Stealthier Blue Pill on the way

The researcher who developed Blue Pill, an attempt at developing undetectable malware for computers running Microsoft's Windows Vista operating system, is working on a stealthier version that could be finished within the next few months.

Polish malware specialist Joanna Rutkowska, who works as a senior researcher for Singapore's Computer Security Initiative Consultancy (COSEINC), unveiled a prototype of Blue Pill earlier this year. "Blue Pill is about hijacking an operating system, moving into a virtual machine, and taking control of it," she said during an interview at the Hack In The Box Security Conference (HITB) in Kuala Lumpur, Malaysia.

Blue Pill works by taking advantage of hardware virtualization technology in processors from Advanced Micro Devices and Intel. Virtualization allows computers to simultaneously run multiple operating systems and applications in separate partitions. "Using this virtualization technology should allow us to develop malware that is 100 percent undetectable," Rutkowska said.

The Blue Pill prototype demonstrated earlier this year came close to achieving this goal, but timing how long a computer takes to complete a given operation can theoretically be used to detect whether or not Blue Pill is running on a computer, Rutkowska said. She is now working on a new version of Blue Pill that is not detectable using this method.

Whether or not timing analysis is a purely theoretical means of detecting Blue Pill has been debated within the security community, with some arguing that this method of detection is easy to implement. Rutkowska is not so sure. "You have to have a trusted time source. But you cannot rely on your internal clock because that can be subverted by Blue Pill," she said, adding that other timing methods are also vulnerable to manipulation.

One way to defend against Blue Pill is to disable the virtualization capability in the processors, but that makes no sense. "People spent years developing those new processors with virtualization, and now you buy those new processors just to disable the virtualization, right? Where's the logic?" she asked.

A more practical defense is for Microsoft to disable the paging of kernel memory in Vista, which means loading the kernel code and drivers, approximately 80MB of data, into main memory. This would prevent Blue Bill from accessing the kernel and executing code. "Who cares about 80MB? That's why I'm so surprised that even though I showed this attack at the end of July at the SysCan conference, it still hasn't been fixed in RC1," Rutkowska said, referring to the latest pre-production version of Vista.

In response, a Microsoft security specialist said the company continues to work on improving the security of Vista RC1 before the production version is shipped to customers. "There's still a few months before the final [version] does get released," said Mike Reavey, the operations manager at the Microsoft Security Response Center.