The botnet market is both growing and consolidating. The top 10 botnets of 2010 -- based on total number of PCs compromised -- began the year with 22% market share, but grew to account for 57% of all botnet infections by the end of the year. Meanwhile, in the same timeframe, the number of unique botnet victims grew by 654%.
Those findings come from a report, released on Tuesday, by anti-botnet security company Damballa. The report finds a botnet landscape that is changing rapidly, driven in part by the ready availability of inexpensive botnet-building toolkits.
Which botnets rule? The biggest botnets in 2010 (based on their percentage of victims) were the TDLBotnetA botnet run by RudeWarlockMob (15% market share), the RogueAVBotnet run by FreakySpiderCartel (6%), the ZeusBotnetB run by FourLakeRiders (5%), followed by Monkif (5%), Koobface.A (4%), and Conficker.C (3%). That list includes one-off botnets created and customized by criminal gangs, many of whom use DIY tools such as Zeus as the base.
Interestingly, 60% of botnets seen in 2010 didn't even exist in 2009. In fact, "only one botnet -- Monkif -- made it to the top 10 of both years," said Gunter Ollmann, VP of research for Damballa, in a blog post.
In general, what sets apart the botnet winners from losers is that the biggest ones get updated frequently with revised fraud targets. They also embrace the latest botnet features and functionality. That includes updating the malware on infected PCs, running multiple infection campaigns at once, generating one-of-a-kind malware for each victim, and using multiple infection vectors.
Today's top botnet are also succeeding thanks to a thriving ecosystem of best-of-breed, complementary services. "The federated ecosystem of botnet building means that malware authoring, drive-by-download infections, content delivery, and [command-and-control] hosting are increasingly distributed amongst multiple unaffiliated service providers," said Ollmann. "The increased accessibility to specialist service providers has made it easier for botnet operators to rapidly grow their botnets and monetize their ill-gotten gains."
Interestingly, this distributed approach to botnets means that a PC today can be infected with malware that places it under the control of multiple pieces of botnet-driven malware. According to Ollmann, "over 35% of botnet victims were simultaneously members of multiple botnets in 2010."