The authors of the prolific Warezov worm are targeting users of Skype.

Warezov variants first cropped up in September 2006 and spread in the attachments of email messages posing as security fixes. Instead of arriving via an email attachment, the latest variant of the worm spreads using a bogus Skype chat message asking users to click on a link, which points to a hacker-controlled website hosting malicious codes.

The plausibility of the attack is increased because infected messages likely come from a target's list of known contacts, though the abrupt dialogue it generates might trigger a few alarm bells.

Some older Warezov variants used other Instant Messaging clients in a similar fashion, but this variant (Warezov-LY) is the first to use Skype, anti-virus firm F-secure reports.

This Warezov family of worms is notable for the rate at which new variants of the malware are being produced, making detection and removal a big challenge for anti-virus vendors who've had to update anti-virus signatures rapidly as a result. ®