Microsoft Windows, Internet Explorer, and Active Template Library (ATL) Vulnerabilities

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Systems Affected

  • Microsoft Windows and Windows Server
  • Microsoft Internet Explorer
  • Microsoft Visual Studio and C++ Redistributable Package
  • ActiveX controls from multiple vendors


Microsoft has released out-of-band updates to address critical vulnerabilities in Microsoft Internet Explorer running on most supported versions of Windows. The updates also help mitigate attacks against ActiveX controls developed with vulnerable versions of the Microsoft Active Template Library (ATL).

Microsoft has released updates for critical vulnerabilities in Internet Explorer. The updates also include mitigations for attacks against vulnerable ActiveX controls that were created using vulnerable versions of the Active Template Library (ATL).

Vulnerabilities present in the ATL can cause vulnerabilities in the resulting ActiveX controls and COM components. For example, the ATL typographical error described in this Security Development Lifecycle blog post caused the Microsoft Video ActiveX control stack buffer overflow (VU#180513, CVE-2008-0015).

Any ActiveX control or COM component that was created with a vulnerable version of the ATL may be vulnerable. For example, Adobe and Cisco are affected.


By convincing a user to view a specially crafted HTML document (e.g., a Web page, HTML email message, or HTML attachment), an attacker may be able to execute arbitrary code.


System Administrators

To address the vulnerabilities in Internet Explorer and mitigate attacks against vulnerable ATL-based ActiveX controls, apply the updates described in Microsoft Security Bulletin MS09-034. Further details about the ATL mitigations are available in a Microsoft Security Research & Defense blog post.

Administrators should consider using an automated update distribution system such as Windows Server Update Services (WSUS).


To stop creating vulnerable controls, update the ATL as described in Microsoft Security Bulletin MS09-035. To address vulnerabilities in existing controls, recompile the controls using the updated ATL. Further discussion about the ATL vulnerabilities can be found in the Security Development Lifecycle blog.



July 28, 2009: Initial release

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