Blogger: Windows 7 UAC feature still vulnerable

Citing a Microsoft document, he said the company won't fix UAC, which has a flaw that allows a remote user to take over a PC

The Microsoft blogger who first called attention to a security vulnerability in Windows 7's User Account Control (UAC) feature claims it still exists and that Microsoft won't fix it, even as the company nears final code completion on the OS.

Long Zheng, who writes the popular "I Started Something" blog, has posted a video online showing how UAC, a security feature first introduced in Windows Vista that sets user privileges on a PC in Windows 7, can be exploited.

Zheng also pointed to an instructional document by Microsoft Technical Fellow Mark Russinovich that attempts to explain UAC, saying it clearly states that Microsoft has no intention of fixing a change it made in the UAC in Windows 7 that leaves the new OS less secure because it allows someone to remotely turn the feature off without the user knowing.

Zheng first pointed out this change and its vulnerability back in February. At the time he said that the new UAC "standard user" default setting, which does not notify a user when changes are made to Windows settings, is where the security risk lies.

A change to UAC is seen as a change to a Windows setting, so a user will not be notified if UAC is disabled, which Zheng said he was able to do remotely with some keyboard shortcuts and code.

UAC has been a controversial feature since Microsoft introduced it in Windows Vista to improve its security and give people who are the primary users of a PC more control over its applications and settings. The features prevents users without administrative privileges from making unauthorized changes to a system.

In Russinovich's document, he does acknowledge that Zheng and others' observations about how third-party software can use the feature to gain administrative rights to a PC is accurate.

However, according to Zheng's blog post, Russinovich seemed to dismiss this possibility for remote code execution and offer no fix for it, because he said that there are other ways for malware to get into the system via UAC prompts.

"The follow-up observation is that malware could gain administrative rights using the same techniques," Russinovich wrote. "Again, this is true, but as I pointed out earlier, malware can compromise the system via prompted elevations as well.

From the perspective of malware, Windows 7's default mode is no more or less secure than the Always Notify mode ("Vista mode"), and malware that assumes administrative rights will still break when run in Windows 7's default mode."

Microsoft did not officially respond to a request for comment on Zheng's claim and video post. However, a company spokesperson said privately that Zheng may have misinterpreted Russinovich's document.

"The point seems to me to make it harder for malware to get on the system in the first place, by helping the end user make better decisions through the prompts they get, and having more and more users run in standard user mode vs. in admin mode (because admin mode is what exposes your machine to risks)," said the spokesperson, who asked not to be named, via e-mail.

Microsoft had stood by the change to UAC's default setting when Zheng made his first vulnerability claim, saying that the feature cannot be exploited unless there is already malicious code running on the machine and "something else has already been breached."

Microsoft has said that Windows 7, currently in a preview release, will be available to both businesses and consumers on Oct. 22. The release to manufacturing of the OS, at which all code will be final, is expected late next month.

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection

Tags exploits and vulnerabilitiesUACWindows 7

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Elizabeth Montalbano

IDG News Service
Show Comments

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

George Khoury

Sharp PN-40TC1 Huddle Board

The biggest perks for me would be that it comes with easy to use and comprehensive programs that make the collaboration process a whole lot more intuitive and organic

David Coyle

Brother PocketJet PJ-773 A4 Portable Thermal Printer

I rate the printer as a 5 out of 5 stars as it has been able to fit seamlessly into my busy and mobile lifestyle.

Kurt Hegetschweiler

Brother PocketJet PJ-773 A4 Portable Thermal Printer

It’s perfect for mobile workers. Just take it out — it’s small enough to sit anywhere — turn it on, load a sheet of paper, and start printing.

Matthew Stivala

HP OfficeJet 250 Mobile Printer

The HP OfficeJet 250 Mobile Printer is a great device that fits perfectly into my fast paced and mobile lifestyle. My first impression of the printer itself was how incredibly compact and sleek the device was.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?