The memory protections in Windows Vista are largely ineffective at preventing browser exploitation. This was the position taken by two researchers presenting at the Black Hat conference in Las Vegas.
To prove the point, the researchers, Alexander Sotirov
and Mark Dowd, showed an exploit that loaded from Internet Explorer despite all
enabled memory protections built into the Vista operating system.
In explaining the problem, the researchers said that most memory protection mechanisms are based on two things: detecting corruption and stopping common exploit patterns, and attempts to reinforce these are integral to Vista. But in many cases, some of the built-in protection mechanisms in Vista are not enabled by default for compatibility reasons.
“At the desktop level, compromises had to be made because
of compatibility issues. Exploiters have a lot more control over browsers,”
And in many cases, third-party applications are not compiled to use the Vista memory protections. For example, Java and Flash are not compiled using the critical protection called ASLR.
According to the researchers, part of the reason for this
situation is Microsoft's focus on Vista server processes, for which the
protections are relatively effective.
According to Sotirov, “This points up the need for more work on secure browser architecture.”