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Microsoft Agent fails to properly handle specially crafted URLs

Vulnerability Note VU#716872

Original Release Date: 2007-09-11 | Last Revised: 2007-09-14


Microsoft Agent fails to properly handle specially crafted URLs, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system


Microsoft Agent is software that provides animated characters to enhance interaction with computer systems. Microsoft Agent comes with Microsoft Windows systems. Microsoft Agent functionality is exposed as an ActiveX control that can be used by web pages. Microsoft Agent fails to properly handle specially crafted URLs, which can result in memory corruption.

According to public reports, exploit code is availabe for this vulnerability.


By convincing a user to view a specially crafted HTML document (e.g., a web page or an HTML email message or attachment), an attacker may be able to execute arbitrary code with the privileges of the user. The attacker could also cause the web browser to crash.

More information is available in Microsoft Security Bulletin MS07-051.


Apply an update
This issue is addressed in Microsoft Security Bulletin MS07-051.

Disable the Microsoft Agent ActiveX controls in Internet Explorer

The vulnerable ActiveX controls can be disabled in Internet Explorer by setting the kill bit for the following CLSIDs:


More information about how to set the kill bit is available in Microsoft Support Document 240797. Alternatively, the following text can be saved as a .REG file and imported to set the kill bit for this control:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{D45FD31B-5C6E-11D1-9EC1-00C04FD7081F}]
"Compatibility Flags"=dword:00000400

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{F5BE8BD2-7DE6-11D0-91FE-00C04FD701A5}]
"Compatibility Flags"=dword:00000400

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{4BAC124B-78C8-11D1-B9A8-00C04FD97575}]
"Compatibility Flags"=dword:00000400

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{D45FD31D-5C6E-11D1-9EC1-00C04FD7081F}]
"Compatibility Flags"=dword:00000400

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{D45FD31E-5C6E-11D1-9EC1-00C04FD7081F}]
"Compatibility Flags"=dword:00000400

Unregister AgentSvr.exe

The Microsoft Agent ActiveX controls interact with the Microsoft Agent Server (AgentSvr.exe) to provide Agent functionality. The Microsoft Agent Server can be unregistered to mitigate this vulnerability by running the following command:

%windir%\msagent\agentsvr.exe /unregserver
Disable ActiveX

Disabling ActiveX controls in the Internet Zone (or any zone used by an attacker) appears to prevent exploitation of this and other ActiveX vulnerabilities. Instructions for disabling ActiveX in the Internet Zone can be found in the "Securing Your Web Browser" document. 

Vendor Information


Microsoft Corporation Affected

Updated:  September 11, 2007



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


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This vulnerability was publicly disclosed in Microsoft Security Bulletin MS07-051. Microsoft in turn credits the Vulnerability Research team of Assurent Secure Technologies, Yamata Li of Palo Alto Networks, and An anonymous researcher working with VeriSign iDefense VCP.

This document was written by Jeff Gennari.

Other Information

CVE IDs: CVE-2007-3040
Date Public: 2007-09-11
Date First Published: 2007-09-11
Date Last Updated: 2007-09-14 13:56 UTC
Document Revision: 13

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