Bach Seat

Japanese researchers have identified a WPA hack that could give hackers a way to read encrypted Wi-Fi traffic  in less than 1 minute. Toshihiro Ohigashi (Hiroshima University) and Masakatu Morii (Kobe University) presented a way to break the WPA (Wi-Fi Protected Access) encryption system at the Joint Workshop on Information Security. The researchers outlined their work in a paper called “A Practical Message Falsication Attack on WPA” on August 7, 2009.

The new attack builds on 2008 research from Darmstadt University of Technology graduate students Martin Beck and Erik Tews who proved that WPA Temporal Key Integrity Protocol (TKIP) could be attacked. The Beck-Tews attack only worked on short packets in a WPA implementation that supported 802.11 quality of service (QOS) features and took between 12 and 15 minutes to work.

The new threat uses “man in the middle” (MITM) attacks on WPA TKIP systems. The MITM attack uses the “chopchop” attack on a short packet (like ARP broadcasts), decipher its 64-bit Message Integrity Code (MIC), and can then craft whatever packet it wants. The new packet is coded with the proper checksums and passed along to the access point, which should accept it as genuine. Dragos Ruiu, organizer of the PacSec security conference where the first WPA hack was demonstrated told IDGNews, “They took this stuff which was fairly theoretical and they’ve made it much more practical.”

Both attacks work only on WPA systems that use the TKIP algorithm. The new attack does not work on newer WPA2 devices or on WPA systems that use the stronger Advanced Encryption Standard (AES) algorithm. Kelly Davis-Felner, marketing director with the Wi-Fi Alliance, said that people should now use WPA2. She told IDGNews, WPA with TKIP “was developed as kind of an interim encryption method as Wi-Fi security was evolving several years ago.”

Enterprise Wi-Fi networks typically include security software that would detect the type of man-in-the-middle attack described by the Japanese researchers, Robert Graham, CEO of Errata Security told ars technica. He continues, the development of the first really practical attack against WPA should give people a reason to dump WPA with TKIP, he said. “It’s not as bad as WEP, but it’s also certainly bad.”

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This is only an issue if the WLAN is secured at all.  Motorola published a report in April 2009  that says 64% of companies are neglecting WLAN security. The report claims that only 47% of companies are using Wired Equivalent Privacy (WEP) or Wi-Fi Protected Access (WPA) encryption on their wireless networks.

These attacks highlight the weaknesses of TKIP-based WLAN encryption. WPA TKIP was developed to fix the worst of the security holes in the first Wi-Fi encryption protocol, WEP. WI-Fi-certified products have had to support WPA2 since March 2006 . Users should move to AES-CCMP which requires WPA2 Personal for home and small office networks or WPA2 Enterprise for larger networks.

Using AES-CCMP may require that some network equipment installed before 2003 be reviewed as AES supports key lengths up to 256 bits, which may not be compatible with older hardware. Any remaining equipment of this vintage may need to be upgraded to newer Wi-Fi adapters, switched to Ethernet only, or retired. WPA2 has not shown any vulnerabilities to date. There is no real good reason to try to secure your WLAN with WPA-TKIP anymore.

Ralph Bach has been in IT long enough to know better and has blogged from his Bach Seat about IT, careers, and anything else that catches his attention since 2005. You can follow him on LinkedIn, Facebook, and Twitter. Email the Bach Seat here.