Friday, February 20, 2009

New Conficker B++ Variant Poses Even Greater Threat

Via TechWorld -

Shortly after Microsoft offered a bounty on the heads of the criminals behind the widespread Conficker worm, a new version of the malware has appeared 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.


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.

Conficker underwent a major rewrite in December, when the B variant was released. But this latest B++ version includes more subtle changes, according to Phil Porras, a program director with SRI. "This is a more surgical set of changes that they've made," he said.

To put things in perspective: There were 297 subroutines in Conficker B; 39 new routines were added in B++ and three existing subroutines were modified, SRI wrote in a report on the new variant. B++ suggests "the malware authors may be seeking new ways to obviate the need for Internet rendezvous points altogether," the report states.

Porras could not say how long Conficker B++ has been in circulation, but it first appeared on 6 February, according to a researcher using the pseudonym Jart Armin, who works on the website, which has tracked Conficker.

Though he does not know whether B++ was created in response to the Cabal's work, "it does make the botnet more robust and it does mitigate some of the Cabal's work," Support Intelligence CEO Rick Wesson said in an e-mail interview.

Also known as Downadup, Conficker spreads using a variety of techniques. It exploits a dangerous Windows bug to attack computers on a local area network, and it can also spread via USB devices such as cameras or storage devices. All variants of Conficker have now infected about 10.5 million computers, according to SRI.

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