Public Vulnerability Reports

Microsoft License Manager and urlmon.dll COM Object Interaction Invalid Memory Access Vulnerability

06.12.07

BACKGROUND

Internet Explorer is a set of core technologies in Microsoft Windows operating systems that provide web browsing functionality. Further information is available at URL shown below.

http://www.microsoft.com/windows/ie/default.mspx

DESCRIPTION

Remote exploitation of an invalid memory access vulnerability in various Microsoft products, including Internet Explorer, while creating certain COM objects may allow an attacker to execute arbitrary code.

When creating certain COM objects in Internet Explorer, memory corruption can occur, which may allow an attacker to execute arbitrary code. When calling the IObjectSafety function, uninitialized memory is accessed in a way that can allow code execution to occur. The IObjectSafety function is used by COM objects to determine if an object is safe to load in a particular context.

ANALYSIS

Exploitation of this vulnerability could allow a remote attacker to execute arbitrary code in the context of the currently logged in user.

One method of exploiting this vulnerability would be to craft a website that performs the required operations. It also may be possible to embed the controls in an Office document.

iDefense Labs successfully constructed exploit code for this vulnerability that causes code execution, although not in a reliable manner. It may be possible to increase the reliability using other techniques.

DETECTION

iDefense confirmed the existence of this vulnerability using Internet Explorer 6 on Windows XP SP2 and Windows Server 2000 SP4. Although Windows Server 2003 contains an affected version, the Enhanced Security Configuration mitigates exposure to this vulnerability.

Microsoft reports that Internet Explorer 7 is not affected.

Other applications that can load COM objects from documents may also be affected.

WORKAROUND

Setting the kill-bits for the CLSIDs associated with urlmon.dll will prevent them from loading as ActiveX controls. While disabling the ability to create these controls from a Web page did not appear to cause any change in behavior, some sites or applications may exhibit changes in functionality.

VENDOR RESPONSE

Microsoft has addressed this vulnerability within MS07-033. For more information, consult their bulletin at the following URL.

http://www.microsoft.com/technet/security/Bulletin/MS07-033.mspx

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-0218 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

10/24/2006 Initial vendor notification
01/03/2007 Initial vendor response
06/12/2007 Coordinated public disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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LEGAL NOTICES

Copyright © 2007 Verisign, Inc.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customer service for permission.

Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.