Transmissions

by Dragorn

It's that time of year again - eggnog, bad Christmas analogies, and struggling to finish an article through the post-turkey torpor.  Employing the method used by sitcoms for decades, I bring you the flashback and clips episode, or "Stuff from the last year you probably should have paid more attention to when it happened."

"Hey Billy, do you remember that time Nancy fell down the stairs, and her TKIP was cracked?"  "Yeah, that reminds me of when..."

If you missed this one, your head must be pretty deep in the sand, but it's certainly a harbinger of future attacks against WPA-TKIP.  In early November, the first significant break against WPA networks was announced by Beck and Tews, allowing the recovery of the plaintext data at a rate of one byte per minute.  This might not sound significant - it is.  A successful decode gives the attacker the ability to generate valid packets, opening the TKIP protection to new attacks which are not limited in speed.

WPA-TKIP was designed as a stopgap measure which could be used with older hardware until everything was able to support WPA-CCMP.  Thusly, it employs the known flawed RC4 encryption.  Those of you who have done your homework know this as the same encryption used in WEP.  Oh dear.

To make this less of a tragic replay of the failings of WEP, instead of using a fixed passphrase, the keystream is built with a temporal key (that is, time limited) which is generated after the network is connecting using the master key, derived from either the WPA passphrase on a PSK network or the exchange with the radius server on an EAP network.

Replay and injection of the same packet over and over again is prevented with a frame counter; Once a packet is seen, the next packet must have a number higher or it will be ignored.  An integrity countermeasure Message Integrity Code (MIC) makes sure you don't mess with the frame counter.  Get it wrong once, the client tells the AP someone is messing with it.  Get it wrong twice in a minute and the whole network shuts itself down and when it comes back it has different keys.

This worked fairly well until the standard for QoS came out.  Since QoS changes the order of packets, different QoS queues must be allowed to get out of order.  Reviving the older KoreK chopchop attack against WEP and replaying a packet in another QoS queue, an attacker can guess at the last byte of plaintext - and be notified by the MIC countermeasures that a valid RC4 packet with an invalid payload was received.

So long as the attacker doesn't guess right twice in 60 seconds, the whole packet can be derived.  Ever better, the secret data used for the MIC can be derived, allowing spamming of packets into the network with no time restrictions, opening the door for more attacks.

Ironically, now that the PCI credit card standard has been updated to ban use of WEP on payment networks, it will have to be updated again to ban use of TKIP.

TKIP isn't dead, but it's definitely mortally wounded.  We're currently in the grace period before it's completely broken.  Shift to WPA-CCMP before the next major attack comes along.

"Yeah, that sure was crazy that time, almost reminds me of when the U.S. government waived constitutional rights if you were crossing a border, or even 'near' one!"

Mass media (and even parts of the government) this year finally began noticing what we've known about for a while: When crossing the U.S. border, you no longer have the same constitutional rights you normally would, most noticeably the right against unreasonable search and seizure.  Last winter, the EFF filed suit against the government to attempt to discern the limits of the search and seizure policies.

When crossing a border, the U.S. Customs and Border Protection agency asserts that information stored in phones, laptops, external hard drives, MP3 players, and other devices is no different from printed information, and therefore subject to search and seizure.

In August, it was revealed that the policies allow the agency to take a laptop to an external facility, keep it for an indefinite period of time, attempt to defeat encryption and to share any information taken with other agencies without restriction.  These policies apply to anything carried over the border which can store information, including hard drives, flash drives, books, printed material, etc.

In October, the (((ACLjU))) brought attention to the official governing regulations of the U.S. Customs and Border Protection agency, which defines the range of CBP activities as within 100 miles of a border (or coastline), in theory granting CBP warrantless search and seizure abilities in the majority of metropolitan areas.  Do you live within 100 miles of a border or coast?  According to the U.S. census, 60 percent of us do.

"...And remember when we used to have as much Internet as we could carry?"

When the FCC issued a judgment against Comcast for injecting forged RST packets into users' connections to control traffic by artificially terminating it, they also opened the door for metered bandwidth as a solution, suggesting it as a viable alternative to aggressive packet shaping.

Already started by several ISPs before the FCC ruling, metered bandwidth caps are currently being tested either network-wide or in "select areas" by Cox, Comcast, Time Warner, Frontier, and AT&T, with caps ranging from 250 GB/month down to 5 GB month for some DSL services.

Users of cellular data plans are used to "unlimited" not meaning "unlimited" at all, but wide-scale bandwidth caps on landline connections are a new experience for most U.S. based users.  Depending on the company, users who exceed the cap are either disconnected or charged overage fees.

With video rental models (rhymes with "Get Bricks") moving towards high-def streaming and even Sony offering downloadable movie content on game systems, legitimate bandwidth use will only be on the rise, and stifling new technology by artificially capping bandwidth is fighting against progress and consumers.  Previously, ISPs have argued that only users breaking the terms of service by sharing illegal files could overrun bandwidth cap, an argument which is rapidly losing weight.

Unfortunately, there doesn't seem to be much that can be done in the U.S. at the moment to fight this trend, other than switch providers to a company which doesn't try to cap.  With government-granted monopolies for cable service, this can be difficult in many areas.

"Wow, we sure have had a lot of good times this year!  Has everyone got their digital converter boxes ready for the analog cut-off?"

"Shut up, Billy."