Virus top 10: Party over for MyParty?

The Klez worm knocked MyParty off the top spot in the last month's virus chart.

Figures for March from anti-virus software company Sophos revealed Klez, an old worm making a comeback, had managed to infect many computers because it was timed to deliver its payload after the machine had been infected.

The "E" and "G" variants of the Klez mass-mailing worms have been around since November 2001, but after a slow start it started to climb higher in the virus charts.

The KW32/Klez worm has a nasty sting in its tail as it drops a timed payload inside a user's computer when the programme is run. Once the time is up, the worm goes on deleting the user's files, such as .doc, .htm, .jpg and .mp3, from the hard drive. The worm can also send itself to all entries in the user's address book.

Klez and its many variants were ahead of Badtrans by just under one per cent. Sircam, Magistr and MNimda are all still in the top 10.

Sophos discovered 510 new viruses in March.

Here's the list in full - percentages denote proportion of total reported infections attributable to each virus:

1. W32/Klez-G (Klez variant) 23.7%
2. W32/Badtrans-B (Badtrans variant) 22.8%
3. W32/Magistr-B (Magistr variant) 6.9%
4. W32/Fbound-C (Bound variant) 6.8%
5. W32/Sircam-A (Sircam) 4.8%
6. W32/Magistr-A (Magistr) 3.6%
7. W32/Gibe-A (Gibe) 3.0%
8. W32/Caric-A (Caricature) 2.1%
9. W32/Hybris-B (Hybris variant) 1.7%
10. W32/Klez-E (Klez variant) 1.5%