According to an article at techjaws.com there have been some add on with malware included. Even after you unistall the add on your computer remains infected. If this is true we better start paying better attention to what plugins and add on we use on Firefox.
According to Mozilla, version 4.0 of Sothink Web Video Downloader is infected with password sniffer Win32.LdPinch.gen and Master Filer is infected with the backdoor Trojan Win32.Bifrose. This Malware has infected Windows systems following installation of the infected browser add-on.
This comes at no surprise as a recent study indicated that nearly half of all computers are infected with some sort of virus or spyware. 2009 was a record year in the amount of attacks on residential and business class computers.
