October saw the biggest increase in virus numbers since anti-virus firm Sophos began tracking outbreaks in 1988. The security vendor now identifies and protects against a total of 112,142 viruses, an increase of 1,685 on September.
Rather than creating new viral strains, the bad guys are churning out multiple new variants of popular backdoor programs such as Agobot, SdBOt, various Trojan downloaders and the like. Anti-virus firm F-Secure notes that many of the malware families have spawned more than 700 variants. Each time hackers add new components to readily available malware code a new variant is created. The trend is showing no signs of slowing down.
September's 1,233 new viruses was followed by a record high of 1,685 viruses in October. Nearly two thirds of the viruses reported to Sophos during the month were versions of the Mytob worm, with the new Mytob-GH and Mytob-EX variants having made a significant impact. One in 60 emails (1.66 per cent), circulating in October were viral, according to Sophos.
Despite all this new activity, NetSky-P, the worm written by convicted German virus author Sven Jaschan, continues to head up Sophos's top ten chart twenty months after it was first detected. Mytob-GH, which first appeared on 16 October 2005, is already in second place and showing no sign of abating. October's chart consists of only three virus families - NetSky, MyTob and Zafi, indicating that virus writers are continuing to create variants of established threats, which prove most effective for financial gain.
"There are six variants of the Mytob worm in the October chart, half of which are new entries," said Carole Theriault, senior security consultant at Sophos. "The creators of Mytob appear to be a gang of virus writers called Hellbot. By having several gang members they can easily issue several different variants in a short space of time." ®
October top ten virus chart, as compiled by Sophos:
NetSky-P Mytob-GH (new entry) Mytob-EX (new entry) Mytob-AS Mytob-BE Zafi-D NetSky-D Mytob-C Zafi-B (re-entry) Mytob-ER (new entry)