Researchers at Black Hat Reveal Major Vista Security Issue

by , 2:00 PM EDT, August 8th, 2008

On day two of the Black Hat security conference, Mark Dowd with IBM and Alexander Sotirov with VMware presented a paper on a technique to completely bypass the memory protection features of Microsoft Vista along with recommendations to Microsoft.

In their talk, entitled, "How to Impress Girls with Browser Memory Protection Bypasses," the researchers showed how take advantage of the way IE and other browsers handle active scripting in the OS.

"Over the past several years, Microsoft has implemented a number of memory protection mechanisms with the goal of preventing the reliable exploitation of common software vulnerabilities on the Windows platform. Protection mechanisms such as GS, SafeSEH, DEP and ASLR complicate the exploitation of many memory corruption vulnerabilities and at first sight present an insurmountable obstacle for exploit developers.

"This talk aims to present exploitation methodologies against this increasingly complex target. We will demonstrate how the inherent design limitations of the protection mechanisms in Windows Vista make them ineffective for preventing the exploitation of memory corruption vulnerabilities in browsers and other client applications.

"Each of the aforementioned protections will be briefly introduced and its design limitations will be discussed. We will present a variety of techniques that can be used to bypass the protections and achieve reliable remote code execution in many different circumstances. Finally, we will discuss what Microsoft can do to increase the effectiveness of the memory protections at the expense of annoying Vista users even more."

Vista, as well as Mac OS X and Linux, uses a technique called ASLR to randomly change the locations of certain addressable memory locations so that malware cannot insert executable code. It's not a substitute for secure code, but can reduce vulnerability. Mr. Dowd's presentation focused on how to get around ASLR and other techniques like Data Execution Prevention (DEP).

Back in June, Mr. Dowd predicted that his coming demonstration would obliterate Vista security improvements.

"We're going to show a couple of ways you can tip the odds in your favour so vulnerabilities can be easily exploited by techniques that bypass these protection mechanisms," he said. "Some completely obliterate the protections."

According to neowin.net, Dino Dai Zovi, a popular security researcher said, "the genius of this is that it's completely reusable. They have attacks that let them load chosen content to a chosen location with chosen permissions. That's completely game over."

Microsoft is aware of the issue, and the verdicts are just starting to come in how how serious this breach is and what can be done to prevent it. The good news is that as these exploits are discovered and analyzed by the good guys at conferences like Black Hat, the OS vendors can work to remain one step ahead of the bad guys.