A new version of the Yaha mass mailing email worm has been released, ready to trip up the unwary on their return to work next week.

Yaha-M (or Yaha-K as it is also described by some AV vendors) is spreading rapidly this week, after first appearing on December 21, MessageLabs notes in an updated advisory. The company has blocked 7,320 copies of the virus in the last 24 hours alone.

Like previous versions of Yaha, the latest variant typically spreads by email with subject lines such as "Enjoy this friendship Screen Saver" and infected attachments with filenames including (Hacker_The_LoveStory.scr, KOF_Sample.exe etc.) A full list is in MessageLabs' advisory and there's more info on the virus in an alert by Finnish AV specialists F-Secure.

F-Secure advises its business users to block this (and similar viruses) by stripping emails with attachments ending with .SCR and .EXE and .COM at the corporate gateway or firewall. AV vendors are updating their signature files to detect this latest mass mailer and protection is now largely in place.

Although nothing special, this virus has the potential to be a real nuisance when Net activity picks up again after the holiday season, at least judging by a large number of copies of the bug personally received by us at El Reg. ®

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