The Trojan uses e-mail and claims that MSN Messenger 8 BETA has been leaked and invites users to click on a link. When they click on the link a virus called Virkel.f Trojan will be downloaded.
Virkel.f adds the compromised machine to a botnet, from which the hacker can update the Trojan with additional malicious code, to make the PC into a spam zombie or along with others, launch a denial-of-service (DoS) attack on Web sites. Virkel.f also shuts down anti-virus and security software, and blocks access to sites that belong to security vendors.More info at InformationWeek.
This bot worm spreads by hijacking IM contact names from an infected computer, then spimming those names with new messages about the "leaked" client.