CVE-2000-0025 in IIS
Summary
by MITRE
IIS 4.0 and Site Server 3.0 allow remote attackers to read source code for ASP files if the file is in a virtual directory whose name includes extensions such as .com, .exe, .sh, .cgi, or .dll, aka the "Virtual Directory Naming" vulnerability.
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Analysis
by VulDB Data Team • 04/20/2026
The CVE-2000-0025 vulnerability represents a critical security flaw in Microsoft Internet Information Services version 4.0 and Microsoft Site Server version 3.0 that fundamentally undermines the security boundaries of web applications. This vulnerability stems from improper handling of virtual directory names that contain executable file extensions, creating a pathway for remote attackers to bypass normal access controls and retrieve sensitive source code files. The flaw specifically affects ASP applications where virtual directories are configured with names containing extensions such as .com, .exe, .sh, .cgi, or .dll, which the web server incorrectly interprets as executable components rather than simple directory names.
The technical mechanism behind this vulnerability involves the web server's interpretation of virtual directory paths and its subsequent handling of file requests. When a virtual directory name contains an extension that the server recognizes as executable, IIS incorrectly processes requests to that directory, allowing unauthorized access to the underlying ASP source code files. This occurs because the server's request processing logic fails to properly validate or sanitize virtual directory names, treating them as if they were actual executable files rather than directory identifiers. The vulnerability essentially creates a directory traversal scenario where the web server's security model is bypassed through cleverly crafted virtual directory naming conventions.
The operational impact of this vulnerability is severe and far-reaching for organizations running affected web servers. Attackers can exploit this weakness to obtain complete source code of ASP applications, potentially exposing sensitive business logic, database connection strings, authentication mechanisms, and other proprietary code elements. This information disclosure vulnerability can lead to comprehensive system compromise as attackers gain insights into application architecture and implementation details. The vulnerability particularly affects environments where sensitive applications are deployed, as the source code exposure can reveal implementation flaws that may lead to additional exploitation opportunities. The risk is amplified because this vulnerability affects widely deployed server software and can be exploited remotely without authentication.
Organizations affected by this vulnerability should implement immediate mitigations including renaming virtual directories to avoid using executable extensions in their names, applying available security patches from Microsoft, and implementing proper access controls for virtual directories. The vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-502 (Deserialization of Untrusted Data) categories, representing path traversal and improper input validation issues. From an ATT&CK framework perspective, this vulnerability maps to T1566 (Phishing with Malicious Attachments) and T1059 (Command and Scripting Interpreter) as attackers can leverage the source code exposure to craft more sophisticated attacks. The remediation process requires careful review of all virtual directory configurations and implementation of proper input validation mechanisms to prevent similar issues in future deployments.