Researchers Put Nail in WEP's Coffin

Its first flaws were exposed more than six years ago, but WEP continues to be one of the industry's most popular means of encrypting wireless transmissions. Now German researchers say they've found a hack that might put the flawed protocol down once and for all.

Speaking at a conference in Hamburg, Germany over the weekend, three researchers from the Darmstadt University of Technology demonstrated their ability to extract a WEP encryption key from an intercepted stream of data in about three seconds.

Wired Equivalent Privacy, which was first shown to be insecure when researchers cracked the RC4 key scheduling algorithm in 2001, has been remarkably stubborn in its growth over the years.

In a study conducted last year, security vendor RSA found that roughly 78 percent of all wireless LAN and WiFi systems found in Paris were encrypted with WEP, compared to only 69 percent in the previous year. In London, RSA found that WEP usage increased to 74 percent of all wireless networks in 2006, up from 65 percent in 2005. In New York, 75 percent of networks found used WEP defenses in 2006, up from 62 percent in 2005.

WEP's growth is attributed mostly to its wide use in wireless hardware. Despite a long string of reports demonstrating various ways to crack the code, vendors continue to include it in their systems, and users -- many of whom don't understand its weaknesses -- continue to use it in their everyday wireless communications. WEP is incorporated into the IEEE's 802.11 standards, which makes it standard-issue on most wireless devices.

In a paper presented this weekend, however, Erik Tews, Ralf-Philipp Weinmann, and Andrei Pyshkin made a strong case that users should never employ WEP, even if it is available on their machines.

"While arguably still providing a weak deterrent against casual attackers in the past, the attack described in this paper greatly improves the ease with which the security measure can be broken and will likely define a watershed moment in the arena of practical attacks on wireless networks," the researchers state.

In a nutshell, the paper describes a method for extending the original RC4 vulnerability to the entire WEP protocol, making it possible to extract the 104-bit WEP key from an intercepted data stream using a 1.7 GHz Pentium M processor.

The researchers emphasized that the crack can be done with a relatively low-performance device, and might even be done with a PDA or mobile phone.

But while the Darmstadt researchers discouraged the use of WEP, one vendor announced a method to reduce the vulnerabilities in WEP transmissions. AirDefense last week unveiled its WEP Cloaking Module, a method of enveloping WEP traffic in a stream of dummy data traffic that uses a different key.

"Our technology enables companies to preserve their existing, and often considerable, investment in wireless devices -- even after their security life-span has seemingly expired," says Mike Potts, president and CEO of AirDefense. The cloaking technology, which is offered as part of the AirDefense suite, is available now.

— Tim Wilson, Site Editor, Dark Reading