CVE-2000-1186 in phf
Summary
by MITRE
Buffer overflow in phf CGI program allows remote attackers to execute arbitrary commands by specifying a large number of arguments and including a long MIME header.
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Analysis
by VulDB Data Team • 08/16/2024
The CVE-2000-1186 vulnerability represents a critical buffer overflow flaw in the phf CGI program that was widely deployed on web servers during the late 1990s and early 2000s. This vulnerability specifically targeted the hypertext preprocessor for CGI (phf) utility, which was commonly used to handle HTTP requests and process form data on web servers. The flaw emerged from inadequate input validation within the program's argument parsing mechanism, where the phf CGI application failed to properly check the length of user-supplied parameters before processing them. This vulnerability falls under the Common Weakness Enumeration category CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations.
The technical implementation of this vulnerability exploited the phf program's handling of HTTP headers and command-line arguments, particularly when processing MIME headers that contained excessive data. Attackers could craft malicious requests with an unusually large number of arguments and include extremely long MIME header values that would exceed the allocated buffer space. When the phf CGI program attempted to process these oversized inputs, it would overwrite adjacent memory regions, potentially corrupting the program's execution stack and allowing arbitrary code execution. The vulnerability was particularly dangerous because it could be triggered through standard web browser interactions without requiring special privileges or authentication. According to the MITRE ATT&CK framework, this represents a command injection technique (T1059.007) that leverages CGI vulnerabilities to achieve remote code execution.
The operational impact of CVE-2000-1186 was severe and widespread, as phf CGI programs were commonly installed on Unix-based web servers and were often accessible through standard HTTP endpoints. Successful exploitation of this vulnerability could allow remote attackers to execute arbitrary commands with the privileges of the web server process, typically running as the web user or root account. This level of access could enable attackers to modify web content, steal sensitive data, install backdoors, or use the compromised server as a launch point for further attacks against internal networks. The vulnerability was particularly dangerous because it could be exploited through simple HTTP requests, making it accessible to attackers with minimal technical expertise. System administrators who had not properly configured their web server environments or had not applied security patches were at high risk of exploitation.
Mitigation strategies for CVE-2000-1186 required immediate action from system administrators and security teams. The most effective approach was to either patch the affected phf CGI program with proper input validation or completely remove the vulnerable program from web server configurations. Organizations should have implemented proper input sanitization techniques, including length validation for all user-supplied inputs and buffer size limits for argument processing. Network-level protections such as firewall rules that restricted access to CGI scripts and intrusion detection systems could provide additional layers of defense. The vulnerability highlighted the importance of secure coding practices and input validation, particularly for applications handling user data through web interfaces. Modern security frameworks emphasize the need for comprehensive testing including fuzzing and boundary condition testing to identify similar buffer overflow vulnerabilities in contemporary web applications. Organizations should have also implemented regular security assessments and vulnerability scanning to identify other potentially vulnerable CGI programs or similar buffer overflow conditions in their web server configurations.