According to one security company, the month October saw the biggest increase in the number of viruses it has ever recorded.
Anti-virus vendor Sophos reported that it logged 1,685 new viruses last month, bringing the total in its database to 112,142. The information was provided as part of a regular update from the company, which reports the top ten viruses it tracks each month.
The biggest proliferator Sophos reported came from the 20-month-old Mytob, of which two new variants appeared last month -- Mytob-GH and Mytob-EX. Mytob opens a back door on infected hosts and allows them to be controlled by malicious users over IRC networks, similar to the method described in a recent EnterpriseNetworkingPlanet feature.
Mytob's biggest "competitor" for vulnerable systems is the Netsky worm, which gathers logs of system information on hosts it infects.
"There are six variants of the Mytob worm in the October chart, half of which are new entries," said Sophos senior security consultant Carole Theriault. "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."
With this rise in viruses, Sophos' research shows that 1.66 percent of e-mails circulating in October were viral.