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Wednesday, January 25, 2006

Cambridge prof warns of Skype botnet threat

A discovery by a Cambridge professor this week highlights an easy to perform denial-of-service (DoS) attack using VoIP as a wrapper for the malicious traffic.  As a growing amount of VoIP traffic is passed across the internet, concern is being raised that bot networks could be orchestrated to overlay VoIP on their attacks, thereby preventing detection of the source.

 

Voice-over-IP apps could be used to cloak networks of zombies, used to launch denial of service attacks, a Cambridge professor has warned.  Armies of ordinary PCs - “botnets” - that have been infected by a virus and put under malicious control, could be controlled and orchestrated by messages hidden in VoIP traffic generated by programs such as Skype, warned Jon Crowcroft, Marconi professor of communications systems at Cambridge University.

Denial-of-service (DoS) attacks are usually shut down by tracing control messages, normally sent by chat and IM programs.

“There isn’t a protocol you can’t use as a covert signalling channel,” responded Kurt Sauer, director of security operations at Skype.  “Some large commercial groupware products have encrypted XML streams - they may not be quite as good at firewall traversal, but that’s still an opaque data stream.”

Some IT managers do not want uncontrolled traffic punching holes in their firewalls, and using bandwidth, and security vendors have launched specific products to block Skype.

Crowcroft would like Skype to publish its routing specifications, so IT managers can work better with the application, tracking it and checking its behaviour.  “There are a whole bunch of reasons why obfuscation is not helpful in the long run.”  Although Skype still wants its proprietary edge, the issue is up for discussion: “The people who own networks and systems have a right to manage as they see fit,” said Sauer.

http://www.techworld.com/security/news/index.cfm?NewsID=5232&inkc=0%3CBR%3E%3C/P%3E%3CP%3E

Posted on 01/25
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