02 July 2009, 15:46

Study shows rise in spam botnets

According to MessageLabs, a Symantec subsidiary, June 2009 saw a worldwide increase in spam being sent using botnets. MessageLabs monthly report shows that 83.2 per cent of all spam emails in June were sent from zombie PCs controlled by botnets. That's a 25.6 percentage point increase when compared to May 2009, which came in at only 57.6 per cent.

The increase drives additional concerns around the fast growth of botnets, such as Cutwail PDF (AKA Pushdo & Pandex). According to Trend Micro, as of the 22nd of May, it was the second largest spam botnet on the planet, sending approximately 7.7 billion emails per day, or approximately 1 out of every 25 emails sent. Since March of this year, the output and size of the botnet has nearly doubled. MessageLabs estimates that the Cutwail administrators now control nearly two million PCs worldwide, making it the the largest botnet on Earth. Other major spam botnets mentioned by MessageLabs include Rustock, Grum, Donbot, Beagle, Xarvester, Mega-D, Gheg, Asprox and Darkmailer.