Kaspersky Lab...has detected two variants of a new worm, Net-Worm.Win32.Koobface.a. and Net-Worm.Win32.Koobface.b, which attack MySpace and Facebook respectively. As part of their malicious payload, the worms transform victim machines into zombie computers to form botnets...Net-Worm.Win32.Koobface.a spreads when a user accesses his/her MySpace account. The worm creates a range of commentaries to friends' accounts. Net-Worm.Win32.Koobface.b, which targets Facebook users, creates spam messages and sends them to the infected users' friends via the Facebook site...