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Vulnerability Note VU#728057

Microsoft Windows Agent fails to properly process crafted URLs

Overview

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

I. Description

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.

II. Impact

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.

III. Solution

Apply an update

This issue is addressed in Microsoft Security Bulletin MS07-020.

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:

    {D45FD31B-5C6E-11D1-9EC1-00C04FD7081F}
    {F5BE8BD2-7DE6-11D0-91FE-00C04FD701A5}
    {4BAC124B-78C8-11D1-B9A8-00C04FD97575}
    {D45FD31D-5C6E-11D1-9EC1-00C04FD7081F}
    {D45FD31E-5C6E-11D1-9EC1-00C04FD7081F}
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. 

Systems Affected
VendorStatusDate NotifiedDate Updated
Microsoft CorporationVulnerable10-Apr-2007

References

http://www.us-cert.gov/reading_room/securing_browser/#Internet_Explorer
http://www.microsoft.com/technet/security/bulletin/ms07-020.mspx
http://secunia.com/advisories/22896/
http://secunia.com/secunia_research/2006-74/advisory/

Credit

This vulnerability was reported by Microsoft, who in turn credit JJ Reyes and Carsten Eiram of Secunia.

This document was written by Will Dormann.

Other Information

Date Public:2007-04-10
Date First Published:2007-04-10
Date Last Updated:2007-04-11
CERT Advisory: 
CVE-ID(s):CVE-2007-1205
NVD-ID(s):CVE-2007-1205
US-CERT Technical Alerts: 
Metric:13.20
Document Revision:5

If you have feedback, comments, or additional information about this vulnerability, please send us email.
 

 
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