Communications within the notorious Waledac botnet have been "effectively decimated," thanks to a novel takedown approach that combined court actions with a variety of technical measures, a Microsoft program manager said Tuesday.
"Operation b49," as Microsoft dubbed the takedown, has severed as many as 90,000 infected PCs from the master control channels that feed them updated malware, spam templates and other malicious data, Microsoft's Jeff Williams wrote here. He cautioned that security watchers can't yet claim victory, but said the initial success of the operation provides a guide for future takedowns.
"While it is still too early to know the entire scope of this particular takedown's impact, early returns show that Operation b49 has been delivering on the disruption of Waledac and helping to map new territory in the fight against botnets," he wrote. He want on to say that data from Microsoft and other researchers "indicate that our actions have effectively decimated communications within the Waledac bot network".
He cited the analysis by the Shadowserver Foundation of honeypot PCs - which are infected and then quarantined so researchers can observe their behavior. It found "an effective cessation of commands to Waledac 'zombies'". The action has severed from 70,000 to 90,000 infected computers from the network, blocking all communication between them and the botmasters.
Williams also cited data from a firm called Sudosecure that tracked a sharp decline in the number of new IP addresses joining the Waledac botnet. That's an indication that the botnet is no longer able to infect new PCs.
The news is encouraging, but it's important to remember that those 70,000 to 90,000 computers remain compromised by malware from Waledac, and likely other crime gangs as well. That may be one reason that spam volumes haven't fallen since Operation b49 was disclosed almost three weeks ago.
Still, the action is significant because Waledac was considered one of the world's top 10 botnets. With hundreds of thousands of computers infected, it churned out more than 651 million spam messages to Hotmail accounts alone between December 3 and December 21. Honeypot machines infected only by Waledac are no longer sending spam, Williams said.
Williams attributed the initial success to a multi-pronged approach that combined a court-issued takedown order against scores of Waledac-related domains with technical measures to disrupt Waledac's peer-to-peer communications and traditional server takedowns to cut off back-end command and control channels. The operation is part of a new approach dubbed MARS, or Microsoft Active Response for Security.
"As we forge ahead with Project MARS, we'll be looking to the lessons of Operation b49 as successful signposts along the road in this uncharted territory," Williams wrote. "While no one action will wipe out every threat, any strong action to disable a botnet is significant progress and each action will inform the next." ®