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Kernel crimps make Windows 8 a hacker hassle

The kernel is the new battleground, says ReactOS and iOS co-author Alex Ionescu

Windows 8 will make hackers' lives hard, says Windows internals expert, security researcher and co-author of Apple's iOS and the open source Windows XP clone ReactOS, Alex Ionescu.

Now chief architect at CrowdStrike, a security company focused on nation-state adversaries, Ionescu says Windows 8 builds on the usermode exploit mitigations introduced into Windows Vista and 7 with new approaches to security that attempt to mitigate kernel mode attacks.

Ionescu will outline those new defences at the Ruxcon Breakpoint security conference in Melbourne, Australia, next week.

He'll tell the audience that many pathways to exploitation will be sealed off in the latest Windows release. "As usermode's been getting tighter and tighter to attack and as in the Windows case more and more services have been moved to the kernel, it's become quite a target … and the rewards are quite great," Ionescu says. "It'll be interesting to see how attackers deal with the new landscape [after the release of Windows 8]."

That Windows will be targeted is hard to doubt, given that in the past hackers have treated security in Microsoft's flagship as an unmitigated joke. Writing exploits for Windows XP was extremely easy and the resulting boom in malware affecting Windows users was unprecedented. But companies like Microsoft and Adobe have made significant headway in recent years by introducing exploit mitigations to their products.

That's not to say the vulnerabilities have all gone away, but features like application sandboxing, Data Execution Prevention (DEP) and Address Space Layout Randomisation (ASLR) make them difficult to exploit.

Microsoft's efforts started taking shape around 2004, when Service Pack 2 for Windows XP was released. It introduced a basic firewall to the operating system and pestered users into installing anti-virus software and opting for automatic OS updates.

Next came Vista with its much-loathed UAC feature and some basic memory mitigations like DEP and ASLR, with those features tweaked and carried over into Windows 7. All of a sudden, exploiting bugs on current-generation Windows became suddenly significantly harder and the number of usable exploits dropped off. The deluge, today, looks more like a trickle.

Ionescu cites the failure of highly-skilled exploit writers to successfully trigger a known, critical vulnerability in Microsoft's Remote Desktop Protocol (RDP) on the Windows 7 operating system this August as a sign of real progress. "We had 90 people in an IRC channel, some of the best exploit writers, and the most we got was a denial of service attack," he says. "No one actually found a way to exploit that bug and get code execution out of it, and I think Windows 8 will make those kinds of things even harder."

"With Windows 8 they've definitely raised the bar and added a laundry list of mitigations and protections and additional security around things that make it honestly a lot harder," he says.

There are further improvements to usermode security, as well, Ionescu says. Applications designed in the Windows 8 Metro language will be sandboxed in similar ways to mobile applications on Apple's iOS and Google's Android operating system.

"Every (Metro) application runs kind of in its own virtual account, its own files, its own registry settings, it's own named objects and it's isolated from all the other objects, files and registry keys that other applications might have [access to]," he says.

There's also support for Early Launch Anti-Malware (ELAM) drivers. "They'll load their drivers before their AV driver comes up and by this time the system is already rootkitted, it's already owned... what ELAM does is say 'let's have a special category of drivers that we can guarantee loads before any other Windows driver'."

Some clever hardware crypto features -- Trusted Platform Modules (TPM) -- will also allow users' hardware to ensure the Windows kernel hasn't been tampered with before it's loaded into memory.

At a stretch it's possible the biggest security risk to users in a Windows 8 will be their own behaviour and not the drive-by download attacks of the last three to four years, Ionescu says.

"Novice users, the way they get attacked is not through advanced exploits... they get a flash banner ad that tells them 'download this and run it' and they just go ahead and download and run it. That takes more than mitigations to prevent," he says. "A well versed person who understands the risks of browsing the Internet and doesn't just run random stuff... they should now feel a lot safer if they're using Windows 8 I think."

Regardless of all the mitigations, disastrous exploits affecting Windows 7 still surface from time to time, and that will no doubt continue with Windows 8. Windows 7 users, for example, were not immune to last month's Internet Explorer bug, or this flaw in Oracle's Java software.

The difference today is exploits affecting the current generation of Windows are considered newsworthy. That's progress. ®


Patrick Gray's Risky Business podcast will bring Reg readers special coverage of the Ruxcon Breakpoint conference. To get a taste of what will be on offer, click here to hear Patrick's full interview with Alex Ionescu.

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