CVE-2009-0235 in Windows
Summary
by MITRE
Stack-based buffer overflow in the Word 97 text converter in WordPad in Microsoft Windows 2000 SP4, XP SP2 and SP3, and Server 2003 SP1 and SP2 allows remote attackers to execute arbitrary code via a crafted Word 97 file that triggers memory corruption, related to use of inconsistent integer data sizes for an unspecified length field, aka "WordPad Word 97 Text Converter Stack Overflow Vulnerability."
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Analysis
by VulDB Data Team • 08/09/2021
The vulnerability identified as CVE-2009-0235 represents a critical stack-based buffer overflow affecting Microsoft WordPad's Word 97 text converter component across multiple Windows operating systems including Windows 2000 SP4, XP SP2 and SP3, and Server 2003 SP1 and SP2. This flaw resides in the legacy text conversion functionality that processes Word 97 formatted documents, creating a remote code execution vector when maliciously crafted files are opened. The vulnerability stems from improper handling of integer data sizes during the parsing of unspecified length fields within the Word 97 file format, leading to memory corruption that can be exploited by remote attackers.
The technical exploitation of this vulnerability occurs through a stack-based buffer overflow condition where an attacker crafts a specially formatted Word 97 document containing malformed data that triggers an integer overflow or underflow during the parsing process. When WordPad attempts to process this malicious file, the inconsistent integer data sizes cause the application to write beyond the allocated buffer boundaries in the stack memory space. This memory corruption can be manipulated to overwrite critical stack variables, return addresses, or function pointers, ultimately allowing an attacker to redirect program execution flow and execute arbitrary code with the privileges of the affected user.
The operational impact of this vulnerability extends beyond simple remote code execution as it affects widely deployed operating systems including Windows 2000 and XP which were prevalent in enterprise environments during the time of discovery. The vulnerability's remote exploitability means that attackers can deliver malicious Word 97 files through various attack vectors including email attachments, web downloads, or malicious websites without requiring local system access. The use of the Word 97 text converter component makes this particularly dangerous as it affects applications that are commonly used for document processing and can be triggered automatically when users open files or when applications attempt to process documents in the background. This vulnerability aligns with CWE-121 Stack-based Buffer Overflow and follows ATT&CK technique T1059.007 for Command and Scripting Interpreter, as it enables attackers to execute arbitrary commands through the compromised application.
Mitigation strategies for this vulnerability primarily involve applying the official Microsoft security patches released as part of the security updates for the affected operating systems. System administrators should prioritize patch deployment across all affected Windows platforms and consider implementing application control measures to restrict WordPad's ability to process untrusted documents. Additional defensive measures include configuring email filtering rules to block suspicious Word 97 file attachments, implementing sandboxing for document processing applications, and monitoring for unusual network activity that might indicate exploitation attempts. The vulnerability also highlights the importance of maintaining up-to-date security practices and the need for organizations to regularly review and update their security postures to address legacy components that may contain unpatched vulnerabilities. Organizations should also consider migrating away from legacy operating systems and applications that are no longer supported by vendors to reduce their attack surface and eliminate exposure to known vulnerabilities like CVE-2009-0235.