Security watchers are warning users about a new worm that spreads via Facebook's instant messaging feature and also inserts itself under the guise of misleading messages on other social networking websites and IM services.
The malware typically arrives in the form of a private Facebook IM that points towards a malware-loaded website, using shortened links to disguise the true destination. Supposed images on these websites are actually malware-tainted .zip archives, harbouring a strain of malware dubbed Steckct-EVL by Trend Micro.
If opened the archive goes to work disabling security software on infected PCs before downloading a second strain of malware onto compromised Windows PCs. This secondary infection is designed to monitor victim's activity on social networking websites. The secondary infection, dubbed Eboom-AC by Trend Micro, is designed to snoop into message-posting, the deletion of posted messages and the sending of private messages via websites including as Facebook, MySpace, Twitter, WordPress and Meebo.
The worm spreads in part by posting messages containing a link to a copy of itself on the websites it targets, which include Twitter and MySpace, as well as Facebook. The dodgy messages are also capable of spreading from infected machines onto Yahoo! and other mainstream IM networks.
Facebook worms have been seen before, most notorious the Koobface worm. The latest threat is nothing like as sophisticated or widespread, but still merits attention.
Trend Micro is working with Facebook to filter out malicious links from users' feeds. The anti-virus firms warns that although infection rates remain low, Steckct-EVL remains a threat because both damage and distribution potential are high.
A write-up of the attack can be found in a blog post here. ®