CVE-2008-1091 in Word
Summary
by MITRE
Unspecified vulnerability in Microsoft Word in Office 2000 and XP SP3, 2003 SP2 and SP3, and 2007 Office System SP1 and earlier allows remote attackers to execute arbitrary code via a Rich Text Format (.rtf) file with a malformed string that triggers a "memory calculation error" and a heap-based buffer overflow, aka "Object Parsing Vulnerability."
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Analysis
by VulDB Data Team • 01/05/2025
The vulnerability identified as CVE-2008-1091 represents a critical heap-based buffer overflow flaw within Microsoft Word's handling of Rich Text Format files. This vulnerability affects multiple versions of Microsoft Office including Office 2000, XP SP3, 2003 SP2 and SP3, and 2007 Office System SP1 and earlier versions. The flaw manifests when Word processes malformed RTF files containing specially crafted strings that trigger memory calculation errors during object parsing operations. According to CWE-122, this vulnerability falls under heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations, potentially leading to arbitrary code execution. The vulnerability is categorized under ATT&CK technique T1203, which involves exploitation of software vulnerabilities for code execution.
The technical implementation of this vulnerability exploits the way Microsoft Word parses RTF documents, specifically during the handling of malformed strings within the document structure. When Word encounters a specially crafted RTF file with incorrect memory calculations, it fails to properly validate input data before allocating memory for processing. This results in a heap-based buffer overflow where attacker-controlled data overflows into adjacent memory regions, potentially allowing remote code execution. The vulnerability occurs because the RTF parser does not adequately validate the length of strings or other data structures before using them to calculate memory allocation sizes. This parsing error creates a condition where a small input can trigger a much larger memory allocation, leading to memory corruption.
The operational impact of CVE-2008-1091 is significant as it enables remote attackers to execute arbitrary code on vulnerable systems without requiring user interaction beyond opening the malicious RTF file. This makes the vulnerability particularly dangerous in email-based attack scenarios where users might inadvertently open malicious attachments. The heap-based nature of the overflow means that attackers can potentially overwrite critical program structures, function pointers, or return addresses, allowing for complete system compromise. The vulnerability affects a broad range of Microsoft Office products, making it a widespread concern for organizations using legacy Office versions. Security researchers have noted that exploitation of this vulnerability often results in privilege escalation, as the malicious code executes within the context of the Word process, which typically runs with elevated privileges.
Mitigation strategies for CVE-2008-1091 should focus on immediate patching of affected systems with the appropriate Microsoft security updates, as well as implementing defensive measures such as disabling RTF file handling in email clients and implementing strict file type filtering. Organizations should also consider disabling automatic execution of macros and implementing application whitelisting policies to prevent execution of untrusted RTF files. According to Microsoft's security guidance, the most effective mitigation is applying the relevant security patches released for each affected Office version. Additionally, network-based defenses such as email filtering systems can be configured to block RTF attachments from untrusted sources, reducing the attack surface. Regular security assessments should include verification of Office installation versions and patch status to ensure complete protection against this and similar vulnerabilities. The vulnerability highlights the importance of proper input validation and memory management in document processing applications, as outlined in industry best practices for secure coding standards.