Bot herders hide master control channel in Google cloud

Google AppEngine co-opted

By Dan Goodin, 9th November 2009

Cyber criminals' love affair with cloud computing just got steamier with the discovery that Google's AppEngine was tapped to act as the master control channel that feeds commands to large networks of infected computers.

The custom application was used to relay download commands to PCs that had already been infected and made part of a botnet, said Jose Nazario, the manager of security research at Arbor Networks. Google shut down the rogue app shortly after being notified of it.

The discovery is the latest to highlight bot herders' growing embrace of the cloud, in which applications and data are hosted on large, publicly available servers instead of stand-alone machines. Last Friday, researchers from Symantec found a Facebook account pumping commands to zombie drones. And in August, Nazario found several Twitter accounts that were doing much the same thing.

Also on Monday, researchers from anti-virus provider Trend Micro reported that the massive Koobface botnet was abusing Google Reader to spam malicious links to Facebook and other social networking sites.

Black hat hackers are being drawn to the cloud by many of the same benefits attracting everyone else, namely cheap and scalable processing exactly when it's needed. But they also like the anonymity and obscurity that come from using many such services.

"It's the low cost, it's the high availability," Nazario told The Reg. "And the security measures in place for most of these things are retroactive, meaning it takes somebody to identify and investigate and take them down. You're really free to swim in the huge flood of user generated content, as long as you don't stick out too much."

Google's AppEngine provides a framework for running custom applications that can handle requests from millions of computers. The app spotted by Nazario appeared to recycle code from Grey Pigeon and Hupigon toolkits available in the attacker underground.

Infected PCs that checked in with the malicious app were instructed to download the PCClient backdoor from a third-party server. Because the channel software was hosted on the heavily fortified Google, he was unable to get his hands on the source code itself or to observe other commands it may have carried out.

And that may be another reason why black hats are flocking to the cloud.

"Going to a company as big as Google and saying 'Can we get an image of that server,' that's a pretty high barrier," he said. ®

Steps to Take Before Choosing a Business Continuity Partner