CVE-2000-0886 in IIS
Summary
by MITRE
IIS 5.0 allows remote attackers to execute arbitrary commands via a malformed request for an executable file whose name is appended with operating system commands, aka the "Web Server File Request Parsing" vulnerability.
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Analysis
by VulDB Data Team • 10/12/2025
The CVE-2000-0886 vulnerability represents a critical file request parsing flaw in Microsoft Internet Information Services version 5.0 that enables remote command execution through specifically crafted HTTP requests. This vulnerability exploits a fundamental weakness in how IIS 5.0 processes file requests containing executable extensions, allowing attackers to append operating system commands directly to file names in the request URI. The flaw specifically affects the web server's interpretation of executable file paths, creating a path traversal and command injection scenario that bypasses normal security controls. This vulnerability operates at the core of the web server's request handling mechanism, where the server fails to properly sanitize or validate file names that contain executable extensions such as .asp, .exe, or .dll, making it particularly dangerous for web applications hosted on vulnerable IIS servers.
The technical implementation of this vulnerability relies on the improper parsing of Uniform Resource Identifiers where the web server accepts file names with executable extensions and processes additional commands appended to those names. Attackers can craft requests that appear to target legitimate executable files while simultaneously injecting operating system commands that get executed with the privileges of the web server process. This typically occurs when the web server interprets the file path in a way that allows command execution rather than simply serving the requested file. The vulnerability stems from the server's failure to properly validate input parameters in the request URI, particularly when the request contains executable extensions followed by command parameters. This parsing error creates an environment where command injection becomes possible, allowing attackers to execute arbitrary code on the target system. The flaw can be classified under CWE-78 as a "Improper Neutralization of Special Elements used in an OS Command" and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Windows Command Shell," making it a significant vector for privilege escalation and persistent access.
The operational impact of CVE-2000-0886 extends far beyond simple remote code execution, as it provides attackers with complete system compromise capabilities when exploited successfully. An attacker who successfully exploits this vulnerability can gain full control over the affected IIS server, potentially leading to data theft, system modification, or use of the compromised server as a launch point for further attacks against internal networks. The vulnerability is particularly dangerous because it can be exploited without authentication, making it a preferred target for automated attack tools and malware. Organizations running IIS 5.0 servers are at risk of complete system compromise, as the executed commands run with the privileges of the web server process, which often has elevated permissions. The vulnerability also enables attackers to establish persistent backdoors, install rootkits, or use the compromised server for launching attacks against other systems. This makes it a prime target for advanced persistent threat actors and automated exploitation campaigns, as it provides a reliable path to system-level access without requiring specialized knowledge of the target environment.
Mitigation strategies for CVE-2000-0886 require immediate action to address the underlying parsing flaw in IIS 5.0 implementations. The most effective immediate solution involves applying Microsoft security patches and updates that correct the file request parsing behavior in the web server. Organizations should also implement network-level restrictions such as firewall rules that limit access to executable file extensions and disable unnecessary web server features. Input validation and sanitization should be enforced at multiple levels including web server configuration, application code, and network infrastructure. Security monitoring should be enhanced to detect unusual patterns in web server requests that might indicate exploitation attempts. Additionally, implementing web application firewalls and intrusion detection systems can help identify and block malicious requests before they reach the vulnerable web server. The vulnerability serves as a critical reminder of the importance of proper input validation and the dangers of insecure file handling in web applications, particularly when dealing with executable file extensions that can be manipulated to execute arbitrary commands. Organizations should also consider migrating away from legacy IIS versions that are no longer supported and receive security updates, as the vulnerability represents a known weakness that cannot be effectively mitigated through configuration changes alone.