Public Vulnerability Reports

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



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.


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.


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.


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.


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.


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


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 (, which standardizes names for security problems.


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


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2007 Verisign, Inc.

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