CVE-2003-0820 in Word
Summary
by MITRE
Microsoft Word 97, 98(J), 2000, and 2002, and Microsoft Works Suites 2001 through 2004, do not properly check the length of the "Macro names" data value, which could allow remote attackers to execute arbitrary code via a buffer overflow attack.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/21/2025
This vulnerability resides in Microsoft Word versions 97, 98, 2000, and 2002, as well as Microsoft Works Suites 2001 through 2004, representing a classic buffer overflow condition that has been documented in the cybersecurity landscape for over two decades. The flaw specifically manifests in the handling of macro names within document files, where the software fails to properly validate the length of data values associated with macro names. This inadequate input validation creates a scenario where an attacker can craft malicious documents containing oversized macro name data that exceeds the allocated buffer space in memory. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow, which directly relates to improper boundary checking during data processing operations. When a user opens a maliciously crafted document, the system attempts to parse the macro names without sufficient length validation, causing the program to write beyond the bounds of the allocated memory buffer.
The operational impact of this vulnerability extends beyond simple code execution, as it provides remote attackers with the capability to gain unauthorized control over affected systems. The buffer overflow occurs during document parsing when macro names are processed, allowing attackers to overwrite adjacent memory locations with malicious code. This can result in arbitrary code execution with the privileges of the user running the vulnerable application, potentially leading to complete system compromise. The attack vector is particularly concerning because it can be delivered through email attachments or web downloads, making it accessible to attackers without requiring local system access. The vulnerability demonstrates how legacy software implementations often lack modern security controls that would prevent such memory corruption issues. From an attack perspective, this vulnerability aligns with ATT&CK technique T1059.005 for command and scripting interpreter, as successful exploitation typically involves executing malicious code through the macro execution environment.
Mitigation strategies for this vulnerability require a multi-layered approach that addresses both immediate remediation and long-term security posture improvements. The most effective immediate solution involves applying the official Microsoft security patches that were released to address this specific buffer overflow condition. Organizations should prioritize patch management processes to ensure all affected systems receive updates promptly, as this vulnerability has been widely exploited in the wild. Additionally, implementing macro security controls through Microsoft Office's built-in security settings can prevent automatic execution of macros from untrusted sources. Network-based mitigations include email filtering and web content filtering to block potentially malicious documents before they reach end users. The vulnerability highlights the importance of input validation and boundary checking as fundamental security practices, principles that are reinforced by security frameworks such as the OWASP Top Ten and NIST cybersecurity guidelines. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of legacy software that may be vulnerable to similar buffer overflow conditions. Organizations should also consider implementing application whitelisting policies and mandatory security training for users to reduce the risk of social engineering attacks that exploit this vulnerability.