Srizbi, Bobax, & Storm – the rankings

From Gregg Keizer’s “RSA – Top botnets control 1M hijacked computers” (Computerworld: 4 October 2008):

Joe Stewart, director of malware research at SecureWorks, presented his survey at the RSA Conference, which opened Monday in San Francisco. The survey ranked the top 11 botnets that send spam; by extrapolating their size, Stewart estimated the bots on his list control just over a million machines and are capable of flooding the Internet with more than 100 billion spam messages every day.

The botnet at the top of the chart is Srizbi. According to Stewart, this botnet — which also goes by the names “Cbeplay” and “Exchanger” — has an estimated 315,000 bots and can blast out 60 billion messages a day.

While it may not have gotten the publicity that Storm has during the last year, it’s built around a much more substantial collection of hijacked computers, said Stewart. In comparison, Storm’s botnet counts just 85,000 machines, only 35,000 of which are set up to send spam. Storm, in fact, is No. 5 on Stewart’s list.

“Storm is pretty insignificant at this point,” said Stewart. “It got all this attention, so Microsoft added it to its malicious software detection tool [in September 2007], and that’s removed hundreds of thousands of compromised PCs from the botnet.”

The second-largest botnet is “Bobax,” which boasts an estimated 185,000 hacked systems in its collection. Able to spam approximately nine billion messages a day, Bobax has been around for some time, but recently has been in the news again, albeit under one of its several aliases.