Swen fends off Mimail to top viral charts

Top Ten Bugs

The Swen virus beat off a strong challenge from various Mimail virus variants to retain its position at the top of the viral charts this month.

Message filtering firm MessageLabs blocked more than 567,000 Swen-infected emails this month. Durnaru-A was the second most prevalent nuisance with just under 386,000 sightings over the last four weeks while the undead Sobig-F worm put in approximately 265,000 appearances.

Sobig F reached number three MessageLabs November Top 10, despite having a built-in expiry date of September 10. Incorrectly set clocks on some infected computers explain why the virus is continuing to circulate.

Overall, one in 97 email MessageLabs scanned were contaminated with viral infections. Just over half (55.1 per cent) of the emails scanned by MessageLabs’ anti-spam service this month turned out to be junk mail.

November 2003 saw the arrival of two variants of the Mimail virus, both of which attempted to trick PayPal users into giving out sensitive account information.

The two viruses illustrate the growing trend among virus writers of using malicious code not just for mischief but for malicious gain, according to MessageLabs.

The viruses Mimail-E and Mimail- appeared at the seventh and eight positions in MessageLabs November charts with just over 100,000 appearances apiece.

Records of the subject of calls received by AV firm Sophos paint a slightly different picture of the viral landscape. Around a third of support calls (32.6 per cent) logged by Sophos in November involved the Sober virus. Calls about Mimail virus variants collectively accounted for 28 per cent of the calls fielded by Sophos over the last four weeks. ®

November 2003 Virus Chart, by MessageLabs

  1. Swen-A
  2. Durnaru-A
  3. Sobig-F
  4. Mimail-C
  5. Klez-H
  6. Mimail-A
  7. Mimail-E
  8. Mimail-J
  9. Sobig-A
  10. Yaha-P


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