Scammers are attempting to trick Firefox users into downloading backdoored software via spam emails that supposedly advertise an "update" to the open-source browser.
A run of spam emails circulating over the weekend all include links to a download that bundles together a Mozilla Firefox 5.0.1 installer and a password-stealing Trojan horse. As a social engineering ruse it is about as subtle as a brick in the head, but there just may be enough credulous users out there to make the scam work. In reality, Firefox automatically updates itself, a point scammers obviously hope prospective marks do not know.
Scams of this type first punted Microsoft security updates but, over time, they have diversified to embrace a wider range of targets.
Net security firm Sophos detects the malware punted via the fake Firefox attack as Troj-PWS-BSF. It also detects the browser/malware bundle. Other vendors can be expected to follow suit.
A write-up of the scam, complete with extracts of the offending email, can be found in a blog post by Sophos here. ®