Microsoft is looking to stamp outa worm that has hit social networking sites and has spread aggressively. Definitions for the Koobface worm had been added to Microsoft's Malicious Software Removal Tool (MSRT) according to a post on the company's malware protection centre blog from researcher Scott Molenkamp.


Koobface, which first appeared in May 2008, struck Facebook again just last week when researchers at Trend Micro tracked its romp through the service. That new Koobface.ac variant, said Trend researcher Jamz Yaneza, tries to trick users into downloading a bogus update to Adobe's Flash, and spreads by hijacking browser cookies to 10 different social networking sites, then uses the cookies to log in to accounts and spew out more fake messages to friends.

According to Molenkamp, the MSRT update, distributed as part of Patch Tuesday,  targets a wide range of components that fall under the Koobface category. "This family is not just a worm, but a collection of different components that can each perform a different task," he said. "These include downloading, Web hosting, password stealing, displaying pop-ups and sending messages to contacts on various social network websites."

MSRT can now seek and destroy Koobface components aimed at users of bebo.com, Facebook, Friendster, fubar.com, hi5.com, LiveJournal, MySpace, myYearbook, Netlog and Tagged. Those sites are the same that Koobface.ac targets when it pilfers browser cookies.

Microsoft has had some success in cleaning infected PCs with the MSRT. Last November, for example, the company crowed that the tool had purged nearly a million machines of phony anti-virus software, dubbed "scareware," in just nine days. In June 2008, MSRT sniffed out 1.2 million PCs infected with a family of password stealers, while in February, it scrubbed the Vundo Trojan horse from about a million machines. During several months at the end of 2007, the tool hit the then-notorious Storm Trojan horse, eradicating it from about a half-million PCs.

The MRST can be downloaded manually from Microsoft's site, or retrieved via the Windows Update service.