A couple of weeks ago, the Firesheep plugin for Firefox caused quite a stir. By exploiting a vulnerability associated with open wireless networks, Firesheep can be used to eavesdrop on other users on the wireless network.
Among other things, Firesheep can easily intercept other users’ login details for Facebook and Twitter, among other things.
From the security company Zscaler there is now a plugin called Blacksheep. Blacksheep is a small plug-in for Firefox that can detect if someone on the local wireless network is trying to eavesdrop on your computer using Firesheep.
However, Blacksheep is not a waterproof protection against Firesheep and can only give you a warning, but not protect against your data being intercepted. The safest solution so far is to use a so-called vpn connection or to completely avoid unencrypted wireless networks.