Microsoft Offers $250,000 Bounty To ID Rustock Botnet Operators

The effort to unmask and apprehend the criminals behind the massive Rustock botnet heated up today as Microsoft put up a $250,000 reward for new information on the botnet's operators.

Rustock -- which in March was knocked offline by federal authorities and Microsoft -- was able to send some 30 billion spam messages a day, such as for phony Pfizer prescription drugs and fake Microsoft lottery scams. FireEye, researchers at the University of Washington, Pfizer, the Dutch High Tech Crime Unit, and the Chinese CERT all assisted in the operation to take down the botnet, which had an army of some 1.6 million machines worldwide at its peak. And there are still some 700,000 machines infected with the botnet's malware, according to a recent report from Microsoft.

Richard Boscovich, senior attorney for Microsoft's Digital Crimes Unit, announced today that the company had decided to supplement its civil discovery efforts with the cash reward. Last month, Microsoft published notices in two Russian newspapers in an effort to alert the Rustock operators of the civil lawsuit against them. The reward was a way to turn up the "heat as a result of the evidence we have secured during the discovery process," Boscovich said in response to an inquiry from Dark Reading. However, he did not elaborate on just what that evidence might be.

The $250,000 reward is available to anyone offering new information that results in the arrest and conviction of the Rustock operators. Microsoft will be gathering information via email, at avreward@microsoft.com.

"This reward offer stems from Microsoft’s recognition that the Rustock botnet is responsible for a number of criminal activities and serves to underscore our commitment to tracking down those behind it. While the primary goal for our legal and technical operation has been to stop and disrupt the threat that Rustock has posed for everyone affected by it, we also believe the Rustock bot-herders should be held accountable for their actions," Boscovich said in a blog post.

He said the company has gathered "strong evidence" in the case, and that Microsoft continues to help clean up Rustock-infected machines.

Gunter Ollmann, vice president of research at Damballa, says a bounty will put pressure on the botnet operators, and on potential informants. "Offering a bounty increases the pressure on all those involved with the Rustock botnet and hopefully serves as a notice to the other botnet operators who’ve picked up the spam-delivery slack to build up their own businesses," he says. "As a threat to the Rustock operators, I believe that the bounty will increase the pressure on other informants to disclose their information. $250,000 will be tempting to many, especially when there are so many competing factions within the spam botnet industry."

The move also shows how Microsoft isn't afraid to flex some muscle in its fight against botnets. "This continues to show the level of commitment Microsoft has to combat cybercriminals and foster international cooperation on these efforts. This bounty is just one example of what they are willing -- and able -- to do to put a serious dent in the cybercrime landscape," says Alex Lanstein, senior researcher at FireEye, who worked on the Rustock takedown.

A copy of Microsoft's notice of pleadings is available here. It includes summons for 11 "John Doe" plaintiffs associated with Rustock.

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