CVE-2009-1136 in Office
Summary
by MITRE
The Microsoft Office Web Components Spreadsheet ActiveX control (aka OWC10 or OWC11), as distributed in Office XP SP3 and Office 2003 SP3, Office XP Web Components SP3, Office 2003 Web Components SP3, Office 2003 Web Components SP1 for the 2007 Microsoft Office System, Internet Security and Acceleration (ISA) Server 2004 SP3 and 2006 Gold and SP1, and Office Small Business Accounting 2006, when used in Internet Explorer, allows remote attackers to execute arbitrary code via a crafted call to the msDataSourceObject method, as exploited in the wild in July and August 2009, aka "Office Web Components HTML Script Vulnerability."
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Analysis
by VulDB Data Team • 10/01/2025
The CVE-2009-1136 vulnerability represents a critical buffer overflow flaw in Microsoft Office Web Components Spreadsheet ActiveX control versions 10 and 11, commonly known as OWC10 and OWC11. This vulnerability specifically affects the msDataSourceObject method within the ActiveX control, which is designed to handle data source operations in web-based spreadsheet applications. The flaw exists in multiple Microsoft products including Office XP SP3, Office 2003 SP3, various Office Web Components service packs, ISA Server 2004 SP3 and 2006 SP1, and Office Small Business Accounting 2006. The vulnerability was actively exploited in the wild during July and August 2009, demonstrating its significance as a real-world threat that required immediate attention from security professionals and system administrators.
The technical nature of this vulnerability stems from improper input validation within the msDataSourceObject method of the Office Web Components ActiveX control. When a malicious web page or document containing crafted parameters is loaded in Internet Explorer, the ActiveX control fails to properly validate the input data passed to the msDataSourceObject method, leading to a buffer overflow condition. This buffer overflow occurs because the control does not adequately check the size of incoming data before copying it into fixed-size memory buffers, allowing an attacker to overwrite adjacent memory locations. The vulnerability specifically relates to CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios, making it a classic example of memory corruption vulnerabilities that enable arbitrary code execution. The flaw is particularly dangerous because it leverages the trust model inherent in ActiveX controls, where legitimate software components are executed with elevated privileges within the browser context.
The operational impact of CVE-2009-1136 is severe and far-reaching across enterprise environments that utilize affected Microsoft Office products. The vulnerability allows remote code execution without user interaction, meaning that simply visiting a malicious website or opening a compromised document could result in complete system compromise. Attackers can leverage this vulnerability to install malware, steal sensitive data, establish backdoors, or pivot to other systems within the network. The exploitation technique typically involves crafting malicious HTML pages or Office documents that contain specially formatted parameters to trigger the buffer overflow in the msDataSourceObject method. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, as successful exploitation can lead to privilege elevation. The widespread distribution of affected Office Web Components across multiple Microsoft products and service packs meant that organizations could be vulnerable regardless of their specific Microsoft product stack, creating a significant attack surface that required immediate remediation efforts.
Organizations affected by CVE-2009-1136 should implement immediate mitigations including disabling ActiveX controls in Internet Explorer, applying Microsoft security patches released in response to this vulnerability, and implementing network-based protections such as firewall rules that block access to known malicious domains. The vulnerability also highlights the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies that reduce reliance on single layers of protection. Microsoft released security updates that addressed the buffer overflow issue in the affected Office Web Components, but many organizations were slow to patch due to compatibility concerns or lack of awareness. Security professionals should consider this vulnerability as part of broader vulnerability management programs that include regular security assessments, patch management automation, and monitoring for exploitation attempts. The vulnerability serves as a reminder of the persistent risks associated with legacy ActiveX controls and the importance of transitioning to modern web standards that provide better security guarantees than traditional browser plugin architectures.