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Windows: denials of service of win32k.sys
Synthesis of the vulnerability
A local attacker can use the PostMessage() function, in order to generate an error in win32k.sys, which stops the system.
Vulnerable software: Windows 2000, Windows 2003, Windows 2008 R0, Windows 2008 R2, Windows 7, Windows Vista, Windows XP.
Severity of this announce: 1/4.
Consequences of an intrusion: denial of service on server.
Attacker's origin: user shell.
Number of vulnerabilities in this bulletin: 2.
Creation date: 23/04/2010.
Références of this computer vulnerability: 2160329, BID-39630, BID-39631, CVE-2010-1734, CVE-2010-1735, MS10-048, VIGILANCE-VUL-9607.
Description of the vulnerability
The PostMessage() function is used to send a message to a window. It uses win32k.sys. Two vulnerabilities of win32k.sys can be exploited via PostMessage().
The PostMessage() function does not check the memory address given as argument, when the message type is 0x4c (SfnLOGONNOTIFY). [severity:1/4; BID-39630, CVE-2010-1735]
The PostMessage() function does not check the memory address given as argument, when the message type is 0x18d (SfnINSTRING). [severity:1/4; BID-39631, CVE-2010-1734]
A local attacker can therefore use the PostMessage() function, in order to generate an error in win32k.sys, which stops the system.
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