The number of compromised computers that are part of a centrally controlled bot net has tripled in the past two weeks, according to data gathered by the Shadowserver Foundation, a bot-net takedown group.
The weekly tally of bot-infected PCs tracked by the group rose to nearly 1.2 million this week, up from less than 400,000 infected machines two weeks ago. The surge reversed a sudden drop in infected systems--from 500,000 to less than 400,000--last December.
The threat to Internet users from bot nets has steadily increased over the past few years. Increasingly, computer systems in China have become infected with bot software and used to attack or spam other targets, according to the latest Internet Security Threat Report published by Symantec, the owner of SecurityFocus. Spammers have taken a shine to bot nets as a way to reliably send stock-touting e-mail campaigns and other mass mailings of junk advertisements. Worms are rapidly being replaced by Trojan horse programs, such as the misnamed Storm Worm, that use a bot net to spam out more copies of the malicious code.
Between December 2006 and March 2007, the Shadowserver Foundation's tally of bot-infected computers has never risen above 600,000.
Posted by: Robert Lemos