Last week, a major security vulnerability was announced in recent and fully patched editions of Windows. Versions of Windows XP, Vista and 7 in 32 and 64 bit configurations are vulnerable to the user input validation exploit. Should a system become exposed to the malicious code, it is possible to execute arbitrary commands at a kernel level authentication, invalidating the User Account Control security mechanisms implemented in the later Windows editions, and giving unprevilidged users administrative access.
The code exploits a flaw in a Win32 API catchily named “NtGdiEnableEUDC”. As it does not properly validate input sent by the code, it can be leveraged to return memory addresses to malicious code, which in turn is executed with kernel-level privileges. This allows unprivilidged users in all affected Windows versions to execute code as administrators; it also directly bypasses the User Account Control security mechanism built in to Windows 7 and Windows Vista to directly counter this kind of attack.
Microsoft has admitted through its Microsoft Security Response Twitter account that it is investigating a vulnerability, but no news has been announced as yet whether there will be a fix or not made available in advance of the next scheduled round of Windows updates. More with The Reg.
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