The three month-old Zafi-B worm was the number one virus in August, indicating that to few users are bothering to update their antivirus software.
According to Sophos, the top 10 reported viruses in August have all been in existence for months. The IT security firm notes that the Zafi-B virus continues to wreak havoc on global email.
"Although we have seen a small, 10 per cent decline in reports of Zafi-B since last month, this email-aware worm doesn't look like it's going to fade into obscurity anytime soon," said Carole Theriault, security consultant at Sophos. "Protection against Zafi-B has been available for a couple of months now, and computer users need to get into the habit of updating their systems in a much more timely manner, or this nuisance will continue to dominate reports."
In spite of the arrest of the Netsky virus author, a number of variants are still affecting businesses, and Netsky.P was number two in Sophos's top 10 chart in August.
Rounding off Sophos's top 10 list are four more variants of the Netsky virus, the MyDoom-O, Bagle-AA and Lovgate-V. "Despite more than 1,200 new viruses being detected in August, not one has made it into the chart this month. In fact, the entire top 10 is made up of viruses which have been doing the rounds for weeks, if not months," said Theriault.
August was a particularly bad month for virus attacks. Sophos analysed and protected against 1,230 viruses in the month, which the company says "is the highest number of new viruses seen in one single month since December 2001."