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vulnerability announce 10562

Microsoft HTML Help: buffer overflow

Synthesis of the vulnerability

An attacker can invite the victim to open a malicious CHM file with Microsoft HTML Help, in order to execute code.
Vulnerable systems: Windows 2000, Windows 2003, Windows 2008 R0, Windows 2008 R2, Windows 7, Windows Vista, Windows XP.
Severity of this threat: 2/4.
Consequences of a hack: user access/rights.
Pirate's origin: document.
Creation date: 13/04/2011.
Références of this weakness: BID-47330, VIGILANCE-VUL-10562.

Description of the vulnerability

Files with a CHM extension are compiled help files for Windows, which are opened with Microsoft HTML Help.

Data are compressed in blocks. Microsoft HTML Help thus uncompresses each block before using it. However, if the size of a block is too large, a buffer overflow occurs.

An attacker can therefore invite the victim to open a malicious CHM file with Microsoft HTML Help, in order to execute code.
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