Sobig eclipsed Blaster in the August viral charts.

More than a third of support calls (37.6 per cent) logged by AV firm Sophos in August involved Sobig, twice as many (18.8 per cent) as that received about the prolific Blaster worm.

Managed services firm MessageLabs has blocked more than 12.8 million Sobig-infected emails, since the appearance of Sobig-F on August 18. At the peak of infection, one in 17 emails MessageLabs scanned harboured the virus. IntY, which provides malicious code screening services for SMEs, reckons one in three emails in a sample of UK small businesses contained the virus at the peak of the outbreak.

August 2003 was the worst month for malicious code on record, according to Sophos, with four of the top ten viral entries in the firm's chart arriving for the first time this month. ®

August 2003 Virus Chart, by Sophos

1. Sobig-F
   
2. Blaster-A
   
3. Nachi-A
   
4. Mimail-A
   
5. Yaha-P
   
6. Klez-H
   
7. Bugbear-B
   
8. Yaha-E
   
9. Dumaru-A
   
10. Sobig-A

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