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Shadowserver to Build 'Sinkhole' Server to Find Errant Bots

New initiative will emulate IRC, HTTP botnet traffic

OWASP AppSec USA 2008 -- NEW YORK -- Ever wonder what happens to the bots when a botnet domain shuts down? The Shadowserver Foundation, a volunteer organization that gathers intelligence on the Internet’s dark side, has begun building a so-called “sinkhole” server that poses as those now-defunct malicious domain servers in order to find out what they left behind.

The project, which is in the early phases, will allow Shadowserver to emulate both botnet IRC and HTTP traffic as a way to study those botnets as well as find bots that remain infected by them, says Steven Adair, a security expert with Shadowserver, who revealed the new project to attendees of the OWASP USA security conference here.

“There are still a lot of [machines] communicating with” these now-defunct servers, Shadowserver’s Adair says. Shadowserver then could trace those infected machines and alert the organizations whose machines or Web servers are still infected by the botnets, he says. “We would register and take those [former malicious] domains.”

Shadowserver’s sinkhole server will be able to accept incoming traffic from infected machines as they try to communicate with their former command and control server, for example. “We’ll be able to see referrers, who came in and which sites or pages are infected,” Adair says.

It will also allow companies who know they have bots to direct their bot-infected traffic to the sinkhole server for Shadowserver to analyze, although Adair says he’s unsure if companies will use it that way.

HTTP remains the favorite communication method for botnets today, he says. One infamous HTTP-based botnet Shadowserver has been studying closely is Black Energy, which traditionally has been used for distributed denial-of-service (DDOS) attacks. (See Botnets Behind Georgian Attacks Offer Clues.) Black Energy this year went from just DDOSing to spreading keyloggers to steal credentials and passwords, Adair says. Like other botnets, it has been updating itself with new malware. “It went from a mundane botnet to stealing [credentials] and taking when it can from the same infection."

But even the deadliest botnets have their flaws. Adair disclosed two major vulnerabilities in the Black Energy bot code -- one that let him bypass authentication with the C&C infrastructure, and several cross-site scripting bugs. Those weaknesses could be used to turn the tables on the botnet -- another botnet could then infect Black Energy, for instance, he says.

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