Virus Writers Perfecting Hit-and-Run Tactics
Repeated spikes of viruses that are not being detected by major anti-virus engines were observed during the last quarter, apparently the result of hit-and-run tactics by virus writers to compromise large numbers of computers and then disappear before they can be countered.
"Malware writers have begun to distribute short, massive outbreaks of different variants of a single malware, and these outbreaks are not immediately blocked by most anti-virus engines that do not have a generic signature that works on them," security firm Commtouch reported in its third-quarter "Internet Threat Trends" report (PDF).
The viruses responsible for much of this summer's activity were variants of Mal-Bredo A and Mal Behav-340. Each had thousands of variants that were altered enough to get past anti-virus detection engines.
Outbreaks were seen every 11 to 13 days, resulting in sharp spikes that peaked quickly and then disappeared, Commtouch said. That reversed an 18-month trend in which generic signatures were adequate to block most new variants.
"The recent attacks are short and massive; each attack ends before a new, updated signature is sent to the endpoints," the report states. "These signatures enable botnet herders to infect enough computers for the two weeks that follow."
William Jackson is the senior writer for Government Computer News (GCN.com).