A new Windows flaw that allows all current, supported versions of Windows to be crashed was
published on Friday by Israeli researcher Gil Dabah. The bug allows a local user to cause a system to suffer a blue-screen of death crash. In principle, this may also allow attackers to run code of their choosing with kernel privileges, though in practice, the looks as if it would be difficult due to the nature of the flaw.
The bug is in a kernel-mode component called win32k.sys, which handles many key Windows features like window management and 2D graphics. This specific flaw is in the component's handling of the system clipboard; by placing specially malformed data onto the clipboard, the system can be made to corrupt the screen or crash outright. In the early days of Windows, the component in question did not run in kernel mode; it was moved there for Windows NT 4, as doing so made 2D desktop graphics substantially faster.
win32k.sys has remained in kernel mode ever since, and as a result, this flaw affects Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, for both x86 and x64, both with or without Service Packs.
Microsoft is aware of the flaw but has not announced when a patch might be made available. Due to the nature of the problem, it has been assigned a "Less Critical" rating by security group
Secunia. This rating is a result of the lack of remote exploitability and the difficulties in using the flaw to execute an attacker's code.
