1/23: Imbot.AC Worm Spreads Via MSN Messenger

Worm_Imbot.AC is a memory-resident worm that may be dropped by other malware or downloaded unknowingly by a user when visiting malicious Web sites.

It propagates via the popular instant messaging application, MSN Messenger. It does this by sending a message and a .ZIP file that contains a copy of itself to target contacts.

The message it sends may be any of the following:

This worm also has backdoor capabilities. It connects to random TCP ports and executes the commands from a remote malicious user. It also terminates certain processes, if found running in memory.

Technical details can be found at this Trend Micro page.