CVE-2003-0347 in Office
Summary
by MITRE
Heap-based buffer overflow in VBE.DLL and VBE6.DLL of Microsoft Visual Basic for Applications (VBA) SDK 5.0 through 6.3 allows remote attackers to execute arbitrary code via a document with a long ID parameter.
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Analysis
by VulDB Data Team • 08/18/2025
The vulnerability identified as CVE-2003-0347 represents a critical heap-based buffer overflow affecting Microsoft Visual Basic for Applications VBE.DLL and VBE6.DLL components within the VBA SDK versions 5.0 through 6.3. This flaw resides in the handling of document parameters, specifically when processing a long ID parameter that exceeds the allocated buffer space. The vulnerability is classified under CWE-121 Heap-based Buffer Overflow, which occurs when a program writes data beyond the boundaries of a heap-allocated buffer, potentially corrupting adjacent memory and allowing arbitrary code execution.
The technical implementation of this vulnerability exploits the insecure memory management practices within the VBA runtime environment where the ID parameter is processed without adequate bounds checking. When a malicious document containing an excessively long ID parameter is opened, the VBE.DLL or VBE6.DLL components fail to validate the parameter length before copying it into a fixed-size buffer on the heap. This failure creates a condition where the overflow can overwrite adjacent memory locations including return addresses and function pointers, enabling attackers to redirect program execution flow. The vulnerability is particularly dangerous because it can be triggered through legitimate document opening operations, making it a prime candidate for social engineering attacks that leverage Microsoft Office document formats.
The operational impact of CVE-2003-0347 extends beyond simple code execution to encompass full system compromise when exploited successfully. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the affected user, potentially leading to complete system takeover. The attack vector requires remote delivery through malicious documents, which aligns with the ATT&CK technique T1204.002 for User Execution via Office Documents and Macros. This vulnerability was particularly concerning in enterprise environments where users regularly opened documents from untrusted sources, as it could be exploited through phishing campaigns or compromised websites distributing malicious Office documents.
Mitigation strategies for CVE-2003-0347 must address both immediate protection and long-term remediation. Organizations should implement immediate defensive measures including disabling macro execution in Office applications, implementing strict file validation policies, and deploying application whitelisting solutions to prevent execution of untrusted code. The vulnerability requires patching through Microsoft security updates, specifically targeting the VBA SDK components and ensuring all affected Office versions are updated with the appropriate security fixes. Additionally, network-based protections such as intrusion detection systems and email filtering solutions should be configured to detect and block malicious Office documents containing suspicious ID parameter lengths. Security awareness training for end users remains crucial to prevent accidental exploitation through social engineering techniques that rely on user interaction with malicious documents. The vulnerability demonstrates the importance of proper input validation and memory safety practices, emphasizing the need for secure coding standards that align with industry best practices for preventing buffer overflow conditions in application development.