Windows 7 UAC Security Feature Raises Concerns

Concerns about the User Account Control feature in Microsoft Windows 7 have resurfaced.

UAC first appeared in Windows Vista as a way to bolster Windows security by limiting standard user privileges until an administrator authorizes a privilege level increase. In Windows 7, Microsoft adjusted the feature to provide the user with four choices for the UAC prompt and set the default setting to notify the user when programs are attempting to change settings.

However Microsoft's changes to UAC have set off red flags for some. In response to complaints about usability, Microsoft changed the feature to reduce the number of notifications for common activities, such as installing applications from Internet Explorer, explained Paul Cooke, director of Windows Client Enterprise Security at Microsoft.

"We have also made it easier for administrators to look at specific Windows settings on the system without needing administrative privileges by refactoring many of our control panel applications to separate interfaces for viewing system settings from those that modify them," he said.

But Ray Dickenson, CTO of Authentium, blogged those changes have come with a security cost.  

"My personal observation as a user is that Windows 7 is much more pleasant to use than Vista … However, as is nearly always the case, increasing operating system usability also increases security risks—risks of infection and compromise of data and functionality," Dickenson blogged. "The changes to Windows 7 UAC have made it easy for malware writers to turn UAC off entirely without the user's knowledge. Microsoft recommends keeping UAC turned on and yet allows malware to turn it off without the user's knowledge."

Earlier in 2009, Windows bloggers Rafael Rivera and Long Zheng posted proof-of-concept code that circumvented UAC in the Windows 7 beta, allowing attackers to use pre-approved Microsoft applications to trick the operating system into granting malware full access rights.

Sophos Security Advisor Chester Wisniewski agreed with the duo in a white paper, stating that "malware has been observed spoofing UAC-style prompts to obtain user permission to operate unimpeded."

Wisniewski wrote, "The UAC concept is user-driven rather than expert-driven, so it is a questionable approach in a world where end-user expertise is rare ... Although personal files and tools will require user approval and operation, core system assets should be more rigorously protected."

In an interview with eWEEK, he added that the UAC controls reduce the number of pop-ups but are "less effective at stopping malware than in Vista if you ignore the flesh between keyboard and chair."

He added, "Vista's UAC was so nag-prone that you became numb to it very quickly. I just re-installed [Windows 7] on my laptop and only had a small number of UAC prompts through loading my entire enterprise application load. Much better."

Cooke said Microsoft's approach with Windows 7 was to give users more control over the number of prompts they receive and to make the prompts more meaningful when they appear by quieting the system in general.

"Before UAC was introduced, most Windows consumer and enterprise users ran with administrative rights, which meant that ISVs could inadvertently make their applications dependent on administrative rights," he said. "Applications running with administrative rights have the ability to tamper with all user and Windows system data, including the ability to disable antivirus and other security measures ... [UAC] gives users a more compatible choice to secure their systems by running with standard user rights instead of administrator rights."