New Worm Poses as Microsoft Patch

Antivirus company TruSecure is warning users about a new e-mail worm that is beginning to spread on the Internet and over the Kazaa peer-to-peer network.

The new worm, dubbed Gruel, is a mass-mailing worm that masquerades as a Windows software patch from Microsoft and as a virus-removal tool from Symantec, according to an alert from TruSecure.

Familiar Attack

Like other mass-mailing worms, Gruel spreads by stealing e-mail addresses from an infected computer's Microsoft Outlook address book and mailing copies of itself to those addresses, TruSecure representatives say.

The worm deletes files from machines it infects and copies itself into various locations. It particularly targets and infests folders used by the Kazaa file-sharing network, enabling it to spread on that network as well, according to TruSecure.

The antivirus company received word of five infections and fielded around 20 calls from users who have received e-mail messages containing the virus, according to Bruce Hughes, content security lab manager at TruSecure.

While the number of infections is still low, Gruel has a number of characteristics that have allowed other worms to successfully spread in recent months, Hughes says.

In addition to its clever use of so-called "social engineering" tricks such as using the names of Microsoft and Symantec to fool recipients, the coupling of mass-mailing techniques and features to spread over peer-to-peer networks makes Gruel more dangerous, Hughes says.

Homes Vulnerable

Unlike other worms, however, Gruel does not spread over shared folders on local area networks, he says.

Most organizations have antivirus software that will block or quarantine the executable attachment containing the Gruel virus, Hughes notes. However, he expects that home users without such protections will bear the brunt of the new worm.

In the coming hours and days, infections on those home systems may bombard corporate mail gateways with infected messages as well, Hughes says.

The company currently has the new worm on "watch," he says.