Zscaler develops free tool to detect Firesheep snooping:

A security company has developed a free Firefox add-on that warns when someone on the same network is using Firesheep, a tool that has raised alarm over how it simplifies an attack against a long-known weakness in Internet security.

Firesheep, which was unveiled at the ToorCon security conference in San Diego last month by Eric Butler, collects session information that is stored in a Web browser's cookie. The session information is easily collected if transmitted back and forth between a user's computer and an unencrypted Wi-Fi router while a person is logged into a Web service such as Facebook.

Zscaler's The Blacksheep add-on, however, will detect when someone on the same network is using Firesheep, allowing its users make a more informed security decision about their behavior while on an open Wi-Fi network, for example. [Date: 8 November 2010; Source: http://www.computerworld.com/s/article/9195398/]