CVE-2004-0420 in Internet Explorer
Summary
by MITRE
The Windows Shell application in Windows 98, Windows ME, Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003 allows remote attackers to execute arbitrary code by spoofing the type of a file via a CLSID specifier in the filename, as demonstrated using Internet Explorer 6.0.2800.1106 on Windows XP.
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Analysis
by VulDB Data Team • 07/12/2025
The vulnerability described in CVE-2004-0420 represents a critical security flaw in the Windows Shell application that affects multiple versions of the Windows operating system including Windows 98, Windows ME, Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003. This vulnerability operates through a sophisticated file type spoofing mechanism that exploits the way Windows handles file associations and component object model (COM) identifiers. The flaw specifically targets the Windows Shell's ability to interpret file types based on CLSID (Class Identifier) specifiers embedded within filenames, creating an attack vector that allows remote code execution through web-based delivery methods.
The technical implementation of this vulnerability relies on the Windows Shell's interpretation of file extensions and their associated COM class identifiers. When a user encounters a specially crafted file name containing a CLSID specifier, the Windows Shell incorrectly processes the file type determination, leading to the execution of malicious code. This occurs because the system fails to properly validate the file type information before executing associated actions. The attack demonstrates how Internet Explorer 6.0.2800.1106 on Windows XP can be exploited to trigger this behavior, highlighting the specific combination of browser and operating system versions that make this vulnerability particularly dangerous. The flaw essentially allows attackers to bypass normal file type validation mechanisms by embedding malicious CLSID information directly within the filename structure itself.
The operational impact of this vulnerability extends far beyond simple remote code execution, as it provides attackers with a persistent method for gaining unauthorized access to affected systems. Once successfully exploited, the vulnerability allows attackers to execute arbitrary code with the privileges of the user running the affected Windows Shell application, potentially leading to complete system compromise. The widespread availability of this vulnerability across multiple Windows versions means that organizations with legacy systems were particularly at risk, as the attack could be delivered through web browsers, email attachments, or other common attack vectors. The vulnerability's ability to be triggered remotely without requiring user interaction beyond visiting a malicious website or opening a crafted file makes it especially dangerous for enterprise environments where users frequently access untrusted web content.
Mitigation strategies for this vulnerability must address both the immediate security risk and the underlying architectural flaws that enable the attack. Organizations should implement comprehensive patch management programs to ensure all affected Windows versions receive the necessary security updates from Microsoft. Additionally, network administrators should deploy web filtering solutions and browser security configurations that restrict access to potentially malicious content. The implementation of least privilege principles and user education programs can help reduce the impact of successful exploitation attempts. From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1203 (Exploitation for Client Execution) and CWE-170 (Improper Null Termination), demonstrating how improper input validation and file type handling can create dangerous attack surfaces. Organizations should also consider implementing application whitelisting policies and disabling unnecessary file associations to reduce the attack surface available to potential adversaries.