represented 22.6 percent of all virus incidents reported to Sophos, the company said. Netsky-P was first spotted in March; it's one of more than 30 variants of the original Netsky mass-mailing worm, which .
"It is simply shocking that Netsky-P and Zafi-B are still infecting computers, months after they were first protected against by antivirus companies," said Graham Cluley, Sophos senior technology consultant. "This indicates most people have still not updated their antivirus, and we believe it's mainly coming from home users, who then spread them to businesses. People should update their antivirus several times a day."
, ranked second, accounting for nearly 19 percent of all virus outbreaks this year, according to the report. Sasser, a , accounted for 14 percent of virus reports and ranked third on the list.
Sven Jaschan, the self-confessed, was taken into custody by German police in May. He is scheduled to go to trial early next year.
His viruses, however, continue to live on--accounting for more than 50 percent of all virus reports this year, according to Sophos.
Sophos detected a total of 10,724 new viruses, worms and Trojan horses in 2004--a 51.8 percent increase over last year.
Sophos expects the number of new viruses to remain at a similar level next year, but the intent of virus writers is expected to continue to shift to, rather than mere bragging rights, Cluley said.
"When the commercial world gets involved, things really get nasty. Virus writers and hackers will be looking to make a tidy sum," Cluley said.
But by the same token, he noted that government authorities are likely to become more heavily involved in capturing and convicting such virus writers.