Peering Inside the IRC Botnet

The average life span of a command and control server in an Internet Relay Chat (IRC)-based botnet is less than two months. And these machines and their drones that make up a botnet are typically scattered around the world, a new study on IRC botnets reveals.

German and Chinese researchers from Peking University in Beijing and from the University of Mannheim in Germany teamed up to track and study traditional IRC-based botnets over the last year. They found and followed 3,290 IRC-based botnets in the wild, using a honeynet of 17 nodes in 16 provinces in China and some automated tools. (See The World's Biggest Botnets .)

The researchers found more proof of what bot hunters have been saying all along: that IRC is becoming less and less the mode of communication for botnet operators as they attempt to evade detection and stay alive. "Botnets seem to shift away from IRC to protocols like HTTP, Peer-to-Peer-based protocols, or custom protocols," the report says. Still, the researchers consider the relatively short life expectancy of the C&C servers a sign of how flexible these traditional botnet infrastructures are. (See Botnets Don Invisibility Cloaks and Black Hat: Botnets Go One-on-One.)

Although there's a healthy geographic distribution of C&C servers and bot-infected machines, the U.S. is the most popular home for IRC-based botnet C&C machines, with 38.8 percent of them residing here, according to the report. Next in line are China, Korea, Germany, and the Netherlands, with anywhere from 7.5 percent to 4.9 percent of the servers.

The researchers logged the activity -- by commands -- of the botnets. Merely infecting or spreading their malware (10,891 events) was the most common command issued by the bot herders, followed by DDOS attacks (9,755 events), botnet cloning (5,621 events), download/update (5,583 events), information theft (3,809 events), bot login (1,863 events), server hosting (398 events), bot control (780 events), and 107 miscellaneous events.

And these older botnets tend to rely on older vulnerabilities, too, such as asn1 (MS04-007) and pnp (MS05-039), which have had patches for some time. Exploiting weak passwords is another common way bot herders infect machines, the researchers found.

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