Crack Program Released for Wireless Nets

By Larry Seltzer  |  Posted 2004-11-06 Print this article Print

Only pre-shared key systems are affected. Dictionary attack, as a practical matter, affects only those with short, simple passphrases.

One year after a vulnerability in the Wi-Fi Protected Access encryption algorithm was reported, a proof-of-concept program for the attack has been released. The attack affects only Wi-Fi networks using WPA in pre-shared key mode. It is a dictionary attack, meaning that it cycles through a list of words and combinations of words attempting to find one that matches the data on the network. Longer, more random passwords or passphrases, and enterprise implementations that use external authentication systems, are not affected by the vulnerability.

The group that released the crack program, Tinypeap, writes Wi-Fi-related software, including a small radius server for certain Linksys routers.

The company also wrote a white paper that explains how the crack works and criticizing WPA for the broadcast of data necessary in the creation and verification of a session key. This is the information that the program subjects to the dictionary attack. The white paper also recommends using the companys Tinypeap radius server as a solution to the problem.

The white paper notes that the Wi-Fi Alliance recommends a passphrase of at least 20 characters, and even better with some non-dictionary words in it. For example, "Red Sox are number 1!" is at the outer edge of weak length and has weak contents, but "Sox rule, Yankees drule, boo-yah!" would likely not be matched by a dictionary attack.

Check out eWEEK.coms for the latest security news, reviews and analysis. And for insights on security coverage around the Web, take a look at Security Center Editor Larry Seltzers Weblog.
Larry Seltzer has been writing software for and English about computers ever since—,much to his own amazement—,he graduated from the University of Pennsylvania in 1983.

He was one of the authors of NPL and NPL-R, fourth-generation languages for microcomputers by the now-defunct DeskTop Software Corporation. (Larry is sad to find absolutely no hits on any of these +products on Google.) His work at Desktop Software included programming the UCSD p-System, a virtual machine-based operating system with portable binaries that pre-dated Java by more than 10 years.

For several years, he wrote corporate software for Mathematica Policy Research (they're still in business!) and Chase Econometrics (not so lucky) before being forcibly thrown into the consulting market. He bummed around the Philadelphia consulting and contract-programming scenes for a year or two before taking a job at NSTL (National Software Testing Labs) developing product tests and managing contract testing for the computer industry, governments and publication.

In 1991 Larry moved to Massachusetts to become Technical Director of PC Week Labs (now eWeek Labs). He moved within Ziff Davis to New York in 1994 to run testing at Windows Sources. In 1995, he became Technical Director for Internet product testing at PC Magazine and stayed there till 1998.

Since then, he has been writing for numerous other publications, including Fortune Small Business, Windows 2000 Magazine (now Windows and .NET Magazine), ZDNet and Sam Whitmore's Media Survey.

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