Microsoft Office Web Components ActiveX Control Memory Allocation Code Execution Vulnerability



Date Discovered

August 11, 2009


Microsoft Office Web Components OWC10 ActiveX control is prone to a remote code-execution vulnerability. An attacker could exploit this issue by enticing a victim to visit a maliciously crafted webpage. Successfully exploiting this issue will allow the attacker to execute arbitrary code within the context of an affected application that uses the ActiveX control (typically Internet Explorer). Failed exploit attempts will result in a denial-of-service condition.

Technologies Affected

  • Microsoft Internet Security and Acceleration Server 2004 Enterprise Editio SP3
  • Microsoft Internet Security and Acceleration Server 2004 Standard Edition SP3
  • Microsoft Internet Security and Acceleration Server 2006
  • Microsoft Internet Security and Acceleration Server 2006 SP1
  • Microsoft Internet Security and Acceleration Server 2006 Supportability Up
  • Microsoft Office 2003
  • Microsoft Office 2003 SP1
  • Microsoft Office 2003 SP2
  • Microsoft Office 2003 SP3
  • Microsoft Office 2003 Web Components SP3
  • Microsoft Office 2003 Web Components for Office 2007 SP1
  • Microsoft Office Small Business Accounting 2006
  • Microsoft Office XP
  • Microsoft Office XP SP1
  • Microsoft Office XP SP2
  • Microsoft Office XP SP3
  • Microsoft Office XP Web Components SP3


Run all software as a nonprivileged user with minimal access rights.
To mitigate the impact of a successful exploit, run the affected application as a user with minimal access rights.

Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of suspicious or anomalous activity. This may help detect malicious actions that an attacker may take after successfully exploiting vulnerabilities in applications. Review all applicable logs regularly.

Do not follow links provided by unknown or untrusted sources.
Never accept files or follow links from untrusted or unknown sources, because they may be malicious in nature.

Set web browser security to disable the execution of script code or active content.
Since a successful exploit of this issue requires malicious code to execute in web clients, consider disabling support for script code and active content within the client browser. Note that this mitigation tactic might adversely affect legitimate websites that rely on the execution of browser-based script code.

Implement multiple redundant layers of security.
Memory-protection schemes (such as nonexecutable stack and heap configurations and randomly mapped memory segments) will complicate exploits of memory-corruption vulnerabilities.

The vendor has released an advisory and fixes. Please see the references for details.



Peter Vreugdenhil of Zero Day Initiative

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