Virus Top 10: 15 months of domination for Klez

Klez is still riding high in the virus top 10 after 15 months - suggesting it is still proving to be a major problem for computer users worldwide.

Yet again Klez was the most common source of virus reports during the month of April, as measured by anti-virus firm Sophos.

However, while many of the most prolific viruses have been doing the rounds for months in one variant form or another, system administrators should also be on the look out for a new entry in the chart - Datemake.

Graham Cluley, senior technology consultant at Sophos Anti-Virus, said: "While Klez refuses to go away, a new entry this month is Datemake - a type of malware known as a dialler. It is programmed to dial a premium rate telephone line, typically with the intent of gaining access to adult material. Businesses should apply strict computing guidelines to prevent getting stung by a huge telephone bill and embarrassed by these seedy programs."

The full top 10 looks like this (percentages show total proportion of virus reports accounted for by each virus):

1. W32/Klez-H (Klez variant) 12.7 per cent 2. W32/Lovgate-E (Lovgate variant) 4.9 per cent 3. W32/Bugbear-A (Bugbear worm) 4.3 per cent 4. W32/Sobig-A (Sobig worm) 3.3 per cent 5=. W32/ElKern-C (Elkern variant) 2.9 per cent 5=. W32/Yaha-E (Yaha variant) 2.9 per cent 5=. W32/Yaha-K (Yaha variant) 2.9 per cent 8. JS/NoClose (NoClose worm) 2.1 per cent 9. W32/Flcss (FunLove) 1.9 per cent RE-ENTRY 10. Dial/Datemake-A (Datemake dialler) 1.6 per cent

Others 60.5 per cent