Virus Top 10: Mytob storms malware chart

But old timer Netsky still plaguing PCs

The Mytob family of worms has continued its march onto PCs across the country and now dominates the chart of the most virulent viruses reported in July.

According to antivirus firm Sophos' top 10 chart of the most reported malware last month, variants of the Mytob worm now make up seven in 10 of the most spotted viruses.

The worm, which now has more than 160 variants in the wild, spreads as an email attachment and over file-sharing networks, turns infected machines into zombies and spams copies of itself to everyone in the PC's address book.

However, despite Mytob's ever-evolving attempts to give the UK's computers a dose of worms, golden oldie Netsky.P made the top of the chart with 13.9 per cent of all reported viruses in July. Netsky.P first made its appearance back in March 2004, one of the many variants spawned by teen virus writer Sven Jaschan.

Graham Cluley, senior technology consultant at Sophos, said the rise of Mytob was a result of the gangs behind the virus creating more and more variants in an attempt to reach the widest number of PCs possible.

"It should be remembered that there are no 'really big' viruses spreading at the moment, and that's why worms like Netsky and Zafi lurked at the top of the chart for so long. Indeed, we believe that more and more of the criminals behind malware attacks are moving away from mass-mailing worms and switching to Trojan horse attacks against specific targets instead," he added.

July's virus chart in full:

1. Netsky.P 13.9 per cent
2. Mytob.AS 11.6 per cent
3. Mytob.BE 9.3 per cent
4. Mytob.EP 5.5 per cent
5. Zafi.D 3.5 per cent
6. Mytob.CX 3.2 per cent
7. Netsky.D 3.1 per cent
8. Mytob.CJ 2.6 per cent
9. Mytob.CN 2.6 per cent
10. Mytob.AT 2.3 per cent

Others: 42.4 per cent