CVE-2008-4476 in sympa
Summary
by MITRE
sympa.pl in sympa 5.3.4 allows local users to overwrite arbitrary files via a symlink attack on the /tmp/sympa_aliases.$$ temporary file. NOTE: wwsympa.fcgi was also reported, but the issue occurred in a dead function, so it is not a vulnerability.
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Analysis
by VulDB Data Team • 03/30/2025
The vulnerability described in CVE-2008-4476 represents a classic symlink attack scenario affecting the sympa mailing list management system version 5.3.4. This flaw exists within the sympa.pl script and demonstrates a critical weakness in temporary file handling that enables local attackers to manipulate system files through symbolic link manipulation. The vulnerability specifically targets the /tmp/sympa_aliases.$$ temporary file, which serves as a staging area for alias management operations within the sympa system. The issue arises from insufficient validation of temporary file creation processes, allowing malicious users to establish symbolic links that redirect file operations to unintended destinations.
The technical implementation of this vulnerability stems from the improper handling of temporary file creation in the sympa.pl script. When the system creates temporary files in the /tmp directory, it does not verify that the target file path actually points to a legitimate temporary file or that the symbolic link has not been manipulated by an attacker. This behavior creates a race condition where an attacker can establish a symbolic link with the same name as the temporary file before the legitimate process creates it. The underlying flaw aligns with CWE-377, which addresses insecure temporary file creation practices, and CWE-378, which covers the creation of temporary files with insecure permissions. The vulnerability operates at the file system level and represents a privilege escalation vector for local attackers who can leverage this weakness to overwrite arbitrary files on the system.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities, as it provides attackers with the ability to modify critical system files and potentially escalate privileges within the sympa environment. Local users who can execute the sympa.pl script or access the system with sufficient privileges to manipulate the temporary file location can exploit this weakness to replace system binaries, configuration files, or other sensitive data. The attack scenario typically involves an attacker creating a symbolic link in the /tmp directory that points to a target file of their choice, then triggering the sympa.pl script which will subsequently overwrite the target file with data from the temporary file. This type of attack is particularly dangerous in multi-user environments where the sympa service runs with elevated privileges and where local users might not have direct access to critical system files. The vulnerability also relates to ATT&CK technique T1059.001, which covers command and script injection, as attackers can leverage this weakness to gain persistent access through modified system files.
The security implications of this vulnerability highlight the importance of proper temporary file handling practices and the need for robust input validation in system administration tools. The fact that wwsympa.fcgi was also mentioned but determined to be a dead function indicates that the vulnerability is specifically tied to active code paths within the sympa.pl script. Organizations running sympa 5.3.4 should implement immediate mitigations including restricting write permissions on the /tmp directory for non-privileged users, implementing proper temporary file creation mechanisms that avoid race conditions, and applying security patches as soon as they become available. The vulnerability demonstrates the critical need for security-conscious development practices and proper file system permissions to prevent attackers from exploiting weaknesses in temporary file handling. System administrators should also consider monitoring for unauthorized symbolic link creation in temporary directories and implementing additional security controls such as SELinux policies or AppArmor profiles to restrict file system access patterns.