CVE-2000-0566 in man
Summary
by MITRE
makewhatis in Linux man package allows local users to overwrite files via a symlink attack.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 06/25/2021
The vulnerability identified as CVE-2000-0566 resides within the makewhatis utility of the Linux man package, representing a classic file overwrite flaw that exploits symbolic link manipulation. This issue specifically affects local users who can leverage the vulnerability to overwrite arbitrary files on the system, potentially leading to privilege escalation or system compromise. The vulnerability stems from inadequate validation of symbolic links during file operations, allowing malicious users to create malicious symlinks that point to critical system files, which are then overwritten when makewhatis processes them during its execution cycle.
The technical flaw manifests when makewhatis processes manual pages and their associated metadata files without properly verifying the integrity of symbolic links in the target directories. When the utility encounters a symbolic link, it follows the link and writes data to the target file, bypassing normal file permission checks and validation mechanisms. This behavior creates a race condition vulnerability where an attacker can create a carefully crafted symbolic link before makewhatis processes it, effectively redirecting the write operation to a file of their choosing. The flaw operates at the file system level and demonstrates poor input validation practices, aligning with CWE-59: Improper Link Resolution, which specifically addresses issues related to symbolic link manipulation in security contexts. This vulnerability type falls under the broader category of privilege escalation through file system manipulation, a common attack vector in Unix-like systems.
The operational impact of this vulnerability extends beyond simple file overwrites, as it can be leveraged to escalate privileges and potentially compromise entire systems. Local attackers can exploit this weakness to overwrite system configuration files, binary executables, or critical system libraries, leading to unauthorized privilege escalation. The attack requires local system access but can be particularly dangerous in multi-user environments where users might have access to the man directory or related system directories. This vulnerability directly relates to ATT&CK technique T1068 which covers Exploitation for Privilege Escalation, and T1059 which covers Command and Scripting Interpreter, as attackers can use this flaw to modify system binaries or configuration files to gain persistent access.
Mitigation strategies for CVE-2000-0566 should focus on immediate system hardening and access control measures. System administrators should ensure that the man package is updated to versions that properly handle symbolic links and implement proper file validation before processing. The most effective immediate solution involves restricting write permissions on directories where makewhatis operates, particularly the man directory and its subdirectories. Implementing proper file system permissions and ensuring that only authorized users have write access to system documentation directories can significantly reduce the attack surface. Additionally, system administrators should monitor for suspicious symbolic link creation in system directories and implement proper file integrity monitoring to detect unauthorized modifications. The vulnerability also highlights the importance of following secure coding practices in system utilities, specifically the need for proper validation of file paths and symbolic link resolution before file operations are performed. Organizations should implement regular security audits to identify similar vulnerabilities in other system utilities and ensure that all file system operations properly validate input to prevent similar symlink-based attacks.