A network of more than 10,000 zombie PCs has been dismantled after security staff at Norwegian telco Telenor located and shutdown its controlling server.
Worms such as MyDoom and Bagle (and Trojans such as Phatbot) surrender the control of infected PCs to hackers. These expanding networks (dubbed 'botnets' by the computer underground) can be used for spam distribution or as platforms for DDoS attacks. By using compromised machines - instead of open mail relays or unscrupulous hosts - spammers can bypass IP address blacklists. Often, as is the case with the Telenor botnet, compromised PCs are controlled across IRC (Internet Relay Chat) channels.
The clients of the Telenot botnet remain compromised, even though the controlling server has been taken out. The Internet Storm Centre advises users with network traffic logs to check for connections from their network to the IRC Server - which was listening on IP 188.8.131.52 tcp port 10009.
The Telenor takedown is a significant step in the fight against botnets, which have been implicated in recent DDoS attacks against Akamai and DoubleClick as well as attacks on numerous online bookies in recent months. Last month, the FBI shut down a large IRC provider, Ohio-based CIT/Foonet, after uncovering evidence it was a middleman between hackers with access to botnet networks and unscrupulous businesses prepared to launch denial of service attacks on rivals. ®
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