Microsoft HxTocCtrl ActiveX Control Invalid Param Heap Corruption Vulnerability
04.08.08BACKGROUND
The HxTocCtrl ActiveX Control is a library used by the Microsoft Help engine. More information is available at the following website.
http://en.wikipedia.org/wiki/Microsoft_Help_2
DESCRIPTION
Remote exploitation of a heap corruption vulnerability in Microsoft Corp.'s Microsoft Help 2.5 ActiveX control allows an attacker to execute arbitrary code with the privileges of the logged-on user.
Microsoft Help 2.5 installs the following ActiveX control, which is marked as safe for scripting:
ProgID: HxVz.HxTocCtrl.1
CLSID: 314111B8-A502-11D2-BBCA-00C04F8EC294
File: %PROGRAM DIR%Common FilesMicrosoft SharedHelphxvz.dll
By providing malformed arguments to this control, it is possible to corrupt heap memory.
ANALYSIS
Exploitation allows attackers to execute arbitrary code with the privileges of the logged-on user. Exploitation would require an attacker to host a maliciously crafted page on a website and entice users to visit that site. No further action is needed other than following a link to a malicious website. Exploitation requires that users have the specified control installed.
DETECTION
iDefense has confirmed this vulnerability in version 2.05.50727.42 of hxvz.dll, which is installed with Visual Studio 2005.
The following products might also include vulnerable versions of the control:
Visual Studio 2005
Visual Studio .NET 2003
Visual Studio .NET 2002
MSDN Library 2002 - Current
BizTalk Server 2004 Standard Edition
WORKAROUND
Setting the kill bit for this control mitigates the threat from web-based attacks that might be conducted via Internet Explorer. The vulnerable CLSID is:
{314111b8-a502-11d2-bbca-00c04f8ec294}
VENDOR RESPONSE
Microsoft has officially addressed this vulnerability with Security Bulletin MS08-023. For more information, consult their bulletin at the following URL.
http://www.microsoft.com/technet/security/bulletin/ms08-023.mspx
CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2008-1086 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.
DISCLOSURE TIMELINE
12/12/2006 Initial vendor notification
12/12/2006 Initial vendor response
04/08/2008 Coordinated public disclosure
CREDIT
The discoverer of this vulnerability wishes to remain anonymous.
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Copyright © 2008 Verisign, Inc.
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