Operating under the theory that if you kill the head, the body will follow, a group of high-profile security researchers is ramping up efforts to find and disable the command-and-control infrastructure that powers millions of zombie drone machines, or bots, hijacked by malicious hackers.
The idea is to open up a new reporting mechanism for ISPs and IT administrators to report botnet activity, especially the C&C (command-and-control) system that remotely sends instructions to botnets.
A botnet, which is short for “robot network,” is a collection of broadband-enabled computers that have been commandeered by hackers for use in spam runs, distributed denial-of-service attacks or malware installation.
The compromised machines are controlled by a “botmaster” via an IRC (Inter Relay Chat) server installed illegally on a high-bandwidth educational or corporate network.
“If that command-and-control is disabled, all the machines in that botnet become useless to the botmaster. Its an important part of dealing with this problem,” said Gadi Evron, a botnet hunter who helps to manage the anti-botnet fightback.
Evron, who serves as the Israeli CERT manager and is a leader in many global Internet security efforts, said the group includes representatives from anti-virus vendors, ISPs, law enforcement, educational institutions and dynamic DNS providers internationally.
Over the last year, the group has done its work quietly on closed, invite-only mailing lists. Now, Evron has launched a public, open mailing list to enlist the general public to help report botnet C&C servers.
The new mailing list will serve as a place to discuss detection techniques, report botnets, pass information to the relevant private groups and automatically notify the relevant ISPs of command-and-control sightings.
“The vetted lists will still do the bulk of the work, but we needed a public place to involve a wider audience,” Evron said in an interview with eWEEK.
Dan Hubbard, senior director of security and technology research at San Diego-based Web filtering software firm Websense, said the threat from botnets should be high on a CIOs worry list. “Were seeing more and more bots being written for multiple use. They used to open a backdoor simply to send spam, but now were seeing bots logging keystrokes or pulling Web-surfing data to build personal identity profiles,” Hubbard explained.
“The botnet has become a web of connections. Theyll send spam for a porn content site and when youre lured there, theyll use sophisticated redirects to bounce you around different sites rigged with exploit code. Its very organized around making money,” he added.
He said Websense Web Security Suite Version 6.2 has been fitted with a new protection mechanism to sniff out bots and bot networks. “Bots and botnets are spreading like wildfire. Were working to control them, but its always a catch-up game,” Hubbard said in an interview. “Even after you cut off the command-and-control, the machines in the botnet are still vulnerable to reinfection. In some cases, a single machine may belong to multiple botnets.”
Roger Thompson, a veteran anti-virus researcher who runs the Atlanta-based Exploit Prevention Labs, said the vigilante approach to targeting botnet command-and-controls comes with upside and downside.
“The upside to these information-sharing efforts is that the right people get involved. We get the right information to law enforcement, which is really whats required,” Thompson said.
However, Thompson worries that culling the herds may breed a stronger beast. “We might just be killing off the [command-and-controls] that are easily found and making them get stronger and more cunning to survive,” he added.
Like Thompson, Evron admits that the command-and-control shutdowns are only a small part of dealing with the growth of botnets. “Anything you do that kills the problem right now has one direct result. The bad guys go back to drawing board and plan a more sophisticated mode of attack. Were always going to be playing catch-up,” Evron conceded.
“Its all about return-on-investment,” he said. “Botnets are being used to make money. Its very well-organized, and its working for the bad guys. If you can change the economics by making it more dangerous and difficult for them to control the botnets, thats the only way to try to get ahead of game.”
With the new mailing list and increased public participation, Evron envisages a scenario where experts in the anti-virus, anti-phishing, anti-spyware and anti-spam industries are all working together on research and development to help curb the growth of botnets.
Websenses Hubbard agrees theres no silver bullet to solve the problem. “Were seeing a major crossover,” he said. “Bots are now coming with keyloggers. Were seeing botnets being used in conjunction with phishing attacks. The effort has to get buy-in from everyone, including law enforcement authorities, ISPs, dynamic DNS providers and the general public.
“I dont think well ever shut down botnets. The problem is just going to change with time,” Hubbard added. “The techniques are becoming better and more sophisticated as we come out with new defense techniques. Were just trying to slow them down, really.”