Hacking the Vista Kernel

If you're counting on Microsoft's Vista to be more airtight than its Windows, don't get your hopes up just yet. A researcher has already found a way to hack it by inserting code into the latest beta version of Vista Beta 2 kernel (x64 edition).

Joanna Rutkowska, senior security researcher for COSEINC, a Singapore-based IT security company, will demonstrate at the Black Hat conference in Las Vegas next week her research proving malware could be slipped into the Vista kernel undetected. It's a proof-of-concept that basically bypasses Vista's security policy of allowing only digitally signed code to be loaded into the kernel, not malware.

Rutkowska's findings were part of overall research on malware vulnerabilities in Microsoft's long-anticipated OS by the COSEINC Advanced Malware Labs. She'll use proof-of-concept code that disables the signature-check mechanism.

That then leaves Vista vulnerable to malware that gets executed in kernel mode, says Rutkowska, such as password sniffers, keyloggers, or even advanced network backdoors that let the attacker gain control of the machine remotely.

This isn't simple for hackers to execute, however. "For the attack to succeed, one needs to find a reliable way to force interesting kernel code to be paged out, then find that code inside a page file and modify it. And finally, the kernel needs to load that code (now modified) again into physical memory and execute it," she says. "The proof-of-concept code I implemented solves all those challenges allowing for very reliable exploitation."

The attack doesn't use your typical buffer overflow or other bug, but basically exploits a Vista (and Windows) design problem -- that user-mode applications are allowed to access raw disk sectors, Rutkowska says.

For Microsoft to patch this, it would likely result in some system performance or usability penalty, she says. "Some of those penalties seem to be small enough, so solving this should be feasible."

Rutkowska, meanwhile, is still impressed overall with what Microsoft has done to secure Vista. "It's just not that easy to turn the general-purpose operating system into a very secure one and not [be] losing on functionality at the same time."

At Black Hat, Rutkowska will demonstrate an attack against Vista's kernel protection as well as a network backdoor for Vista based on Blue Pill technology, a stealth technology that can be abused by hackers to "hide" malware.

There's no reason for future Vista customers to sweat about these security problems at this point. "Hopefully, Microsoft will find a workaround against the presented attack before shipping the final release of Vista next year." And Microsoft will need to enlist the help of a processor vendor to combat Blue Pill-based attacks, which don't exploit OS weaknesses.

The only means of protection right now is to ensure a Vista machine's admin privileges aren't at risk of being highjacked -- Blue Pill can't be installed without admin access, either. "So protecting your machines from being 'owned' in the first place is a good idea," Rutkowska says.

— Kelly Jackson Higgins, Senior Editor, Dark Reading