New Sober variant hits inboxes

Sober S arrives in an email in German or English

Antivirus vendors have warned of a fresh outbreak of the Sober virus, which security firm Symantec referred to as Sober S.

In an unprecedented move, police in Bavaria sent out a press release warning about the worm on Monday, a day before the actual outbreak. 

"For more than one year the Bavarian justice department has monitored the people spreading the Sober computer worm, which affects PCs on a regular basis with ever changing variants," the release stated.

The announcement provided information on the contents of the email which carries the worm, and warned computer users not to open the attachment.

Sober S arrives in an email in German or English. One of the emails claims that the sender has received the recipient's email messages through a misconfiguration. An attachment promises to provide a screen shot as well as the missed messages.

The Sober worm first surfaced in October 2003 and has become one of the most widespread worms in history.

Variants have been surfacing on a constant basis. Last May the virus was spread through a spam email message that promised free tickets to the 2006 football World Cup in Germany.

Similar to previous versions, Sober S scans the computer for email addresses as well as a series of file formats. It installs its own SMTP engine to send out new emails with the virus to the harvested addresses.

Antivirus vendor Trend Micro rated the latest Sober risk as 'low' and said that it is seeing only limited infections. However, the firm rated the worm's damage and distribution potential as 'high'.