In the new edition of PCI 1.2 DSS requirements, WEP Security has been removed from the accepted list of security strategies for wireless communication only devices - only WPA and WPA2 are now accepted. Companies have until June 30, 2010 to replace their wireless communication with 80211i. This week it looks like WPA TKIP will soon join WEP on the list of prohibited wireless security strategies, although the PCI 1.2 Standard recommends stong encryption like AES. Erik Tews and Martin Beck plan on speaking at PacSec conference on how they can crack WPA TKIP in 12 to 15 mins. TKIP, Temporal Key Integrity Protocol, was initially created as a stepping stone for companies with older wireless devices that need to move off WEP security easily without the purchase of new hardware. WPA Message Integrity (MIC) or Michael was never strong because of hardware concerns.
Martin Beck and Eric Tews have published papers: Practical attacks against WEP and WPA.
Glen Fleishman has also written a nice review of the WPA crack.
In the document Practical attacks against WEP and WPA, they say they collect traffic until they get an ARP request or response. Ethernet addresses are not protected by WEP or TKIP, then they use their chopchop attacks to decrypt the unknown plaintxt bytes of the packet.
The Message Integrity (MIC) prevents replay attacks because on 2 failures the MIC is shutdown, there is a 60 second communication penalty and then the keys are renegotiated.
They use 802.11e to send the keystream over different queues and avoid the MIC. This is only successful if the rekey interval is long and chopchop is able to complete the decryption of the packet without rekeying. They state that TKIP is not much different from WEP, and that the same WEP attacks can be used against TKIP.
Glen Fleishman concludes in his article that if TKIP is set to rekey on the AP at a regular interval - not 3600 seconds - say 120 seconds - that it makes the attack harder to accomplish. Choose a long network key 20 characters that are random.
I am sure that most Network Administrators, Security Analysts and Auditors have their old wireless routers and clients updated and have moved to AES-CCMP. There may be those that have client devices, appliances, notebooks, or tablets that use 802.11b and to save money have moved to some firmware upgrades that allows WPA TKIP.
This new release on the exposure of weakness of TKIP will hopefully move the process for modernization of the Wireless environment as a must have.
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