CVE-2009-0565 in Office Word Viewer
Summary
by MITRE
Buffer overflow in Microsoft Office Word 2000 SP3, 2002 SP3, and 2007 SP1 and SP2; Microsoft Office for Mac 2004 and 2008; Open XML File Format Converter for Mac; and Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2 allows remote attackers to execute arbitrary code via a Word document with a malformed record that triggers memory corruption, aka "Word Buffer Overflow Vulnerability."
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Analysis
by VulDB Data Team • 11/01/2025
This vulnerability represents a critical buffer overflow flaw in Microsoft Office applications that affects multiple versions across different platforms including Windows and Mac operating systems. The vulnerability specifically targets the parsing mechanisms within Word documents, where malformed records trigger memory corruption that can be exploited to execute arbitrary code. The affected products include Microsoft Office Word 2000 Service Pack 3, Word 2002 Service Pack 3, Word 2007 Service Pack 1 and 2, Microsoft Office for Mac 2004 and 2008, Open XML File Format Converter for Mac, and the Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2. This widespread impact across multiple versions and platforms demonstrates the severity of the underlying flaw in the document parsing architecture. The vulnerability operates through a classic buffer overflow attack vector where insufficient input validation allows attackers to write data beyond the allocated memory boundaries, potentially leading to complete system compromise. The flaw falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and aligns with ATT&CK technique T1203 for exploitation of remote services and T1059 for command execution through compromised applications. The attack requires a remote attacker to craft a malicious Word document containing malformed records that, when opened by an affected application, triggers the buffer overflow condition. This vulnerability is particularly dangerous because it can be delivered through email attachments, web downloads, or any method that delivers Word documents to users, making it a prime target for phishing campaigns and targeted attacks. The memory corruption occurs during the parsing of structured document formats, specifically when the application attempts to process records that exceed the expected buffer size, allowing attackers to overwrite critical memory locations including return addresses and function pointers.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and potential data exfiltration. When successfully exploited, the buffer overflow allows attackers to gain arbitrary code execution privileges within the context of the affected application, which typically runs with the same privileges as the user. This can lead to privilege escalation scenarios where attackers can elevate their access level to gain administrative rights on the compromised system. The vulnerability affects not only individual users but also enterprise environments where Microsoft Office is widely deployed, creating potential for widespread compromise across organizational networks. Organizations that rely on document sharing and collaboration features are particularly at risk since the attack vector can be as simple as opening a malicious document, making it extremely difficult to defend against through traditional user education alone. The exploitation process typically involves crafting a specially formatted Word document that contains oversized data structures, which when processed by the vulnerable parsing engine causes the buffer overflow to occur. This attack vector is especially concerning because it can be automated and delivered through various communication channels including email, web browsers, and file sharing systems. The vulnerability represents a significant weakness in Microsoft's document processing architecture and highlights the importance of robust input validation and memory safety mechanisms in widely deployed software applications. The attack can result in persistent backdoors, data theft, system monitoring, and further lateral movement within compromised networks, making it a critical security concern for all organizations using affected Microsoft Office versions.
Mitigation strategies for this vulnerability must address both immediate protection and long-term remediation measures to ensure comprehensive security coverage. The most effective immediate solution involves applying the security patches released by Microsoft as part of their regular security updates, which include fixes for the buffer overflow conditions in the affected Office applications. Organizations should implement strict document validation policies that scan and quarantine potentially malicious documents before they reach end users, utilizing advanced threat detection systems that can identify malformed records and suspicious file structures. Network-based protections should include filtering of Office document file types at network boundaries and implementing sandboxing mechanisms for document processing to isolate potential exploits. Users should be trained to avoid opening documents from untrusted sources and to verify document authenticity before opening attachments. System administrators should consider implementing application whitelisting policies that restrict execution of unauthorized Office versions or disable unnecessary document processing features. The mitigation approach should also include monitoring for signs of exploitation attempts and implementing intrusion detection systems that can identify suspicious network traffic patterns associated with document-based attacks. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of affected Office versions within the organization. Additionally, organizations should maintain updated backup and recovery procedures to ensure rapid restoration of systems in case of successful exploitation. The vulnerability serves as a reminder of the critical importance of keeping software updated and maintaining robust security hygiene practices across all organizational systems. Proper patch management processes combined with layered security controls provide the most effective defense against this type of remote code execution vulnerability.