Conficker worm gets an evil twin

February 20, 2009 – 5:37 AM

The criminals behind the widespread Conficker worm have released a new version of the malware that could signal a major shift in the way the worm operates.

The new variant, dubbed Conficker B++, was spotted three days ago by SRI International researchers, who published details of the new code on Thursday. To the untrained eye, the new variant looks almost identical to the previous version of the worm, Conficker B. But the B++ variant uses new techniques to download software, giving its creators more flexibility in what they can do with infected machines.

Conficker-infected machines could be used for nasty stuff — sending spam, logging keystrokes, or launching denial of service (DoS) attacks, but an ad hoc group calling itself the Conficker Cabal has largely prevented this from happening. They’ve kept Conficker under control by cracking the algorithm the software uses to find one of thousands of rendezvous points on the Internet where it can look for new code. These rendezvous points use unique domain names, such as, that the Conficker Cabal has worked hard to register and keep out of the hands of the criminals.

The new B++ variant uses the same algorithm to look for rendezvous points, but it also gives the creators two new techniques that skip them altogether. That means that the Cabal’s most successful technique could be bypassed.


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