Ads by TechWords

See your link here
Receive the latest technology news and information.
Security
Computerworld Daily News (First Look and Wrap-Up)
Computerworld Blogs Newsletter
The Weekly Top 10
Cloud Computing
View all newsletters




Privacy Policy
 

Utility evades Vista kernel defenses

Aussie software can get around 64-bit Vista's signed-code requirement

July 30, 2007 12:00 PM ET

Computerworld - A security feature in the 64-bit version of Windows Vista can be easily circumvented with a free utility that loads unsigned drivers into the kernel, according to researchers at Symantec Corp.

Among 64-bit Vista's security provisions is one new to Microsoft Corp.'s operating systems: only digitally-signed code can be loaded into the kernel. Under those new rules, code destined for the kernel -- typically drivers -- must be accompanied by a signed certificate available from a limited number of issuing authorities. Drivers not equipped with a legitimate certificate aren't loaded.

The thinking behind the move was that it would stymie rootkits, which load driver code into the kernel as part of their cloaking tactics.

But a pair of Symantec security researchers pointed to a free utility from Australian developer LinchpinLabs as one easy end run. LinchpinLabs' Atsiv, said Ollie Whitehouse, an architect with Symantec's advanced threats research team, uses signed drivers to load other, unsigned code, into the Vista kernel.

"[Atsiv's] command line tool loads [its own] appropriate driver, which then in turn allows loading of unsigned drivers due to the implementation of their PE loader," said Whitehouse. "A side effect of using their own load is noted by the authors in their design documentation: 'Atsiv doesn't add the driver to the PsLoadedModuleslist so it is not visible in the standard drivers list.'

"This is rootkit-type behavior," said Whitehouse.

One of LinchpinLabs' developers, identified only as "Dan," argued on rootkit.com that Vista's signing requirement "doesn't prevent malware, it just prohibits freedom to choose." Dan also claimed that Microsoft could never prevent hackers from obtaining legitimate certificates.

"A signed file uniquely identifies the company that developed that file, but when companies can be created and registered in jurisdictions known for protecting the privacy of company founders and directors you have to ask what does driver signing actually represent?" Dan asked. "While driver signing certificates can be revoked, new certificates, with enough money, can be created faster than it takes to change a file's signature. If this is indeed the case, then it is the hobbyists and home user that end up paying the cost."

Whitehouse agreed that the only way Microsoft can enforce the ban on unsigned kernel code is to revoke the certificate. "It'll be interesting to see how long it takes Microsoft to do this," Whitehouse said. "Secondly, as [Dan] points out, all it will take is someone to register another company, obtain another signing certificate, and the process will start over again."

Although both involve the Vista 64-bit kernel, the code signing requirement is not directly connected with PatchGuard, a protection scheme that bans so-called "kernel patching" or "kernel hooking" techniques. PatchGuard was the focus of a long-running dispute between Microsoft and several security vendors, Symantec included, over access to the kernel.

Symantec, McAfee and others argued that they needed to inject their own code into the kernel in order to protect users from the stealthiest kinds of malware.

Microsoft did not immediately reply to questions about whether it would revoke the certificate used by Atsiv.

Read more about security in Computerworld's Security Knowledge Center.



Jump to comments

Windows Vista

Additional Resources

Microsoft
Here are some of the key reasons why you would want to run Unified Access Gateway with DirectAccess.
Microsoft
Review how one energy firm tightened protection and simplified IT work using business-ready security solutions.
Sybase
In this white paper, IDC analyzes the role of next-generation mobile enterprise platforms as organizations seek a more strategic deployment of mobile solutions.

Learn the important issues you must consider before starting your next mobility initiative. Get your mobility white paper from IDC now, compliments of Sybase.

What People Are Saying

White Papers & Webcasts

Death to PST Files
Download Now  

Web 2.0, Social Media and the Dark Web - A Web Criminals Paradise?
In this discussion, learn about the challenges of protecting your users from the potentially unsafe content hidden in the "Dark Web".

eGuide: Enterprise Security
Smart Security Strategies for 2010. Read now!  

Disaster Recovery 2008: Reduced Costs and Improved Performance
How long can your Enterprise afford to be without your data? With an accelerated disaster recovery program, you never have to answer this...


IT Jobs