CVE-2003-0645 in man
Summary
by MITRE
man-db 2.3.12 and 2.3.18 to 2.4.1 uses certain user-controlled DEFINE directives from the ~/.manpath file, even when running setuid, which could allow local users to gain privileges.
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Analysis
by VulDB Data Team • 11/16/2024
The vulnerability described in CVE-2003-0645 affects the man-db package version 2.3.12 and versions 2.3.18 through 2.4.1, representing a critical privilege escalation flaw that exploits the handling of user-controlled configuration directives within the setuid context. This issue specifically manifests when the system processes the ~/.manpath file, which contains user-defined MANPATH definitions that should normally be ignored or properly sanitized when running with elevated privileges. The flaw lies in the improper validation of these DEFINE directives, allowing local attackers to inject malicious content that gets executed with the privileges of the setuid process. The vulnerability creates a path for privilege escalation because the man-db utility, when running with setuid permissions, fails to properly isolate or sanitize user input from the manpath configuration file, thereby enabling arbitrary code execution with elevated privileges. This represents a classic case of insufficient input validation in setuid programs, where user-controllable data is processed without adequate sanitization or privilege separation mechanisms.
The technical exploitation of this vulnerability relies on the fundamental security principle that setuid programs must be extremely careful about handling user input, as they operate with elevated privileges and any flaw in input processing can be leveraged for privilege escalation. The man-db package, which manages manual page access and path resolution, should never allow user-defined configuration values to influence its behavior when running with elevated permissions. The DEFINE directives in the ~/.manpath file are processed in a context where the program assumes the user input is safe, but in reality, these directives can contain shell commands or other malicious content that gets executed with root privileges. This flaw directly violates the principle of least privilege and demonstrates poor security design in the configuration processing logic. The vulnerability is particularly dangerous because it operates silently in the background without requiring special conditions for exploitation, making it a persistent threat in systems where users have access to the home directory and can modify their manpath configuration.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and persistent access. An attacker with local access can craft malicious entries in their ~/.manpath file that, when processed by the setuid man-db utility, result in arbitrary code execution with root privileges. This creates opportunities for attackers to install backdoors, modify system files, or escalate their access to other system resources. The vulnerability affects systems where man-db is installed with setuid permissions, which is standard on most unix-like systems, making it widely exploitable across different environments. The flaw can be exploited by any local user who has write access to their home directory and can manipulate the manpath configuration file, potentially leading to complete system compromise. Additionally, this vulnerability aligns with attack patterns described in the attack tactic of privilege escalation within the MITRE ATT&CK framework, specifically targeting the use of setuid binaries as a method for gaining elevated privileges.
The mitigation strategies for this vulnerability require immediate patching of affected man-db versions, as well as implementing proper privilege separation and input validation mechanisms. System administrators should ensure that all man-db packages are updated to versions that properly sanitize user input from configuration files, particularly when processing setuid contexts. The recommended approach involves implementing strict input validation that prevents the execution of shell commands or other dangerous directives within user-controlled configuration files. Security hardening measures should include ensuring that configuration files are not processed in setuid contexts or that appropriate privilege separation mechanisms are implemented to prevent the execution of user-controllable content with elevated privileges. The vulnerability also highlights the importance of following security guidelines such as those outlined in the CWE catalog under CWE-20, which addresses improper input validation, and emphasizes the need for careful design of setuid programs to prevent information leaks and privilege escalation attacks. Organizations should conduct thorough security reviews of all setuid programs and their configuration handling mechanisms to prevent similar vulnerabilities from existing in their systems.