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Zscaler Helps Identify FireSheep Usage with New Extension

BlackSheep Extension Helps Identify FireSheep Session Hijacking

BlackSheep Extension Helps Identify FireSheep Session Hijacking

Zscaler today released “BlackSheep,” a plugin for Firefox that helps end users identify usage of FireSheep, the controversial Firefox extension that makes it dead simple to tap into someone’s social networking and email accounts (and many others) by “hijacking” user sessions while connecting via unsecured wireless networks.


By design, BlackSheep is a countermeasure to Firesheep to help consumers combat this threat and avoid falling victim by displaying a warning when Firesheep is detected.

There is one twist that makes BlackSheep a bit more challenging to use: Firesheep and BlackSheep cannot be installed on the same Firefox instance as they share much of the same code base. In order to run both Firesheep and BlackSheep on the same machine, Zscaler suggests that they be installed in separate Firefox profiles. It’s also important to realize that BlackSheep simply *identifies* usage of FireSheep and doesn’t actually block it or protect users from having their browser sessions hijacked.

“We essentially used Firesheep against itself to combat the threat it poses,” said Julien Sobrier, senior researcher at Zscaler Labs and developer of the new BlackSheep plugin. “In fact, BlackSheep leverages much of the Firesheep code, but the twist is that rather than being used to hijack sessions, it instead detects when a session is being hijacked and alerts the user.” Once the user becomes aware that they have a “visitor” they are advised to log out immediately and stop using the network, he advises.

Michael Sutton, VP of Security Research, said: “While session hijacking is not a new form of attack, Firesheep has garnered considerable attention due to the fact that it makes session hijacking exponentially easier and can bring this capability to the masses. Any person capable of running a Firefox plugin can now access private data. At least now, with BlackSheep, people can be alerted when they’re at risk.”

BlackSheep is free and can be downloaded from:

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