Windows 7: The Top 10 Enterprise Botnets.

Four little-known botnets were behind half of all botnet infiltrations in enterprises last year -- and the No. 1 botnet hitting corporate networks carried the infamous Zeus crimeware.

Damballa, which provides anti-botnet services for enterprises, today revealed the Top 10 botnets it found in its customers' networks in 2009; the so-called ZeusBotnet accounted for nearly 20 percent of all bot infections, while the KoobfaceBotnetB botnet accounted for 15 percent.

Koobface overall had a surprisingly large representation. The worm, typically spread via social networks such as Facebook and MySpace, was the main malware carried by two additional botnets, Koobface.D (5 percent) and Koobface.C (4 percent). The malware was used as a foot in the door to hijack corporate users' accounts and to spread among other systems within the organization, according to Gunter Ollmann, vice president of research for Damballa.