Microsoft is trying to stamp out the Koobface worm, which has spread aggressively on social networking sites such as Facebook and MySpace, the company said Tuesday. In a post to the company's malware protection center blog, researcher Scott Molenkamp said that definitions for Koobface have been added to the Malicious Software Removal Tool (MSRT), the free anti-malware utility that Microsoft automatically delivers every month to users on Patch Tuesday.

Microsoft puts the kibosh on Koobface worm