Swen trumps Sobig to top virus league

The most commonly received virus for September is a new entry – the Swen worm, which fools users into opening an attachment by masquerading as a Microsoft security update email.

The virus made up 23.5 per cent of all reported viruses last month pushing the malware big boys of the last few months down the chart, according to figures from Sophos. Swen, which also goes by the name Gibe, is thought to be spreading so well due to the professional look of the email that carries it. It purports to be from 'Microsoft Technical Assistance', offering a cumulative anti-virus patch. Swen spreads via email and through IRC, Kazaa and LANs.

The second most widely received virus last month was Dumaru.A, which uses similar tactics to Swen to infect users' PCs. While it claims to be from security@microsoft.com and encourages users to 'use this patch immediately', its approach is not as sophisticated as Swen's, using a text-based email featuring the less than convincing line: "Dear friend, use this Internet Explorer patch now! There are dangerous virus in the internet now!"

August's number one virus, Sobig, has two entries in this month's chart, with the Sobig.F rating a miserable fourth at 5.6 per cent of all reported viruses and Sobig.A at number six with 4.4 per cent. The equally popular Blaster fares equally badly, scraping in with just 2.7 per cent – despite extensive publicity and warnings on the subject, it seems users are still not patching against virus threats.

September's full chart:

1. W32/Gibe-F 23.5 per cent 2. W32/Dumaru-A 18.1 per cent 3. W32/Mimail-A 15 per cent 4. W32/Sobig-F 5.6 per cent 5. W32/Nachi-A 5.5 per cent 6. W32/Sobig-A 4.4 per cent 7. W32/Bugbear-B 2.9 per cent 8= W32/Klez-H 2.7 per cent 8= W32/Blaster-A 2.7 per cent 10. W32/Parite-B 1.3 per cent

Others 18.3 per cent