Security researchers are warning of a new worm, dubbed "Funner," targeting Microsoft's MSN Messenger instant messaging application.
The worm propagates by sending a copy of itself, disguised as "funny.exe," to contacts found through MSN Messenger.
The worm then makes registry modifications and overwrites entries in the Hosts file, a list used to map IP (Internet Protocol) addresses to Web sites.
Only certain Windows systems, including Windows XP, are vulnerable, according to security researchers.
Rating the Threat
Researchers currently grade Funner a low threat because of light distribution, though Trend Micro rates its damage and distribution potential as "high."
Computer Associates International grades Funner's destructiveness as "medium," while Symantec reports fewer than 50 known infections so far.
All three vendors have removal instructions posted in security alerts on their Web sites.