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By | John Leyden 12th May 2008 18:17

Researchers dig into x86 chips for stealthier rootkits

Hiding under the radar

Security researchers have discovered a new technique for developing rootkits, malicious packages used to hide the presence of malware on compromised systems.

Instead of hiding a rootkit in the virtualisation layer, Shawn Embleton and Sherri Sparks of Clear Hat Consulting have discovered an approach for smuggling rootkit technology into System Management Mode (SMM), an isolated memory and execution environment supported in Intel chips that's designed to handle problems such as memory errors and the like.

By running rootkits in SMM, miscreants could make hidden malware harder to detect, since they're hiding code in an area anti-virus scanners don't check. Embleton and Sparks are due to present their research, along with a proof of concept demonstration, at the Black Hat conference in Vegas in August.

An abstract for their talk explains; "SMM code is invisible to the Operating System yet retains full access to host physical memory and complete control over peripheral hardware. We will demo a proof of concept SMM rootkit that functions as a chipset level keylogger. Our rootkit hides its memory footprint, makes no changes to the host Operating System, and is capable of covertly exfiltrating sensitive data across the network while evading essentially all host based intrusion detection systems and firewalls."

While keeping the rootkit well away from the operating system makes the malicious code more stealthy, it also introduces problems. Hackers would need to develop device specific driver code, a factor that makes attacks far more difficult. "I don't see it as a widespread threat, because it's very hardware-dependent," Sparks told PC World. "You would see this in a targeted attack."

Rootkit technology is set to become a major theme of Black Hat this year, according to a preliminary agenda. And Embleton and Sparks look to be stars of the show. As well as giving a talk entitled A New Breed of Rootkit: The System Management Mode (SMM) Rootkit the duo are scheduled to present a talk on a proof of concept 'chipset' level rootkit. Other presentations in the Root Kit Arms Race track at Black Hat will investigate defensive techniques. ®

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