CVE-2008-4953 in firehol
Summary
by MITRE
** DISPUTED ** firehol in firehol 1.256 allows local users to overwrite arbitrary files via a symlink attack on (1) /tmp/.firehol-tmp-#####-*-* and (2) /tmp/firehol.conf temporary files. NOTE: the vendor disputes this vulnerability, stating that an attack "would require an attacker to create 1073741824*PID-RANGE symlinks."
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Analysis
by VulDB Data Team • 08/25/2025
The vulnerability identified as CVE-2008-4953 pertains to firehol version 1.256 and represents a local privilege escalation issue through symbolic link attacks. This flaw exists in the temporary file handling mechanisms of the firehol network firewall management tool, which creates temporary files in the /tmp directory during its operation. The vulnerability occurs when firehol generates temporary files using predictable naming patterns that include process identifiers and timestamps, making them susceptible to symlink-based attacks. The specific temporary files affected are located at /tmp/.firehol-tmp-#####-- and /tmp/firehol.conf, both of which are created with insufficient security measures to prevent malicious manipulation by local users.
The technical exploitation of this vulnerability requires an attacker to establish symbolic links in the /tmp directory that point to sensitive system files before firehol creates its own temporary files. This type of attack falls under the category of time-of-check to time-of-use vulnerabilities, where the system checks for file existence and permissions at one point but the actual file operations occur later when the attacker has had opportunity to manipulate the filesystem. The attack vector specifically targets the insecure creation of temporary files without proper atomic operations or file permission checks that would prevent symlink attacks. According to the MITRE ATT&CK framework, this vulnerability aligns with the technique of "Exploitation for Privilege Escalation" under the T1068 category, where local users can leverage system weaknesses to gain elevated privileges.
The operational impact of this vulnerability is significant for systems running firehol 1.256, as local users could potentially overwrite critical system files with malicious content, leading to privilege escalation and system compromise. The vendor's response indicates that the attack would require creating an enormous number of symbolic links - specifically 1073741824 multiplied by the PID range - which suggests the vulnerability may be difficult to exploit in practice. However, this assessment should not be taken as a complete dismissal of the risk, as the mathematical complexity of the attack does not eliminate the possibility of successful exploitation in certain environments. The vendor's statement references the use of the PID range in the calculation, indicating that the number of potential symlinks needed varies based on system configuration, making the attack surface potentially more extensive than initially described. This vulnerability demonstrates the importance of proper temporary file handling and the principle of least privilege in system security.
The mitigation strategies for this vulnerability should focus on implementing secure temporary file creation practices, including the use of atomic file creation methods that prevent symlink attacks. System administrators should ensure that firehol is updated to a version that addresses this issue, as the vendor's position on the vulnerability's severity remains questionable. Security measures should include monitoring for unauthorized symbolic link creation in the /tmp directory and implementing proper file permission controls. The vulnerability also highlights the need for comprehensive security testing of network management tools, particularly those that create temporary files during execution. Organizations should consider implementing additional controls such as restricted /tmp filesystem permissions, noexec flags, or dedicated temporary directories with proper access controls to prevent similar issues. This vulnerability serves as a reminder of the critical importance of secure coding practices in system administration tools, particularly those with elevated privileges or system-level access. The issue also relates to CWE-377, which addresses insecure temporary file handling, and demonstrates how seemingly minor implementation flaws can create significant security risks in system-level software.