Researcher says PatchGuard changes helped Microsoft

A security researcher says Microsoft has inappropriately relaxed restrictions in its PatchGuard kernel protection software

Microsoft has come under fire for quietly releasing a fix to its PatchGuard kernel protection software in order to improve the performance of its Virtual Server 2005 product.

PatchGuard is a much-touted security addition to Windows Vista that restricts access to the Windows kernel, making it harder for hackers to run nasty software such as rootkits. But it has also broken some legitimate software programs, leading to complaints from software vendors including Symantec Corp. and McAfee Inc.

Microsoft beefed up PatchGuard, which also ships with 64-bit versions of Windows XP and Server 2003, last July, according to Stephen Toulouse, senior product manager with Microsoft's security technology group. But one of the changes Microsoft introduced at that time harmed the operating system's ability to take advantage of Advanced Micro Devices (AMD) virtualization technology. As a result, Virtual Server 2005 couldn't work properly on AMD systems. In September, Microsoft published a "hotfix" patch that corrected the problem.

Microsoft has rolled the fix into the 64-bit version of Vista, but the only place it has notified users of the hotfix is on a Virtual Server 2005 documentation page, prompting one security researcher to cry foul, and say that Microsoft has violated its own policy on making exceptions to PatchGuard's kernel restrictions, to the benefit of its own product.

Microsoft has had to be careful about permitting changes to PatchGuard, as any changes it makes to the software could possibly become a new avenue of attack for hackers. Initially, the software giant said it would not make any exceptions to PatchGuard's restrictions, but in September, security vendors asked Microsoft for a way to get around PatchGuard, arguing PatchGuard would ultimately make their software less secure.

After a warning from the European Commission, Microsoft eventually pledged to create a set of APIs (application programming interfaces) that would give the security vendors access to the kernel-level computing resources they require. Those APIs are expected to be included in the first service pack for Windows Vista.

But according to researcher Ken Johnson, who has published a paper on the new PatchGuard features, Microsoft violated its own rules by releasing the hotfix. Johnson, a developer with Positive Networks Inc., has researched the paper on his own time and published it under his hacker alias, Skywing.

"Microsoft's policy on PatchGuard is that if a driver's functionality is being blocked by PatchGuard, and there is no way to achieve that functionality with PatchGuard in place, then that functionality will be unsupported on Windows," Johnson wrote in an e-mail interview.

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Robert McMillan

IDG News Service
Show Comments

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?