CVE-2003-0620 in man-db
Summary
by MITRE
Multiple buffer overflows in man-db 2.4.1 and earlier, when installed setuid, allow local users to gain privileges via (1) MANDATORY_MANPATH, MANPATH_MAP, and MANDB_MAP arguments to add_to_dirlist in manp.c, (2) a long pathname to ult_src in ult_src.c, (3) a long .so argument to test_for_include in ult_src.c, (4) a long MANPATH environment variable, or (5) a long PATH environment variable.
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Analysis
by VulDB Data Team • 11/17/2024
The vulnerability described in CVE-2003-0620 represents a critical privilege escalation flaw affecting man-db versions 2.4.1 and earlier when installed with setuid permissions. This vulnerability stems from multiple buffer overflow conditions within the manual page management system that can be exploited by local attackers to execute arbitrary code with elevated privileges. The affected components include core functions within manp.c and ult_src.c that handle environment variable processing and directory list management. These buffer overflows occur during the parsing of user-supplied input through various environment variables and command-line arguments that are processed by the setuid root binary, creating a significant security risk for systems where the man-db utility is installed with elevated permissions.
The technical implementation of this vulnerability involves several distinct attack vectors that all exploit the same underlying buffer overflow principle. The primary attack surface includes the MANDATORY_MANPATH, MANPATH_MAP, and MANDB_MAP arguments processed by add_to_dirlist function in manp.c, which can be manipulated to overflow buffers and overwrite return addresses or other critical memory structures. Additionally, the ult_src.c component contains multiple overflow points including a long pathname argument to ult_src function, a lengthy .so argument to test_for_include function, and both long MANPATH and PATH environment variables. These vulnerabilities are classified under CWE-121 Stack-based Buffer Overflow and CWE-122 Heap-based Buffer Overflow categories, representing fundamental memory safety issues that allow attackers to manipulate program execution flow.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially enable full system compromise. When man-db is installed setuid root, any successful exploitation of these buffer overflows can result in local users gaining root privileges, which provides complete control over the affected system. Attackers can leverage these vulnerabilities to install backdoors, modify system files, or establish persistent access. The attack vectors are particularly concerning because they can be triggered through normal environment variable usage, making them difficult to detect and prevent through standard input validation measures. This vulnerability aligns with ATT&CK technique T1068 for Local Privilege Escalation and T1548.001 for Abuse of Sudo or Setuid, as it exploits the setuid binary execution model to achieve elevated privileges without requiring network access or complex attack chains.
Mitigation strategies for this vulnerability require immediate system hardening and patching approaches. The most effective solution involves upgrading to man-db version 2.4.2 or later where these buffer overflows have been addressed through proper input validation and memory management. System administrators should also consider removing setuid permissions from man-db binaries where possible, as this eliminates the privilege escalation vector entirely. Additional protective measures include implementing strict environment variable validation, using security modules like SELinux or AppArmor to restrict binary execution, and monitoring for unusual environment variable usage patterns. The vulnerability demonstrates the critical importance of secure coding practices in setuid applications and highlights the need for comprehensive input validation and buffer management in system utilities that handle user-provided data. Regular security audits of setuid binaries should be conducted to identify similar vulnerabilities that could provide unauthorized privilege escalation opportunities.