Attackers can quickly compromise Windows PCs via a FireWire port, according to a security researcher who has published a software tool to enable the hack.
The tool, which can be used only by attackers with physical access to a system, comes shortly after the publication of research on gaining access to encrypted hard drives via physical access to memory.
Researcher Adam Boileau, a consultant with Immunity, originally demonstrated the access tool at a security conference in 2006, but decided not to release the code any further at the time. Two years later, however, nothing has been done toward fixing the problem, so he decided to go public.
"This means you can completely own any box whose FireWire port you can plug into in seconds," said Boileau in a recent blog entry.
An attacker must connect to the machine with a Linux system and a FireWire cable to run the tool.
The tool, called Winlockpwn, allows users to bypass Windows authorisation, was originally demonstrated at Ruxcon in 2006 at a talk called 'Hit by a bus: physical access attacks with FireWire'. (download PDF.)
At the time, Boileau also demonstrated some of the malicious uses of the tool, but said he wouldn't be releasing the code for those attacks.
The attack takes advantage of the fact that FireWire can directly read and write to a system's memory, adding extra speed to data transfer. According to Boileau, because this capability is built into FireWire, Microsoft doesn't consider the problem a standard bug.
On the other hand, Boileau said he feels PC users need to be more aware of the fact that their systems can be unlocked via FireWire.
"Yes, it's a feature, not a bug," Boileau stated. "Microsoft knows this. The OHCI-1394 spec knows this. People with FireWire ports generally don't."
Microsoft was not immediately available for comment. In the past the company has downplayed security problems that require physical access.
FireWire has become common on Windows systems in the past few years, and is especially prevalent on laptops.
Researcher Maximillian Dornseif demonstrated a similar exploit on Linux and Mac OS X systems at the CanSec conference in 2005, connecting to those systems via a malicious iPod and FireWire.
According to security researchers, the problem can be remedied by disabling FireWire when not in use.