeting.
     I tried returning Ann's call, but she'd already left Bolling Air Force
Base. Not much else to do but call the FBI.
     The raspy voice at the Alexandria FBI office didn't want to waste
time. "Agent Gibbons is not available right now, but I have a message for

                  THE CUCKOO'S EGG

you," the guy said officiously. "Your case is closed and you are to shut
things off."
     "Huh? Who said that?"
     "I'm sorry, but that's the whole message. Agent Gibbons will be back
next week."
    "Did Mike say anything more?" After dozens of conversations,
wouldn't he at least tell me in person?
     "I told you, that is the entire message."
     Great. Pester the FBI for five months. Trace a connection around the
world. Prove that the hacker's breaking into military computers. Just when I
most needed the FBI's help . . . poof.
      Ann Funk called back an hour later. "I just heard that the FBI decided
there's insufficient grounds to continue their investigation."
     "Do the break-ins at the Air Force Space Command make any differ-
ence?" I asked.
     "That's the Systems Command, Space Division, Cliff. Get it right, or
you'll confuse us." But Space Command sounds neater. Who'd want to
command a system?
     "OK, but doesn't the FBI care about them?"
     Ann sighed. "According to the FBI, there's no evidence of actual
     "Did Mike Gibbons say that?"
     "I doubt it," she said. "I got the word from a duty officer who said
that Mike's been taken off the case and can't talk about it."
     "So who decided?" Mike was the only computer literate FBI agent I'd
spoken to.
     "Probably some middle management at the FBI," Ann said. "They can
catch kidnappers easier than computer hackers."
     "So how do you feel?" I asked her. "Should we close up shop or try to
catch the bastard?"
     "The FBI says to shut down the hacker's access ports."
     "That's not what I asked."
     ". . . and to change all your passwords . . ."
     "I know what the FBI says. What does the Air Force say?"
     "Uh, I don't know. We'll talk later on and call you back."
     "Well, unless someone tells us to continue, we'll close up shop and the
hacker can play in your computers all he wants. For five months we've been

                                 ST 0 L L

chasing this spy and not one government agency has contributed a dime." I
hung up angrily.
       A few minutes later, my local FBI agent called. Fred Wyniken left no
doubt about their decision. In an official tone of voice, he informed me that
the FBI felt there was no way to extradite this hacker because of unclassified
       "Cliff, if you can show that some classified material has been compro-
mised, or that he's done significant damage to systems, then the FBI will
step in. Until that happens, we're not going to move."
       "What do you consider damage? If someone rifles my desk drawers
and duplicates the plans for a new integrated circuit, is that damage? Who
do I turn to?"
       Fred wouldn't answer. "If you insist on pursuing this case, the FBI can
assist under the domestic police cooperation act. Your lab should contact the
Berkeley District Attorney and open an investigation. If your local DA will
extradite the hacker, then the FBI will assist in handling the proper paper-
       "Huh? After five months you're bouncing me back to my local Dis-
trict Attorney?" I couldn't believe what I was hearing.
       "If you choose to go in that way, the FBI will serve as a conduit
between your local police and the German authorities. The LBL police
would be the center of the investigation, and prosecution would be in
       "Fred, you can't be saying that. This guy's broken into thirty com-
puters around the country, and you're telling me that it's a local, Berkeley
       "I'm telling you this much," my local G-man continued. "The FBI has
decided to drop the case. If you want to continue, you'd better handle it
though your local police force."
       Not an hour later, Steve White called from Tymnet. He'd just re-
ceived the following electronic message from the German Bundespost:
       "It is most urgent that the U.S. authorities contact the German prose-
cutor or else the Bundespost will no longer cooperate. We cannot remain
hanging, without any official notification. We will not trace phone lines
without the proper warrants. You must arrange for the FBI to contact the
German BKA immediately."
       Oh hell. Spend months building cooperation between agencies, and the
FBI backs out. Just when we need them.

                  THE CUCKOO'S EGG

       Well, I didn't have much of a choice. We could do what we were told
and close up, toss away five months of tracking, or we could stay open and
risk censure by the FBI.
       Closing down would give the hacker freedom to roam our networks
without anyone watching him. Staying open wouldn't lead us to the hacker,
since the Bundespost wouldn't trace unless the FBI gave the go-ahead.
Either way, the hacker wins.
       Time to call on my boss. Roy Kerth believed the news right away. "I
never did trust the FBI. We've practically solved the case for them, yet they
won't investigate."
       "So what do we do?"
       "We don't work for the FBI. They can't tell us what to do. We'll stay
open until the Department of Energy tells us to shut down."
       "Should I call DOE?"
       "Leave that to me. We've put in a hell of a lot of work, and they're
going to hear about it." Roy mumbled a bit-it didn't sound like praise for
the FBI-then stood up and said firmly, "We'll stay open, all right."
       But monitoring the hacker in Berkeley wasn't tracing him in Ger-
many. We needed the FBI, even if they didn't need us.
       What'll the CIA say?
       "Hi, it's Cliff. Our friends at the, uh, 'F' entity have lost interest."
       "Who'd ya talk to?" Teejay asked.
       "The entity's local representative and an officer from their East Coast
office." I was learning spookspeak.
       "OK. I'll check into it. Hold still till you hear from me."
       Two hours later, Teejay called back. "The word is close up shop. Your
contact, Mike, is off the case. His entity is off chasing pickpockets."
       "So what do we do?"
       "Just sit still," the spook said. "We can't get involved-FCI belongs to
 Mike's entity. But someone may lean on Mike's entity. Just wait."
       FCI? Federal Cat Inspector? Federation of Carnivorous Iguanas? I
couldn't figure it out. "Uh, Teejay, what's FCI?"
       "Shhh, Don't ask questions. Wheels are turning in places you don't
 know about."
       I called Maggie Morley-our scrabble whiz and all-knowing librarian.
Took her three minutes to find the acronym. "FCI means Foreign Counter-
 Intelligence," she said. "Met any spies lately?"
       So the CIA doesn't handle counterintelligence. The FBI doesn't want

                                S TaL L

to waste time on this one. And the Deutsche Bundespost wants an official
notice from the United States. Whee.
      One other agency might be able to help. Zeke Hanson at the National
Security Agency was sympathetic-he'd watched every step of progress
we'd made, and knew how much we needed the FBI's support. Could he
help out?
      "I'd love to help, Cliff, but we're not able to. The NSA listens rather
than talks."
      "But isn't this what the National Computer Security Center is for? To
solve computer security problems?"
      "You know the answer. No and no. We're trying to secure computers,
not catch hackers."
      "Can't you call the FBI and at least encourage them?"
      "I'll spread the word, but don't hold your breath."
      At best, NSA's computer security center tried to set standards and
encourage computer security. They had no interest in serving as a clearing-
house for problems like mine. And they certainly couldn't get a search
warrant. NSA had no connections with the FBI.
      Teejay called back in a couple of days. "We made a grandstand play,"
the CIA agent said. "Mike's entity is back on track. Tell me if they give you
any more trouble."
      "What'd you do?"
      "Oh, talked to a couple friends. Nothing much." What kind of friends
does this guy have? To turn the FBI around in two days . . . who's he
talking to?
      It didn't take long before Mike Gibbons of the FBI called. He ex-
plained German law to me: hacking into a computer wasn't a big deal there.
As long as you didn't destroy the computer, breaking into a system wasn't
much worse than double parking.
      This didn't make sense to me. If German law was this lenient, why did
the Deutsche Bundespost take the case so seriously?
      Mike understood my concerns, and at least agreed to keep working on
 the case. "You should know, though, that last year a German hacker was
caught in a Colorado computer, but couldn't be prosecuted."
      Would the FBI's Legal Attache get off his butt?
      "I'm working on that," Mike said. "Tell your friends at the
Bundespost that they'll hear from us soon."
      That evening, we had another chance to catch the guy. While Martha

                      THE CUCKOO'S EGG

    and I waited in line at the grocery store, my beeper chimed in. I dropped
    my copy of the National Enquirer ("Alien Visitors from Mars!") and dashed
    to the pay phone, dialing Steve White.
           "Our friend's on the line," I told him.
           "OK. I'll call Germany."
           Quick conversation and a quick trace. The hacker was on for only five
    minutes, yet Steve tracked him into DNIC #2624-4511-049136. A public
    access dialup line in Hannover, Germany.
           Afterwards, Steve White filled me in on the details. Wolfgang Hoff-
    man, awakened at 3 A.M., started tracing that line from Frankfurt. But the
    telephone engineer assigned to the Hannover exchange had already gone
    home for the night. Close, but no cigar.
           Wolfgang had one question for us. The University of Bremen was
    willing to cooperate in catching this guy, but who's going to pay? The
    hacker was wasting the University's money-hundreds of dollars a day.
    Would we be willing to pay for the hacker?
           Impossible. My lab's paper-clip budget was squeezed-no way would
    they spring for this. I passed the message back that I'd ask around.
           Steve pointed out that someone would have to pay, or the Bundespost
    will just chop the hacker's access. Now that they knew how he's ripping off
    the Datex network, the Germans wanted to plug the holes.
           Yet more news arrived from Germany. A couple of nights ago, the
    hacker connected into Berkeley for two minutes. Long enough to track him
     to the University of Bremen. Bremen, in turn, tracked him back to Hanno-
    ver. It seemed like the hacker wasn't just breaking into our Berkeley labora-
     tory, but snuck into European networks as well.
           "Since they had the chance, why didn't the Germans trace him within
           Steve explained the problems in Hannover's telephone system. "Amer-
     ican telephones are computer controlled, so it's pretty easy to trace them.
     But they need someone at the exchange to trace the call in Hannover."
           "So we can't trace him unless the hacker calls during the day or
           "Worse than that. It'll take an hour or two to make the trace once it's
           "An hour or two? Are you kidding? Why it takes you ten seconds to
     trace Tymnet's lines from California across a satellite and into Europe. Why
     can't they do the same?"

                                ST 0 L L

    "They would if they could. The hacker's telephone exchange just isn't
computerized. So it'll take a while for the technician to trace it."
     Lately, the hacker had been showing up for five minutes at a time.
Long enough to wake me up, but hardly enough for a two-hour trace. How
could I keep him on for a couple of hours?
     The Bundespost couldn't keep technicians on call forever. In fact, they
could hardly afford to keep them around for more than a few days. We had
one week to complete the trace. After next Saturday evening, the telephone
technicians would call it quits.
     I couldn't make the hacker show up at a convenient time. And I
couldn't control how long he hung around. He came and went as he

o     0     0   "Wake up, you sloth," said Martha at the obscenely early
hour of nine on a Saturday morning. "Today we prepare the ground for our
tomato plants."
      "It's just January," I protested. "Everything is dormant. Bears are
hibernating. I am hibernating." I pulled the covers over my head, only to
have them snatched away. "Come on outside," said Martha, taking a vise-
like grip on my wrist.
      At first glance, it seemed that I was right. The garden was dead and
brown. "Look," Martha said, kneeling beside a rose bush. She touched the
swelling pink buds. She pointed at the plum tree, and looking more closely,
I saw a mist of tiny green leaves emerging from the bare branches. Those
poor California plants-without a winter to sleep through.
     Martha gave me a shovel, and we began the yearly cycle; turning over
the soil, adding fertilizer, planting tiny tomato seedlings in their furrows.
Every year we carefully planted several varieties that took different amounts
of time to ripen, and staggered the planting by several weeks, so we would
have a steady supply of tomatoes all summer. And every year, every single
tomato ripened on the fifteenth of August.
     It was slow, heavy work because the soil was dense with clay and wet

                  THE CUCKOO'S EGG

from the winter rains. But we finally got the plot spaded, and, dirty and
sweaty, stopped to take a shower and have brunch.
     In the shower, I felt revived. Martha sudsed my back while I basked in
hot water. Maybe the wholesome rustic life wasn't so bad after all.
     Martha was in the midst of shampooing my hair when the nasty whine
of my beeper, buried in a pile of clothing, destroyed our peace. Martha
groaned and started to protest: "Don't you dare. . . ."
     Too late. I jumped out of the shower and ran to the living room,
switched on my Macintosh, and called the lab computer. Sventek.
     A second later, I'm talking to Steve White at his home. "He's here,
     "OK. I'll trace him and call Frankfurt."
     A moment later, Steve's back on the line. "He's gone. The hacker was
here a moment ago, but he's disconnected already. No use calling Germany
now. "
      Damn. I stood there in utter frustration; stark naked, wet and shiver-
ing, standing in a puddle in our dining room, dripping blobs of shampoo
onto my computer's keyboard.
      Claudia had been practicing Beethoven, but startled by the sight of her
roommate charging, naked, into the living room, she'd put down her violin
and stared. Then she laughed and played a few bars of a burlesque tune. I
tried to respond with a bump and grind, but was too obsessed with the
hacker to pull it off.
      I wandered sheepishly back into the bathroom. Martha glowered at
me, then relented and pulled me into the shower again, under the hot water.
     "I'm sorry, sweetheart," I apologized. "It's our only chance to nail
him, and he wasn't around long enough to catch."
     "Great," Martha said. "Long enough to drag you out of the shower,
but not enough time to find out where he is. Maybe he knows you're
watching him, and he's purposely trying to frustrate you. Somehow, he
telepathically knows when you're in the shower. Or in bed."
     "I'm sorry, sweetheart." I was, too.
     "Honey, we've got to do something about this. We can't let this guy
keep yanking us around. And all those spooks in suits you keep talking to-
what have they ever done to help? Nothing. We have to take this into our
own hands."
     She was right: I'd spent hours on the phone to the FBI, CIA, NSA,

                                ST 0 L L

OSI, and the DOE. Still others, like the BKA, knew about our problem, yet
nobody took the initiative.
      "But what can we do without the government's help?" I asked. "We
need search warrants and all that. We need official permission to do phone
      "Yeah, but we don't need anyone's permission to put stuff in our own
      So what?
      Under the steaming water, Martha turned to me with a sly look.
      "Boris? Darlink, I hev a plan . . ." Martha shaped a goatee and mus-
tache out of soap suds on my face.
      "Yes, Natasha?"
      "Ees time for ze secret plan 35B."
      "Brilliant, Natasha! Zat will vork perfectly! Ah, darlink . . . vhat is
secret plan 35B?"
      "Ze Operation Showerhead."
      "Vell, you see, zee spy from Hannover seeks ze secret information,
yes?" Martha said. "We give him just vhat he vants-secret military spy
secrets. Lots of zem. Oodles of secrets."
      "Tell me, Natasha dahlink, zees secrets, vhere shall ve get them from?
Ve don't know any military secrets."
      "Ve make zem up, Boris!"
      Yow! Martha had come up with the obvious solution to our problem.
Give the guy what he's looking for. Create some files of phony informa-
tion, laced with bogus secret documents. Leave'em laying around my com-
puter. The hacker stumbles on them, and then spends a couple hours lapping
it up, copying it all.
      How much stuff? As I rinsed Martha's hair, I calculated: we want him
on for two hours. He's connected over a 1200-baud line, which means he
can read about one hundred twenty characters a second. In two hours, he
could scan about one hundred fifty thousand words.
      "Oh, Natasha, my charming counter-counter-spy, there's just vun
problem. Where do ve find five hundred pages of fake secrets?"
      "Simple, dollink. Ze secrets, ve invent. Ze regular data, ve use vhat's
already lying around."
      As the hot water ran out, we clambered out of the shower. Martha

                  THE CUCKOO'S EGG

grinned as she explained further. "We can't invent that much information
overnight. But we can create it as we go along, staying just ahead of him.
And we can take ordinary bureaucratic documents, modify them a bit, and
give them secret-sounding titles. Real secret documents are probably thick
with boring, bureaucratic jargon . . ."
      ". . . So we'll just take a bunch of those unintelligible Department of
Energy directives that are always littering my desk, and change them to
look like state secrets."
      Martha continued. "We'll have to be careful to keep it bland and
bureaucratic. If we head a document with 'CHECK OUT THIS TOP
SECRET ULTRA-CLASSIFIED NEAT STUFF,' then the hacker's going
to get suspicious. Keep it all low-key. Forbidden enough to keep him
interested, but not an obvious trap."
      I rolled her ideas around my mind and realized how to implement
them. "Sure. We invent this secretary, see, who works for people doing this
secret project. And we let the hacker stumble onto her word processing files.
Lots of rough drafts, repetitive stuff, and interoffice memos."
      Claudia greeted us in the living room, where she had mopped up the
pond I'd left behind. She listened to our plan and suggested a new wrinkle:
"You know, you could create a form letter in your computer that invites
the hacker to write in for more information. If the hacker fell for it, he
might include his return address."
      "Right," said Martha, "a letter promising more information, of
      The three of us sat around the kitchen table with devious grins, eating
omelets and elaborating on our plan. Claudia described how the form letter
should work: "I think it ought to be like a prize in a crackerjack box. Write
to us, and we'll send you, uh . . . a secret decoder ring."
      "But come on," I said, "there's no way he'll be stupid enough to send
us his address." Seeing that I had thrown cold water on my coconspirators, I
added that it was worth a try, but the main thing is to give him something
that'll take a couple of hours to chew on.
      Then I thought of another problem. "We don't know enough about
military stuff to make sensible documents."
      "They don't have to make sense," Martha grinned diabolically. "Real
military documents don't make sense either. They're full of jargon and
double-talk. You know, like 'the procedure for implementing the highly
prioritized implementation procedure is hereinafter described in section

                                 ST 0 L L

two, subparagraph three of the procedural implementation plan.' Eh, Bo-
      Well, Martha and I biked up to the laboratory and logged onto the
LBL computer. There we shoveled through a mound of real government
documents and directives, which were overflowing with far more turgid
bureaucratese than we could ever invent, changing them slightly so that
they'd look 'classified.'
      Our documents would describe a new Star Wars project. An outsider
reading them would believe that Lawrence Berkeley Laboratory had just
landed a fat government contract to manage a new computer network. The
SDI Network.
       This bogus network apparently linked together scores of classified
computers and extended to military bases around the world. By reading our
files, you'd find lieutenants and colonels, scientists and engineers. Here and
there, we dropped hints of meetings and classified reports.
      And we invented Barbara Sherwin, the sweet, bumbling secretary try-
ing to figure out her new word processor and to keep track of the endless
stream of documents produced by our newly invented "Strategic Defense
Initiative Network Office." We named our fictitious secretary after an as-
tronomer, Barbara Schaefer, and used the astronomer's real mailing address.
I mentioned to the real Barbara to watch for any strange mail addressed to
Barb Sherwin.
      Our fake memoranda included budget requests ($50 million for com-
munications costs), purchase orders, and technical descriptions of this net-
work. We cribbed most of them from files laying around the computer,
changing the addresses and a few words here and there.
     For a mailing list, I grabbed a copy of the lab newsletter's list of names
and addresses. I just flipped every "Mr." to "Lieutenant," every "Mrs." to
"Captain," every "Dr." to "Colonel," and every "Professor" to "General,"
The addresses? Just stir in an occasional "Air Force Base" and "Pentagon."
In half an hour, my ersatz mailing list looked like a veritable military
who's Who.
      Some of the documents, however, we fabricated completely: corre-
spondence between managers and petty bureaucrats. An information packet
describing the technical capabilities of this network. And a form letter
saying that the recipient could get more information on the SDI Network
by writing to the project office.

                  THE CUCKOO'S EGG

       "Let's label the account, the 'Strategic Information Network Group,' "
I said. "It's got a great acronym: STING."
       "Naw, He might catch on. Keep it bureaucratic," Martha said. "Use
SDINET. It'll catch his eye, all right."
       We put all the files under one account, SDINET, and made certain
that I was the only one who knew the password. Then I made these files
entirely inaccessible to everyone except the owner-me.
       Large computers let you make a file world-readable, that is, open to
anyone who logs into the system. It's a bit like leaving an office cabinet
unlocked-anyone can read the contents when they wish. You might set
world-read on a file containing the scores of the office's volleyball tourna-
       With a single command, you can make a file readable by only certain
people, for example, your co-workers. The latest sales report, or some
manufacturing designs, need to be shared among a few people, but you
don't want everyone to scan them.
       Or a computer file can be entirely private. Nobody but you can read
it. Like locking your desk drawer, this keeps everyone out. Well, almost
everyone. The system manager can bypass the file protections, and read any
       By setting our SDI files to be readable only by their owner, I made
sure that nobody else would find them. Since I was the owner and the
system manager, nobody else could see them.
       Except, perhaps, a hacker masquerading as system manager.
       For the hacker could still break in and become system manager. It
would take him a couple of minutes to hatch his cuckoo's egg, but he'd
then be able to read all the files on my system. Including those bogus SDI
       If he touched those files, I'd know about it. My monitors saved his
every move. Just to make certain, though, I attached an alarm to those SDI
network files. If anyone looked at them-or just caused the computer to try
to look at them-I'd find out about it. Right away.
       My snare was baited. If the hacker bit, he'd take two hours to swallow
the bait. Long enough for the Germans to track him down.
       The next move was the hacker's.

                                 ST 0 L L

o     0     0   I'd screwed up again. Operation Showerhead was ready, all
right. It might even work. But I'd forgotten an important detail.
     I hadn't asked anyone's permission.
     Normally, this wouldn't be a problem, since nobody cared what I did
anyway. But bicycling up to the lab, I realized that every organization I'd
been in contact with would want to know about our phony SDI files. Each
place would have a different opinion, of course, but to go ahead without
telling anyone would piss them all off.
      But what if I asked their permission? I didn't want to think about it.
Mostly, I worried about my boss. If Roy stood behind me, then the three
letter agencies couldn't touch me.
      On January 7, I went straight to his office. We talked about relativistic
electrodynamics for a while-which mostly meant my watching the old
professor at the chalkboard. Say what you will about crusty college profes-
sors, there's no better way to learn than to listen to someone who's paid his
      "Say, boss, I'm trying to get out from under this hacker."
     "CIA leaning on you again?" Roy was joking, I hoped.
     "No, but the Germans will only trace the line for one more week.
After next weekend, we might as well call it quits."
    "Good. It's been too long anyway."
    "Well, I was thinking about planting some misleading data           1ll   our
computer, to use as bait in catching the hacker."
    "Sounds good to me. It won't work, of course."
     "Why not?"
     "Because the hacker's too paranoid. Still, go ahead. It'll be a useful
exercise." Hot damn!
     My boss's approval insulated me from the rest of the world. Still, I
ought to tell the three letter folks about our plans. I wrote a short proposal,
framed as a scientific paper:

                  THE CUCKOO'S EGG

     Proposal to Determine the Address of the Hacker
     A persistent hacker has invaded LBL's computers. Because he is coming from
     Europe, it takes an hour to trace the phone lines. We would like to learn his
     exact location.
          1. He is persistent
          2. He confidently works within our computers, unaware that we are
              watching him.
          3. He searches for phrases like "sdi," "stealth," and "nuclear."
          4. He is a competent programmer and is experienced at breaking into
     Suggested solution:
          Provide fictitious information to keep him connected for more than an
     hour. Complete the phone trace during this time.

     My paper went on and on about History, Methodology, Implementa-
tion Details, and had footnotes about the chances of actually catching him.
As boring as I could make it.
     I sent this paper to the usual list of 3 letter agencies: the FBI, CIA,
NSA, and DOE. I included a note saying that unless someone objected, we'd
carry out this plan next week.
     A few days later, I called each agency. Mike Gibbons of the FBI
understood what I was getting at, but wouldn't commit his agency one way
or another. "What does the CIA have to say about it?"
     Teejay at the CIA had also read my proposal, but was equally non-
     "What did the guys at the 'F' entity say?"
     "Mike said to call you."
     "Well, ain't that dandy. Have you called the northern entity?" North-
ern entity? What's north of the CIA?
     "Vh, Teejay, who's the northern entity?"
     "You know, the big Fort M."
     Oh-Fort Meade in Maryland. The NSA.
     Yes, I had called Fort Meade, and Zeke Hanson at the NSA's National
Computer Security Center had read my proposal. He seemed to like it, but
he didn't want to have anything to do with it.
     "Well, I sure can't tell you to go ahead," Zeke said. "Personally, 1'd

                                 ST 0 L L

love to see what happens. But if you get into trouble, we don't have
anything to do with it."
      "I'm not looking for someone to take responsibility. I'm wondering if
it's a bad idea." Sounds strange, but that's just what I was trying to do.
Before you start an experiment, get the opinions of people who've been
there before.
     "Sounds good to me. But you really ought to check with the FBI."
That closed the circle-everyone pointed their finger at someone else.
      Well, I called the Department of Energy, the Air Force OSI, and a guy
at the Defense Intelligence Agency. Nobody would take responsibility, of
course, yet nobody blocked the idea. That's all I needed.
      By Wednesday, it was too late for anyone to object. I was sold on
Martha's idea, and was willing to back it up.
      Sure enough, Wednesday afternoon, the hacker showed up. I'd been
invited to lunch at the Cafe Pastorale in Berkeley with Dianne Johnson, the
field representative of the Department of Energy. Along with Dave Stevens,
the computer center's math whiz, we enjoyed some fine fettucini, while
talking about our progress and plans.
      At 12:53 PST, in the middle of a cup of cappuccino, my beeper went
off. The morse code said the hacker was into our Unix-4 computer as
Sventek. I didn't say a word-just ran to the phone booth and called Steve
White at Tymnet ($2.25 in quarters), and he started the trace running. The
hacker was on for only three minutes-just long enough to see who was
logged onto my computer. I was back at the table before the coffee cooled
      That spoiled the rest of lunch for me. Why had he stayed around only
three minutes? Did he sense a trap? I couldn't tell until I saw the printout up
at the lab.
     The monitors showed him logging on as Sventek, listing the names of
everyone currently logged on, and then disappearing. Damn him. He didn't
look around long enough to discover our bogus files.
     Oh-maybe our bait was too well hidden. The German phone techni-
cian would be around for only a couple more days, so I'd better make it
more obvious.
     From now on, I'd stay logged on to my computer. I would play sweet
Barbara Sherwin, connected to the computer on the SDINET account. The
next time the hacker raised his periscope, he'd see SDINET clunking away,

                    THE CUCKOO'S EGG

trying to edit some file or another. If that didn't catch his attention, then
nothing would.
      Naturally, he didn't show up the next day, Thursday. We were
running out of time. Nothing the next morning. I was about to call it
quits, when my beeper sounded at 5:14 P.M, Friday, January 16. There's the
      And I'm here, working in the SDINET account, playing with a word
processing program. His first command, "who," listed ten people. I was the
seventh on his list:


     There's the bait. Come on, go for it!

     Ibl> grep sdinet/etc/passwd           he's searching for user "SDINET" in our
                                           password file
     sdinetsx4sd34xs2:user    somet    files in/u4/sdinet, owner sdi network

      Ha! He swallowed the hook! He's hunting for information about the
user SDINET! I knew what he'd do next-he'd search over in the SDINET

     Ibl> cd /u4/sdinet           he's moving over to the SDINET directory
     Ibl> Is                      and trying to list the file names
     file protection violation - - you are not the owner.           But he can't see

     Of course he can't read the SDINET data-I've locked everyone out
of those files. But he knows how to evade my lock. Just plant a little egg,
using the Gnu-Emacs software. Become super-user.
     None of my files are hidden from the system manager. And my visitor

                                ST 0 L L

knows exactly how to grab those privileges. It just takes a few minutes.
Would he reach into the monkey bottle?
      There he goes. He's checking that the Gnu-Emacs move-mail program
hasn't been changed. Now he's creating his own false atrun program. Just
like the old days. In a couple more minutes, he'll be system manager.
      Only this time, I'm on the phone to Steve White.
      "Steve, call Germany. The hacker's on, and it'll be a long session."
      "Spot-on, Cliff. Call you back in ten minutes."
      Now it's the Germans' turn. Can they pull the plum from the pie?
Let's see, it's 5:15 P.M. in Berkeley, so in Germany, it's uh, 2:15 in the
morning. Or is it 1:15? Either way, it's sure not ordinary business hours.
Sure hope that the Hannover technicians stayed late tonight.
      Meanwhile, the hacker's not wasting time. Within five minutes, he'd
built a special program to make himself super-user. He twisted the tail of
the Gnu-Emacs program, moving his special program into the systems area.
Any minute now, Unix will discover that program and . . . yep, there it
goes. He's super-user.
      The hacker went straight for the forbidden SDINET files. (I'm glued
to my monitor, thinking, "Come on, guy, wait till you see what's sitting
there for you.") Sure enough, he first lists the file names:

     Ibl> Is

   Many of these files aren't just single memos. Some are file directories
-whole file cabinets full of other files.
   Which one will he look at first? That's easy. All of them.
   For the next forty-five minutes, he dumps out file after file, reading all

                   THE CUCKOO'S EGG

the garbage that Martha and I created. Boring, tedious ore, with an occa-
sional nugget of technical information. For example:

     Dear Major Rhodes:
     Thank you for your comments conceming access to SOINET. As you
     knCMI, a Network User Identifier (NUl) is required for access to both the
     Classified and Unclassified SDINET. Although these NUl's are distributed
     from different locations, it is important that users who use both sections
     of the network retain the same NUl.
     For this reason, your command center should contact the network
     controllers directly. At our laboratory in Berkeley, we can easily modify
     your NUl, but we would prefer that you issue the appropriate request to
     the network controllers.
     Sincerely yours,
     Barbara Sherwin

     Aah . . . there's a pointer in that letter saying that you can reach the
SOlNET from Lawrence Berkeley Laboratory. I'll bet that he'll spend an
hour or two searching for the portal to reach that mythical SOlNET.
     Did he believe what I'd fed him? There's an easy way to find out. Just
watch what he does-a disbeliever won't go hunting for the Holy Grail.
     The files made a believer out of him. He interrupted his listing to
search for a connection into our SOl network. On my monitor, I watched
him patiently scan all our links to the outside world. Without knowing our
system thoroughly, he couldn't search exhaustively, but he spent ten minutes
checking the system for any ports labelled "SOL"
     Hook, line, and sinker.
     He returned to reading our fake SOlNET files, and dumped the file
named form-letter:

                                                       SOl Network Project
                                                       Lawrence Berkeley Lab
                                                       Mail Stop 50-35 J
                                                       1 Cyclotron Road
                                                       Berkeley, CA 94720
     name name
     address address
     city city, state state, zip zip
     Dear Sir.
     Thankyou foryour inqUiry about SOlNET. We arehappy to complywith
     your request for more information about this network. The follCMIing
     documents are available from this office. Please state which documents
     you wish mailed to you:

                                 ST 0 L L

    #37.6 SDINET OverviewDescription Document
          19 pages, revised Sept 1985
    #41.7 Strategic Defense Initiative and Computer Networks:
          Plans and implementations (Conference Notes)
          227 pages, revised Sept J985
    #45.2 Strategic Defense Initiative and Computer Networks:
          Plans and implementations (Conference Notes)
          300 pages, June, 1986
    #47.3 SDINET Connectivity Requirements
          65 pages, revised April, 1986
    #48.8 How to link into the SDINET
          25 pages, July 1986
    #49.1 X25 and X75 connections to SDINET
          (includes Japanese, European, and Hawaii nodes)
          8 pages, December, 1986
    #55.2 SDINET management plan for J986 to 1988
          47 pages, November 1985
    #62.7 Unclassified SDINET membership list
          (includes major Milnet connections)
          24 pages, November 1896
    #65.3 Classified SDINET membership list
          9 pages, November, 1986
    #69.1 Developments in SDINET and Sdi Disnet
          28 pages, October, 1986
     NUl Request Form
          This form is available here, but
          should be retumed to the Network Control Center

         Other documents are available as well. If you wish to be added to
            our mailing list please request so.
         Because of the length of these documents, we must use the postal
         Please send your request to the above address, attention Mrs.
            Barbara Sherwin.
         The next high level review for SDINET is scheduled for 20 February,
            1987. Because of this, all requests for documents mustbe received
            by us no later than close of business on 11 February, 1987.
            Requests received laterthan this date may be delayed.

         Sincerely yours,
         Mrs. Barbara Sherwin
         Documents Secretary
         SDINET Project

     I wondered how he'd react to this letter. Would he send us his address?
     It didn't make much difference. Steve White called back from Tymnet.
"I've traced your connection over to the University of Bremen."

                  THE CUCKOO'S EGG

      "Same as usual, huh?"
      "Yeah. I guess they've reopened for classes," Steve said. "At any rate,
the Bundespost has traced the Datex line from Bremen into Hannover."
      "OK. Sounds like the hacker's in Hannover."
      "That's what the Bundespost says. They've traced the Datex line into a
dial-in port located near downtown Hannover."
      "Keep going, I follow you."
      "Now comes the tough part. Someone has dialed into the Datex sys-
tem in Hannover. They're coming from Hannover, all right-it's not a long
distance line."
      "Does the Bundespost know that phone number?"
      "Almost. In the past half hour, the technician traced the line and has
narrowed it down to one of fifty telephone numbers."
      "Why can't they get the actual number?"
      "Wolfgang's unclear about that. It sounds like they've determined the
number to be from a group of local phones, but the next time they make a
trace, they'll zero in on the actual telephone. From the sound of Wolfgang's
message, they're excited about solving this case."
      One in fifty, huh? The Bundespost is almost there. Next time, they'll
have him.
      Friday, January 16, 1987. The cuckoo laid its eggs in the wrong nest.

o     0     0 The trace almost reached the hacker. If he came by once
more, we'd have him.
      But the deadline was tomorrow night. Saturday, when the German
telephone technicians would give up the chase. Would he show up?
      "Martha, you don't want to hear this, but I'm sleeping at the lab again.
This may be the end of the road, though."
      "That's the dozenth time you've said that."
      Probably was. The chase had been a constant stream of "I've almost
got him" followed by "He's somewhere else." But this time it felt different.
The messages from Germany were confident. They were on the right scent.
      The hacker hadn't read all our bogus files. In the forty-five minutes

                                 ST 0 L L

that he'd linked into our system, he listed about a third of the data. He
knew there was more, so why didn't he stay around and browse?
      All the more likely that he'd come back soon. So once again, I crawled
under my desk and fell asleep to the sound of a computer disk drive whin-
ing in the distance.
      I woke up, for once, without a beeper squawking in my ear. Just a
peaceful Saturday morning, alone in a sterile office, staring at the bottom of
my desk. Oh well, I'd tried. Too bad the hacker didn't show up.
      Since nobody else was around, I started to play with an astronomical
program, trying to understand how mistakes in mirror-grinding affect im-
ages from a telescope. The program was just about working when my
beeper called at 8:08 a.m.
      A quick jog down the hall, and a glance at the monitor's screen.
There's the hacker, just logging into the Unix-S computer, on one of his old
account names, Mark. No time to figure what he's doing here, just spread
the word fast. Call Tymnet, and let them call the Bundespost.
      "Hi Steve!"
      "The hacker's back on, eh?" Steve must have heard it in the tone of
my voice,
      "Yep. Can you start the trace?"
      "Here goes." He was gone for thirty seconds-it couldn't have been a
full minute-when he announced, "He's coming from Bremen this time."
      "Same as yesterday," I observed.
      "I'll tell Wolfgang at the Bundespost." Steve hung up while I watched
the hacker on my screen. Every minute the hacker visited, we were that
much closer to unmasking him.
      Yes, there he was, methodically reading our false data files. With every
bureaucratic memo he read, I felt more satisfied, knowing he was being
misled in two ways: his information was patently false, and his arrogant
strides through our computer were leading him straight into our arms.
      At 8:40, he left our computer. Steve White called back within a
      "The Germans traced him through the University of Bremen again,"
he said. "From there, into Hannover."
      "Did they make any progress in getting his phone number?"
      "Wolfgang says they've got all the digits of his phone number except
the last two."
      All but the last two digits? That didn't make sense-it meant that

--~~-   -   ~-~   -----------------------------------
                       THE CUCKOO'S EGG

    they'd traced the call to a group of one hundred phones. "But that's worse
    than yesterday, when they said they'd isolated him to one of fifty phones."
         "All I can tell you is what I hear."
         Disturbing, but at least they were tracing the lines.
         At 10:17, he came back. By now, Martha had bicycled up to the lab,
    and the two of us were busy inventing new SDI files to feed him. We both
    ran to the monitors and watched him, expecting him to discover our latest
          This time, he wasn't interested in SDI files. Instead, he went out over
    the Milnet, trying to break into military computers. One by one, trying to
    guess his way past their password protection.
          He concentrated on Air Force and Army computers, occasionally
    knocking on the Navy's door. Places I'd never heard of, like the Air Force
    Weapons Lab, Descom Headquarters, Air Force CC OIS, the CCA-amc.
    Fifty places, without success.
          Then he slid across the Milnet into a computer named Buckner. He
    got right in . . . didn't even need a password on the account named
          Martha and I looked at each other, then at the screen. He'd broken into
    the Army Communications Center in Building 23, Room 121, of Fort
    Buckner. That much was obvious: the computer greeted the hacker with its
    address. But where's Fort Buckner?
          About all I could tell was that its calendar was wrong. It said today
    was Sunday, and I knew it was Saturday. Martha took charge of the
    monitors, and I ran to the library, returning with their now familiar atlas.
          Paging through the back pages, I found Ft. Buckner listed.
          "Hey, Martha, you're not going to believe this, but the hacker's bro-
    ken into a computer in Japan. Here's your Fort Buckner," I said, pointing to
    an island in the Pacific Ocean. "It's on Okinawa."
          What a connection! From Hannover, Germany, the hacker linked to
    the University of Bremen, across a transatlantic cable into Tymnet, then into
    my Berkeley computer, and into the Milnet, finally reaching Okinawa.
         If someone in Okinawa had detected him, they'd have to unravel a
    truly daunting maze.
          Not that this worldwide link satisfied him-he wanted Fort Buckner's
    database. For half an hour, he probed their system, finding it amazingly
    barren. A few letters here and there, and a list of about seventy-five users.

                                 ST 0 L L

Fort Buckner must be a very trusting place: nobody set passwords on their
      He didn't find much on that system, outside of some electronic mail
messages talking about when supplies would arrive from Hawaii. A collec-
tor of military acronyms would love the Fort Buckner computer, but any
sane person would be bored.
      "If he's so interested in military gobbledegook," Martha asked, "why
not enlist?"
      Well, this hacker wasn't bored. He listed as many text files as he could,
skipping only the programs and Unix utilities. A bit after eleven in the
morning, he finally grew tired, and logged off.
      While he'd circled the globe with his spiderweb of connections, the
German Bundespost had homed in on him.
      The phone rang-had to be Steve White.
      "Hi, Cliff," Steve said. "The trace is complete."
      "The Germans got the guy?"
      "They know his phone number."
      "Well, who is he?" I asked.
      "They can't say right now, but you're supposed to tell the FBI."
      "Just tell me this much," I told Steve, "is it a computer or a person?"
      "A person with a computer at his home. Or should I say, at his
      Martha overheard the conversation and was now whistling a tune
from the Wizard of Oz: "Ding-dong, the witch is dead. . . ."
      At last, the trace was over. The police would bust him, he'd be ar-
raigned, we'd press charges, and he'd be pacing a jail cell. So I thought.
      But more important, my research was finished. Five months ago, I
asked myself, "How come my accounts are imbalanced by 75 cents?" That
question had led me across the country, under the ocean, through defense
contractors and universities, to Hannover, Germany.
      Martha and I biked home, stopping only to pick up a pint of heavy
cream. We picked the last of our garden's strawberries and celebrated with
homemade milkshakes. No doubt-there's no substitute for mixing 'em
yourself. Toss in some ice cream, a couple bananas, a cup of milk, two eggs,
a couple spoonfuls of vanilla, and a handful of homegrown strawberries.
Thicken it with just enough malt. Now that's a milkshake.
      Claudia, Martha, and I danced around the yard for a while-our plans
had worked out perfectly.

                   THE CUCKOO'S EGG

      "In a couple days, the police will bust him, and we'll find out what he
was after," I told them. "Now that someone knows who's behind this, it
can't be long."
      "Yow, you'll get your name in the newspaper," Claudia marveled.
"Will you still talk to us?"
      "Yeah, I'll even keep washing the dishes."
      The rest of the day, Martha and I spent in San Francisco's Golden Gate
Park, riding the merry-go-round and roller-skating.
      After all these months, the problem was solved. We'd thrown a net
around the cuckoo.

o     0       0 He stared bleakly at the broken greasy venetian blinds, a
cigarette butt dangling from his clammy lips. The sickly green glow of the
screen reflected on his sallow tired features. Silently, deliberately, he invaded
the computer.
      Six thousand miles away, her longing white arms craved for him. He
could feel her hot breath on his cheek, as her delicate fingers curled through
his long brown hair. Her negligee parted invitingly, he sensed every curve
through the thin silken gauze. She whispered, "Darling, don't leave
me. . . . "
      Suddenly the night was shattered-that sound again-he froze and
stared at the night stand. A red light beckoned across the pitch black room.
His beeper sang its siren song.
      Sunday morning, at 6:30, Martha and I were dreaming when the
hacker stepped on my electronic tripwire. Damn. Such a great dream, too.
      I slid out from under the quilts and called Steve White. He passed the
message along to the Bundespost, and five minutes later, the trace was
complete. Hannover again. Same guy.
      From home, I couldn't observe him-he might notice me watching
him. But only yesterday he'd finished reading all our phony SDI files. So
why come back now?
      It wasn't until I biked into work that I saw the hacker's targets. Milnet
again. The printout showed him logging into my Berkeley computer, then

                                S TO L L

reaching out over the Milnet, then trying to log onto a system at the Eglin
Air Force Base.
       He tried account names like guest, system, manager, and field ser-
vice . . . all his old tricks. Eglin's computer didn't put up with such non-
sense: it kicked him out after his fourth try. So, he went on the European
Milnet Control computer, and tried again. Still no luck.
       Sixty computers later, he still hadn't gotten into a military computer.
But he kept trying.
       At 1:39 P.M., he succeeded in logging into the Navy Coastal Systems
Center in Panama City, Florida. He got into their system by trying the
account "Ingres" with the password "Ingres."
       Ingres database software lets you quickly search thousands of account-
ing records for the one entry you need. You make queries like, "Tell me all
the quasars that emit X rays," or "How many Tomahawk missiles are
deployed in the Atlantic fleet?" Database software is powerful stuff, and the
Ingres system is among the finest.
       But it's sold with a backdoor password. When you install Ingres, it
comes with a ready-made account that has an easily guessed password. My
hacker knew this. The Navy Coastal Systems Center didn't.
      'Once logged on, he meticulously checked that nobody was watching
him. He listed the file structures and searched for links to nearby networks.
He then listed the entire encrypted password file.
       There he goes again. That's the third or fourth time I'd seen him copy
the whole password file into his home machine. Something's strange here-
the passwords are protected by encryption, so he can't possibly figure out
the original password. Still, why else would he copy the password file?
       After an hour inside the navy computer, he grew tired and went back
to knocking on doors along the Milnet. That, too, lost its excitement after a
while; after fifty or a hundred times, even he tired of seeing the message,
"Invalid Login-bad password." So he printed out some SDINET files
again, pretty much the same stuff he'd seen in the past couple of days.
Around 2:30 in the afternoon he called it quits. He'd spent eight hours
hacking on the military networks.
       Plenty of time to trace his call. And time enough to learn that the
German Bundespost has been in close contact with the Public Prosecutor in
Bremen, Germany. They're contacting the authorities in Hannover, and
 they're also talking to the German BKA. Sounds like someone is about
ready to close in on the hacker and make the arrest.

                  THE CUCKOO'S EGG

       Who should I call about this break-in into the Navy computer?
       A week ago, the Air Force OSI warned me not to call the system
managers directly. Jim Christy said, "It's just runs against military policy."
       "I understand," I said. "But is there a clearinghouse to report these
problems to?"
       "No, not really," Jim explained. "You can tell the National Computer
Security Center, but they're pretty much a one-way trap. They listen, all
right, but they don't publicize problems. So if it's a military computer, call
us," Jim said. "We'll go through channels and get the word to the right
       Monday morning brought the hacker again. Time to twist some more
doorknobs. One by one, he scanned Milnet computers, ranging from the
Rome Air Development Center in New York to someplace called the Naval
Electronic Warfare Center. He tried fifteen places before he struck pay dirt
-the Ramstein Air Force Base computer. This time, he discovered that the
account, "bbncc,' wasn't protected. No password needed.
       Ramstein's computer seemed to be an electronic mail system for of-
ficers. He started listing everyone's mail. Quickly, it opened my eyes-this
was stuff that he shouldn't be seeing.
       OK, what should I do? I couldn't let him grab this information, yet I
didn't want to tip my hand. Disconnecting him won't do much good-he'll
just find another pathway. I can't call the place-I've no idea where Ram-
stein Air Force Base is. I can call Air Force OSI, but I've got to take action
now-not in five minutes-before he reads the rest of their data.
       I reached for the phone to call Jim Christy of the Air Force OSI.
Naturally I can't remember his phone number. There in my pocket is a key
chain. Of course, the old key chain trick. Just add some noise to his connec-
       I jangled my keys against the connector, shorting out the hacker's
communications line. Just enough to appear as noise to the hacker. "Static
on the line," he'd think. Every time he asked for electronic mail from
Ramstein, I garbled his commands, and Ramstein's computer misunderstood
       After a few more attempts, he gave up on Ramstein Air Force Base,
 and went back to scanning the Milnet, trying to get into other places.
       I fmally reached Jim Christy at Air Force OSI. "The hacker's gotten
into someplace called Ramstein Air Force Base. Wherever it is, you'd better
 tell them to change all their passwords."

                                 S TaL L

      "Ramstein's in Germany."
      "Huh?" I asked. I'd thought the occupation of Europe had ended in
the '50s. "What's the u.s. Air Force doing in Germany?"
      "Protecting you. But let's not go into that. I'll warn them right away.
Go back to watching the hacker."
      I'd missed ten minutes of the hacker. He was trying to break into more
military systems, slowly and methodically trying dozens of sites.
      The Milnet addresses seemed to be in alphabetical order; right now he
was working near the end of the alphabet. Mostly R's and S's, Aha! Yes,
that was it. He was working from an alphabetized list. Somehow, he'd
obtained the Milnet directory, and was checking off each site after he tried
      He'd made it halfway through the S's when he tried a computer called
Seckenheim. Logged right in as "Guest." No password. This was getting
      But though he got into that computer, he didn't stay long. A few
minutes to make a couple scans of their system files, then he logged off. I
wondered why.
      Still, I'd better do something. Time to call the Air Force.
      "Hey, the hacker just got into someplace called Seckenheim. It's on the
Milnet, so it must be a military computer. But I've never heard of it."
      "Snake in the grass," Jim growled.
      "Damn. Seckenheim is the Army Material Command in Europe. Near
Heidelberg. Germany again."
      "Oops. Sorry about that."
      "I'll take care of it." The hacker's success meant problems for the narcs.
I wondered how many overseas military bases the United States has. The
technology I could handle. It was geography and bureaucracies that tripped
me up.
      After having cracked three computers today, the hacker was still not
satisfied. He continued to bang away on the Milnet, so I kept watch in the
switchyard. One by one, I watched as he tried passwords. At 11:37, he got
into a Vax computer named Stewart. Logged right in there as "Field,"
password, "Service." I'd seen it before. Another Vax computer running
VMS that hadn't changed their default passwords.
      The hacker dived right in. The field service account was privileged,
and he wasted no time taking advantage of this. He first disabled account-

                  THE CUCKOO'S EGG

ing, so that he'd leave no tracks behind. Then he went directly to the
authorize utility-the system software in charge of passwords-and selected
one user, Rita, who hadn't used the system for the past few months. He
modified Rita's account to give it full system privileges. Then he set a new
password. "Ulfmerbold."
      Where had I heard that word? Ulfmerbold. It sounded German. Some-
thing to figure out later. Meanwhile, I've got to watch my hacker.
      Finally, a bit after noon, the hacker left Berkeley. A productive day
for him.
      The Stewart computer turned out to belong to Fort Stewart, an army
base in Georgia. I called Mike Gibbons of the FBI, and he took care of
calling them.
      "Mike, have you ever hear of the word, Ulfmerbold?"
      "Nope. Sounds German, though."
      'Just checking. Say, the Germans have completed the trace. The
Bundespost now knows who's making the calls."
      "Did they tell you?"
      "Naw, Nobody ever tells me anything. You know that."
      Mike laughed. "That's the way we operate, all right. But I'll get the
legat on the case right away."
      "Oh, Legal Attache. You know, the guy in Bonn that handles our
     "How soon until they arrest the guy?" I just wanted to know who and
why-the last pieces of the puzzle.
     "I don't know. But when it happens, I'll tell you. Shouldn't be long
now. "
     By chance, around 3 P.M. Teejay called from the CIA. "What's new?"
     "We completed the trace over the weekend."
     "Where is he?"
     "In Hannover."
     "Mmmm, Know the guy's name?"
     "No, not yet."
     "Does the 'F' entity know?"
     "I don't think so. But call them and find out. They never tell me a
thing." I doubted that the FBI would tell the CIA, and I didn't want to be
squeezed between the two. It was weird enough to talk to either.
     "Any clues to his identity?"

                               ST 0 L L

      "Hard to say. Ever hear of the word Ulfmerbold?"
      "Mmmm, What's that from?"
      "The hacker chose that as a password when he broke into a computer
this morning. At Fort Stewart, Georgia."
      "He's not letting the grass grow, huh?" Teejay still tried to sound
uninterested, but his voice had a tremor that gave it away.
      "Yeah. He got into a couple other places too."
      "Oh," I said, "no place special. Just a couple military bases in Ger-
many. And a place called Fort Buckner."
      "Son of a bitch."
       "You know them?"
       "Yeah. I used to work at Fort Buckner. Back in my Army days. Lived
on base with my wife." A CIA agent with a wife? I'd never thought of it.
Spy novels never mention spouses or kids.
       The hacker had chosen a strange password for his use. Ulfmerbold.
Nothing in my dictionary. Not in Cassell's German-English dictionary. The
trusty atlas showed nothing. Yet I'd heard this word before.
       Martha hadn't heard of it. Nor had any of my friends. Not even my
sister, the one who'd risked her life prowling around a high school in
McLean, Virginia.
       It took three days, but my boss, Roy Kerth, figured it out. ulf
Merbold is the West German astronaut who'd made astronomical observa-
 tions from the space shuttle.
       Another clue to Germany, unnecessary, now that the evidence was
 overwhelming. But why pick an astronaut's name? Hero worship? Or some
more sinister motive?
       Could this explain why he kept breaking into computers? Could I
 have been following someone obsessed with the U.S. space program-a guy
 who dreamed about becoming an astronaut and collected information about
 the space program?
       Nope. This hacker sought out military computers-not NASA sys-
 tems. He wanted SDI data, not astronomy. You don't search for the space
 shuttle on Okinawa. You don't find an astronaut's biography by looking up
 the Army's nuclear warfare plans for Central Europe.

                  THE CUCKOO'S EGG

o    0      0Tuesday morning greeted me with a pile of messages from
Tymnet. Steve White read some electronic mail from the Deutsche
Bundespost. "Since the University of Bremen won't pay for any more
international calls, you'll have to carry that cost."
      He knew that we couldn't afford it. "Steve, my boss balks at paying
my salary, let alone this hacker's connections."
     "How much time are you putting in on this chase?"
     "Oh, about ten hours a day." I wasn't kidding. Even a five-minute
connection by the hacker ballooned into a morning of phone calls. Every-
one wanted to hear what had happened. Nobody offered support.
     "Well then, I've some good news for you," Steve said. "Wolfgang
Hoffman says there's a meeting in Hannover tomorrow. Something about
coordinating legal, technical, and law-enforcement activities."
     "Why's that good news?"
     "Because they expect to make an arrest this weekend."
     "But there's a couple problems. The Germans haven't heard from the
FBI yet. So they're putting things on hold. Wolfgang asks that you pass this
message to the FBI."
     "Will do."
     My next call to the FBI showed the flip side of the coin. Special Agent
Mike Gibbons explained the situation.
     He'd sent telegrams to Bonn telling the FBI's Legat to contact the
German police. At the same time, he shipped by air a folder of information
to the Attache. But somewhere, the messages weren't getting through-
Wolfgang still hadn't heard about any warrants from the FBI.
      "You see, we can't talk to anyone except through our Legat," Mike
said. "Still, I'll rattle the cage again, and see that they're awake in Bonn."
      Well, that FBI agent sure wasn't dragging his heels. I never did find
out much about the Legal Attache-do they work for the FBI or the State
Department? Is it one part-time person or a whole staff? What do they

                                  ST 0 L L

really do? Who do they talk to in the German government? What do you
have to do to wake them up?
      The CIA wouldn't leave me alone. Teejay wanted every detail about
the past weekend. But the juicy stuff-the guy's name, his motives, and his
backers-remained a mystery. All I knew was that he'd been fingered.
      "Say, Teejay, if! find out some of this for you, is there any chance you
might, uh, trade some gossip?"
      "I don't copy," the spook said.
      "I mean, suppose you figure out who was behind all this. What'll you
tell me about it?" I really wanted to know if he could send some spy over
there and find out what this clown was up to.
      "Sorry, Cliff. We're listeners, not talkers."
      So much for learning anything from the CIA.
      Within a day, however, more news came by way of Tymnet. Having
traced the hacker's phone number, they compared his name to that on the
German Datex accounts.
      Hmmm. They're doing their homework!
      Seems that the hacker used three different identifiers when he manipu-
lated the Datex network. The first identifier belonged to the hacker. Same
name, same address. The second one belonged to another person. And the
third . . . well, it belonged to a company. A small company in Hannover
that specialized in computers.
      Were these identifiers stolen? It's as easy to steal a network user identi-
fier as it is to steal a telephone credit card number-just watch over some-
one's shoulder as she makes a call. Perhaps the hacker has ripped off several
people's Datex network account numbers. If they worked for big multina-
tional firms, they might never notice.
      Or was this guy in collusion with someone else?
      I'd pretty much convinced myself that he was acting alone. If a couple
people were working together, they'd have to constantly exchange pass-
words. Moreover, the hacker had a single personality-patient, methodical,
an almost mechanical diligence. Someone else wouldn't have quite the same
style when prowling around the Milnet.
      A few of his targets weren't sleeping. The day after he tried to pry
their doors open, two of them called me. Grant Kerr, of the Hill Air Force
Base in Utah, phoned. He was annoyed that one of my users, Sventek, had
tried to break into his computer over the past weekend. And Chris McDon-
ald of White Sands Missile Range reported the same.

                    THE CUCKOO'S EGG

      Super! Some of our military bases keep their eyes open. Thirty-nine in
forty are asleep. But there are a few system managers who vigilantly analyze
their audit trails.
      For the next few days, the hacker kept me hopping. He kept scanning
my SDINET files, so every few hours, I'd add a couple more. I wanted the
files to reflect an active office-a backlog of work and a busy, chatty
secretary who didn't quite know how her computer worked. Pretty soon, I
was wasting an hour a day generating this flimflam, just feeding the hacker.
       Zeke Hanson of the National Computer Security Center helped with
these bogus files. I knew nothing about military ranks, so he gave me a few
       "The military's just like any other hierarchy. Up at the top, there's the
flag officers. Generals. Below them are colonels, except in the Navy, where
there's captains. Then there's lieutenant colonels, then majors and cap-
tains . . ."
      Things are easier in grad school. Just call everyone with a tie, "Profes-
sor," and anyone with a beard, "Dean." When in doubt, just say "Doctor."
      Well, every couple days the hacker would log into my system and read
the SDINET files. If he had any doubts about the validity of this informa-
tion, he never showed it. In fact, he soon began trying to log into military
computers using the account, SDINET.
      Why not? Some of these ersatz files described network links into
Milnet computers. I made sure they were crammed with lots of jargon and
      Still, feeding the hacker bait wasn't leading us to an arrest. Every time
he appeared, we traced him all right, but I kept waiting for a phone call
saying, "He's at the police station now."
      Now that the Germans had a suspect in mind, Mike Gibbons met with
the U.S. attorney in Virginia. The FBI's news was mixed: if a German
citizen is involved, extradition is unlikely, unless there's underlying espio-
        By the end of the week, the hacker had returned for five more sessions,
each an hour or more. He checked into the Navy and Army computers,
making sure that they still let him in. I wondered why they hadn't closed
their holes yet. Then he played around our laboratory computer, again
checking over the SDINET files.
      Perhaps he worried that we knew he'd stolen Sventek's account, for he

                                 ST 0 L L

found yet another unused account at our lab, changed its password, and
began using it for his hacking.
      With all the high-powered computer folks in my department, I wor-
ried that one of them would post a notice to an electronic bulletin board, or
casually leak the story in a conversation. The hacker still searched our
system for words like "security" and "hacker," so he'd stumble onto this
news and our bird would fly the coop.
       The Germans had promised a bust this weekend. The hacker had what
I hoped was his last fling on Thursday, January 22, when he broke into a
computer at Bolt, Beranak, and Neumann, in Cambridge, Massachusetts.
This computer, called the Butrerfly-vax, was as unprotected as the rest: you
just logged in as "guest," with no password.
       I'd heard of BBN-they had built the Milnet. In fact, most of the
Milnet would soon be controlled by their Butterfly computers. The hacker
had found a particularly sensitive computer-if he planted the right kind of
Trojan horse in this computer, he might steal all the passwords that ever
 crossed the Milnet. For this was where BBN developed their network soft-
       Stealing passwords at Lawrence Berkeley Labs only gives you access to
nearby computers. The place to booby-trap software is where it's distrib-
 uted. Slip a logic bomb into the development software; it'll be copied along
 with the valid programs and shipped to the rest of the country. A year later,
 your treacherous code will infest hundreds of computers.
       The hacker understood this, but probably didn't realize that he'd stum-
 bled into such a development system. He searched the system and found one
 glaring security hole: the root account needed no password. Anyone could
 log in as system manager without so much as a challenge. Whoa!
       Someone was sure to discover such an obvious hole, so he wasted no
 time in exploiting it. He became system manager and created a new, privi-
 leged account. Even if the original flaw was discovered, he'd added a new
 backdoor into BBN's computer.
       He created an account under the name Langman, with a password of
 "Bbnhack." I understood the password, all right, but why Langman? Could
 that be his real name? The German Bundespost won't tell me, but maybe the
 hacker himself did. What's the meaning of the name Langman?
       No time to worry about it now. The hacker found a letter on the
 BBN computer, saying, "Hi, Dick! You can use my account at the Univer-
 sity of Rochester. Log in as Thomas, with the password 'trytedj'

                  THE CUCKOO'S EGG

     It didn't take him fifteen seconds to reach into the Rochester com-
puter. He then spent an hour reading information about integrated circuit
designs. Apparently, a graduate student at Rochester designed sub-micron
circuits, using an advanced computer-controlled technique. The hacker
started to grab everything, including the programs.
      I wouldn't let him: this would be industrial espionage. Every time he
started to copy some interesting files, I jingled my keys on the wires. He
could look, but he'd better not touch. Finally, at 5:30, he gave up.
     Meanwhile, I wondered about the word Langman. Was it someone's
     Aah-there's a way to find out. Look it up in the phone book.
Maggie Morley, our librarian, couldn't find a Hannover telephone direc-
tory, so she ordered one. A week later, with suitable aplomb, Maggie
delivered the Deutschen Bundespost Telefonbuch, issue number seventeen,
covering Ortsnetz and Hannover, with a rubber-stamp on the side, "Funk-
Taxi, 3811."
       My atlas presented a dry, geographic Hannover. And the tourist guides
spoke of a historic, scenic city, nestled along the river Leine. But the phone
book, well, here's the city: the opticians, the fabric stores, a few dozen auto-
hauses, even a perfumerie. And people . . . I spent an hour just paging
through the white pages, imagining a whole different world. There were
listings for Lang, Langhardt, Langheim, and Langheinecke, but not one
Langman. Bum steer.
       Steve White relayed a message from Germany. The Germans had been
doing their homework. Apparently, when the hacker called a phone, the
German police had printed out that phone number. Eventually, they figured
out who was involved, just by piecing together the web of phone calls
centered on the hacker.
      Were the German authorities planning a simultaneous bust? Tymnet
passed along a chilling message: "This is not a benign hacker. It is quite
serious. The scope of the investigation is being extended. Thirty people
are now working on this case. Instead of simply breaking into the apart-
ments of one or two people, locksmiths are making keys to the houses of the
hackers, and the arrests will be made when the hackers cannot destroy the

                                ST 0 L L

o     0     0     If you pester an organization long enough, eventually
they'll hold a meeting. After all my calls to the FBI, NSA, CIA, and DOE,
it was the Air Force Office of Special Investigations that gave in first. On
February 4, they invited everyone to Bolling Air Force Base, in hopes of
resolving the problem.
       Suburban Washington's world is measured by position on the beltway.
Bolling Air Force Base is somewhere around five o'clock, sort of south by
southeast. Even with such explicit directions, I got royally lost: bicycling
along Berkeley side streets isn't quite the same as driving a car around a DC
       At 11:30, three Department of Energy people met me at a restaurant
near the Air Force base. Over some tortellini, we talked about DOE's
computer security policies. They worry about atomic bomb secrets. But
they're also painfully aware that security gets in the way of operations.
High security computers are difficult to get onto, and unfriendly to use.
Open, friendly systems are usually insecure.
       Then we went to Bolling. It was the first time I'd ever walked on a
military base. The movies are accurate: people salute officers, and some poor
guy at the guardhouse spends his day saluting every car that comes through.
Nobody saluted me, of course-with long hair, jeans, and a beat up jacket, a
Martian would have been less conspicuous.
       About twenty people showed up, from all the three letter agencies. At
last I could hook voices from the telephone to people's faces. Mike Gibbons
actually did look like an FBI agent-thirty years old or so, neatly pressed
suit, mustache, and probably lifted weights in his spare time. We talked
about microcomputers for a while-he knew the Atari operating system
inside and out. Jim Christy, the Air Force computer crime investigator, was
tall, lanky, and exuded confidence. And there was Teejay, sitting over in the
corner of the room, silent as ever.
       Barrel-chested and smiling, Zeke Hanson of the NSA greeted me with
a slap on the back. He knew his way around both computers and bureaucra-
cies. Occasionally, he whispered interpretations like, "That guy's important

                  THE CUCKOO'S EGG

to your cause" or "She's just spouting the party line." I felt uncomfortable
among all the suits, but with Zeke's encouragement I managed to stand up
and talk to the gathering.
       I babbled for a while, describing the network connections and weak
spots, and then the others discussed national policy on computer security.
Seems that there wasn't any.
       Through the whole meeting, people kept asking, "Who's in charge?" I
looked over at the contingent from the FBI. Mike Gibbons, the agent
handling this case, squirmed in his chair. Sitting next to Mike, George Lane
of the FBI handled the questions. "Since we can't extradite the guy, the FBI
isn't going to devote many resources to this case. We've already done all we
can. "
       The DOE people didn't let this slide. "We've been begging you to call
the Germans. They're begging you to contact them. But Bonn still hasn't
seen your warrant."
       "Uh, we've had a few problems in our Legat office, but that doesn't
concern us here," Lane said. "The bottom line is that there's been no damage
done by this hacker."
       Russ Mundy, a wiry colonel from the Defense Communication
Agency, could take it no longer. "No damage! This guy breaks into two
dozen military computers and it's no damage? He's stealing computer time
and network connections. Not to mention programs, data, and passwords.
How long do we have to wait before he gets into something really serious?"
       "But no classified data has been compromised," the FBI agent said.
"And how much money has been lost-75 cents of computer time in Berke-
       I listened as the colonel tried a different approach. "We rely on our
 networks for communications. Not just military people, but engineers, stu-
 dents, secretaries, hell, even astronomers," he said, gesturing towards me.
 "This bastard is undermining the trust that holds our community together."
       The FBI saw the hacker as a minor annoyance; perhaps just some kid
 messing around after school. The military people took it as a serious attack
 on their communications lines.
       The Department ofJustice backed up the FBI. "Germany won't extra-
 dite a German citizen, so why bother? And anyway, the FBI gets a hundred
 reports like this every year, and we can prosecute only one or two."
        He went on to say that we already had enough evidence to convict the
 hacker: my logbook and printouts would stand up at a trial. And according

                                ST 0 L L

to U.S. law, we didn't have to catch the hackerfiagrante delicto: busting in
on him while he was connected to a foreign computer. "So you really
ought to close up shop. You're not strengthening your case, and we already
have enough evidence to bring him to trial."
     In the end, the Air Force OSI asked each group for direction. The FBI
and Department of Justice wanted us to close up shop and lock the hacker
out of our Berkeley computer. Neither Teejay of the CIA nor Zeke of
NSA's National Computer Security Center felt there was anything to gain
by staying open.
     Leon Breault of the Department of Energy stood up. "We've got to
support the guys in the trenches and catch this guy. If the FBI won't, then
we will," he said, glaring at the Department of Justice attorney.
     The people being hit by the hacker wanted to keep the monitoring
going. Closing our monitoring station just meant that the hacker would
prowl around using a different, unobserved pathway.
     But who should we turn to for help? The FBI didn't want to touch
the case, The military groups had no authority to issue warrants.
     Where was a clearinghouse for reporting problems? This hacker had
shown us several novel computer security problems. Who should we report
them to?
      Why, to the National Computer Security Center, of course. But Zeke
told me otherwise: "We set standards for secure computers, and stay away
from operational problems. All the same, we're always willing to collect
reports from the field."
      "Yeah, but will you warn me about other's problems?" I asked. "Will
you send me a report describing security holes in my computer? Can you
call me on the phone if sorneone's trying to break into my computer?"
      "No, we're an information collection point." Just what I'd expect
from a an organization run by NSA. The giant vacuum cleaner that sucks in
information, yet never says a thing.
     Suppose I find a computer security problem, and it's widespread. Per-
haps I should keep my mouth shut, and hope that nobody else figures it out.
Fat chance.
      Or perhaps I should tell the world. Post a notice to lots of electronic
bulletin boards saying, "Hey, you can break into any Unix computer
by . . ." That would at least wake up the folks who manage the systems.
Maybe even prod them into action.

                    THE CUCKOO'S EGG

        Or should I create a virus, one that takes advantage of this security
      If there were a trusted clearinghouse, I could report to them. They, in
turn, could figure out a patch for the problem, and see that systems are
fixed. The National Computer Security Center seemed like a logical place
for this. After all, they specialize in computer security problems.
      But they didn't want to touch it. The NCSC was too busy designing
secure computers. For the past few years, they'd published an unreadable
series of documents describing what they meant by a secure computer. In
the end, to prove that a computer was secure, they'd hire a couple program-
mers to try to break into the system. Not a very reassuring proof of secu-
rity. How many holes did the programmers miss?
      The meeting at Bolling Air Force Base broke up with the FBI and
Department of Justice dead set against our continuing to monitor the
hacker. The CIA and NSA didn't say much, and the military groups and the
Department of Energy wanted us to stay open. Since DOE paid our bills,
we'd stay open, so long as an arrest seemed likely.
      While I was around Washington, Zeke Hanson invited me to give a
talk at the National Computer Security Center. It's just down the road from
Fort Meade, NSA's headquarters; even so, I got lost trying to find the place.
There, under the exhaust of Baltimore Airport, a guard inspected my
backpack for floppy disks, tape recorders, and viewgraphs.
      "Hey, what can I steal on a viewgraph?"
      The guard scowled. "Them's our orders. Make trouble and you won't
pass." He had a pistol on his side. OK.
      You enter the meeting room through a door with a combination lock.
Twenty people greeted me, leaving one chair empty, up near the front of
the room. Ten minutes into my talk, a thin, bearded fellow wandered into
the room, sat down in front, and interrupted my description of Tyrnnet's
      "What's the adiabatic lapse rate on Jupiter?"
      Huh? I'm talking about transatlantic networks, and this guy asks me
about the atmosphere of Jupiter? Well, hot dog-I can handle that.
      "Oh about two degrees per kilometer, at least until you reach the two
hundred millibar level." By chance, this guy had asked me something
straight from my dissertation.
      Well, I continued my story, and every ten minutes the bearded guy
stood up, left the room, and returned. He'd ask questions about the core of

                                ST 0 L L

the moon, the cratering history of Mars, and orbital resonances among the
moons of Jupiter. Weird. Nobody else seemed to mind, so I dovetailed my
talk on the hacker with technical responses to this guy's astronomical inter-
      About quarter to five, I finished up and was walking out of the room
(with a guard standing nearby). The bearded guy pulled me aside and said
to the guard, "It's OK, he's with me."
      "What are you doing tonight?"
      "Oh, going out to dinner with an astronomer friend."
      "Cool it. Tell him you'll be a couple hours late."
      "Why? Who are you?"
      "I'll tell you later. Call your friend now."
      So I canceled my Friday evening dinner and was hustled into this guy's
dark blue Volvo. What's happening here? I don't even know his name and
I'm traveling down the road. Some sort of kidnapping, I guess.
      "I'm Bob Morris, the chief scientist at the Computer Security Center,"
he said once we were on the highway. "We're going to Fort Meade, where
you'll meet Harry Daniels. He's the assistant director of NSA. Tell him your
      "But . . ."
      "[ust tell him what happened. I called him out of a congressional
meeting in Washington to meet you. He's driving up here right now."
      "But . . ." This guy wouldn't let me get a word in.
      "Look, the atmosphere of Jupiter is fine-though I'd thought all at-
mospheres were adiabatic so long as they convected-but we've got a seri-
ous problem on our hands." Bob chain smoked and kept the windows rolled
up. I gasped for breath. He went on. "We've got to bring it to the attention
of people who can do something about it."
      "Yesterday's meeting at Bolling was supposed to resolve that."
      "[ust tell your story."
      If security at the Computer Security Center was tough, over at NSA's
headquarters-well, it took ten minutes to clear me through. Bob had no
problem: "This badge lets me in anywhere, so long as I'm carrying a classi-
fied document."
      He entered a password and slid the card through the badge reader;
meanwhile the guard fumbled with my viewgraphs. By the time we got to
the director's office, Harry Daniels had just arrived.
      "This had better be important," he said, glaring at Bob. This guy

                 THE CUCKOO'S EGG

looked impressive-thin and about six-foot-six, he stooped when walking
through doors.
      "It is. I wouldn't have called you otherwise," Bob said. "Cliff, tell
hi "
       There was no room on his table-it was covered with cryptography
equipment-so I spread out a diagram of the hacker's connections on the
      Harry Daniels followed the chart meticulously. "Does he use the Ger-
man Datex-P system to access the international record carriers?"
      Holy smoke! How does someone this important know communica-
tions networks in such detail? I was impressed. I described the hacker's
break-ins, but the two of them wouldn't let me speak two sentences without
interrupting with a question.
      Bob Morris nodded and said, "Here's your smoking gun, Harry."
      The NSA honcho nodded.
      The two of them talked for a few minutes, while I played with a
World War II Japanese encryption machine. I wished I'd brought my Cap-
tain Midnight Secret Decoder Ring to show them.
      "Cliff, this is important," Harry Daniels said. "I'm not sure we can
help you, but you can sure help us. We've had a real problem convincing
various entities that computer security is a problem. We'd like you to talk
to the National Telecommunications Security Committee. They make na-
tional policy, and we'd like them to know about this."
      "Can't you just tell them?"
      "We've been telling them for years," Harry Daniels said. "But this is
the first documented case."
      Bob Morris continued. "Mind you, he said, 'Documented.' The only
difference between your case and others is that you've kept a logbook."
      "So this has been going on before?"
      "I wouldn't have called Harry up from Washington if I didn't think it
was serious."
      Driving back from Fort Meade, Bob Morris introduced himself. "I've
worked on Unix security for the past ten years, up at Bell Labs in New
      Wait a second. This must be the Morris that invented the Unix pass-
word protection scheme. I'd read papers by him about securing computers.
Of course-Bob Morris, the violinist. His eccentricity was legendary: I'd

                                S TO L L

heard stories of him eating dessert and lying down so a cat could lick the
whipped cream from his beard.
     Bob continued. "Next month's meeting will be for policy making. If
we're ever going to progress beyond writing standards documents, we've
got to demonstrate a danger to these people." At last-someone at NSA
who realized that computer security meant more than designing computers.
"Any system can be insecure. All you have to do is stupidly manage it."
     "Well, yes, that about sums it up," I agreed. "Some of the problems are
genuine design flaws-like the Gnu-Emacs security hole-but most of them
are from poor administration. The people running our computers don't
know how to secure them."
      "We've got to turn this around," Bob said. "Secure computers might
keep the bad guys out, but if they're so balky that nobody will use 'em, it
won't be much progress."
     Tightening one computer was like securing an apartment house. But a
network of computers, all sharing files and interchanging mail, well, this
was like securing a small city. Bob, as chief scientist of the Computer
Security Center, directed that effort.
     By the time we'd returned, 1'd almost grown accustomed to riding in a
smoke-filled car. We started to argue about how planetary orbits interact-a
subject that I ought to be able to hold my own in. But this guy knew his
celestial mechanics. Ouch. 1'd been away from astronomy too long if I
couldn't bat off his questions.

o 0        0 It was neat to talk with Bob Morris. Still, I was glad to
come back home to Martha. I caught the bus home from the airport and
jaywalked across College Avenue-striking another blow for anarchy. My
roommate, Claudia, was practicing her violin when I walked in the door.
      Claudia greeted me with a teasing smile. "Where have you been-
running around with loose women, I bet!"
      "Nope. Meeting dark, handsome spies with trench coats, in dark al-

                  THE CUCKOO'S EGG

     "Did you bring one home for me?" Claudia was perpetually on the
lookout for a good man.
     I didn't have time to get out a clever answer, because Martha caught
me from behind in a bear hug, and hoisted me into the air. "I missed you,"
she said, setting me down with a kiss. It's fun, but a little startling, to live
with a woman who can beat me in a wrestling match.
     I was worried that she'd be mad that I had gone away again, but she
shrugged. "You're in time for dinner, so you're fine. Get in the kitchen and
      Martha was making her famous curry, which started with fresh coco-
nut. I was out on the back porch whacking a coconut with a hammer when
I heard Laurie pull up on her motorcycle.
      Laurie was Martha's best friend and college roommate. Despite her
fierce exterior-crew cut, leather jacket, boots and black muscle shirt-she
was a gentle country girl from New Mexico. She and Martha shared a
special bond that made me just slightly jealous. But I guess I passed her test,
for she treated us both as family.
      "Hey, Cliffer," she greeted me, mussing my hair. Looking hungrily at
the coconut, she guessed what we were having. She tromped inside, hugged
Martha, winked at Claudia, and scooped up the cat.
     "Put that lazy thing down and chop some onions." Martha was
kitchen despot.
     At last, dinner was on the table: a platter of curried rice, and dishes of
chopped vegetables, nuts, raisins, fruit, and chutney. If it grows, Martha will
curry it.
     "Hey, where've you been for the past couple days?" Laurie asked me.
     "Oh, I was summoned to Washington-the Reagans, you know, asked
me to dinner," I answered. I didn't want to say that I'd just talked to a
bunch of spies and spooks. Laurie hated the government, and I didn't want
to get her started.
      "Oh, do tell what Nancy was wearing," Laurie simpered, taking a
third helping of curry. "Hey, what's the latest on that hacker that you were
      "Oh, we haven't caught him yet. Maybe never will."
      "Still think he's a Berkeley student?" I hadn't talked to Laurie about
this thing for a couple months.
      "Hard to say. For all I know, he's coming from abroad." I was getting

                                  ST 0 L L

nervous, surprised at my own reluctance to tell a close friend what I'd been
up to. I wasn't ashamed, exactly, but . . .
      "Why are you spending so much time trying to catch some poor
computer geek who's just fooling around?"
      "Fooling around? He broke into thirty military computers." Whoops.
Instantly, I wanted to unsay that.
      "So what? That sounds like a good reason not to chase him," Laurie
said. "For all you know, he's a pacifist from the German Green Party.
Maybe he's trying to find out what secret weird things the military is doing,
and expose them to public scrutiny."
      I'd thought of that months ago and worried about it then. By now I
was certain those weren't his motives. I had done the obvious experiment:
categorize his interests. Back in January, I'd created a variety of different-
flavored baits. Alongside the bogus SDINET files, I'd placed equally coun-
terfeit files about Berkeley's local politics. Other files appeared to be finan-
cial statements, payroll accounts, games, and academic computer science
      If he were a peace activist, he might look at those political files. A
thief, interested in ripping off our lab's payroll, would go for the financial
records. And I'd expect a student or computer nerd to reach for the games
or academic files. But he wasn't interested in any of these.
      Except the SDI files.
      This experiment, and a lot of more subtle things about his way of
operating, convinced me that he was no idealist. This hacker was a spy.
      But I couldn't exactly prove that, and even after I explained my
experiment to Laurie, she wasn't convinced.
      She still thought of anyone working against the military as one of
"us," and in her eyes I was persecuting someone on "our own" side.
      How do I explain that, having been mixed up in this thing so long, I
had stopped seeing clear political boundaries? All of us had common inter-
ests: myself, my lab, the FBI, the CIA, NSA, military groups, and yes, even
Laurie. Each of us desired security and privacy.
      I tried a different tack. "Look, it's not a question of politics, but simple
honesty. This guy violated my privacy and the privacy of all the other users.
If someone broke into your house and rifled through your stuff, would you
stop to ask if they were a fellow socialist?"
      That didn't work either. "A computer system isn't private like a
house," Laurie responded. "Lots of people use it for many purposes. Just

                   THE CUCKOO'S EGG

because this guy doesn't have official permission to use it doesn't necessarily
mean he has no legitimate purpose in being there."
      "It's damned well exactly like a house. You don't want someone pok-
ing around in your diary, and you sure as hell don't want them messing
with your data. Breaking into these systems is trespassing without permis-
sion. It's wrong no matter what your purpose is. And I have a right to ask
these government agencies to help me get rid of this bastard. That's their
      My voice had risen, and Martha looked anxiously from my angry face
to Laurie's. I realized that I sounded like a shotgun-toting redneck, yelling
about law and order. Or worse-was I so blindly patriotic that I thought
anyone who had an interest in military secrets was a traitor or a Commie
      I felt trapped and confused, and, unfairly, felt it was all Laurie's fault
for being so simplistic and self-righteous. She hadn't had to deal with this
hacker, and hadn't had to call on the CIA for help, hadn't talked to them
and found they were real people. She thought of them as comic-book
villains, killing innocent peasants in Central America. And maybe some of
them were. But did that make it wrong to work with them at all?
      I couldn't talk anymore. I got up, rudely pushing away my half-
finished plate of curry. I stomped off to the garage, to sand some bookcases
we were making, and sulk in peace.
      After an hour or so, it got harder to keep up the sulking. I thought of
the fireplace, pie for dessert, and Laurie's great back rubs. But, having
grown up in a large, argumentative family, I was a dedicated, world-class
sulker. I stayed in the cold garage, sanding furiously.
      I suddenly noticed that Laurie was standing quietly by the door.
"Cliff," she said softly, "I really didn't mean to give you such a hard time.
Martha's crying in the kitchen. Come on, let's go inside."
      I thought of how easily I hurt Martha with my temper. I didn't want
to spoil the rest of the evening, so I went inside. We hugged, Martha wiped
her face, and then served dessert. The rest of the evening, we talked brightly
of other things.
      But the questions Laurie had stirred up inside me came back to haunt
me through the night. I lay awake and wondered where all this was leading
me, and what kind of person I was being turned into by this strange chase.
      I took flack from all directions, of course. The spooks didn't trust me
- I had no security clearance and didn't work for a defense contractor.

                                 ST 0 L L

Nobody had asked me to do this work, and we ran on zero budget. And
how do I tell my Berkeley friends that I'd just returned from the CIA?
       Since we had neither funding nor authority, the three-letter agencies
saw no reason to listen to us. I was little more than an annoyance to them. I
felt like a grad student again.
       A week after I'd returned, Mike Gibbons called from the FBI. "We're
closing our end of the investigation. There's no reason for you to stay
     "Mike, is that you speaking, or one of your bosses?"
     "It's the FBI's official policy," Mike said, obviously annoyed.
     "Has the Legal Attache ever talked to the Germans?"
     "Yes, but there's confusion. The German federal police-the BKA-
aren't running the phone traces, so not much information filters back to the
legat's office. You might as well close up shop."
       "What'll that do for the rest of the sites the hacker decides to hit?"
       "Let them worry about it. Most of them won't care anyway."
       Mike was right. Some of the places that had been broken into really
didn't care if they'd been hit. The Pentagon's Optimis database, for example.
Mike had notified them that a foreigner was using their computer. They
didn't bat an eyelash. Today, for all I know, anyone can read about the
Army's nuclear and biological warfare plans by logging onto their com-
puter as Anonymous, with password Guest.
       But though the FBI wanted us to close up, the Department of Energy
still supported us. Halfway between, the CIA and NSA didn't say one way
or another.
      No support either. For all that we'd told them, the NSA had never
coughed up a nickel. And while it might seem fun to rub shoulders with
secret agents, it did little for my astronomy, and even less for my reputation.
      For several weeks during February, the hacker evaporated. None of
my alarms went off, and his accounts remained dormant. Was he on to us?
Had someone tipped him off to his impending arrest? Or was he sneaking
through other computers?
      Whatever the answer, his disappearance relieved some of the pressure
to decide. For three weeks, I had nothing to report, so it made no difference
if we stayed open. Without a half dozen agencies on my neck, I managed to
actually write some software during that time.
      Then, routinely scanning my monitor's printouts, I noticed someone

                  THE CUCKOO'S EGG

using the Lawrence Berkeley Lab's Petvax computer. It looked like they
were entering the Petvax from a Caltech computer called Cithex.
      I'd been warned about Cithex-Dan Kolkowitz at Stanford had no-
ticed German hackers using that system to break into his computers. So I
looked closely at the traffic from our Petvax to the Cithex computer.
     Yeah. There it was. Someone had connected into the Caltech machine
from the Petvax, and was trying to break into a place called Tinker, in
     Tinker? I looked it up in the Milnet directory. Tinker Air Force Base.
      Uh oh. A little bit later, there's a connection into the Optimis database
at the Pentagon. Then he tries the Letterman Army Institute. The Comp-
troller of the Army at Fort Harrison.
     Oh hell. If it's not the same hacker, then someone's behaving just like
him. That's why the hacker's been quiet for three weeks. He's been using a
different set of computers to get onto the Milnet.
      Obviously, closing up my laboratory's security holes won't keep him
off the networks. This pestilence would have to be eradicated at the source.
      The Petvax, of all computers! An outsider would think it's a toy-
after all, a pet Vax computer, no?
      Hardly. Pet is an acronym for Positron Emission Tomography. It's a
medical diagnostic technique to locate where oxygen is consumed in peo-
ple's brains. By injecting a patient with an activated isotope, LBL's scientists
create images of the brain's interior. All you need is a particle accelerator to
create radioactive isotopes, a hypersensitive particle detector, and a powerful
     That computer is the Petvax. Stored within it are patient records,
analysis programs, medical data, and scans of people's brains.
      This hacker was playing games with medical tools. Break this com-
puter, and someone's going to get hurt. A bad diagnosis or a dangerous
injection. Or what?
      The doctors and patients who used this instrument needed it to work
perfectly. This was a sensitive medical device, not a plaything for some
cyberpunk. Some poor computer geek, indeed.
      Was it the same hacker? Two minutes after he disconnected from the
Petvax, he entered my Unix computer, using the name Sventek. Nobody
else knew that password.
      We locked up the Petvax, changing its passwords and setting alarms on

                                 ST 0 L L

it. But the incident worried me. How many other computers was this
hacker slithering through?
       On February 27, Tymnet forwarded some electronic mail from Wolf-
gang Hoffman of the Bundespost. Apparently the German police can only
arrest the hackers while they're connected. There's no shortage of evidence
to bring them to trial, but without positive identification, the charges won't
stick. We had to catch them red-handed.
       Meanwhile, one of the LBL computer masters described the whole
incident to a programmer at the Lawrence Livermore Lab. He, in turn, sent
out electronic mail to several dozen people, saying that he was going to
invite me to give a talk on "how we caught the German hackers." Dumb.
       Ten minutes after he posted his note, three people called me up, each
asking, "I thought you were keeping this hush-hush. Why the sudden pub-
       Terrific. How do I undo this? If the hacker sees the note, it's all over.
       John Erlichman observed that once you squeeze the toothpaste tube,
it's tough to get the stuff back in. I called Livermore; it took five minutes to
convince them to erase the message from all of their systems. But how do
we prevent this kind of leak in the future?
       Well, I could start by keeping my officemates better informed. From
now on, every week I told them what was happening and why we had to
keep quiet. It worked remarkably well . . . tell people the truth, and
they'll respect your need for secrecy.
       The hacker showed up occasionally during March. Just often enough
 to upset my life, but not quite enough to let the Germans nail him.
       Thursday, March 12, was an overcast Berkeley day. Dry in the morn-
 ing, so I biked in without a raincoat. At 12:19, the hacker visited his old
haunt for a couple minutes. Listed a few of my SDINET files-he found
 out that Barbara Sherwin had recently bought a car and that SDINET was
 expanding overseas. He saw the names of thirty new documents, but he
 didn't read them. Why not?
        Steve White had shown up in town, passing through to visit Ron
 Vivier at Tyrnnet's office in Silicon Valley. He and Martha and I had a date
 at a Thai restaurant, so I had to be home by six.
        It started to rain about four, and I realized that I would get drenched
 bicycling home. Not much choice in the matter, so I insanely biked home-
 the rain turned the bike's brakes into banana peels. My raincoat wouldn't
 have been much defense against the sheet of water thrown up by an old

                  THE CUCKOO/S EGG

DeSoto. Traffic splashed me from the side, and my bike's tires got me from
      By the time I got home, I was sopping wet. Well, I've plenty of dry
clothes. But only one pair of shoes. The grungy sneakers I was wearing.
And they were soaked. I couldn't dry 'em out in time, so I looked around.
There's Claudia's new microwave oven. I wonder . . .
      So I popped my sneakers into Claudia's microwave, and pressed a few
buttons. The display read "120." I wondered whether that meant 120 sec-
onds, 120 watts, 120 degrees, or 120 light-years. I dunno.
      It didn't make any difference. I'd just watch the sneakers through the
window and make sure nothing goes wrong. For the first few seconds, no
problem. Then the phone rang.
      I ran into the front room to answer it. It was Martha.
      "I'll be home in half an hour, honey," she said. "Don't forget dinner
with Steve White."
      "I'm getting ready right now. Uh, Martha, how do I set the micro-
wave oven:'
      "You don't need to. We're going out for dinner, remember?"
      "Suppose I want to dry out my sneakers," I said. "What should I set
on the microwave?"
      "Be serious."
      "I am being serious. My sneakers are wet."
      "Don't you dare put them in the microwave."
      "Well, theoretically speaking, how long should I hypothetically set the
microwave for?"
      "Don't even think about it. I'll come home and show you how to dry
them out."
      "Well, uh, sweetheart, " I tried to interrupt.
      "No. Don't touch the microwave," she said. 'Just sit tight. Bye for
now. "
      As I hung up the phone, I heard four beeps from the kitchen. Uh oh.
      Boiling out of the back of Claudia's new Panasonic microwave oven
was an angry cloud of thick, black smoke. The kind you see in newsreels,
when the oil refinery blows up. And the stench-it smelled like an old tire
      I swung open the microwave, and another cloud of smoke belched out.
I reached in and tried pulling out the sneakers-they still looked like sneak-
ers, but had the texture of hot mozzarella cheese. I tossed them and the glass

                                 ST 0 L L

tray out the kitchen window. The tray shattered in the driveway, and the
smoldering sneakers lay seething next to the plum tree.
      Now I'm in deep yogurt. Martha's due home in half an hour and the
kitchen smells like Akron during the tire-burning festival. Time to clean up
the mess.
      I got out the paper towels and started scrubbing the microwave. Black
soot all over. Not the kind of soot that washes away, either. Wiping the
glop only spreads the black plague further.
       Half an hour. How do you get rid of the delicate fragrance of burning
rubber? I swung open the windows and door, letting the wind blow the
stench away. It didn't do much for the smell, and now the rain was blowing
in the windows.
       When you make a mess, cover it up. I remembered a homemakers'
column: to mask household aromas, boil a small amount of vanilla on the
stove. Well, it can't make things worse. I dump a couple of ounces of
vanilla in a pan and crank up the heat.
       Sure enough, in a couple minutes, the vanilla works. The kitchen no
longer smells like a burning old blackwall tire. No, now it smells like a
burning new whitewall tire.
       Meanwhile, I'm cleaning the walls and ceiling. But I forgot the va-
nilla. The vanilla evaporates, the pot burns, and I've now screwed up twice.
Three times, if you count the soggy floor.
       Fifteen minutes. What to do? Appeasement. I'll bake her some cookies.
 Reach into the refrigerator for last night's cookie dough, and slap lumps of
 it onto a cookie pan. Set the oven at 375, just right for chocolate chips.
       Well, a third of the cookies slid off the pan and stuck on the bottom of
 the oven where they turned to cinders.
       Martha walks in, takes one sniff, sees the black welt on the ceiling, and
 says, "You didn't."
       "I'm sorry."
       "I told you."
       "I'm sorry twice."
       "But I said . . ."
       The doorbell rings. Steve White enters, and with British aplomb says,
 "I say, old chap. Is there a tire factory nearby?"

                  THE CUCKOO'S EGG

o      0 0 Through March and early April, the hacker laid low. Occa-
sionally, he'd pop in, just long enough to keep his accounts on the active
list. But he seemed uninterested in reaching into other computers, and pretty
much ignored my new SDINET files. What was happening to this guy? If
he's been arrested, he wouldn't show up here. And if he's busy on other
projects, why does he just show up for a minute, then disappear?
      On April 14, I was working on the Unix system when I noticed Marv
Atchley logged into the system.
     Odd. Marv's upstairs, giving a pep talk to some programmers. I wan-
dered over to his cubicle and looked at his terminal. Not even turned on.
     Who's using Marv's account? I ran over to the switchyard and saw
someone coming in through our Tymnet port. They were connected into
the system as Marv Atchley.
    I called Tymnet-Steve traced the line quickly. "It's from Hannover,
Germany. Are you sure it's not the hacker?"
      "Hard to say. I'll call you right back."
      I ran up four flights of stairs and peered into the conference room. Yep,
there was Marv Atchley, giving an animated talk to twenty-five program-
     By the time I returned to the switchyard, the pseudo-Marv was gone.
But I could see that he'd entered the system without any tricks. Otherwise
he would have set off my alarms. Whoever it was must know Marv's
     When the meeting ended, I showed the printout to Marv.
     "Damned if I know who it is. I sure never gave my password to
     "How long since you changed it?"
     "Oh, a few weeks ago."
     "And what's your password?"
     "Messiah. I'll change it right now."
     How the hell did this hacker get Marv's password? I would have

                                ST 0 L L

noticed if he'd set a Trojan horse. Could he have guessed the word "Mes-
     uh oh. There's a way he could have.
      Our passwords are stored encrypted. You can search the entire com-
puter, and you'll never find the word "Messiah." You will find it encrypted
as "p3kqznqiewe." Our password file was filled with such encrypted gibber-
ish. And there's no way to reconstruct the avocado from that guacamole.
      But you can guess passwords. Suppose the hacker tried to log in as
Marv, then tried the password "Aardvark." My system says, "no good." The
hacker, being persistent, then tries again, using the password "Aaron."
Again, no luck.
      One by one, he tries to log on using passwords that he looks up in a
dictionary. Eventually, he tries the password "Messiah." The door opens
      Each trial takes a couple seconds. His fingers would wear out before he
tried the whole dictionary. Such a brute-force method of guessing pass-
words will only work on a completely mismanaged computer.
      But I saw this hacker copy our password file into his own computer.
How could he use a list of our encrypted passwords?
      The Unix password scheme uses an encryption program that's public.
Anyone can get a copy of it-it's posted to bulletin boards. With a hundred
thousand Unix computers in the world, you couldn't keep the program
      The Unix encryption program works in one direction only: it will
encrypt from English text into gibberish. You can't reverse the process to
translate encrypted passwords into English.
      But with this encryption program, you can encrypt every word in the
dictionary. Make a list of encrypted English words from your dictionary.
Then, it's a simple matter to compare what's in my password file to your list
of encrypted passwords. This must be how the hacker is cracking passwords.
      On his computer in Hannover, he'd run the Unix password encryption
program. He'd feed it the whole dictionary, and one by one, his program
would encrypt every word in the English language. Something like this:
      Aardvark encrypts to "vi4zkcvlsfz." Is that the same as
"p3kqznqiewe"? No, so go on to the next word in the dictionary.
      Aaron encrypts to "zzole9cklg8." Not the same as "p3kqznqiewe," so
go on to the next word in the dictionary.

                  THE CUCKOO'S EGG

      Eventually, his program would discover that Messiah encrypts to
      When his program found a match, bingo-it would print it out.
      My hacker was cracking passwords using a dictionary. He could find
anyone's password, so long as it was an English word.
      This was serious stuff. It meant that every time I'd seen him copy a
password file, he could now figure out legitimate users' passwords. Bad
news. I checked my logbook. He'd copied these files from our Unix com-
puter, the Anniston system, and the Navy Coastal Systems Command. I
wondered if he'd be back in those computers.
      Hey-I'd proven that he was cracking passwords on his computer.
There are around a hundred thousand words in an English dictionary. It had
been about three weeks since he copied my password file. If his password
cracker worked continually for three weeks, could he have guessed Marv's
      Well, on an ordinary Vax computer, it takes about a second to encrypt
one password. A hundred thousand words, then, would take around a day.
On an IBM PC, maybe a month. A Cray supercomputer might take an
      But according to Marv, this guy did it in three weeks. So he wasn't
using a little home computer. He must be running the password cracker on a
Vax or a Sun workstation. I had to be careful about this conclusion, though.
He might use a faster algorithm or have waited a few days after cracking
Marv's password.
      Still, I patted myself on the back. Just by noticing that he'd been
cracking passwords, I knew what type of computer he was using. Remote-
control detective work.
      This explained why he'd always copied our password files to his sys-
tem. He was cracking our passwords in Germany.
      Even one guessed password was dangerous. Now, if I erased Sventek's
account, he could sneak in on someone else's account. Good thing that I'd
not closed the door on him. What I'd thought to be bulletproof-my
passwords-turned out to be riddled with holes.
      Password cracking. I'd not come across it before, but I suppose that
experts had. Well, what do the experts say about it? I called Bob Morris, the
big shot I'd met at NSA. He'd invented the Unix password encryption
      "I think the hacker's cracking my passwords," I told Bob.

                                S TaL L

     "Eh?" Bob was obviously interested. "Is he using a dictionary or has
he actually reversed the data encryption algorithm?"
     "A dictionary, I think."
     "Big deal. Why, I've got three good password cracking programs.
One of them will pre-compute the passwords, so it runs a couple hundred
times faster. Want a copy?"
     Egads, he was offering me a copy of a password-cracking program!
"Uh, no, I don't think so," I said. "If I ever need to decrypt passwords,
though, I'll call you. Say, how long have people known about password
     "This kind of brute force stuffiOh maybe five or ten years. It's child's
      Cracking passwords as a game? What kind of a guy is this?
     Bob continued. "Guessing won't work when you choose good pass-
words. Our real concern is with the encryption programs. If someone fig-
ures out a way to reverse that software, we're in deep trouble."
      I now understood what he meant. The program that translated "Mes-
siah" into "p3kqznqiewe" is a one-way street. It needs just a second to
encrypt your password. But if someone found a way to crank that sausage
machine backwards-a way to convert "p3kqznqiewe" into "Messiah,"
then they could figure out every password, without guessing.
      Well, I'd at least told the NSA. Maybe they'd known these techniques
for years, but now they officially knew that someone else was using them.
Would they publicize it? Come to think of it, if NSA had known of this for
ten years, why hadn't they publicized it already?
      Systems designers needed to know about this problem-to build
stronger operating systems. Computer managers ought to know, too. And
every person who used a password should be warned. It's a simple rule:
don't pick passwords that might show up in a dictionary. Why hadn't
anyone told me?
      The National Computer Security Center didn't seem interested in real-
world problems of thousands of Unix computers out in the field. I wanted
to know about weaknesses in my Unix system. What problems had been
reported? Before, I'd discovered a bug in the Gnu-Emacs editor. A wide-
spread security hole. 1'd dutifully reported it to the National Computer
Security Center. But they never told anyone about it. Now, I'd discovered
that passwords that appeared in dictionaries weren't safe.
      How many other security holes were lurking in my system?

                  THE CUCKOO'S EGG

      The NCSC might know, but they weren't saying.
      NSA's motto, "Never Say Anything," seemed to come into play. Yet
by keeping silent about these computer security problems, they hurt us all. I
could see that the hackers had long ago discovered and exploited these holes.
Why wasn't someone telling the good guys?
      "It's not our bailiwick," Bob Morris said. "We collect this information
so as to better design future computers."
      Somewhere, somehow, something was wrong here. The guys in black
hats knew the combinations to our vaults. But the white hats were silent.
      Well, forget the NSA for now. What more could I do? It was time to
prod the other agencies.
      By late April the Bundespost still hadn't received the proper papers
from the United States. Their traces were based on an official complaint
filed by the University of Bremen.
      But although the Bundespost had completed several traces, they
wouldn't tell me the suspects' names or phone numbers. German law pro-
hibited this. Sounded familiar. Briefly, I wondered if my sister Jeannie
would be willing to snoop around Hannover. She'd been the most respon-
sive investigator so far.
       I phoned Mike Gibbons. "We're no longer handling this as a criminal
case," he said.
      "Why give up when the Germans have traced the line and know the
suspects' names?"
       "I didn't say we were giving up. I just said that the FBI isn't treating
this as a criminal case."
       What did that mean? As usual, Mike clammed up when I asked ques-
       Had the Air Force made much progress? They were quietly getting the
word out that reptiles were crawling through the Milnet, trying to break
into military computers. One by one, sites were tightening up security.
       But the Air Force relied on the FBI to catch the hacker. Ann Funk and
Jim Christy wished they could help, but couldn't.
       "Tell me anything except, 'It's not my bailiwick,' " I said.
       "OK," Ann replied, "it's not within my command."

                                S TaL L

o    0 0 I didn't like leaving Berkeley, partly because I missed my
sweetheart, but also because it left the hacker unwatched.
       I was to talk to the NTISSIC, a governmental organization whose
acronym has never been decoded. Bob Morris said they set policy for tele-
communications and information security, so I could guess some of the
       "While you're in the area," Teejay said, "how about stopping by our
headquarters in Langley?"
      Me? Visit the CIA? I'm in way over my head now. Meeting the
spooks on their own ground. I could just imagine it: hundreds of spies in
trench coats, skulking around hallways.
      Then the NSA invited me to Fort Meade as well. But not quite so
informally. Over the phone, Zeke Hanson said, "We'd like you to prepare a
talk for the X-l department. They'll send you questions in advance."
     Department X-l of the National Security Agency? Yow, now this
was cloak-and-dagger. As usual, I couldn't get any more information out of
them . . . Zeke wouldn't even tell me what X-l stood for.
     Well, I arrived at NSA, and Bob Morris greeted me in his office. The
three chalkboards were covered with Russian writing ("They're rhyming
riddles," he explained) and a few mathematical equations. Where else but at
     I chalked a short note in Chinese, and Bob hit me with an easy number
problem: OTTFFSS. "What's the next letter, Cliff?"
     That was an oldie. One. Two. Three. Four. Five. Six. Seven. "The
next letter is E for Eight," I announced.
     Well, we fooled around with puzzles and palindromes for a while,
until he wrote out this series of numbers: 1, 11,21,1211,111221.
      "Complete that series, Cliff."
      I looked at it for five minutes and gave up. I'm sure it's easy, but to
this day, I still haven't solved it.
     It was weird. Here I was, hoping to light a fire under NSA's feet. And

                 THE CUCKOO'S EGG

here was Bob Morris, their top guru, competing with me in number games.
Fun, sure. But disquieting.
      We drove down to Washington, to the Department of Justice. We
talked about computer security, and I pointed out to him that, for all he
knew, I could be making up this whole story.
      "You don't have a way of checking up on me."
     "We don't need to. NSA is a house of mirrors-each section checks on
another section."
     "You mean you spy on yourself?"
      "No, no, no. We constantly check our results. For instance, when we
solve a mathematical problem by theoretical means, we check the result on a
computer. Then another section might try to solve the same problem with a
different technique. It's all a matter of abstraction."
      "Think anyone will mind that I don't have a tie?" I'd worn a clean
pair of jeans, figuring there might be some important people. But I still
didn't own a suit or tie.
     "Don't worry," Bob said. "At your level of abstraction, it doesn't
make any difference."
      The meeting was top secret, so I couldn't listen-someone fetched me
when my turn came. In a small room, lit only by the viewgraph machine,
there were around thirty people, most of them in uniforms. Generals and
admirals, like you see in the movies.
      Well, I talked for half an hour, describing how the hacker was break-
ing into military computers and skipping through our networks. One gen-
eral in the back kept interrupting with questions. Not easy ones, like,
"When did you discover this guy?" but toughies, like "How can you prove
that electronic mail hasn't been forged?" and "Why hasn't the FBI solved
this case?"
      Well, the questions didn't let up for another half hour, when they
fmally let me off the rack. Over cheese sandwiches, Bob Morris explained
what had happened.
     "I've never seen so many brass in one room before. You know, that
one guy who asked the good questions-he's one of the junior people in the
room. Just a Major General."
     I know as little about the military world as the next person. "I guess
I'm impressed, though I'm not sure why," I said.
     "You ought to be," Bob said. "These are all flag officers. General John

                                   ST 0 L L

Paul Hyde works at the Joint Chiefs of Staff. And that guy in the front row
-he's a big shot from the FBI. It's a good thing he heard you."
      I wasn't so sure. I could imagine a honcho in the FBI having a rough
time of it: he knows that his agency ought to be doing something, yet
something gets corked up. He didn't need flack from some Berkeley long-
hair; he needed our support and cooperation.
      I was suddenly queasy. I pressed the replay button in my mind. Did I
screw up? It's a weird feeling of being nervous after you do something. The
more I thought about it, the more impressed I was with the military people.
They'd zeroed in on the weak points of my talk, and understood both the
details and importance of what I'd said.
      How far I'd come. A year ago, I would have viewed these officers as
war-mongering puppets of the Wall Street capitalists. This, after all, was
what I'd learned in college. Now things didn't seem so black and white.
They seemed like smart people handling a serious problem.
      The next morning I was to speak at NSA's X-l department. Sure
enough, they'd prepared a list of questions, and asked me to concentrate on
the following themes:

     1.   How was the penetrator tracked?
     2.   What auditing features exist?
     3.   How to audit someone with system-level privilege?
     4.   Supply technical details on how to penetrate computers.
     5.   How were passwords obtained for the Livermore Crays?
     6.   How were super-user privileges obtained?
     7.   Did the penetrator guard against detection?

      I stared at these questions, and gulped. Oh, I understood what the NSA
folks were asking me, but there was something wrong here.
      Was it that the answers to these questions could be used to break into
systems? No, that wasn't my objection. They covered essentially defensive
      Or did I object to NSA's role of gathering information but not sharing
it with anyone else? No, not really. I had resigned myself to that.
       Reading them a third time, I sensed that they showed an underlying
assumption that I found offensive. I scratched my head, wondering what
was annoying me.
      Finally I realized what galled me about their questions.

                  THE CUCKOO'S EGG

      It wasn't the content of the question, it was their intrinsic neutrality.
They assumed an impersonal adversary-a sanitized "penetrator." They im-
plied that this was an emotionless, technical problem, to be solved by purely
technical means.
      So long as you think of someone ripping you off as a "penetrator,"
you'll never make any progress. As long as they remained impersonal and
detached, the NSA people would never realize that this wasn't just a com-
puter being penetrated, but was a community being attacked.
      As a scientist, I understood the importance of remaining detached from
an experiment. But I'd never solve the problem until I got involved; until I
worried about the cancer patients who might be injured by this guy; until I
became angry that this hacker was directly threatening all of us.
      I rephrased the questions and scribbled a new viewgraph:

     1. How does this scoundrel break into computers?
     2. Which systems does he slither into?
     3. How did this bastard become super-user?
     4. How did the louse get passwords to the Livermore Cray?
     5. Did the skunk guard against detection?
     6. Can you audit a varmint who's system manager?
     7. How do you trace an eggsucker back to his roost?

     Now those questions, I can answer.
     These NSA spooks spoke in morally null jargon, while I felt genuine
outrage. Outrage that I was wasting my time following a vandal instead of
doing astrophysics. Outrage that this spy was grabbing sensitive information
with impunity. Outrage that my government didn't give a damn.
      So how do you pump up a bunch of technocrats when you're a long-
haired astronomer without a tie? Or without any security clearance? (There
must be some rule like, "No suit, no shoes, no clearance.") I did my best,
but I'm afraid that the NSA people were more interested in the technology
than any ethical implications.
   Afterwards they showed me a few of their computer systems. It was a bit
disconcerting: every room I walked into had a flashing red light on the
ceiling. "It warns everyone not to say anything classified while you're here,"
I was told.
      "What's the meaning of section X-I?" I asked my guide.
      "Oh, that's boring," she replied. "NSA has twenty-four divisions, each

                                S TaL L

with a letter. X is the secure software group. We test secure computers. X-l
are the mathematical folks who test software theoretically-trying to find
holes in its design. X-2 people sit at the computer, trying to break software
once it's written."
      "So that's why you're interested in computer, weaknesses."
      "Yeah. One division of NSA may spend three years building a secure
computer, X-l will examine its design and then X-2 will bang on it,
searching for holes. If we find any, we'll return it, but we won't tell them
where the bug is. We leave it for them to puzzle out."
      I wondered if they would have picked up the problem with Gnu-
      Along the way, I asked several people at NSA if there was any way
that they could support our work. Individually, they regretted that our
funding came entirely out of physics grants. Collectively, though, they
offered no help.
      "It would be easier if you were a defense contractor," one spook told
me. "NSA shies away from academics. There seems to be a kind of mutual
distrust." So far, my total outside support was $85, an honorarium for
speaking at the San Francisco Bay Technical Librarians' Association.
      The tour of NSA lasted well into lunch, so I left Fort Meade late, and
got plenty lost on my way to the CIA in Langley, Virginia. Around 2 P.M.,
I found the unmarked turnoff and pulled up to the gatehouse, an hour late.
      The guard stared at me like I'd recently arrived from Mars. "Who are
you here to see?"
      "Your last name?"
     "Stoll." The guard looked over her clipboard, handed me a form to fill
out, and slipped a blue pass on the rental car's dashboard.
     A VIP parking pass from the CIA. That's gotta be worth $5.00 back in
The People's Republic of Berkeley. Maybe $10.00.
      Me? A VIP? At the CIA? Surreal. I dodged a few joggers and bicycles
on my way to the VIP lot. An armed guard assured me that I didn't have to
lock the car doors. In the background, the seventeen-year locusts were
buzzing and a mallard quacked. What's a flock of ducks doing at the portals
of the CIA?
     Teejay hadn't said how technical a talk he wanted, so I stuffed my
viewgraphs into a grungy envelope. Then, off to the CIA building.

                  THE CUCKOO'S EGG

      "You're late," Teejay called from across the foyer. What do I tell him?
That I always get lost on freeways?
      In the middle of the foyer's floor is a five-foot-diameter seal of the
CIA, a terrazzo eagle set behind an official seal. I expected everyone to walk
around the grey symbol, just as the high school students do in Rebel Without
a Cause. No such luck. Everyone walks on top of it, showing the poor bird
no respect.
      On the wall, there's a marble inscription, "The Truth Shall Set You
Free." (I wondered why they'd use Caltech's motto-then I noticed the
quote came from the Bible.) Four-dozen stars were engraved on the oppo-
site wall-I could only guess about the forty-eight lives they represented.
      After a ritualistic search of my belongings, I received a fluorescent red
badge with a V. The visitor tag wasn't necessary-I was the only guy
around without a tie. Not a trench coat in sight.
      The atmosphere was that of a subdued campus, with people strolling
the hallway, practicing languages, and arguing around newspapers. Every
once in a while, a couple would wander by, arm in arm. This was a long
way from Boris and Natasha cartoons.
      Well, not exactly like a campus. As Teejay showed me to his first-floor
office, I noticed that each door was a different color, but none had cartoons
or political posters on them. Some, however, had combination locks, al-
most like bank vaults. Even the electrical boxes had padlocks.
      "Because you're late, we've rescheduled the meeting," Teejay said.
      "I've got to select viewgraphs," I said. "How technical a talk should I
      Teejay gave me the hairy eyeball and said, "Don't worry about it. You
won't need viewgraphs."
      I sensed trouble ahead. No escaping this time. While sitting around
Teejay's desk, I discovered that he had a fantastic set of rubber stamps. Real
"TOP SECRET" stamps, along with things like "CLASSIFIED," "EYES
AFTER READING," and "NOFORN." I figured the last one meant "No
Fornicating," but Teejay set me straight: "No Foreign Nationals." I stamped
each one on a sheet of paper, and stuffed it in my pack of viewgraphs.
      Greg Fennel, the other spook who had visited me in Berkeley, stopped
by and took me up to the CIA's computer room. More like a stadium. In
Berkeley, I was accustomed to a dozen computers in a big room. Here, there
were hundreds of mainframe computers packed tightly together in a huge

                                  ST 0 L L

cavern. Greg pointed out that, outside of Fort Meade, it's the world's largest
computer installation.
      All IBM mainframes.
      Now, among Unix aficionados, big IBM systems are throwbacks to
the 1960s, when computing centers were the rage. With desktop worksta-
tions, networks, and personal computers, Goliath centralized systems seem
      "Why all this IBM stuffi''' I asked Greg. "Those things are dinosaurs."
 I snidely showed my Unix bias.
       "Well, we're changing," Greg answered. "We've got a dedicated artifi-
 cial intelligence group, active robotics researchers, and our image-processing
 lab really cooks."
       I remembered proudly showing Teejay and Greg through my lab's
 computing system. Suddenly, I felt incredibly embarrassed-our five Vaxes,
_scientific workhorses to us, seemed mighty puny next to these.
      Yet our purposes were different. The CIA needs a giant database sys-
 tem-they want to organize and associate lots of diverse data. We needed
 number crunchers: computers that were fast with math. It's always tempting
 to measure the speed of a computer or the size of its disks, and then
 conclude that "this one is better."
      The question isn't, "Which computer is faster," no, not even, "Which
is better." Instead, ask, "Which is more suitable?" or "Which will get your
job done?"
      After touring the CIA's computing division, Teejay and Greg took me
up to the seventh floor. The staircase is labeled with the floor numbers in
different languages: I recognized the fifth floor (Chinese) and the sixth floor
       I was shown to an anteroom with a Persian rug on the floor, Impres-
 sionist art on the walls, and a bust of George Washington in the corner. A
 real mixed bag. I settled down into a sofa with Greg and Teejay. Across
 from us were two other guys, each with a picture badge. We talked a bit-
 one of the guys spoke fluent Chinese; the other had been a veterinarian
 before joining the CIA. I wondered what kind of talk I was expected to
       The office door swung wide, and a tall, gray-haired man called us in.
 "Hi, I'm Hank Mahoney. Welcome in."
       So this is the meeting. It turns out that the seventh floor is the hide-out

                   THE CUCKOO'S EGG

for the CIA's high-muckity-mucks. Hank Mahoney's the CIA's deputy di-
rector; grinning nearby was Bill Donneley, the assistant director, and a
couple others.
        "You mean that you've heard about this case?"
     "We've been following it daily. Of course, this case alone may not
seem like much. But it represents a serious problem for the future. We
appreciate your taking the effort to keep us informed." They presented me
with a certificate of appreciation-wrapped up like a diploma.
      I didn't know what to say, so I stammered out my thanks and looked
at Teejay, who was chuckling. Afterward, he said, "We wanted to keep it a
      Surprise? ]eez-I'd expected to walk into a room of programmers and
give a shoptalk on network security. I glanced at the certificate. It was
signed by William Webster, director of the CIA.
     On my way out, sure enough, the guards searched my stack of view-
graphs. Halfway down, there was that page of paper with its telltale stamp,
"TOP SECRET." Uh oh.
     Red alert-visitor caught leaving CIA with document stamped "TOP
SECRET"! Nothing else on the page, of course. Five minutes of explaining
and two phone calls later, they let me out. But not without confiscating the
rubber stamp sampler. And a lecture on how "we take security seriously
around here."
     I flew back to Berkeley, sitting next to Greg Fennel, who was flying
west for some secret business. Turns out that his background is astronomy-
he used to run an observatory. We talked a bit about Space Telescope, the
billion-dollar, high-precision instrument that's soon to be launched.
    "With a ninty-four-inch telescope in space, we'll be able to see phe-
nomenal detail on planets," I remarked.
        'just think what you could do if you pointed it at the earth," Greg
     "Why bother? All the interesting things are in the sky. And anyway,
the Space Telescope physically can't point to the earth. Its sensors will burn
out if you try."
      "What if someone made such a telescope and pointed it to the earth.
What could you see?"
      I fiddled a few numbers in my head. Say, three hundred miles up in
orbit, a ninty-four-inch telescope. The wavelength of light is about four

                                ST 0 L L

hundred nanometers . . . . "Oh, you could easily see detail of a couple feet
across. The limit would be around a couple inches. Not quite good enough
to recognize a face."
      Greg smiled and said nothing. It took a while, but it eventually sunk
in: the astronomical Space Telescope wasn't the only big telescope in orbit.
Greg was probably talking about some spy satellite. The secret KH-ll, most
     I returned home, wondering if I should tell Martha what happened. I
didn't feel any different-I'd still rather be doing astronomy than chasing
some hacker-but I worried that Martha might not approve of who I'd
been rubbing shoulders with.
     "Have fun?" she asked when I returned.
     "Yeah, in a weird way," I answered. "You don't want to know who I
     "Makes no difference. You've been crunched up in an airplane all day.
Let me rub your back."
     Home sweet home.

o     0     0 I still seethed with frustration when I thought of the eight
months that we'd been stuck to this tar baby. My boss wouldn't let me
forget that I was doing nothing useful.
     Then on Wednesday, April 22, Mike Gibbons called to say that FBI
Headquarters had decided we should keep monitoring the hacker. It seems
the German police wanted to catch this guy; the only way this could happen
was if we notified the Germans immediately when our alarms sounded.
     Meanwhile, the FBI had put in an official request for cooperation and
speedy telephone traces. They were talking to the administrator ofjustice in
Germany, via the U.S. State Department.
     Well, yippee. Why this sudden change in policy? Had the NTISSIC
committee made a decision? Or was it due to my constant pestering? Or had
the Germans finally contacted the FBI?
     Although the FBI was only now interested, I'd never disabled my

                  THE CUCKOO'S EGG

monitoring station. Even when I was away for a couple days, the monitors
remained on guard. Last week's printouts showed him on the system from
9:03 to 9:04 A.M. on Saturday, April 19. Later that day, he appeared again
for a couple minutes. Quiet for a few days, then he popped up, checked that
the SDINET files were still around, and left.
      For the past month, I'd been leaving new bait for the hacker. He saw it
-at least he glanced at the names of the files-but he didn't read any of it.
Was he worried that he was being watched? Did he know?
      But if he thought we were watching him, he'd be a fool to show up at
all. Maybe he couldn't afford longer connections? No, the Bundespost told
us that he was charging these calls to a small company in Hannover.
      Throughout the spring, I kept making new bait. To an outsider, the
bogus SDINET files were the product of a functioning office. My mythical
Barbara Sherwin created memos and letters, requisitions and travel orders.
Here and there she sprinkled a few technical articles, explaining how the
SDI network interconnected all sorts of classified computers. One or two
notes implied that you could use the LBL computers to link into the net-
     Everyday, I wasted an hour juggling these SDINET files. My hopes
were to keep the hacker occupied here, rather than going out into military
systems. At the same time, it gave us an opportunity to trace the hacker.
      On Monday, April 27, I'd biked in late and began writing a program
to let our Unix system talk to Macintosh computers on people's desk tops. If
I could connect those together, any of our scientists could use the
Macintosh's printer. A fun project.
       By 11:30, 1'd fouled up two programs-what had worked an hour ago
wasn't working now-when Barbara Schaefer called from five floors up-
    "Hey, Cliff," the astronomer said, "a letter just arrived for Barbara
     "Be serious." For once, it was my turn to say that.
      "Really. Come on up and let's open it." I had told Barbara about the
dummy SDINET project and mentioned that I was using her mailbox as a
mail drop. But I never really expected the hacker to actually send something
in the mail.
     Good grief! Had this hacker greeted us with a letter?
     I ran up the five flights of stairs-the elevator's too slow. Barb and I

                               ST 0 L L

looked at the letter. Addressed to Mrs. Barbara Sherwin, SDINET project,
Mail Stop 50-351, LBL, Berkeley, CA. Postmarked from Pittsburgh, Penn-
     My heart was thumping from the run up the stairs, but I felt the
adrenaline rush when I saw that envelope.
     We carefully slit the envelope and shook out this letter:

                                     Triam International, Inc.
                                     6512 ventura Drive
                                     Pittsburgh, PA 15236
                                     April 21, 1987

                             SDI Network Project
                             LBL, Mail Stop 50-351
                             1 Cyclotrov Road
                             Berkley, California 94720
                             ATTENTION: Mrs. Barbara
    SUBJECT:       SDINetworkProject

    Dear Mrs. Sherwin:
       I am interested in the following documents.
    Please send me a price list and an update on the SDI
    Network Project. Thank you for your cooperation.
                                      Very truly yours,
                                      Laszlo J. Balogh

       #37.6 SDI    Network    Overview Description
    Document, 19 pages, December 1986
       #41.7 SDI Network Functional Requirement
    Document, 227 pages, Revised September 1985
       #45.2 Strategic Defense Initiations and
    Computer Network Plans and Implementations of
    Conference Notes, 300 pages, June 1986
       #47.3 SDI Network Connectivity Require-
    ments, 65 pages, Revised April 1986
       #48.8 How to Link to SDI Network, 25 pages,
    July 1986
       #49.1 X. 25 and X. 75 Connection to SDI Network
    (includes Japanese, European, Hawaiian, 8 pages,
    December 1986)
       #55.2 SDI Network Management Plan for 1986 to

                  THE CUCKOO'S EGG
    1988, 47 pages, November Membership list (in-
    cJ.udes major connection, 24 pages, November 1986)
        #65.3 List, 9 pages, November 1986

      Son of a bitch! Someone had swallowed our bait and was asking for
more information! I could understand it if the letter came from Hannover.
But Pittsburgh? What's happening here?
      I asked Barb Schaeffer to tell this to nobody and called Mike Gibbons
at the Alexandria FBI office.
      "Hey Mike, remember those carrots I left out for bait in January?"
      "You mean those SDI files you concocted?"
      "Yeah," I said. "Well, my dear, sweet, nonexistent secretary just re-
ceived a letter."
      "Be serious."
       "Someone in Pittsburgh wants to learn about SDI."
       "And you've got that letter?"
       "Right in front of me."
       "OK," Mike said. "Listen up carefully. Don't touch that letter. Espe-
cially, don't touch around the edges. Go find a glassine envelope. Gently
insert the paper in the envelope. Then fed-ex it to me. Whatever you do,
don't handle it. Wear gloves if you must."
       "Well, the real Barb Schaeffer's already touched it."
       "We may have to fingerprint her, then. Oh, before you put it in the
envelope, initial the middle of the back side."
       This sounded like Dick Tracy's "Crimestoppers," but I followed or-
ders. I handled it like an astronomical negative-except that I made a
photocopy for myself. I suspected that Mike might forget to return the
       After I'd chased around for an hour (ever hunt for glassine envelopes?)
and shipped the letter to the FBI, I dug out my logbook.
       The information in that letter showed up in exactly one of my bogus
files. That file, named form-letter, had been read only once. On Friday,
January 16, the hacker had read that file.
       I could prove that nobody else had seen it. 1'd protected that file,form-
letter, so nobody could read it except the system manager. Or someone
who'd illegitimately become system manager.
       Well, maybe someone else had figured out a way to read that file.
Nope. Whenever the computer touched that file, for any reason, my alarm

                                 ST 0 L L

sounded and I got a printout. Only one person set off that alarm. The
       I compared Laszlo Balogh's letter from Pittsburgh with my fabricated
letter of January 16. He'd pretty much asked for everything that the bait
       Except he'd carefully deleted the word "classified" when asking for
document #65.3.
       Several errors jumped out: it's Cyclotron, not Cyclotrov. Berkeley,
not Berkley. I wondered if the writer's native tongue might not be English
-who would say, "Plans and Implementations of Conference Notes"?
       Strange. Who's behind this?
       Oh-I know what's happening! This hacker lives in Pittsburgh, Penn-
sylvania. He calls Hannover, connects   to   the German telephone system, and
then invades my computer. What a way to hide!
      Naw, That one doesn't hold water. Why wouldn't he call directly-
straight from Pittsburgh to Berkeley?
       I reread my logbook of January 18. On that day, we'd traced the
connection all the way back     to   the hacker's phone in Hannover. That
confirms it. The electronic connection went to someone's home in Hanno-
ver, not Pittsburgh.
      Information had moved from my computer in Berkeley, across
Tymnet, into Hannover, Germany. Three months later, a letter arrives from
       I scratched my head and looked for a phone number on the letter.
None. Maybe Laszlo's listed in the Pittsburgh directory service? Nope.
Triam isn't listed either.
       That name, though . . . I called my sister Jeannie.
     "Hey, sister, what kind of name is Balogh?" Jeannie knows this kind
of thing.
       "Sounds like Central or Southern Europe. Hungary or Bulgaria. Have
a first name?"
       "Hungary for sure. Why, I had a boyfriend, once, whose fa-
       "Any chance it's German?" I interrupted.
       "Doesn't sound like it to me."

                   THE CUCKOO'S EGG

     I told her about the letter and the misspellings. "Substituting 'trov' for
'tron' sounds like a Hungarian error," she said. "I'll bet on Hungary."
     "Ever hear of the name 'Langman?' "
     "No, can't say I have. It means long man in German, if that's any
     "The hacker once created an account for T. G. Langman."
     "Sounds like an alias to me," Jeannie said. "And how do you know
this Laszlo character is real? Might well be another pseudonym."
     Computer hackers hide behind pseudonyms. In the past seven months,
I'd come across Pengo, Hagbard, Frimp, Zombie . . . but T. G. Langman
and Laszlo Balogh? Maybe.
     A hacker in Hannover, Germany, learns a secret from Berkeley, Cali-
fornia. Three months later, a Hungarian, living in Pittsburgh, writes us a
letter. Fascinating.
     Three months, huh? I thought on this for a while. Suppose two friends
were communicating with each other. News would take a couple of days to
move between them. A week or two, perhaps. But not three months.
    So Laszlo in Pittsburgh probably wasn't a close friend of the Hannover
      Now suppose that the information was filtered through some third
party. How many people were involved? If two or three people meet, make
a decision, and act, it'll only take a week or two. But if five or ten people
meet, decide, and act, it'll take a month or two.
     Yet I'm pretty sure that only one person is operating the computer.
Nobody else would have such a tedious, methodical, and persistent manner.
The German Bundespost says they're following at least two guys. What's
happening here?
     Whatever's going on, I'm in over my head. They don't teach you this
kind of stuff in graduate school. Seemed like the CIA's bailiwick. I called
Teejay and got two sentences into my description.
      "Wait a second. Let me call you back on a different line." A secured
phone line.
      No doubt, this latest wrinkle hit him where he lived. I had to explain
it to him twice-he also wanted an express copy of Laszlo's letter. News
travels fast in certain circles: half an hour later, Greg Fennel of the CIA
called, asking if Laszlo might have logged into my computer. I explained

                                ST 0 L L

about my alarms and tripwires. "No, the only guy that's seen that file is a
hacker in Hannover."
      Greg was quiet on the phone for a second, then said, "A real smoking
      That reminded me of the NSA guy's comment. Time to call Bob
Morris. I told him about the letter and he seemed mildly interested. "Want
me to send you a copy by Federal Express?"
      "That won't be necessary. First class is good enough."
      He seemed more interested in my techniques of setting alarms than the
content of the letter. In a way, that's not surprising-he'd already concluded
that something serious was happening.
      Air Force OSI sent an investigator over to examine the letter. Their
man, Steve Shumaker, had the common sense to show up in dungarees and a
T-shirt, so as not to alarm the natives. He asked for a copy of the letter and
the printouts from the Air Force System Command Space Division. They
were going to do a postmortem analysis of the hacker's break-in.
      "I'll give you a copy of the letter-that's no problem," I told Shu-
maker, "but I can't let you have the original printouts. The FBI's warned
me to keep all of this locked up since it might be used as evidence."
      "Can you Xerox it?"
      Aargh. Xerox five hundred pages of computer printout?
      Well, we spent an hour in front of the copier, feeding the damned
paper through the machine. I asked the OSI detective what he thought of
the letter from Pittsburgh.
      "We've been warning everyone that this was bound to happen. Maybe
they'll wake up now."
      "What have you been doing so far?"
      "We visit sites and try to raise their security awareness," he said.
"We've formed a team to test their computer security by trying to break
into Air Force systems. What we found isn't encouraging."
      "You mean you're the only ones who test Air Force computers for
security?" I asked. "You must have thousands of computers."
      "Well, there's also a group in San Antonio, the Air Force Electronic
Security Command, that searches for electronic security breaches," Shu-
maker said. "They mostly worry about communications security-you
know, keeping radio transmissions secret. They're sharpies over there, all
      Gibbons of the FBI was a sharpie, too. Finally, now that he was

                       THE CUCKOO'S EGG

    actively committed, he wanted to know everything. Every time the hacker
    appeared, Mike wanted to know about it immediately. Throughout the day,
    he called repeatedly, asking for my logs and notes, floppy disks and print-
    outs. Descriptions of the monitors. Everything. That's the way to make
          I couldn't get this letter out of my mind. I kept searching for some
    innocent explanation, some way that it might be written off as a fluke.
         Finally I gave up and admitted victory. I couldn't explain it any other
    way: the letter must mean my plan had worked. No, not my plan, it was
    Claudia's. My sweet, guileless roommate, who didn't know a computer
    from a toaster, had trapped this cunning hacker!
         Cycling home, I swerved suddenly from my usual route, scooted into
    the Double-Rainbow ice cream store and the video rental place. Then I
    hurried home, waving a copy of Laszlo's letter. Elated at the news, Martha
    and Claudia cackled evilly and dropped into Boris and Natasha accents.
    Zecret plan 35B vas a success!
          We crowded into Claudia's room, munched out on popcorn and ice
    cream, and cheered the monsters in Godzilla Versus Monster Zero.

    o     0      0   "Don't say anything to anyone!"
         It was Mike Gibbons on the phone, telling me not to spread the word
    to the CIA.
         "Uh, I'm sorry, Mike, but I've already told this guy Teejay." I won-
    dered if Mike had heard of Teejay.
         "I'll take care of it, then. This letter you sent us is intriguing. We ran it
    through some lab tests."
         "What'd you learn?" Mike was being more communicative than usual,
    so I might as well push my luck.
         "Can't tell you, but we're not treating this case lightly. Aspects of it
    are quite, well, intriguing." That's the second time Mike used that word.
    Something's up. "Oh, by the way, could you send me a half-dozen sheets of
    your letterhead?"

                                 ST 0 L L

     The FBI wants my lab's letterhead? Sounds like they're going to reply
to Laszlo's letter.
     What would "I" tell this guy? How about,

    Dear Mr. Balogh:
       You have been selected as a grand prize winner
    in the SDINET sweepstakes . . . .

      The hacker played hide-and-seek for the next few days. He'd show up
for three minutes, look at our password file, then log out. My bait grew
tastier every day. Yet he wasn't nibbling.
       Monday morning, May 18, he came into our system at 6:54 A.M.
Awakened by an insistent beep, I reached over and whapped the alarm
clock. Wrong noisemaker-the beep continued. Three beeps. S for Sventek.
It's the hacker, over on the Unix-4 computer.
     Mechanically I ran to my Macintosh, switched it on, and called Steve
White at Tymnet.
     "Steve, someone's tripped my alarm," I said, still a bit hazy. "I haven't
checked it out yet, but could you start the trace?"
     "Right-c. It'll be up in ten seconds," he said. "Here it is. Coming
through the Westar satellite. Calling address 2624 DNIC 5421-0421. That's
Bremen. I'll ring the Bundespost."
      I copied down the number; by now my home computer was warmed
up. Steve had just completed an international trace in less than a minute. I
dialed my lab's system from my pipsqueak home computer and examined
the Unix-4 computer. There was Sventek, just leaving.
      He'd been on for four minutes. Long enough to detect him and com-
plete a trace. Long enough to ruin my morning. I wouldn't be able to get
back to sleep, so I biked up to the lab. Over in the east, the morning star
kept me company. Venus.
      In four minutes this hacker had pried at a new part of my operating
system. He searched for a program called X-preserve on our Unix com-
      Hey-I know what he's doing. He's looking for the X-preserve hole
in the VI-editor. Dave Cleveland and I had patched that almost a year ago.
But this hacker is only now trying to exploit it.
      VI is the Unix screen editor. When Bill Joy wrote it, back in 1980,
people thought it was the neatest invention around. It let you watch as you

                   THE CUCKOO'S EGG

moved words around! If you wanted to remove a word in the middle of a
paragraph, you just moved the blinking box to that word, and presto!
      VI was predecessor to hundreds of word processing systems. By now,
Unix folks see it as a bit stodgy-it hasn't the versatility of Gnu-Emacs, nor
the friendliness of more modern editors. Despite that, VI shows up on every
Unix system.
      What happens if you're writing a long article and the computer hic-
cups? Say, there's a power blackout or some moron pulls the plug. Used to
be that you'd lose everything you had typed in.
      The VI editor uses X-preserve to recover what you've done. When the
computer returns from the dead, X-preserve will reassemble the pieces of
your work. It'll then ask you where to store this knit-together file. Most
people will say, "Oh, put it in my home directory."
      But X-preserve didn't check where you stashed that file. You could
say, "Stick the file in the systems directory," and it would do so.
      That's what the hacker tried. He made a file that said, "Grant system
privilege to Sventek." He fired up the VI-editor, then tripped up the editor
by feeding it an interrupt character. VI, sensing a problem, stored his file in
      The hacker's next step? Tell X-preserve to slip that file into the systems
directory. In a couple minutes, Unix would hatch it, and he'd become
system manager.
      But the cuckoo's egg fell out of this nest. We'd fixed the X-preserve
program . . . it now checks who you are and won't let you move a file
into the systems area.
      Poor guy. He must feel crestfallen. A nifty trick to break into systems,
but it just won't work here in Berkeley.
      Oh, I'd left our other holes open. He can still use Gnu-Emacs to plant
his egg-program in the systems nest. And I've purposely left two other holes
in our system waiting around for him to discover. Just to measure his skill.
So far, he's batting one for three.
      All this took three minutes. He entered his program perfectly-not a
single typing error. It's as if he'd done this often. As if he'd practiced
breaking into other computers.
      How many other system managers hadn't yet patched X-preserve?
How many other holes were still waiting to be discovered? Where would I
go to warn people about this? How would I tell the people in the white
hats, without tipping off the bad guys?

                                ST 0 L L

      Too late for that. The guys in the black hats already know.
       Although this connection lasted only a few minutes in Berkeley, the
University of Bremen reported that he was connected for forty-five min-
utes. In turn, the Bundespost once again traced the entire link back to the
same individual in Hannover.
       Turned out that the University of Bremen was also printing the hack-
er's traffic. Two of us were now watching this guy. He could run, but he
couldn't hide.
       For the past couple months, he'd just nibbled at the SDINET files.
He'd seen the names of these files and noticed that everyday I added new
memos and letters but didn't read them right off. I'd begun having my
doubts whether he was still interested in our creative writing.
       On Wednesday, May 20, my doubts cleared up. He connected at five
in the morning and dumped all the SDINET files. Here was one letter
asking the Pentagon for more funding. Another talking about "over-the-
horizon radar" -a catch phrase I'd found in an electronics magazine. Yet
another note described tests of a new supercomputer, complete with parallel
processors. I tried to conceal my utter lack of knowledge of these subjects
by ftlling the letters with jargon.
       He swallowed them, all right. One by one. I wanted him to ask for
each bogus memo by name rather than saying, "Give me all the files." So I
added a few ringers. Files that were far too long to type out. A few short
files that were filled with gibberish-computer guacamole. He couldn't
print these poisoned files, so he'd have to check each file first. This slowed
him down and he stayed on the system longer: more time to trace.
       Nine months? We'd been watching this one skunk for the better part
of a year. And Mitre's telephone bills said he'd been breaking in for more
than a year. What persistence!
       I wondered again, what's driving this guy? Sure, I'd get a charge out
of fooling around for a night or two. Might even be fun for a couple
weeks. But a year? Night after night, patiently twisting doorknobs to com-
puters? Why, you'd have to pay me.
       Paid? Was someone paying this hacker?
       The next few times he showed up, I hadn't added much more to his
SDINET feeding grounds. My puppet secretary, Barbara Sherwin, wrote a
word-processed memo asking for a week's vacation. The hacker read this
and should have understood why there was so little new information.
       Instead of pawing through LBL's files, then, he went out over the

                  THE CUCKOO'S EGG

Milnet, once again patiently trying to guess passwords. One of my bogus
SDINET reports mentioned a special project at White Sands Missile Range;
sure enough, he spent fifteen minutes scratching at their door. White Sands'
computers recorded a dozen attempts to break in, but none were successful.
      Chris McDonald, White Sands' computer security ace, called me
within the hour. "Someone's setting off alarms inside my WSMROS com-
      "I know. It's the same hacker."
      "Well, he's trying accounts that don't exist. Names like SDINET.
There's no way he'll get in that way," Chris said confidently. "Anyway,
that machine needs two passwords, and we changed 'em all last week."
White Sands didn't fool around.
      He wasted his time trying thirty other computers as well. The Korean
Advanced Institute of Science and Technology. The Army Safety Center at
Fort Rucker. Strategic Air Command. The Defense Nuclear Agency at
Kirtland Air Force Base. Though he still tried account names like "guest"
and "system," he used "SDINET" as well. No doubt that he's a believer.
       Mostly the hacker's trips through my system were becoming routine. I
still ran to the switchyard whenever my beeper called, but I guess I'd
become accustomed to having this mouse in a cage.
       I'd waited eight months, I could wait some more. Around the second
week of June, he stopped into my computer from 3:38 until 4:13 in the
afternoon. We traced him completely-Hannover again-and stayed in
touch with the FBI throughout.
       Immediately after logging onto my Berkeley computer, he jumped
onto the Milnet and tried to log onto some computers at the Unisys Corpo-
ration, in Paoli, Pennsylvania. Systems named "Omega," "Bigburd," and
"Rosencrantz" (I kept waiting to see Guildenstern, but he never found it).
Then he tried the Unisys Burdvax system.
       He got in on his first try. Account name Ingres, password, "Ingres."
Not bad . . . he remembers the Ingres database. But why did he just try
those Unisys computers? What brought them to his attention? Maybe some-
one told him to look for them.
       Maybe Laszlo Balogh in Pittsburgh worked in Paoli. The atlas said
otherwise. Paoli's a suburb of Philadelphia, hundreds of miles away from
       As an Ingres user, the hacker only had limited privileges, but he took
what he could find. Most useful to him, he found a way to read the Unisys

                                 ST 0 L L

password file. Copied the whole thing to his home computer. Then he listed
several files which should never be world-readable: the list of phone num-
bers that the Unisys computer knew, and Unisys's network address file.
       I already knew what he'd do with the Unisys password file. He'd
decrypt it by blasting a dictionary at it. Then he'd log into a more privi-
leged account and garner still more power.
      Those other files were just as worrisome. They provided the hacker
with phone numbers to nearby computers and a map of the Unisys local
network. Now he knew how to connect from the Burdvax into other
computers . . . he didn't need to explore.
       But even as I watched, he disconnected. Was he scared? No, just pa-
tient. He was going to check up on other computers. First, the Fort Buckner
system in Okinawa. Yes, his password was still good there. Despite our
warnings, they hadn't changed a thing.
       Next, he tried the Naval Coastal Systems Command in Panama City,
Florida. But he couldn't get in on his old Ingres account. They'd changed
the password on him.
       Didn't faze him for an instant. He turned around and logged in as user
"Ovca," password, "Baseball." This worked perfectly.
       Aha! More evidence for password cracking. Two months ago, the
hacker logged into that naval computer as "Ingres," and copied their en-
crypted password file. Now, even though they deleted the Ingres account,
he can still log in, using some other account. The fools had only changed
one password. And their passwords were ordinary English words. Jeez.
       While he was at it, he checked into his old haunts. Ramstein Air Force
Base. Fort Stewart. University of Rochester. The Pentagon Optimis Data
Center. Finally he left the network.
       Today he'd broken into a new computer at Unisys. Where had I heard
that name? Of course-they're a defense contractor that makes computers
for the military. Not just any computers. Unisys builds secure computers,
systems that you can't break into.
       Wait a second. What other defense contractors had been hit? I scrib-
bled a list on a pad of paper:

     Unisys. Makers of secure computers.
     TRW. They make military and space computers.
     SRI. They've got military contracts to design computer security systems.

                  THE CUCKOO'S EGG

     Mitre. They design high-security computers for the military. They're the
            people that test NSA's secure computers.
     BBN. The builders of the Milnet.

     What's wrong with this picture? These are the very people that are
designing, building, and testing secure systems. Yet hackers traipse freely
through their computers.
     These companies don't have dinky budgets, either. They charge our
government tens of millions of dollars to develop secure software. No
doubt about it: the shoemakers' kids are running around barefoot.
     I'd seen this guy break into military computers, defense contractors,
universities, and laboratories. But no banks. Oh-I know why. Their net-
works aren't as public as the Arpanet. But if he got on their networks, I'd
bet he'd be about as successful.
      For it doesn't take brilliance or wizardry to break into computers. Just
patience. What this hacker lacked in originality, he made up for in persis-
tence. A few of the holes he exploited were news to me: the Gnu-Emacs
problem, for instance. But mostly, he took advantage of administrators'
blunders. Leaving accounts protected by obvious passwords. Mailing pass-
words to each other. Not monitoring audit trails.
      Come to think of it, was it foolish to remain open? It had been almost
ten months, and he was still free. Despite his breaking into more than thirty
computers, despite Laszlo's letter from Pittsburgh, despite all these traces,
this hacker was still at large. How much longer would this go on?

o     0     0   It was June-summer in paradise. I biked home, enjoying
the scene, Berkeley students with Frisbees, sailboards, and an occasional
convertible top down in the balmy air. Our garden was full of roses,
marigolds, and tomatoes. The strawberries were thriving, promising still
more milkshakes.
     Inside the house, however, Martha was imprisoned, studying for her
bar exam. This last ordeal looked even harder than three years of law
school. In summer, when everyone else can go out and play, you're stuck in

                                 ST 0 L L

dreary review classes, cramming your head with legal rules, counting the
days until the exam-a three-day ordeal modeled on the Spanish Inquisi-
       Martha coped, patiently reading her books, making intricate outlines
of each subject with colored pens, meeting with fellow sufferers to quiz each
other. She was philosophical about it; she put in exactly ten hours each day,
then slammed the books shut. Aikido became her salvation-she took out
her frustrations by flipping people over her head.
       Martha rarely talked about the lurking horror of the exam itself, but it
was always there. Watching her go through this brought back memories of
my own grad school days.
       In astronomy, you first enjoy three or four years of confusing classes,
impossible problem sets, and sneers from the faculty. Having endured that,
you're rewarded with an eight-hour written exam, with questions like:
"How do you age-date meteorites using the elements Samarium and Neo-
dymium?" If you survive, you win the great honor and pleasure of an oral
exam by a panel of learned professors.
       I remember it vividly. Across a table, five profs. I'm frightened, trying
to look casual as sweat drips down my face. But I'm keeping afloat; I've
managed to babble superficially, giving the illusion that I know something.
Just a few more questions, I think, and they'll set me free. Then the exam-
iner over at the end of the table-the guy with the twisted little smile-
starts sharpening his pencil with a penknife.
       "I've got just one question, Cliff," he says, carving his way through
the Eberhard-Faber. "Why is the sky blue?"
       My mind is absolutely, profoundly blank. I have no idea. I look out
 the window at the sky with the primitive, uncomprehending wonder of a
 Neanderthal contemplating fire. I force myself to say something-anything.
"Scattered light," I reply. "Uh, yeah, scattered sunlight."
       "Could you be more specific?"
       Well, words came from somewhere, out of some deep instinct of self-
preservation. I babbled about the spectrum of sunlight, the upper atmo-
sphere, and how light interacts with molecules of air.
       "Could you be more specific?"
       I'm describing how air molecules have dipole moments, the wave-
 particle duality of light, scribbling equations on the blackboard, and . . .
       "Could you be more specific?"
       An hour later, I'm sweating hard. His simple question-a five-year-

                  THE CUCKOO'S EGG

old's question-has drawn together oscillator theory, electricity and magne-
tism, thermodynamics, even quantum mechanics. Even in my miserable
writhing, I admired the guy.
       So Sunday morning I'm looking at Martha, calmly working on an
outline, the dining table strewn with books. She'll pass, all right, but I also
know how scared she is and how an exam can make anyone feel absolutely
stupid and helpless. I can't make her ordeal easier, but I can at least make
breakfast. I slip quietly into the kitchen and crack a few eggs . . .
       At 9:32, the damned hacker steps on my tripwire. The pager beeps. I
call Steve White. He calls Germany. Like the old double play: Tinker to
Evers to Chance.
       Steve needed a minute to find the hacker coming from address 2624
DNIC 4511 0199-36. Direct from Hannover. (Or as direct as transatlantic
satellite connections can be.)
       The Bundespost was hot. Took them only a few minutes to confirm
that they'd started a trace. Nice. Meanwhile, having started the ball rolling,
I pulled on some clothes and biked up to the lab. No time for yard sales this
       I arrived with plenty of time to spare. My visitor was still pawing
through the bogus SDINET files, carefully copying each one into his own
computer. One file described how the Strategic Defense Initiative was to be
used in tracking satellites in space. Another file seemed to say that you could
connect directly into several Air Force computers from my laboratory.
       The hacker wanted to try, but couldn't figure out where we'd installed
the network software. So he scoured our entire computer, searching for any
program containing the phrase "SDI." He found quite a few, but none
seemed to do the job for him.
       Then he rifled Dave Cleveland's mail. Dave had prepared for this-
he'd written a letter talking about how he'd hidden the SDINET access
ports. Dave's letter contained the sentence, "I've concealed the SDI network
port, and I doubt that many people will discover it."
       That was enough to set the hacker on an hour-long wild goose chase.
He combed through our system, groping for what he knew was a hidden
program that would be his northwestern passage to military computers
       I sat back, smiling at the screen. He'd been suckered in, all right. He
still felt challenged to uncover the SDI network connection and truly be-
lieved that he could reach those classified computers.

                                 S TaL L

      Yet my system looked vanilla. Because it was vanilla. Oh, here and
there, I sprinkled hints that other people were using the SOl network. One
physicist cooperated and sent a complaint to the system manager, saying that
the SOl network wasn't functioning last Tuesday night. Another wrote a
mundane program full of subroutines with names like SOl-link and Copy-
      Though it took hours, the hacker eventually discovered these, and
must have scratched his head, wondering why others had such an easy time
using the network. He tried logging into computers named Sdi and
Sdinetwork. Over and over, he sifted through our system, but to no avail.
      Eventually he gave up and let me go home. Martha wasn't pleased, of
course. She'd been studying all morning, and she was hungry and grouchy.
The two eggs stared at me from the pan, uncooked, just as I'd left them.
      So I made a brunch of omelets, hot cocoa, and fruit salad; she dumped
her books off the table with a vengeance, and we sat down, enjoying a few
moments of peace in the quiet sunny room. The more strange life gets, the
more precious those times are, with food and friends and the Sunday Times
crossword puzzle.
      Monday morning, Teresa Brecken, the Petvax system manager, re-
ported that someone had attacked her computer. He couldn't get into it but
had been probing it, searching for weak places. His pounding had set off
alarms, and Teresa called me.
      He'd come in over her port to the High Energy Physics Network.
That didn't mean much-there's a couple thousand other computers on that
net. Moreover, the Hepnet ties to SPAN, the Space Physics Applications
Network, run by NASA. Altogether there's well over ten thousand com-
puters on those networks.
      Had the hacker been laughing at me all the time? While I'd been
watching the Tymnet mouse hole, had he been waltzing in through some
NASA network?
      Teresa's monitors showed this hacker had come from computer 6.133,
the National Severe Storms Data Center's computer at NASA's Goddard
Spaceflight Center. Not much to do but call them.
      I didn't get very far. They were worried about hackers on their com-
puter and had discovered one or two problems, but couldn't go much
further. I pestered them, and they finally said that this particular connection
had originated at NASA's Marshall Spaceflight Center in Huntsville, Ala-
bama. From there, who knows? Marshall didn't keep records.

                   THE CUCKOO'S EGG

      Same guy? I doubted it. The NASA computers aren't secret-NASA
does civilian space research and has nothing to do with the Strategic Defense
Initiative. Still, worth remembering the incident: I wrote it down in my
      I called Mike Gibbons again, wondering how much longer we'd have
to wait before the FBI and their German partners began to move.
      "Any day now," Mike replied. "The warrants are in order and we're
just waiting for the right time."
      "Give me a figure, Mike. Do you mean hours, days, weeks, or
      "More than days, less than weeks."
      I wondered if the FBI was feeding some false information through
Laszlo Balogh. "Ever reply to the Pittsburgh letter?" I asked.
      "Hey, how about them Yankees winning another game?" As usual,
Mike played his cards close to his chest.
      Almost every day now, the hacker logged in for a few minutes. Some-
times he'd grab any new files from the SDINET account. Other days he'd
try to break into military computers. Once he spent half an hour trying to
guess the password for our Elxsi computer-I'd dropped a hint that our
Elxsi was a central SDINET controller.
      I could embroider fake military documents as fast as he could read
them. Knowing that he was passing my handiwork to some agent in Pitts-
burgh, I added just a dash of verifiable information: the Pentagon was
scheduling a secret satellite to be launched on the Atlantis space shuttle. This
was common knowledge to anyone reading the newspapers. But I imagined
that in his quest for secret information, he'd feel that these nuggets of truth
confirmed that he'd struck the mother lode.
      Sunday, June 21, 1987, at 12:37 P.M., he logged into our Unix com-
puter as Sventek. For five minutes he checked the system status and listed a
few mail files. This intrusion seemed just like his others.
      But this session was different in one important way.
      It was his last.

                                ST 0 L L

o      0 0 "Hi, Cliff, it's Steve." I put down my chocolate chip
      "I just got a message from Wolfgang Hoffman at the German
Bundespost. He says that there'll be a full-time policeman outside the hack-
er's apartment on Monday through Wednesday of next week. They'll keep
watch continually, and they'll rush in to make an arrest as soon as he
connects to Berkeley."
      "How will the cop know when to bust in?"
      "You'll give the signal, Cliff."
      The next time the hacker touched my system, I would call the FBI and
Tymnet, They'd make the trace, tell the German BKA, and the cops would
bust into his apartment.
      Finally, after ten months.
      Will he show up? And what ifhe doesn't? Will they bust him anyway
or give up on the whole thing? With my luck, they'll drop the whole thing.
      I spent the weekend at home with Martha, arriving at the lab late
Sunday evening. With the best of luck, the hacker would show up on
Sventek's account, I'd call the FBI, and while he was dumping a file of my
concocted SOl baloney, he'd be busted. I could imagine him frantically
trying to conceal his computer as police break down his apartment's door.
      With dreams like those, I nestled under my desk, wrapped in the quilt
that Martha and I had made last winter. In case my beeper failed, two
personal computers stood watch, each wired to a bell. After ten months, I
wasn't going to miss my big chance.
      Monday afternoon, June 22, Wolfgang Hoffman cabled this message:
"Arrests expected shortly. Notify us immediately if hacker shows up."
      OK, I'm waiting. Every few minutes, I walk over to the switchyard
and everything's quiet. Oh yeah, a couple physicists are using Tymnet to
analyze some high-temperature superconductors. But there's no other traffic.
My alarms and tripwires are in place, but not a peep.
      Another night under the desk.
      Tuesday morning, June 23, Mike Gibbons called from the FBI.

                   THE CUCKOO'S EGG

      "You can close up shop, Cliff."
      "What's happened?"
      "Arrest warrants were issued this morning at 10 A.M."
      "But I didn't see anyone on my system then."
      "Makes no difference."
      "Anyone arrested?"
      "I can't say."
      "Where are you, Mike?"
      "In Pittsburgh."
      Something was happening. But Mike wouldn't say what. I'd wait for a
while before closing my doors to this hacker.
      A few hours later, Wolfgang Hoffman sent a message: "An apartment
and a company were searched, and nobody was home at the time. Printouts,
disks, and tapes were seized and will be analyzed in the next few days.
Expect no further break-ins."
      What does this mean? I guess the police busted his apartment. Why
didn't they wait for our signal? Should I celebrate?
      Whatever happened, at last we could seal our doors. I changed our
Tymnet passwords and patched the hole in the Gnu-Emacs editor. What
should we do about everyone's passwords?
      The only way to guarantee a clean system would be to change every
single password overnight. Then certify each user, one by one, the next
morning. Easy if there's only a few people on your system. Impossible for
our twelve hundred scientists.
      Yet if we didn't change every password, we couldn't be sure that some
other hacker might not have purloined an account. All it takes is one stolen
account. In the end we expired everyone's passwords and asked everyone to
pick a new one. One that's not in the dictionary.
      I set traps on all the hacker's stolen accounts. If anyone tries to log in
as Sventek, the system will reject the try-but it'll capture all the informa-
tion on where the call originates. Just let him try.
      Martha and I couldn't celebrate in a big way-her bar-exam cram
course was a ball and chain-but we played hooky for a day and escaped to
the North Coast. We wandered on the high cliffs covered with wildflowers
and watched the waves crash over the rocks a hundred feet below us. We
climbed down to an isolated little cove-our own private beach-and for a
few hours all my worries were far away, unreal.
      Within the next few days, word filtered back from Germany. Appar-

                                   ST 0 L L

ently the Hannover police had simultaneously searched an office at a small
computer company in Hannover, and the apartment of one of their employ-
ees. They seized eighty disks at the computer firm, and twice that at the
apartment. The evidence? Shipped to somewhere called Wiesbaden for
"analysis by experts." Hell, I could analyze it easily enough myself. Just
search for the word, "SDINET." As the inventor of that word, I could tell
instantly whether their printouts were the real McCoy.
       What's the hacker's name? What was he up to? What's the connection
with Pittsburgh? What's happened to him? Time to ask Mike of the FBI.
       "Now that it's all over, can you tell me the guy's name?" I asked.
       "It's not all over, and no, I can't tell you his name," Mike replied,
showing more than his usual annoyance at my questions.
       "Well, can I find out more about this guy from the Germans?" I knew
the prosecutor's name, even if I didn't know the hacker's.
       "Don't contact the Germans. This is sensitive, and you'll bollix things
       "Can't you even tell me if the hacker's in jail? Or is he wandering the
streets of Hannover?"
       "It's not for me to say."
       "Then when will I find out what happened?"
       "I'll tell you at the right time. Meanwhile, keep all your printouts
locked up."
       Lock up the printouts? I looked across my office. Sandwiched between
bookshelves of computer manuals and astronomy books, were three boxes
of the hacker's printouts. My office door doesn't have a lock, and the
building is open twenty-four hours a day. Oh-the janitor's closet can be
locked. I could stash the boxes up over the sink, on the shelf next to the
       While he was still on the phone, I asked Mike when I could expect to
hear back on this case.
       "Oh, in a few weeks. The hacker will be indicted and brought to
trial," Mike said. "Meanwhile, keep silent about this. Don't publicize it and
stay away from reporters."
       "Why not?"
       "Any publicity may let him off. The case is tough enough without
being tried in the newspapers."

                  THE CUCKOO'S EGG

      "But surely this is an open-and-shut case," I protested. "The u.s.
Attorney said that we had more than enough evidence to convict the guy."
      "Look, you don't know everything that's going on," Mike said. "Take
my word for it: don't talk about it."
      The FBI was happy with their work, as well they should be. Despite
several false starts, Mike had stuck with the investigation. The FBI wouldn't
let him tell me anything; there wasn't much I could do about that. But he
couldn't stop me from checking on my own.
      Ten months ago, Luis Alvarez and Jerry Nelson had told me to treat
the hacker as a research problem. Well, at last the investigation was com-
plete. Oh, there were a few details to figure out, but the real work was over.
Yet the FBI wouldn't let me publish what I'd learned.
      When you run an experiment, you take notes, think for a while, then
publish your results. If you don't publish, nobody will learn from your
experience. The whole idea is to save others from repeating what you've
      It was time for a change anyway. I spent the rest of the summer
making weird computer pictures of telescopes and teaching a few classes at
the computer center. The pursuit of the German had taught me about how
to connect computers together.
      Sooner or later, the FBI would let me publish. And when it did, I'd be
ready. Around the beginning of September, I started writing a dry, scientific
paper about the hacker. I just distilled my lab notebook-all 125 pages of it
-into a boring article and got it ready for some obscure computer journal.
      Still, letting go of the hacker project wasn't entirely easy. For a year,
the chase had consumed my life. In the course of my quest, I'd written
dozens of programs, forsaken the company of my sweetheart, mingled with
the FBI, NSA, aSI, and CIA, nuked my sneakers, pilfered printers, and
made several coast-to-coast flights. I pondered how I would now spend my
time, now that my life wasn't scheduled around the whims of some faceless
foe from overseas.
      Meanwhile, six thousand miles away, someone was wishing that he'd
never heard of Berkeley.

                                ST 0 L L

o    0      0    A month before the Hannover hacker was caught, Darren
Griffith had joined our group, having moved up from Southern California.
Darren liked punk music, Unix networks, laser typography, and friends
with spiked haircuts-in that order. Besides the coffeehouses and concerts,
Berkeley attracted him because of its hundreds of Unix computers tied
together with an ethernet, making an intricate maze for Darren to explore.
      At work, our boss set him loose to work in his own rhythm and at
whatever projects interested him. After five, when the normal folks left, he
cranked up the stereo in his cubicle, and wrote programs to the sound of
U2. "The louder the music, the better the code."
      I filled him in on the past year's hack and figured that he'd be de-
lighted with the hole in Gnu-Emacs, but he just shrugged. "Eeh, anyone
could see how to exploit that. Anyway, it's only on a few hundred systems.
Now if you want a tasty security hole, check out VMS. They've got a hole
you could drive a truck through."
      "Yeah. It's in every Vax computer from Digital Equipment Corpora-
tion that runs the VMS operating system Version 4.5."
      "What's the problem?"
      Darren explained. "Anyone that logs into the system can become sys-
temmanager by running a short program. You can't stop 'em."
      I hadn't heard of this problem. "Isn't DEC doing something about it?
After all, they sell those systems."
      "Oh, sure, they're sending out patches. But they're being real quiet
about it. They don't want their customers to panic."
      "Sounds reasonable."
      "Sure, but nobody's installing those patches. What would you do-
some tape shows up in the mail saying, 'Please install this program or your
system may develop problems' . . . you'll ignore it, because you've got
better things to do."
      "So all these systems are open to attack?"
      "You got it."

                         THE CUCKOO'S EGG

       "Wait a second. That operating system was certified by NSA. They
tested it and certified it secure."
       "Sure they spent a year testing it. And a month after they verified the
system, DEC modified it slightly. Just a little change in the password pro-
gram." The National Computer Security Center's verification program had
a hole in it as well.
       "And now fifty thousand computers are insecure." I couldn't believe
it. If my hacker knew, he'd have a field day. Good thing we'd nailed him.
       This problem seemed important, so I called Bob Morris at the Na-
tional Computer Security Center. He'd not heard of it before, but he prom-
ised to check into it. Well, I'd done my job and warned the authorities.
       Around the end of July, Darren picked up a message from the net-
work. Roy Omond, a system manager in Heidelberg, Germany, had de-
tected a group called Chaos Computer Club breaking into his Vax com-
puter. They'd used the hole that Darren had described. Omond's message
described how these vandals had broken in, set up Trojan horses to capture
passwords, then erased their trails behind them.
       The Chaos Computer Club, huh? I'd heard rumors that back in 1985, a
few German hackers banded together to "explore" computer networks. To
them the government monopoly only made trouble-they called it the
"Bundespest."* They soon developed into a gang that systematically at-
tacked computers in Germany, Switzerland, France, and eventually the
United States. Those pseudonyms I'd heard of before-Pengo, Zombie,
Frimp-were all members . . . self-styled cyberpunks who prided them-
selves on how many computers they could break into.
       Sounded familiar.
       By the end of the summer, the problem had spread. The Chaos gang
broke into a hundred computers around the world, using the NASA SPAN
network. Wait a second. The Petvax computer! Those alarms in June-I'd
traced them back to the NASA network. I'll bet that the connection wended
its way all the way back to Germany. Uh oh.
       Pretty soon, I realized what was happening. The Chaos Computer
Club had broken into computers at the CERN physics laboratory in Swit-
zerland, and caused endless headaches there-they were said to have stolen
passwords, destroyed software, and crashed experimental systems.
       All for the fun of it.

* In   truth, German telephone rates are exorbitant compared to those in North America.

                                ST 0 L L

      From the Swiss laboratory, Chaos members had stolen passwords to
reach into computers at American physics labs-Fermilab in Illinois,
Caltech, and Stanford. From there, it was a short hop to the NASA network
and into NASA's computers.
      Every time they entered a computer, they used the bug to become
system manager. Then they modified the operating system to let them in
with a special password-one known only to them. Now, whenever a
Chaos Club member used the magic password on an injured Vax computer,
they'd get in . . . even if the original hole was fixed!
      Whoa! Serious stuff here. Hundreds of computers were at risk. They
could easily wreck the software on each system. But what to do? NASA's
not responsible for each computer connected to its network. Half of them
are at universities, running scientific experiments. NASA probably doesn't
even have a list of all the computers attached to its network.
      The NASA network, like the Milnet, is a roadway connecting com-
puters around the country. A burglar will naturally use that road, but that's
hardly the fault of the road's builder. NASA's only responsible for keeping
the road intact. The security of each computer rests in the hands of the
people running it.
      The Chaos Computer Club created headaches for network folks-they
were thumbing their noses at hundreds of system managers and thousands of
scientists. If you owned a Vax computer, you had to rebuild the system
software from scratch. That's an afternoon's work. Multiply that by a thou-
sand sites. Or was it fifty thousand?
      At last the Chaos Club triumphantly announced their break-ins to the
press, painting themselves as brilliant programmers. I searched for any men-
tion of my laboratory, of Milnet, or of Hannover. Nothing. It was as if
they'd never heard of my hacker. Yet what a coincidence: a couple months
after I nail a German hacker breaking into computer networks, a German
club goes public, saying that they've prowled through NASA's networks.
      Could this be who had broken into my computer? I thought for a
while. The Chaos gang seemed to work with the VMS operating system
and knew little about Unix. My hacker certainly knew VMS, but he seemed
more at home on Unix. And he had no hesitation to exploit any bug in the
computer. Hannover is close to Hamburg, the home of Chaos. Less than a
hundred miles.
      But my hacker was arrested on June 29. The Chaos Club was breaking
into systems during August.

                  THE CUCKOO'S EGG

      Hmmm. If the LBL hacker from Hannover was in contact with the
Chaos Club, his arrest would send shock waves through the entire club.
They'd evaporate as soon as they heard that one of their members had been
      Another wrinkle . . . NASA doesn't have secrets. Oh, perhaps the
military shuttle payloads are classified. But almost everything else about
NASA is public. Right down to the design of their rockets. Hell, you can
buy the space shuttle's blueprints. Not the place for a spy.
      No, my hacker wasn't in Chaos. Probably he was loosely tied into
their club . . . perhaps he checked into their electronic bulletin board. But
they didn't know about him.
      Chaos Club members justify their actions with a peculiar set of ethics.
They claim that it's perfectly all right for them to roam through others'
databases, so long as they don't destroy any information. In other words,
they believe their technicians' curiosity should take precedence over my
personal privacy. They claim the right to peruse any computer they can
break into.
      Information in databases? They've no qualms, if they can figure out
how to get it. Suppose it's a list of AIDS patients? Or your last year's
income tax return? Or my credit history?
      Darren had been great to talk to about all of this, with his knowledge
of networks and sharp eye for holes. But whenever we talked, he seemed
amused and distant, looking at the hacker problem purely as an intellectual
game. I felt that he looked down at me for getting caught up in it, being
out to get the hacker.
      Finally one afternoon after Darren had patiently listened to my whin-
 ing about the hacker and my gloomy predictions of future trouble, he fixed
 me with a stare.
      "Cliff," he said, "you're an old fart. Why do you care so much that
someone's frolicking in your system. That could have been you, in your
distant youth. Where's your appreciation of creative anarchy?"
      I tried to defend myself-as I'd tried with Laurie, months ago. I hadn't
set out be be a network cop. I'd started with a simple puzzle: why did my
accounting show a 75-cent error? One thing led to another, and I ended up
on the trail of our friend.
      And I didn't just blunder around in a blind rage, trying to nab the guy
just because he was there. I learned what our networks are. I had thought of

                                S TaL L

them as a complicated technical device, a tangle of wires and circuits. But
they're much more than that-a fragile community of people, bonded to-
gether by trust and cooperation. If that trust is broken, the community will
vanish forever.
      Darren and other programmers sometimes expressed respect for hack-
ers because they test the soundness of systems, reveal holes and weaknesses. I
could respect this view-it takes a rigorous, honest mind to feel gratitude to
someone who exposes our mistakes-but I could no longer agree with it. I
saw the hacker not as a chess master, teaching us all valuable lessons by
exploiting the weak points in our defenses, but as a vandal, sowing distrust
and paranoia.
      In a small town, where people never locked their doors, would we
praise the first burglar for showing the townspeople how foolish it was to
leave their houses open? After it happened, the town couldn't. ever go back
to open doors.
      Hacking may mean that computer networks will have to have elabo-
rate locks and checkpoints. Legitimate users will find it harder to communi-
cate freely, sharing less information with each other. To use the network,
we all might have to identify ourselves and state our purpose-no more
logging on casually just to gossip, doodle around, see who else is on the net.
      There's plenty of room for truly "creative anarchy" on the networks as
they are-nobody is in charge of them, nobody makes the rules-they exist
purely out of cooperative effort and they evolve freely at the whim of their
users. A hacker's abuse of this openness might mean the end of the casual,
communal way the networks are run.
      I could finally answer Darren. All my buddying up with spooks in
suits and playing computer cop came from my appreciation for creative
anarchy. To have the networks as our playground, we have to preserve our
sense of trust; to do that, we have to take it seriously when people break
that trust.
      But though I finally felt like I knew why I'd done it, I still didn't
know what I had done. What was the guy's name in Hannover? Who was
behind the whole thing? Nobody would tell me.
      As the summer stretched on, the case showed every indication of dying
out. Mike Gibbons didn't call and seldom returned my calls. It was as if
nothing had happened.
      I understood the technical aspects of the case-the computer's holes

                  THE CUCKOO'S EGG

and the hacker's location. Wasn't that all I'd wanted? But something was
wrong. This wasn't satisfying.
     I knew the whats and the hows. I wanted to know the who's and

o     0 0 Who's behind it? Only one way to find out. Do research.
      The FBI wouldn't tell me anything except, "Be quiet and don't ask
questions." Not helpful.
      Maybe my poking around would upset some trial that was going on.
But if there was a trial, surely they'd need my cooperation. After all, I had
the crucial evidence: a couple thousand pages of printouts, all neatly folded
into boxes and locked up in a janitor's closet.
      Well, even if I couldn't ask questions, I could still do science. Publish-
ing your results is as much a part of research as investigating a weirdness. In
my case probably more important. As rumors of this hacker spread, military
people began to call, asking for more information. What should I tell them?
      The end of August marked a year after we'd first detected this hacker
in our computers, and two months after we finally nailed him in Hannover.
The FBI still told me to keep quiet.
      Of course, the FBI couldn't legally prevent me from publishing, or
even poking around. Martha was adamant: "You're free to write what you
wish. That's what the First Amendment's all about."
      She should know. She was in the midst of studying constitutional law
for her bar exam. Just three more weeks, and it'd be all over. To take her
mind off the exam, we began sewing a quilt. Just a few minutes here and
there, but the design grew and grew, and though I didn't realize it, some-
thing wonderful was growing with it.
      We split up the work of making the quilt the way we always had.
She'd do the piecing, I'd sew the squares, and we'd both share the quilting.
We'd just started cutting the pieces when Laurie stopped by for brunch.
      Martha showed her the design and explained that the quilt would be
called "Garden Star." The central blazing star would be bright yellow and
orange, like the peonies in our garden. Surrounding it would be a ring of

                                 ST 0 L L

tulips, and then a border called "snowball," like the snowball bushes we had,
the first plants to bloom in spring. Laurie suggested another border, called
"flying geese," to represent the birds in the garden.
      Listening to Laurie and Martha talk about quilting patterns, each one
with its ancient, romantic name, I felt a deep warmth. Here was my home,
my love. The quilt we were making now would last our whole lives, in
fact, it would outlive us and still be there to comfort our grandchil-
dren . . .
      Whoa. I was getting carried away. After all, Martha and I weren't
married or anything, just living together, just sharing our lives while it was
good for both of us, free to move on if things weren't working out. Yeah. It
was better that way, more open and enlightened. None of this old-fashioned
"till death do us part" stuff.
      Yeah, sure.
      Laurie startled me, her words somehow picking up on my private
thoughts. "This should be your wedding quilt." Martha and I both stared at
      "Really. You two are already married-anyone can see it. You've been
best friends and lovers for almost eight years. So why don't you make it
official and celebrate?"
      I was completely at a loss. What Laurie had said was so true and
obvious that I'd been blind not to see it. I had been stuck thinking that we
should just go on, one day at a time, being together "for now," while things
were good. But really, would I leave Martha if we were going through
hard times? Would I leave her if someone else attracted me more? Was that
the kind of person I wanted to be, and the way I wanted to live the rest of
my life?
      At that moment I realized what to do, and how I wanted to live. I
looked at Martha, her face calm and still, bent over the bright pieces of
calico. There were tears in my eyes, and I couldn't speak. I looked at Laurie
for help, but the moment she saw my face, she vanished into the kitchen to
make tea, leaving Martha and me alone together.
      She raised her head and looked at me steadily.
      "When do you want to get married?"
      "What about next spring, after the rainy season, when there are roses?"
      So it was done. No looking back, no regrets, no glancing around to see
if someone better would come along. Martha and me, for the rest of our

                   THE CUCKOO'S EGG

lives. Laurie poured out the tea, and we all sat together, not saying much,
but so happy.
      By October I started thinking about the hacker again. Darren and I
argued about whether to publish a paper. "If you don't say something,"
Darren argued, "some other hacker will wreck someone else's computer."
      "But if I do publish, it'll teach a dozen hackers how."
      That's the problem with talking about security problems. If you de-
scribe how to make a pipe bomb, the next kid that finds some charcoal and
saltpeter will become a terrorist. Yet if you suppress the information, people
won't know the danger.
      January marked six months since the hacker had been busted, a year
and a half since we'd first detected him. Yet I still didn't know his name. It
was about time to publish my results.
      So I sent the paper to Communications of the Association of Computer
Machinery. Though you won't find it on newsstands, Communications reaches
most computer professionals, and it's a real scientific journal: every article is
refereed. Which meant that three other computer scientists checked over my
article and made anonymous comments on whether it should be published.
      The paper was to come out in the May issue. Together, the Association
for Computer Machinery and Lawrence Berkeley Labs scheduled a joint
announcement for May first.
     May would be a goofy month. Martha and I planned on getting
married at the end of the month. We'd reserved the Berkeley Rose Garden,
sewn our wedding clothes, and invited our friends and relatives. Even with-
out the publicity of the hacker, this month wouldn't be calm.
     Well, we were pretty much all set when the German magazine Quick
got there first. On April 14, they printed a story about how a German
hacker had broken into three dozen military computers. Although their
reporter had managed to meet the hacker, most of their story came from my
     My logbook! How did Quick magazine, a cross between Life and the
National Enquirer, manage to get ahold of my laboratory logbook? 1'd kept
my logbook on my computer-it lived on disks, not on paper. Did some-
one break into my computer and read my logbook?
     Impossible. My logbook was on my Macintosh: I never connected to
any network, and I hid the disk in my desk every night.
     I reread the translation of the article, and realized that someone had

                                ST 0 L L

leaked a copy of my logbook from a year ago, January. Before I'd set up the
phoney SDINET sting. Had I given a copy of that logbook to anyone?
      Yes, I had. On January 10, I'd sent the logbook to Mike Gibbons at the
FBI. He must have forwarded it to the Legal Attache in Bonn. Who knew
where it landed next?
      Someone had leaked it to Quick magazine. And they published the
story two weeks before I was going to. Damn.
      One year of silence. A year of covert cooperation with the authorities.
Betrayed to a cheap tabloid in Germany. How ignominious.
      Even with a copy of my notebook, Quick was anything but accurate.
Not much to do but get the facts out ourselves. Damn.
      Whatever we did, we'd be late. John Markoff-now at the New York
Times-had heard about the story and was asking questions. Damn. Only
one thing to do: my lab announced a press conference. With me at center
stage. Damn.
      That evening, at 11 P.M., I was nervous and worried sick. Me? At a
press conference? A phone call from the NSA didn't help, either.
      Sally Knox, an administrator with NSA's computer security center,
was in town. She'd heard about tomorrow's press conference. "Don't you
dare mention our name," she barked into my ear. "We get enough bad press
as it is."
      I look at Martha. She hears this woman's voice from the phone and
rolls her eyes. I try to soothe the spook's worries.
      "Look, Sally, NSA hasn't done anything wrong. I'm not about to say
that your funding ought to be cut."
      "It doesn't matter. As soon as the media hears our name, there'll be
trouble. They distort everything about us. They'll never publish a fair
       I look at Martha. She's motioning me to hang up.
      "OK, Sally," I said. "I'll make sure that I don't even mention your
agency. If anyone asks, I'll just say, 'No comment.' "
      "No, don't do that. Then those pigs will sniff around and pick up
more. Tell them that we had nothing to do with it."
      "Look, I'm not gonna lie, Sally. And anyway, isn't the National Com-
puter Security Center a public, unclassified agency?"
      "Yes, it is. But that's no reason to let the press prowl around."
      "Then why don't you send one of your people to my press confer-

                     THE CUCKOO'S EGG

         "None of our employees are authorized to talk to the media."
          With this attitude, it's no wonder her agency gets such bad press.
          Martha wrote me a note: "Ask her if she's ever heard of the First
    Amendment," but I couldn't get a word in edgewise. Sally went on about
    how the Congress was out to get them, the press was out to get them, and I
    was out to get them.
          She ranted for twenty-five minutes, trying to convince me not to
    mention NSA or the National Computer Security Center.
          It's 11:30 at night, I'm exhausted, and I can't take any more. I'll do
    anything to get off the phone.
          "Listen, Sally," I say, "where do you get off, telling me what I can't
          "I'm not telling you what to say. I'm telling you not to mention the
    Computer Security Center."
          I hung up.
          Martha rolls over in bed and looks at me. "Are they all like that?"
          The next morning's press conference was a zoo. I'm accustomed to
    scientific meetings and technical seminars. You always hear about press con-
    ferences, but I'd never actually seen one. Now I'm the target of one.
          It was nuts. Along with my boss, Roy Kerth, I spouted for half an
    hour, answering questions from reporters. The television reporters asked
    easy ones ("How do you feel now that it's over?"), while the newspaper
    people asked jagged, tough questions-"What should be the national policy
    on computer security?" Or "Was Admiral Poindexter justified in clamping
    down on sensitive but unclassified material?"
          Nobody asked about the NSA. Not a mention of the National Com-
    puter Security Center. Sally had blathered for half an hour in vain.
          Beforehand, I'd been pretty jaded on the press. Figured that they'd
    distort whatever happened. Now here was a technical story, spanning two
    continents and a year's work. How would the American media report it?
          Amazingly accurately. My technical article had more details-the
    Gnu-Emacs hole, how the hacker cracked passwords-but I was astounded
    by how well newspapers conveyed the story. The important stuff was there
    -the military computers, the sting, even Operation Showerhead.
          And these reporters did their homework. They called Germany and
    somehow dug up what I had never found: the hacker's name. They phoned
    the hacker.

                                ST 0 L L

o     0      0 "Hello, is this Markus Hess in Hannover?"
      "This is Richard Covey. I'm a reporter here in California. May I talk
with you?"
      "I cannot talk."
      "About this hacker case-could you tell me if you worked alone or
with someone else?"
      "I cannot answer that. The case is still running in the German courts."
      "What were your intentions?"
      "It was strictly a hobby."
      "Are you a student?"
      "Uh, yes. I cannot speak on the phone because I do not trust the lines.
They may be tapped."
      "Do you have a lawyer?"
      "What is his name?"
      No answer.
      "Do you know Laszlo Balogh in Pittsburgh?"
      "No. Never heard of him, except for the newspaper stories."
      "Can you speculate on how Balogh got the false data?"
      "I cannot answer that question."
      "Did you work with anyone?"
      "I cannot say. I am not comfortable talking. I am not sure that the
lines are clean."
      "Were you a spy?"
      "Ha. Anyone who believes that is ridiculous. I was just curious."
      "Can you guess how the data got to Pittsburgh?"
      "No, I cannot guess. I did not show it to anyone. It is dangerous for
me to say anything more because I do not know if the telephone lines are
      "Were you paid for your work?"
      "I must go now. I cannot talk." Click.

                  THE CUCKOO'S EGG

      Markus Hess. After all this time, my cuckoo's name is Markus Hess.
      Well, he speaks English, although without contractions. And he's as
paranoid on the telephone as he is on the computer-always looking over
his shoulder. German newspapers report that Hess is five foot ten inches,
twenty-five years old, broad-shouldered, and known to his friends as a solid
but not brilliant Unix programmer. And he chain-smokes Benson and
      Once again, I page through the Hannover telephone directory. There's
his name, all right, but who is he? What's this guy up to? I'll never find out
from Berkeley.
      Maybe I should call someone in Germany? Who do I know there? A
couple students at the Max Planck Institute. Some astronomers in Darm-
stadt. And a college buddy in Hamburg.
      Around the end of the summer, a friend of a friend sent a letter to me:
"I need a place to stay while visiting San Francisco. Mind if I sleep on your
floor?" Seemed it was a high school student visiting from abroad.
      Martha, Claudia, and I don't exactly run a youth hostel, but our door's
always open for visitors. Michael Sperber stayed for a couple nights and
kept us amused with tales of touring the States.Just as interesting to me: his
dad, Jochen Sperber, is a reporter in Northern Germany and could make
contact with hackers around Hannover.
      I struck paydirt. By chance, I'd found someone who was curious,
persistent, and able to dig up the facts in Germany. Over the next five
months, Jochen Sperber found enough information to piece together what
happened at the other end of the trail.
      What really happened? Here's my estimate, based on interviews, police
reports, newspaper accounts, and messages from German computer pro-
      I'd been chasing a shadow. Now I could sketch a portrait.

                                   * * *
       In the early '80s, the Bundespost expanded the German telephone
service to include data networking. Their Datex service got off to a slow
start, but by 1985 businesses and universities began subscribing. It was a
convenient, if not cheap, way to interconnect computers spread across Ger-
       As everywhere, students started to exploit this service. First, discover-

                                 ST 0 L L

ing flaws in the system's protections; later, finding ways to connect abroad
through the network. The Bundespost had its hands full in starting up
Datex, and pretty much ignored these hackers.
      A dozen hackers started the Chaos Computer Club, whose members
specialize in creating viruses, breaking into computers, and serving as a
computer counterculture. Some are cyberpunks; a few are extremely profi-
cient in computing, others little more than novices. Through electronic
bulletin boards and telephone links, they anonymously exchanged phone
numbers of hacked computers, as well as stolen passwords and credit cards.
      Markus Hess knew of the Chaos Club, although he was never a central
figure there. Rather, he kept his distance as a free-lance hacker. During the
day, he worked at a small software firm in downtown Hannover.
      Over a crackling phone connection, Jochen Sperber said, "You see,
Hess knew Hagbard, who kept in touch with other hackers in Germany,
like Pengo and Bresinsky. Hagbard is a pseudonym, of course. His real name
1S • • •

      Hagbard. I'd heard that name before. After I hung up the phone, I
searched my logbook for Hagbard. There he was-he'd broken into Fermi-
lab and Stanford. Yet I'd seen it elsewhere. I searched databases at school and
asked friends. Not a peep. For the next three days, I asked every person I
met, in hopes that it might ring a bell with someone.
      At last, at a Berkeley bookstore, the woman behind the counter said,
"Why sure. Hagbard is the hero of the Illuminati books." It's a series of
science fiction novels, about an international conspiracy that controls the
world. The Illuminati run-and ruin-everything. Against this age-old
secret cult, Hagbard leads a small band of anarchists.
      So Hess's compatriot runs under the alias of Hagbard. He must really
believe that there's a conspiracy out there. And he probably feels that I'm
one of the secret Illuminati-out to suppress the good guys!
      Maybe he's right. A couple of my radical friends would agree with
him. But I sure don't know any secrets.
      Well, Hagbard worked closely with Markus Hess. The two drank
beers together at Hannover bars, and spent evenings behind Hess's computer.
   Who's Hagbard? According to the German magazine Der Spiegel,
Hagbard-Karl Koch-was a twenty-three-year-old programmer who
needed money to support a stiff cocaine habit, not to mention monthly
telephone bills for overseas hacking adventures.

                  THE CUCKOO'S EGG

   During 1986, some hackers from Berlin and Hannover discussed (over
alcohol and drugs) how to raise some money.
   Pengo-real name Hans Huebner-was an accomplished eighteen-year
old programmer who claimed to be in it for the pure technical challenge.
He was bored with those computers that he had legal access to, so he started
breaking into systems via the international networks. In a message posted to
a bulletin board, Pengo said that he was involved with "a circle of persons
who tried to make deals with an eastern secret service."
   Why? Since the software on the systems that he had legal access to
"didn't turn me on anymore, I enjoyed the lax security of the systems I had
access to by using [international] networks." Computing had become an
addiction for Pengo.
   But why sell the information to the Soviet bloc agents? According to Der
Spiegel, he needed money to invest in his computing company. So Pengo
got together with a couple others in West Berlin. One of them, Dirk
Brezinski, is a programmer and troubleshooter for the German computer
firm Siemens. Another, Peter Carl, also in Berlin, is a former croupier who
"always had enough cocaine."
   These five worked together to discover new ways to break into com-
puters, exploring military networks and sharpening their skills at cracking
operating systems. Pengo specialized in Digital's Vax VMS operating system
and frequently talked with Hagbard.
   Pengo had no scruples about selling information to Soviet bloc agents.
He saw himself as ethically neutral-he didn't want to give the Russians
any advantage; he just wanted to have fun on the networks.
   And pick up some cash along the way.
   Hess, too, just played around the networks, searching for ways to connect
around the world. He'd dropped out of the University of Hagen, where he
didn't quite fmish a degree in mathematics and physics. (Physics? If only
he'd known!)
      At first, Hess apparently just played around the networks, searching for
ways to connect around the world. Like a ham radio operator, he started out
a hobbyist, trying to reach as far away as possible. At first, he managed to
connect to Karlsruhe; later he reached Bremen over the Datex network.
      Soon, he discovered that many system managers hadn't locked their
backdoors. Usually these were university computers, but Markus Hess began
to wonder: how many other systems were wide open? What other ways
could you sneak into computers?

                                ST 0 L L

      In early 1986, Hagbard and Pengo were routinely breaking into com-
puters in North America: mostly high-energy physics labs, but a few NASA
sites as well. Hagbard described his exploits to Hess.
     The challenge was there. Hess began to explore outside of Germany.
But he no longer cared about universities and physics labs-he wanted real
excitement. Hess and Hagbard would target the military.
   The leaders of the Chaos Computer Club had issued a warning to their
members: "Never penetrate a military computer. The security people on the
other side will be playing a game with you-almost like chess. Remember
that they've practiced this game for centuries." Markus Hess wasn't listen-
     Hess found his way into an unprotected computer belonging to a
German subsidiary of the U.S. defense contractor, Mitre. Once inside that
system, he could have discovered detailed instructions to link into Mitre's
computers in Bedford, Massachusetts, and McLean, Virginia.
    Why not? The system was wide open, and let him call anywhere in
     By summer 1986, Hess and Hagbard were operating separately, but
frequently comparing notes. They collaborated in methodically twisting all
doorknobs as they walked down the streets of the military networks.
      Hess soon expanded his beachhead at Mitre. He explored their system
internally, then sent out tentacles into other American computers. He col-
lected telephone numbers and network addresses, and methodically attacked
these systems. On August 20, he struck Lawrence Berkeley Lab.
     Even then, Hess was only fooling around. He'd realized that he was
privy to secrets, both industrial and national, but kept his mouth shut. Then,
around the end of September, in a smoky Hannover beer garden, he de-
scribed his latest exploit to Hagbard.
   You can't make money by breaking into universities and colleges.
Who's interested in data from physics labs, other than a few grad students?
      But military bases and defense contractors? Hagbard smelled money.
      And Hagbard sensed who to contact: Pengo, in West Berlin.
     Pengo, with his contacts to hackers across Germany, knew how to use
Hess's information. Carrying Hess's printouts, one of the Berlin hackers
crossed into East Berlin and met with agents from the Soviet KGB.
   The deal was made: around 30,000 Deutschmarks-$18,000-for print-
outs and passwords.

                   THE CUCKOO'S EGG

  The KGB wasn't just paying for printouts, though. Hess and company
apparently sold their techniques as well: how to break into Vax computers;
which networks to use when crossing the Atlantic; details on how the
Milnet operates.
  Even more important to the KGB was obtaining research data about
Western technology, including integrated circuit design, computer-aided
manufacturing, and, especially, operating system software that was under
u.s. export control. They offered 250,000 Deutschmarks for copies of Digi-
tal Equipment's VMS operating system.
   Peter Carl and Dirk Brezinski apparently met with the KGB a dozen
times, filling many of their requests: source code to the Unix operating
system, designs for high-speed gallium-arsenide integrated circuits, and com-
puter programs used to engineer computer memory chips.
  Alone, the source code to Unix isn't worth $130,000. Chip designs?
Perhaps. But a sophisticated computer design program . . . well, maybe
the KGB did get its money's worth.
   Hagbard wanted more than Deutschmarks. He demanded cocaine. The
KGB was a willing supplier.
      Hagbard passed some of the money (but none of the cocaine) to Hess,
in return for printouts, passwords, and network information. Hagbard's cut
went to pay his telephone bill, sometimes running over a thousand dollars a
month, as he called computers around the world.
      Hess saved everything. He kept a detailed notebook and saved every
session on a floppy disk. This way, after he disconnected from a military
computer, he could print out the interesting parts, and pass these along to
Hagbard and on to the KGB.
     Also the KGB's wish list was SDI data. As Hess searched for it, I
naturally detected SDI showing up in his requests. And Martha's Operation
Showerhead fed Hess plenty of SDI fodder.
     But could the KGB trust these printouts? How could they be certain
that Hagbard wasn't inventing all of this to feed his own coke habit?
     The KGB decided     to   verify the German hacker ring. The mythical
Barbara Sherwin served as a perfect way to test the validity of this new
form of espionage. She had, after all, invited people to write to her for
more information.
     But secret services don't handle things directly. They use intermedi-
aries. The KGB contacted another agency-either the Hungarian or Bulgar-

                                 ST 0 L L

ian intelligence service. They, in turn, apparently had a professional rela-
tionship with a contact in Pittsburgh: Laszlo Balogh.
     The Bulgarian embassy in America probably has a standing agreement
with Laszlo along the lines of "We'll pay you $100 for mailing the follow-
ing letter . . ."
     Laszlo Balogh didn't care one way or another. According to Roger
Stuart of the Pittsburgh Press, Laszlo billed himself as a Hungarian refugee; a
draftsman; a credit corporation employee; a trucking company owner; a
diamond dealer; a world traveler; a bodyguard for Kuwaiti princesses; a
CIA hit man; and an FBI informant.
     The reporter wrote "Although he has claimed extensive foreign gov-
ernment contacts and driven expensive foreign cars, he once testified that he
had difficulty recording an undercover conversation for the FBI because the
recorder kept slipping beneath his sweat suit."
      Apparently Balogh ran a now-defunct company when a forged check
drawn on a nonexistent bank was used to obtain a garbage hauling contract.
Other times he was involved in schemes to steal $38,000 in diamonds, and to
sell computer equipment to the Soviets. Indeed, he once claimed to have
been held captive at the Soviet embassy.
      As long as the money was green, Laszlo didn't care where it came
from. He knew nothing about SDINET, knew nobody in Hannover, and
said he didn't even own a computer.
      Hmmm. I looked over Laszlo's letter. It had been word-processed-
not a typewriter, but a word processor. If Laszlo Balogh doesn't own a
computer, then who'd created this letter? The Bulgarian embassy perhaps?
    Does the FBI have enough evidence to indict Laszlo Balogh? They
won't tell me. But the way I see it, Laszlo's in deep yogurt: the FBI is
watching him, and whoever's pulling his puppet strings isn't pleased.
      The West German police, though, have plenty of evidence against
Markus Hess. Printouts, phone traces, and my logbook. When they broke
into his apartment on June 29, 1987, they seized a hundred floppy disks, a
computer, and documentation describing the U.S. Milnet. Not much doubt
    But when the police raided Hess's apartment, nobody was home.
Though I was waiting patiently for him to appear on my computer, the
German police entered his place when he wasn't connected.
    At his first trial, Hess got off on appeal. His lawyer argued that since

                  THE CUCKOO'S EGG

Hess wasn't connected at the moment his apartment was raided, he might
not have done the hacking. This, along with a problem in the search war-
rants, was enough to overturn the case against Hess on computer theft. But
the German federal police continued to investigate.
      On March 2,1989, German authorities charged five people with espio-
nage: Pengo, Hagbard, Peter Carl, Dirk Bresinsky, and Markus Hess.
      Peter Carl met regularly with KGB agents in East Berlin, selling any
data the others could find. When the German BKA caught up with him, he
was about to run off to Spain. He's now in jail, awaiting trial, along with
Dirk Bresinsky, who was jailed for desertion from the German Army.
      Pengo is having second thoughts about his years working for the
KGB. He says that he hopes he "did the right thing by giving the German
police detailed information about my involvement." But as long as there's
an active criminal case, he'll say no more.
      All the same, the publicity hasn't helped Pengo's professional life. His
business partners have shied away from backing him, and several of his
computing projects have been canceled. Outside of his business losses, I'm
not sure he feels there's anything wrong in what he did.
      Today, Markus Hess is walking the streets of Hannover, free on bail
while awaiting a trial for espionage. Smoking Benson and Hedges cigarettes.
And looking over his shoulder.
      Hagbard, who hacked with Hess for a year, tried to kick his cocaine
habit in late 1988. But not before spending his profits from the KGB: he
was deep in debt and without a job. In spring 1989 he found a job at the
office of a political party in Hannover. By cooperating with the police, he
and Pengo avoided prosecution for espionage.
      Hagbard was last seen alive on May 23, 1989. In an isolated forest
outside of Hannover, police found his charred bones next to a melted can of
gasoline. A borrowed car was parked nearby, keys still in the ignition.
      No suicide note was found.

                                ST 0 L L

o       0 0 When I began this hunt, I saw myself as someone engaged
in mundane tasks. I did what I was assigned to do, avoided authority, and
kept myself peripheral to important issues. I was apathetic and outside the
political sphere. Yeah, I vaguely identified myself with the old '60s left
movement. But I never thought much about how my work interacted with
society . . . maybe I picked astronomy because it has so little to do with
earthly problems.
       Now, after sliding down this Alice-in-Wonderland hole, I find the
political left and right reconciled in their mutual dependency on computers.
The right sees computer security as necessary to protect national secrets; my
leftie friends worry about an invasion of their privacy when prowlers pilfer
data banks. Political centrists realize that insecure computers cost money
when their data is exploited by outsiders.
      The computer has become a common denominator that knows no
intellectual, political, or bureaucratic bounds; the Sherwin Williams of ne-
cessity that covers the world, spanning all points of view.
       Realizing this, I've become pro-active-almost rabid-about com-
puter security. I worry about protecting our vulnerable data banks. I won-
der what happens on financial networks, where millions of dollars slosh
around every minute. I'm ticked that the Feds don't seem to be minding the
mint. And I'm upset that looters have proliferated.
       It took a lot of crap to make me give a damn. I wish that we lived in a
golden age, where ethical behavior was assumed; where technically compe-
tent programmers respected the privacy of others; where we didn't need
locks on our computers.
       I'm saddened to find talented programmers devoting their time to
breaking into computers. Instead of developing new ways to help each
other, vandals make viruses and logic bombs. The result? People blame
every software quirk on viruses, public-domain software lies underused, and
our networks become sources of paranoia.
       Fears for security really do louse up the free flow of information.
Science and social progress only take place in the open. The paranoia that

                  THE CUCKOO'S EGG

hackers leave in their wake only stifles our work . . . forcing administra-
tors to disconnect our links to networked communities.
   Yes, you can make secure computers and networks. Systems that outsiders
can't easily break into. But they're usually difficult to use and unfriendly.
And slow. And expensive. Computer communications already costs too
much-adding cryptographic encoding and elaborate authentication
schemes will only make it worse.
   On the other hand, our networks seem to have become the targets of (and
channels for) international espionage. Come to think of it, what would I do
if I were an intelligence agent? To collect secret information, I might train
an agent to speak a foreign language, fly her to a distant country, supply her
with bribe money, and worry that she might be caught or fed duplicitous
    Or I could hire a dishonest computer programmer. Such a spy need never
leave his home country. Not much risk of an internationally embarrassing
incident. It's cheap, too-a few small computers and some network connec-
tions. And the information returned is fresh-straight from the target's
word processing system.
   Today there's only one country that's not reachable from your telephone:
Albania. What does this mean for the future of espionage?
   Yow! What am I thinking about? I'm not a spy-I'm just an astronomer
who's been away from science for too long.
      As I turned off my monitors and wound up the cables, I realized that
for a year, I'd been caught in a maze. I'd thought I'd been setting traps;
actually, I'd been trapped the whole while. While the hacker was searching
military computers, I was exploring different communities-on the net-
works and in the government. His journey took him into thirty or forty
computers; mine reached into a dozen organizations.
      My own quest had changed. I thought I was hunting for a hacker. I'd
imagined that my work had nothing to do with my home or country . . .
after all, I was just doing my job.
      Now, with my computers secured and holes patched, I biked home,
picked a few strawberries, and mixed some milkshakes for Martha and
      Cuckoos will lay their eggs in other nests. I'm returning to astronomy.


o      0 0 While I was desperately trying to wrap up the hacker chase,
we also had a wedding to plan. It was a hectic time, and I cursed my work
(and Hess) for distracting me from my home life. We were going to be
married at the end of May, so the April revelations were particularly awk-
ward, Martha ending up with more than her share of the preparations.
      She was coping, however, firmly resolved to make the wedding true
to who we were. We silk-screened our own invitations, saying that the two
of us, along with our families, were doing the inviting. Naturally, the ink
on the silk-screen leaked through, and half the invitations had our finger-
prints, but that's a part of the home brew.
      Martha decked out in a white dress and veil, and me in a tux? Absurd.
And Laurie in a bridesmaid's outfit? Nobody ever made Laurie wear a dress
for any reason. Somehow we managed. Laurie wore white linen pants and a
tailored jacket, Martha made a simple pale yellow dress, and I sewed my
own cotton shirt. (Try sewing your own shirt sometime. You'll learn a new
respect for shirtmakers, especially after you sew the cuffs on backward.)
      So it rained on our wedding and there wasn't a place to hide in the
rose garden. Claudia's string quartet unraveled a tarp, protecting their vio-

                                 ST 0 L L

lins from the downpour. My sister Jeannie showed up, straight from her last
class at Navy War College-and straight into a political argument with
Laurie. Of course, after the ceremony, we got lost driving to a remote inn
by the ocean.
       It was wonderful, all the same. Say what you will about marriage, this
was the happiest day of my life.
       Sure, I could have just stayed living with Martha, never quite commit-
ting myself beyond next month's rent. I'd lived with several other people in
this casual way, saying we were in love, but always ready to split if things
got tough. We dressed it up with talk about openness and freedom from
oppressive conventions, but for me it was just an excuse. The truth was, I
had never dared to give myself fully to anyone, committing myself to make
it work no matter what. But now I'd found someone I loved and trusted
enough to gather my courage and stand by, not just for now but forever.
       But domestic happiness doesn't solve every thing-I still had to figure
out what to do next. With Hess unmasked, I could return to astronomy, or
at least, computing. Not quite tracking an international spy ring, but then,
there's research to do everywhere. The best part is not knowing where your
science will lead you.
       It wasn't the same. The computer people felt I'd wasted the past couple
years rubbing shoulders with spies. The spies didn't have much use for me-
who needs an astronomer? And the astronomers knew I'd been away from
the field for two years. Where do I go from here?
       Martha had passed her bar exam and was clerking for a judge across
the bay, in San Francisco. She loved it-taking notes on trials, researching
case law, helping to write decisions. A sort of grad school for law.
       She found another clerkship in Boston, starting in August '88. Over a
strawberry milkshake, she described her possibilities:
       "I'd clerk for the circuit court in Boston. It'll be more academic there
-no trials, just appeals. Might be fun."
       "And the alternatives?"
       "Well, I'm thinking about returning to school, to finish my degree in
jurisprudence. That'll take a few more years." Always the academic.
       Would I leave Berkeley to follow her to Massachusetts?
       Simple decision: I'd follow her anywhere. If she's going to Boston, I'd
dredge up a job there. Fortunately, the Harvard Smithsonian Center for
Astrophysics was looking for a half-breed astronomer-computer jockey,
someone to play with their X-ray astronomy database.

                  THE CUCKOO'S EGG

      I can mess up a database as well as the next person, and they didn't
mind my hiatus from astronomy. And, being astronomers, they were al-
ready accustomed to people showing up late and sleeping under desks.
      It wasn't easy to leave Berkeley-the strawberries, the street vendors,
the sunshine-but we signed a nonaggression pact with our roommates: we
could visit anytime and wouldn't have to wash the dishes. In return, they
could stay at our place in Massachusetts, so long as they brought some
California kiwi fruit.
      The hardest part was leaving our roommate Claudia. I'd grown accus-
tomed to her late-night Mozart practicing (a long way from the Berkeley
Grateful Dead concerts!). She hadn't quite settled down with a mate, al-
though several promising musicians were courting her just as we left. The
latest gossip? Oh, there's this handsome orchestra conductor that's simply
lusting after her . . .
      So, in August 1988, we packed a couple suitcases for a year in Massa-
      Being uprooted and towed to the East Coast had a few advantages.
My computer network address changed . . . a good thing, since several
hackers had tried to break into it after I published my article. One or two
had threatened me in various ways-better not to give 'em a standing
target. And various three-letter agencies stopped calling me, asking for
advice, opinions, and rumors. Now, in Cambridge, I could concentrate on
astronomy, and forget about computer security and hackers.
      Over the past two years, I'd become an expert on computer security,
but hadn't learned a thing about astronomy. Worse, the physics of X-ray
astronomy was totally foreign to me: I'm accustomed to planetary science,
and planets don't give off X-rays.
      So what do X-ray astronomers look at? The sun. Stars and quasars.
And exploding galaxies.
      "Exploding galaxies?" I asked Steve Murray, my new boss at the
Center for Astrophysics. "Galaxies don't explode. They just sit there in
      "Bah. You learned your astronomy in the '70s," Steve replied. "Why,
we're looking at stars exploding into supernovas, bursts of X-rays from
neutron stars, even stuff falling into black holes. Hang around here for a
while and we'll teach you some real astronomy."
      They didn't fool around. Within a week, I was settled behind a com-
puter, building databases of X-ray observations. Classical computing, but

                                S TaL L

there's good physics in there. Yow! There really are black holes in the
middle of galaxies. I've seen the data.
       The Smithsonian Astrophysical Laboratory shares buildings with Har-
vard Observatory. Naturally, everyone's heard of Harvard Observatory.
But the Smithsonian? That's in Washington, isn't it? Only after I moved to
Cambridge did I realize that the Smithsonian had a hot-damn astronomy
section, the Center for Astrophysics. Makes no difference to me, so long as
they're doing good astronomy.
       Cambridge, Massachusetts, might be across the country, but culturally,
it's just around the corner from Berkeley. Lots of '60s hippies, left-wing
politics, bookstores, and coffeehouses. There's street musicians most every
night, and you're serenaded at the downtown subway stations by guitars and
mandolins. And the neighborhoods-some of these houses are a hundred
years old. Bicycling in Cambridge is sheer excitement-the drivers aim
right at you. History, weird people, good astronomy, cheap pizza . . . all
the ingredients for a good place to live.
       Marriage? Except that Martha keeps me away from microwave ovens,
it's been a kicker.
       Wednesday, November 2, 1988, Martha and I stayed up late, reading a
novel out loud. Around midnight we pulled up the quilt and fell asleep.
       I was dreaming about floating through the air on an oak leaf when the
phone rang. Damn. The glow-in-the-dark clock said 2:25 A.M.
       "Hi, Cliff. It's Gene. Gene Miya at NASA Ames Laboratory. No
apologies for waking you up. Our computers are under attack." The excite-
ment in his voice woke me up.
       "Wake up and check your system," Gene said. "Better yet, stay asleep
and check it. But call me back if you see anything strange."
       I'd hung up the phone for ten seconds when it rang again. This time,
the line just beeped. A Morse code beep.
       My computer was calling. It wanted my attention.
       Oh hell. Can't hide. I stumbled over to the trusty old Macintosh,
dialed into Harvard Observatory's computer, and typed in my account
name, Cliff. Then my non-dictionary password, "Robotcar."
       Slow logging in. After five minutes, I gave up. My computer just
wasn't responding. Something was wrong.
       Well, as long as I was awake, I might as well see what's on the West
 Coast. Maybe there's some electronic mail waiting for me. I connected over
Tymnet into Lawrence Berkeley Labs-no long-distance phone calls for me.

                   THE CUCKOO'S EGG

     The Unix system at Berkeley was slow, too. Frustratingly slow. But
only one other guy was using it. Darren Griffiths.
     Over the screen, we exchanged a couple notes:

     Hi Darren--Irs Cliff. How's things :-)
     Cliff. call me on the phone right away. We're under attack.
     OK 0-0

     0-0 means Over and Out. And the :-) is a crude smiley face. You
look at it sideways, and it smiles at you.
    2:15 A.M. in Massachusetts isn't yet midnight in Berkeley. Darren was
nowhere near asleep.
    "Hi, Darren. What's this attack?"
     "Something's eating our system, starting a lot of processes running.
Slowing the system down."
     "A hacker?"
     "No. I'd guess a virus, but I can't tell right now." Darren spoke slowly
as he typed. "I've been working on it for ten minutes, so I'm not sure."
     Then I remembered Gene Miya's call. "NASA Ames Labs says the same
      "Yeah. I bet we're under attack from the Arpanet," Darren said. "Yeah,
look at all these network connections!"
     I couldn't see any-as long as I talked on the phone, my computer was
disconnected and I was blind. With a single phone line, either I could speak
on the phone, or my Macintosh could talk to another computer, but not
both. I hung up and dialed into my Harvard computer, a desktop computer
made by Sun. Slow. Something was chewing on it.
     I looked at the processes running (with a ps command, like the hacker
had taught me). There was the virus. But not just running one or two jobs.
Hundreds of connections to other computers.
     Each process was trying to talk to some other computer. The connec-
tions came from all over: nearby systems at Harvard, distant computers from
the Arpanet.
     As fast as I'd kill one program, another would take its place. I stomped
them all out at once; not a minute later, one reappeared. Within three
minutes, there were a dozen. Holy smoke!
     What's crawling around my computer?

                                 ST 0 L L

o     0     0  A biological virus is a molecule which sneaks into a cell and
convinces the cell to copy the virus molecule, instead of the cell's DNA
molecules. Once duplicated, the virus then breaks out of the cell to infect
other cells.
       Similarly, a computer virus is a program that replicates itself. Like its
biological namesake, it enters a system, duplicates itself, and sends copies of
itself to other systems.
       To the host computer, a virus looks like a series of commands which
appear perfectly legitimate, yet have dire consequences. Often these com-
mands are buried within ordinary programs, hibernating until the program
is executed. When the infected program is run, all seems fine until the virus
is executed. Then the computer is tricked into copying the virus instructions
      Where? Probably the virus will copy itself into another program on
the same computer, making it tough to eradicate. Or maybe onto another
disk, so that someone will transport it to another computer.
      Perhaps the virus will do nothing more than duplicate itself into other
programs. A malicious virus maker, however, might throw in a side effect:
"Copy yourself four times, then erase all the word processing files."
     Computer viruses spread most easily on personal computers: these ma-
chines have no protections built into their operating systems. At a PC, you
can run any program you wish and change any part of memory. On small
computers, it's hard to tell if a program has been changed on a disk.
     Bigger computers, like Unix systems, are more resistant: their operat-
ing systems isolate one user from another, and set limits on how much you
can modify. In addition, you can't change system programs without permis-
sion-the operating system's walls seal you out of those sensitive areas.
      The virus writer must carefully tailor the program to a target com-
puter. A program that runs on your IBM PC won't work on my Macintosh,
or my lab's Unix system. Then too, the virus program can't occupy much
space, or it'll easily be discovered and removed.

                  THE CUCKOO'S EGG

    A virus is a good place to hide time bombs. It's easy to design a virus
whose instructions work like this:
     "Copy me into four other programs."
     "Wait until February 13."
     "Erase all the files on the system."
     The virus must find a way to propagate. Simply infecting programs on
one computer will only hurt one person. The creator of a malicious virus
wants the virus to infect hundreds of systems. How do you pass a program
to hundreds of others?
       People exchange software on disks. Infect one program on a disk, and
it'll infect every system that runs that program. As the disk is passed from
office to office, dozens of computers can be infected and possibly wiped out.
      Public bulletin boards also exchange software. These dial-in computers
are run by hobbyists, schools, and a few companies. You dial their number
and copy programs from the bulletin board into your home computer. You
can just as easily copy a program from your home system into the bulletin
board. There it'll wait until someone requests it. And if your program has a
virus buried inside, well, you won't discover it until it's too late.
      So computer viruses spread by interchanging programs. Someone
brings an infected program-a fun game-into work and runs it on her
office machine. The virus copies itself into her word processing program.
Later she gives her word processing disk to a friend. Her friend's system gets
infected. Oh, each program appears to work properly. But when February
13 rolls around . . .
      The obvious way to prevent viruses is to avoid exchanging programs.
Don't take candy from strangers-don't accept untrusted programs. By
keeping your computer isolated from others, no virus program can infect it.
      This canonical wisdom overlooks our daily needs. Unless we exchange
programs and data, our computers won't be much use to us. There's a
wealth of public-domain software-much of it ideal for solving our prob-
      Viruses and logic bombs poison this communal well. People stop trust-
ing public software, and eventually the sources of public software dry up.
      But there's another way for a virus to propagate: directly over a
      Our Arpanet interconnects eighty thousand computers across the coun-
try. You can send mail to anyone on these computers, send or receive files

                                    3   J   1
                                 ST 0 L L

over the Arpanet, or (as Markus Hess showed) interactively log into com-
puters connected to the Arpanet.
       Could a virus propagate over the Arpanet? A program that copies
itself from one computer, out over the network, into another . . .
       I'd thought of this before, but had always dismissed the possiblity.
Arpanet computers have defenses against viruses: you need passwords to log
into them. Hess got around this by guessing passwords. Could a virus guess
       At 3:30 in the morning, shivering behind my Macintosh at home, I
dialed into my observatory's computer. It's a Sun workstation, running the
popular Berkeley flavor of Unix. All those hundreds of jobs were still
running . . . my system was grossly overloaded. No hacker was logged in.
Just me.
       Same symptom at Lawrence Berkeley Labs. And NASA Ames. Smells
like a virus.
       I called Darren Griffiths at LBL. "It's a virus," he affirmed. "I can
watch it replicate. Try killing the jobs. They'll come right back."
       "From where?"
       ''I'm getting connections from five places. Stanford, University of
Rochester, Aerospace Company, the Berkeley campus, and somewhere
called BRL."
       "That's the Army's Ballistics Research Lab," I said, remembering a
conversation with BRL's Mike Muuss. "How's the virus getting into your
       "I can't tell, Cliff. The connections are all from the Arpanet, but it's
not the usual way of logging into the system. Looks like the virus is
breaking in through a hole in the mail system."
       Someone's built a virus that exploits a security hole in Unix systems.
The hole is in the mail system, and the virus spreads over the network.
What's the virus doing? Just copying itself, or does it have a time bomb
built in?
       It's 4 A.M. What to do? I'd better call the Arpanet controllers and warn
 them. There's a twenty-four-hour duty officer at the Network Operations
Center that watches over the network. This morning, they've heard nothing
of this virus. "Better call around, because it'll be all over the place by nine
 this morning."
       The Networks Operations Center hasn't heard. The virus is only a few
hours old. I'm seeing viruses coming from a dozen other sites. Virulent. By

                   THE CUCKOO'S EGG

 morning it will have spread to scores or even hundreds of systems. We've
 got a problem. A major problem.
      An epidemic.
       We've got to understand this virus and spread the word. For the next
 thirty-six hours I knocked myself out, trying to understand and defeat this
 thing. I knew I wasn't alone. At the same time, groups at Berkeley, MIT,
 and Purdue University were already hot on the trail.
      Here I'm only describing what I saw, but my struggle was minor
compared to the work of Unix wizards across the country. One by one,
programmers reacted-gurus like Keith Bostic, Peter Yee, Gene Spafford,
Jon Rochlis, Mark Eichin, Donn Seeley, Ed Wang, and Mike Muuss. I was
but a small part of an unorganized but dedicated response to this disaster.
      I dig into the code in my system in Cambridge. Right off I can see
two versions of the virus. One's customized for Vax computers running
Unix. The other's for Sun workstations. Each file is forty-five thousand
bytes long. If it were English, it would fit in about thirty pages. But it's not
text-I dump the file and it looks like gibberish. It doesn't even look like
machine code.
     Now this doesn't make sense: computer programs look like machine
code. This one doesn't. There's no header block information and only a few
commands that I recognize. The rest is guacamole.
     Patiently I try to understand what those few commands do. Suppose I
were a Sun workstation, and someone fed those commands to me. How
would I respond? With a pad of paper, hand calculator, and a booklet of
machine instructions, I start unwinding the virus's code.
     The first few commands just strip off some encryption from the rest of
the virus. That's why the virus looks strange. The actual commands have
been purposely obscured.
     Aha! The virus writer has hidden his virus: he's tried to prevent other
programmers from understanding his code. Throwing nails on the road to
slow down his pursuers.
       Time to call Darren again. It's 5 A.M. and we're comparing notes-he's
discovered the same thing and more: "I've unmasked part of the virus, and I
can see it's breaking in through the mail system. Then, it uses finger and
telnet to spread itself to other computers. It's decrypting passwords by brute
force guessing."
     Together, over the phone, we pry apart the program. Its whole pur-

                                 ST 0 L L

pose seems to be to copy itself into other computers. It searches for network
connections-nearby computers, distant systems, anything that it can reach.
      Whenever the virus program discovers a computer on the network, it
tries to break into it, using several obscure holes in the Unix operating
     Holes in Unix? Sure.
      When you send mail from one Unix computer to another, the Unix
Sendmail program handles the transfer. A mail message arrives from the
network and Sendmail forwards it to the addressee. It's an electronic post
office that pigeonholes mail.
     Sendmail has a hole. Normally, a foreign computer sends messages into
this program and everyone's happy. But if there's a problem, you can ask
the program to enter debug mode-the program's backdoor.
     When you're in debug, Sendmail lets you issue ordinary Unix com-
mands from a foreign computer. Commands like "Execute the following
     So that's how this virus spawned copies. It mailed copies of itself to
other computers and commanded them to execute the virus program.
      After the virus program started, it searched for other computers to
infect and sent mail messages to them.
     On some systems, Sendmail had been fixed. If so, the virus tried yet
another hole: the finger daemon.
       To see if I've been using a Unix system, you can issue the command,
finger cliff. If I've been logged in, Unix will respond with my name, phone
 number, and what I'm up to. It works well over the network; often I'll just
 finger someone before calling their telephone.
     The virus invaded through the program that handled finger requests.
The finger daemon has room for 512 characters of data; the virus sent 536
characters. What happened to the extra 24 characters? They got executed as
commands to Unix.
     By overflowing the finger daemon, the virus found a second way to
execute the command, "Execute the following program," on someone else's
      If that wasn't enough, the virus had a password guesser built in. It tried
to log into nearby, trusted computers, using a few hundred common pass-
words. If it guessed a valid password, it copied itself into the computer and
started all over.

                   THE CUCKOO'S EGG

      Whew! Anyone of these ways would impregnate a lot of computers.
Taken together, they formed a fiendishly effective virus.
      Like a sorcerer's apprentice, the program kept copying itself from one
computer to another. Erase one copy, and a new one would spring into its
place. Plug up one hole, and the virus would try a different hole.
      Did I say virus?
      "You know, Cliff, a virus modifies other programs when it runs. This
thing doesn't change other programs; it just copies itself," Darren explained.
"It's really not a virus, it's a network worm."
      A virus copies itself into other programs, changing the program itself.
A worm copies itself from one computer to another. Both are contagious;
either can spread havoc.
      Viruses usually infect personal computers, spreading through floppy
disks and copied programs. Worms strike over networks, spreading through
the very connections used for electronic mail and communications.
       But at 5 A.M., all I knew was that my computers were bogged down
and it's the fault of this self-replicating program. It's a cuckoo, laying eggs
in other birds' nests.
       Worm or virus, whoever built it has deliberately thrown up road-
blocks to prevent anyone from understanding it. The code's encrypted, and
it hides its internal tables. It erases any evidence of its parent worm. It feints
by appearing to send a message to a Berkeley computer, while actually
sending nothing at all-an attempt to draw attention away from the real
source of the program.
       By 6 A.M., Thursday morning, I'm thinking about the effects of this
worm: a disaster's brewing, and someone needs to be notified. Who?
       I've called the Arpanet Network Operations Center. They can't do
much-even if they turn off the whole network, the worm will still breed,
moving around local networks. Better call the National Computer Security
Center. Who do I know there? Bob Morris, their chief scientist.

                                ST 0 L L

o    0     0      I knew Bob Morris was on his computer at 6:30 A.M. Thurs-
day morning.) could see him logged into NSA's Dockmaster computer.
After posting a message to that machine, I called him on the phone.
      "Hi, Bob. We've got troubles. A virus is spreading over the Arpanet,
and it's infesting Unix computers."
      "When did it start?"
      "Around midnight, I'd guess. Maybe earlier-I just don't know. I've
been up all night trying to understand it."
      "How's it spread?"
      "Through a hole in the Unix mail program."
      "You must mean Sendmail. Hell, I've known about that for years."
Bob Morris might have known, but he had never told me.
      "Whoever wrote the virus must be laughing, but it's going to mean a
rough day for everyone."
      "Any ideas who started it?"
      "Don't worry about it. I'll look into it and see what I can do."
      We chatted awhile, then I hung up. Well, I've warned the authorities.
As chief scientist of the National Computer Security Center, Bob had a few
hours to rouse his troops and begin figuring out what this virus was all
about. I stared at my computer screen for a while, then, clad in a bathrobe,
fell asleep on the keyboard.
      Two hours later the phone rang. It's Don Alvarez from MIT on the
      "Hey, Cliff," he says, "something weird is going on. There's a hundred
jobs running on our computer. Smells like a virus."
      "You've got it too, huh?" We compared notes and quickly realized
 that Unix systems across the country must be infected. There's not much to
do but patch the bugs in the systems.
      "There are only two ways to understand this virus," Don said. "The
obvious way is to disassemble it. Follow the computer code, step by step,
and figure out what it does."

                  THE CUCKOO'S EGG

       "OK," I said, "I've tried that, and it's not easy. What's the other way?"
       "Treat it as a black box. Watch it send signals to other computers, and
estimate what's inside of it."
       "There's a third way, Don."
       "What's that?"
       "Find out who wrote it."
       I scanned the computer network news: Peter Yee and Keith Bostic of
the University of California at Berkeley were unraveling the virus; they
described the Unix holes and even published a way to patch the software.
Well done!
       Within the day, Jon Rochlis, Stan Zanarotti, Ted Ts'o, and Mark
Eichin of MIT were dissecting the program, translating the bits and bytes
into ideas. By Thursday evening-less than twenty-four hours after the
virus was released-the MIT and Berkeley groups had disassembled the
code and were well along to understanding it.
       Mike Muuss of the Ballistics Research Lab was making progress, too.
Within a few hours, he built a test chamber for the virus and used his
software tools to prod it. From his experiments, he understood how it
spread, and which holes it used to infest other computers.
       But who wrote it?
       Around eleven in the morning, someone from NSA's National Com-
puter Security Center called me.
       "Cliff, we've just held a meeting about the virus," the voice said. "I've
got just one question for you: did you write the virus?"
       I was stunned. Me? Write this virus?
       "No, damn it, I didn't write it. I've spent the past night trying to
extinguish it."
       "A couple people at the meeting suggested that you were the most
likely creator. I'm just checking."
       You've got to be joking. Me? What could make them think that I had
written it? Then I realized: I'd posted a message to their computer. I was the
first to call them. What paranoia!
       Their call set me to thinking. Who had written the virus? Why? You
don't accidentally write a virus. This one had taken weeks to build.
       Late Thursday afternoon, I called Bob Morris back. "Any news?" I
asked him.
       "For once, I'll tell you the truth," Bob said. "I know who wrote the
VIrus. "

                                 ST 0 L L

     "Are you going to tell me?"
     Now that's efficient. Ten hours after I call them, the National Com-
puter Security Center has found the culprit.
      But I hadn't. He's still a mystery to me, so it's back to snooping
around the networks. If I could only find the computer that had been first
infected. No, that won't work. There's thousands out there.
     John Markoff, a reporter from the New York Times, called. "I heard a
rumor that the person who wrote the virus has the initials RTM. Is that any
     "Not much, but I'll check it out."
    How do you find someone from his initials? Of course . . . you look
him up in the network directory.
      I log into the Network Information Center and search for anyone
with the initials RTM. One guy pops up: Robert T. Morris. Address:
Harvard University, Aiken Laboratory.
      Aiken. I've heard of that. It's three blocks from my house. I think I'll
stroll by.
      I pull on a coat and walk along Kirkland Street, then over to Oxford
Street, where the sidewalks are brick. Across the street from Harvard's
Cyclotron Laboratory, there's a lunch truck selling Middle Eastern food. A
hundred feet away, Aiken Computer Lab-an ugly modern concrete build-
ing surrounded by old Victorian masterpieces.
      I walk up to a secretary. "Hi. I'm looking for Robert Morris."
     "Never heard of him," she says. "But I'll check my machine." She
types into her terminal,

Finger Morris

     Her computer responds:

Login name: rtm          In real life: Robert 1. Morris
Phone: 617/49~2247
Last login Thu Nov 3 00:25 on ttyp2 from J28.84.254.126

      Well-the last time that Robert Morris used the Harvard computer
was twenty-five minutes after midnight, on the morning that the virus
struck. But he's not here in Massachusetts. That address,, is at

                  THE CUCKOO'S EGG

Cornell University. He entered the Harvard system from a computer at
Cornell University. Curious.
      The secretary sees the message, looks up, and says, "Oh, he must have
once been a student here. That phone number is in Room 111.
      I wander over to room 111 and knock on the door. A student in a T-
shirt peers out. "Ever hear of Robert Morris?" I ask.
      His face blanches. "Yeah. He's not here anymore." And he slams the
door in my face.
      I walk away, think for a moment, then return. "Have you heard about
the virus?" I ask the guy at the door.
      "Oh, RTM wouldn't have done that. I'm sure."
      Wait a second. I hadn't even asked if Morris had written the virus and
this guy's denying it. There's an easy way to test this guy's veracity.
"When's the last time that Morris has used Harvard's computers?"
      "Last year, when he was a student. He's at Cornell now, and he doesn't
log into our computer anymore."
      This guy's story doesn't jibe with the accounting records of his com-
puter. One of 'em's telling the truth. I'll bank on the computer.
      We talked for five minutes, and this guy tells me how he's a good
friend of Morris, how they were officemates together, and how RTM
would never write a computer virus.
      "Yeah, right," I'm thinking.
      I leave, thinking that Morris's old officemate is covering for him.
Morris must be talking to this guy, and they're both frightened. I'd be
scared, too, in that squeeze. Half the country's looking for the creator of this
      Where did the virus start from? I checked other computers in Cam-
bridge, searching for connections to Cornell. One machine, over at MIT's
Artificial Intelligence Lab, showed late-night connections from Robert
Morris's computer at Cornell.
       Now things made sense. The virus was designed and built at Cornell.
Then the creator used the Arpanet to connect to MIT and release the virus
there. A while later he panics when he realizes that his creature is out of
control. So he logs into the Harvard computer, either to check on the virus's
progress, or to ask his friends for help.
      The joke was on me, though. It didn't occur to me that Robert T.
Morris, Jr., was the son of Bob . . . er, Robert Morris, Sr. Yeah, son of
Bob Morris, who only yesterday told me he'd known of the Sendmail hole

                                 ST 0 L L

for years. Bob Morris, the head honcho who'd grilled me on astrophysics,
then nearly asphyxiated me with cigarette smoke.
   So Bob Morris' son froze two thousand computers. Why? To impress his
dad? As a halloween prank? To show off to a couple thousand computer
   Whatever his purposes were, I don't believe he was in cahoots with his
father. Rumors have it that he worked with a friend or two at Harvard's
computing department (Harvard student Paul Graham sent him mail asking
for "Any news on the brilliant project"), but I doubt his father would
encourage anyone to create a virus. As Bob Morris, Sr., said, "This isn't
exactly a good mark for a career at NSA."
   After dissecting the code, MIT's Jon Rochlis characterized the virus as
"not very well written." It was unique in that it attacked computers
through four pathways: Bugs in the Unix Sendmail and Finger programs,
guessing passwords, and by exploiting paths of trust between computers. In
addition, Morris camouflaged the program in several ways, so as to avoid
detection. But he made several programming mistakes-like setting the
wrong replication rate-and the worm probably could have been written
by many students or programmers.
      All it takes is knowledge of Unix flaws and no sense of responsibility.
      Once you understand how this particular worm-virus infests com-
puters, the cure becomes evident: repair Sendmail and the finger daemon,
change the passwords, and erase all the copies of the system's virus. Evident,
yes. Easy, no.
      Spreading the word isn't easy when everyone's chopping off their
electronic mail system. After all, that's how this worm propagates its chil-
dren. Slowly, using alternate networks and telephone calls, the word went
out. Within a couple days, Morris's worm was pretty much squashed.
      But how do I protect against other viruses? Things aren't so hopeful.
Since viruses masquerade as sections of legitimate programs, they're tough
to detect. Worse, once your system is infected, these are difficult beasts to
understand. A programmer has to decompile the code: a time-consuming,
boring job.
      Fortunately, computer viruses are rare. Although it's become fashion-
able to blame system problems on viruses, they mostly hit people who
exchange software and use computer bulletin boards. Fortunately, these are
usually knowledgeable people who make backup copies of their disks.
      A computer virus is specialized: a virus that works on an IBM PC

                  THE CUCKOO'S EGG

cannot do anything to a Macintosh or a Unix computer. Similarly, the
Arpanet virus could only strike at systems running Berkeley Unix. Com-
puters running other operating systems-like AT&T Unix, VMS, or DOS
-were totally immune.
      Diversity, then, works against viruses. If all the systems on the Arpanet
ran Berkeley Unix, the virus would have disabled all fifty thousand of
them. Instead, it infected only a couple thousand. Biological viruses are just
as specialized: we can't catch the flu from dogs.
      Bureaucrats and managers will forever urge us to standardize on a
single type of system: "Let's only use Sun workstations" or "Only buy IBM
systems." Yet somehow our communities of computers are a diverse popula-
tion-with Data General machines sitting next to Digital Vaxes; IBMs
connected to Sonys. Like our neighborhoods, electronic communities thrive
through diversity.
     Meanwhile, how much astronomy was I doing?
    None. For thirty-six hours, I worked on disinfecting our computers.
Then came meetings and then papers to write. And a couple copycat virus
makers-fortunately, none as clever as the original.
     The last I heard, Robert T. Morris was laying low, avoiding inter-
views and wondering about the chances of an indictment. His father's still at
NSA, still the chief scientist at their computer security center.
     How much damage was done? I surveyed the network, and found that
two thousand computers were infected within fifteen hours. These machines
were dead in the water-useless until disinfected. And removing the virus
often took two days.
     Suppose someone disabled two thousand automobiles, say, by letting
the air out of their tires. How would you measure the damage? By one
measure, there's been no damage at all: the cars are intact, and all you need
to do is pump some air.
     Or you can measure damage by the loss of the cars. Let's see: how
much do you lose if your car is disabled for a day? The cost of sending a
tow truck out? Or the price of a rental car? Or the amount of work that
you've lost? Hard to say.
      Perhaps you'd thank the person who let the air out of your tires-
award him a medal for raising your consciousness about automotive secu-
      Here, someone crippled some two thousand computers for two days.

                                 ST 0 L L

What was lost? Programmers, secretaries, and managers couldn't work. Data
wasn't collected. Projects were delayed.
      The virus writer caused that much damage at least. Deeper damage,
too. A while after the virus hit, some astronomers and programmers took a
poll. Some of the computer people felt the virus was a harmless prank-one
of the finest jokes ever.
      The astronomers had a different opinion: for two days, they couldn't
work. Their secretaries and grad students weren't working. Proposals and
papers weren't being written. We pay for their network connections out of
our pockets-and this caper made it even more difficult to expand their
astronomy networks.
      Some programmers see this virus as a useful exercise in raising con-
sciousness about computer security. The virus writer should be thanked.
Yeah, sure. Like going into a small town and breaking into people's homes,
so as to impress upon the townsfolk the need to buy strong locks.
      Once, I too, would have seen no mischief in this virus. But over the
past two years, my interest changed from a micro-problem (a 75-cent dis-
crepancy) to macro-issues: the welfare of our networks, a sense of common
fair play, legal implications of hacking, the security of defense contractors,
commonweal ethics in computing . . .
      Omigod! Listening to myself talk like this, I realize that I've become a
grown-up (sob!)-a person who really has a stake. My graduate student
mentality of earlier days let me think of the world as just a research project:
to be studied, data extracted, patterns noted. Suddenly there are conclusions
to be drawn; conclusions that carry moral weight.
      I guess I've come of age.

o     0     0   The greatest B-movie of all time, The Blob, finishes off with
the malignant monster being towed off to Antarctica: it's harmless when
frozen. Then, the words "The End" flash across the screen, but at the last
minute, a blob-shaped question mark appears. The monster isn't dead, only
      That is how I felt when I finally dismantled my monitors, made the

                  THE CUCKOO'S EGG

last entry in my logbook, and said good-bye to midnight chases after Mar-
kus Hess.
      The monster is still out there, ready to come alive again. Whenever
someone, tempted by money, power, or simple curiosity, steals a password
and prowls the networks. Whenever someone forgets that the networks she
loves to play on are fragile, and can only exist when people trust each other.
Whenever a fun-loving student breaks into systems as a game (as I might
once have done), and forgets that he's invading people's privacy, endanger-
ing data that others have sweated over, sowing distrust and paranoia.
      Networks aren't made of printed circuits, but of people. Right now, as
I type, through my keyboard I can touch countless others: friends, strangers,
enemies. I can talk to a physicist in Japan, an astronomer in England, a spy
in Washington. I might gossip with a buddy in Silicon Valley or some
professor at Berkeley.
      My terminal is a door to countless, intricate pathways, leading to
untold numbers of neighbors. Thousands of people trust each other enough
to tie their systems together. Hundreds of thousands of people use those
systems, never realizing the delicate networks that link their separate worlds.
      Like the innocent small town invaded in a monster movie, all those
people work and play, unaware of how fragile and vulnerable their commu-
nity is. It could be destroyed outright by a virus, or, worse, it could con-
sume itself with mutual suspicion, tangle itself up in locks, security check-
points, and surveillance; wither away by becoming so inaccessible and
bureaucratic that nobody would want it anymore.
      But maybe, if Hess was an exception, if enough of us work together to
keep the networks safe and free, this will all be over. I can finally get back
to astronomy and have time to spend with my long-suffering bride. I don't
want to be a computer cop. I don't want our networks to need cops.
      The phone's ringing. It's Lawrence Livermore Laboratory-a place
I've stayed away from because they design nuclear bombs. A hacker's break-
ing into their computer. They want my help. They think I'm a wizard.

                        THE END


o     0     0     If you'd like the technical details behind this book, read my
article, "Stalking the Wily Hacker," in the May 1988 issue of the Communi-
cations of the ACM. It's a dry, academic paper which highlights the tech-
niques that the hacker used to break into computers.
   In addition, I described how to track hackers in "What Do You Feed a
Trojan Horse?"-found in the Proceedings of the 10th National Computer
Security Conference (September 1987). Because I wrote that paper while the
hacker was still actively breaking into computers, it's about how to trace
networks and doesn't mention our problems.
    For more details about the NSA and a bit about their computer security
problems, read The Puzzle Palace by James Bamford. Bamford describes the
tug of war between the code makers and code breakers-he must have had
fun prying those details out of the super-secret agency. David Kahn's book,
The Codebreakers, is a fascinating description and history of ciphers, which
suggests how computers use cryptography to protect their data. In Deep
Black William E. Burrows writes mostly about secret observations from spy
satellites, but also hints at the use of computers in espionage.
    For more mundane, yet valuable descriptions of the problems and tech-


niques of computer security, read Defending Secrets, Sharing Data, available
from the u.s. Congress, Office of Technology Assessment, OTA-CIT-310.
For a still more technical discussion, try Cryptography and Data Security by
Dorothy Denning. The hacker probably wouldn't have broken into our
system had we read (and applied) Unix System Security by Wood and
    Computer security problems are usually heard first on Internet and
Usenet network conferences. These are worldwide electronic bulletin boards
-this is often where first rumors of trouble show up. To hear about the
latest computer security problems, watch the Unix-wizards, Info-oax, Secu-
rity, TCP-IP, and Virus-L conferences. There's a lively, moderated discus-
sion on the Risks-forum conference, where participants discuss social issues
relating to computers. There are a few private security conferences as well;
their "invitation only" membership is indicative of the paranoia surround-
ing the field. There are also anonymous and pirate bulletin boards; these
seldom have much useful information-but they do tell you what one
segment of the population is thinking.

About the Author

o    0     0     Clifford Stoll is an astronomer by training and a computer
security expert by accident. Since catching the "Hannover Hacker," he has
become a leading authority on computer security, delivering more lectures
on the subject than he cares to admit. He's given talks at the CIA and NSA,
and has appeared before the u.s. Senate. Stoll is now building software for
the Harvard-Smithsonian Center for Astrophysics, and lives in Cambridge
with two cats he pretends to dislike.