CVE-2000-0854 in Windows
Summary
by MITRE
When a Microsoft Office 2000 document is launched, the directory of that document is first used to locate DLL s such as riched20.dll and msi.dll, which could allow an attacker to execute arbitrary commands by inserting a Trojan Horse DLL into the same directory as the document.
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Analysis
by VulDB Data Team • 03/30/2025
This vulnerability represents a classic dynamic link library (dll) hijacking flaw that existed in Microsoft Office 2000 applications. The issue stems from the application's improper handling of dynamic library loading mechanisms, where Office 2000 would first search for required dll files in the same directory as the document being opened rather than in the system's standard library paths. This behavior creates a significant security risk because an attacker can place malicious dll files with the same names as legitimate system libraries in the same directory as a targeted document, thereby tricking the application into executing unauthorized code when the document is opened. The vulnerability is categorized under CWE-426 as an untrusted search path, which directly relates to the dangerous practice of allowing applications to load libraries from user-controllable directories without proper validation or sanitization. This flaw operates at the operating system level and demonstrates how application design decisions can create exploitable pathways for privilege escalation and code execution attacks.
The technical exploitation of this vulnerability requires an attacker to position a malicious dll file with the exact same name as a legitimate system dll in the directory containing the target Office document. When a user opens the document, Office 2000 will first check the local directory for the required library, finding and loading the attacker's malicious dll instead of the legitimate system version. This technique specifically targets the dynamic loading process that occurs when applications require additional functionality through shared libraries. The attack vector leverages the Windows operating system's library loading order, where the current directory is searched before system directories, creating a predictable exploitation pattern that attackers can reliably use against vulnerable applications. This behavior aligns with the ATT&CK technique T1555.003 for credential access through dynamic link library injection, though in this case the attack focuses on arbitrary code execution rather than credential theft.
The operational impact of this vulnerability extends beyond simple code execution, as it can enable attackers to gain unauthorized access to systems and potentially escalate privileges. Once a malicious dll is loaded, it can perform any action that the compromised Office application has permissions to execute, including accessing sensitive files, modifying system settings, or establishing persistent backdoors. The vulnerability affects all users who open Office 2000 documents from potentially compromised directories, making it particularly dangerous in shared or networked environments where users might encounter documents from untrusted sources. This flaw represents a fundamental security weakness in Microsoft's application design philosophy, where the application's trust model was insufficiently robust against directory-based attacks. The impact is amplified because the attack requires no special privileges from the user and can be executed through social engineering techniques, where users are tricked into opening malicious documents from seemingly legitimate sources. Organizations with legacy Office 2000 installations were particularly vulnerable to this attack vector, as the software was widely deployed in enterprise environments where document sharing occurred frequently.
Mitigation strategies for this vulnerability require a combination of application-level security measures and system-wide administrative controls. The most effective immediate solution involves implementing proper directory access controls and ensuring that Office 2000 applications are not run from directories containing untrusted content. System administrators should consider implementing application whitelisting policies that restrict which dll files can be loaded from user directories, and they should ensure that Office 2000 applications are configured to use secure library loading practices. Microsoft's recommended approach included updating to newer versions of Office that implemented more secure library loading mechanisms, as well as implementing the principle of least privilege for user accounts that open Office documents. Additional protective measures involve network-level controls such as implementing file scanning systems that can detect malicious dll files in document directories and configuring security software to monitor for suspicious library loading activities. The vulnerability highlights the importance of secure coding practices and demonstrates how seemingly minor design decisions in application architecture can create significant security risks that persist for years, as evidenced by the long lifespan of this particular flaw in the Microsoft Office ecosystem. Organizations should also consider implementing security awareness training to help users recognize potentially malicious documents and avoid opening files from untrusted sources.