CVE-2006-3647 in Office
Summary
by MITRE
Integer overflow in Microsoft Word 2000, 2002, 2003, 2004 for Mac, and v.X for Mac allows remote user-assisted attackers to execute arbitrary code via a crafted string in a Word document, which overflows a 16-bit integer length value, aka "Memmove Code Execution," a different vulnerability than CVE-2006-3651 and CVE-2006-4693.
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Analysis
by VulDB Data Team • 04/24/2026
This vulnerability represents a critical integer overflow flaw affecting multiple versions of Microsoft Word including Word 2000, 2002, 2003, 2004 for Mac, and v.X for Mac. The vulnerability stems from improper handling of string length values within the document processing engine, specifically when processing crafted strings in Word documents. The flaw manifests when a 16-bit integer length value is overflowed during memory operations, creating conditions that can be exploited by remote attackers with user assistance. This vulnerability is classified under CWE-190 as an integer overflow condition, where the overflow occurs during arithmetic operations on integer values that are insufficiently constrained. The attack vector requires a malicious Word document to be opened by an unsuspecting user, making it a user-assisted remote code execution vulnerability that aligns with ATT&CK technique T1204.1002 for Exploitation for Client Execution.
The technical implementation of this vulnerability involves the memmove function which is used for copying memory blocks in the Word processing engine. When a specially crafted string is processed, the length parameter exceeds the maximum value that can be represented by a 16-bit signed integer, causing an overflow that results in unpredictable memory behavior. This overflow corrupts memory structures and can be manipulated to redirect execution flow, allowing attackers to inject and execute arbitrary code with the privileges of the victim user. The vulnerability is particularly dangerous because it leverages the legitimate document processing functionality of Word, making it difficult to distinguish between benign and malicious content at runtime. The integer overflow occurs in the memory management subsystem where string processing routines fail to validate input lengths against the maximum representable values for 16-bit integers, creating a direct path for code execution.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise when exploited successfully. An attacker who successfully exploits this vulnerability can gain full control over the affected system, potentially leading to data exfiltration, persistence mechanisms installation, or further network reconnaissance activities. The vulnerability affects a broad range of Microsoft Word versions, indicating a widespread exposure across different product generations and platforms. The user-assisted nature means that the attack requires the victim to open the malicious document, but once opened, the exploitation occurs automatically without further user interaction. This makes the vulnerability particularly effective in phishing campaigns or targeted attacks where social engineering can be used to convince users to open malicious documents. The vulnerability also represents a significant concern for enterprise environments where Word documents are frequently shared and processed, creating numerous potential attack vectors.
Mitigation strategies for this vulnerability require immediate patch application from Microsoft as the primary defense mechanism, as the vulnerability exists in legacy versions of Word that are no longer supported with current security updates. Organizations should implement strict document filtering policies that prevent execution of documents from untrusted sources, particularly those containing embedded macros or complex formatting elements. Network segmentation and email filtering solutions should be configured to detect and block suspicious Word documents that may contain malicious content. Security awareness training for end users remains crucial in preventing successful exploitation, as the vulnerability requires user interaction to be triggered. Additionally, system administrators should consider implementing application whitelisting policies that restrict execution of Word processes in potentially hostile environments. The vulnerability demonstrates the importance of proper input validation and integer overflow protection in memory management functions, reinforcing the need for secure coding practices that align with industry standards such as the CERT Secure Coding Standards and OWASP Secure Coding Practices. Organizations should also conduct vulnerability assessments to identify systems running affected Word versions and prioritize remediation efforts based on risk exposure and business criticality.