Firefox Extension Malware:

A malicious Firefox extension called FirestarterFox is being installed by some of the latest malware variants. Luckily the extension can’t be silently installed since Firefox alerts users to all new extensions. So if you ever start Firefox and get the message that a new extension called FirestarterFox has been installed you will immediately know that you have malware on your system and should take steps to remove it or reformat your system.

Reference: http://blog.misec.net/2008/09/25/new-malic...firestarterfox/