The Zafi-D and Netsky viruses continue to top the latest malware charts compiled by security researchers.

Antivirus software company Sophos said that Zafi-D, which first appeared at the end of 2004, has been the most regularly spotted malware, followed by Netsky P.

Sophos noted that February's top 10 is dominated by old viruses, with only two new entries this month, Bagle-BK and Sober-K.

"It looks like the Zafi-D worm is going to be hanging around like a bored teenager for some time to come, unless more home users realise how important it is to update their antivirus software. This Hungarian worm accounts for almost one in three viruses reported," said Carole Theriault, security consultant at Sophos.

Theriault predicted that the Sober-K worm will be one to watch in March. "It can pose in a number of disguises, including a bogus bogus email from the FBI or raunchy videos of celebrity heiress Paris Hilton," she said.

One in 23 emails circulating last month carried viruses, according to Sophos.

Kaspersky Labs added that the number of malware detected overall in February "in absolute terms was low enough to make this month the quietest for the past 12 months".

But the company warned that the detection of six new Bagle variants today is likely to have an impact.

"We will undoubtedly see some of them in the March top 20. We will undoubtedly see a new crop of Trojan-Proxy.Win32.Mitglierder in the next few days, since this is the Trojan that Bagle typically downloads. We should then see a burst of spammer activity and new phishing emails," the antivirus company said.

Sophos top 10 viruses in February 2005:

1. W32/Zafi-D
2. W32/Netsky-P
3. W32/Zafi-B
4. W32/Bagle-BK
5. W32/Netsky-D
6. W32/Netsky-Z
7. W32/Sober-K
8. W32/Sobig-F
9. W32/Netsky-B
10. W32/MyDoom-O