CVE-2014-3219 in FiSH
Summary
by MITRE
fish before 2.1.1 allows local users to write to arbitrary files via a symlink attack on (1) /tmp/fishd.log.%s, (2) /tmp/.pac-cache.$USER, (3) /tmp/.yum-cache.$USER, or (4) /tmp/.rpm-cache.$USER.
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Analysis
by VulDB Data Team • 02/06/2023
The vulnerability identified as CVE-2014-3219 affects the fish shell version 2.1.1 and earlier, presenting a significant security risk through insecure temporary file handling. This flaw enables local attackers to manipulate the filesystem by exploiting symbolic link attacks against specific temporary files used by the shell during its operation. The vulnerability stems from the shell's failure to properly validate or secure temporary file creation processes, creating opportunities for privilege escalation and unauthorized file manipulation.
The technical implementation of this vulnerability involves four specific temporary file locations that fish shell creates during execution: /tmp/fishd.log.%s, /tmp/.pac-cache.$USER, /tmp/.yum-cache.$USER, and /tmp/.rpm-cache.$USER. These files are susceptible to symlink attacks because the shell does not perform proper file existence checks or validation before writing to these locations. An attacker can create symbolic links with the same names as these temporary files, causing the fish shell to write data to locations controlled by the attacker rather than the intended system locations. This represents a classic race condition vulnerability where the timing of file creation and access can be exploited by malicious actors.
From an operational impact perspective, this vulnerability allows local users to potentially overwrite or manipulate critical system files, leading to unauthorized data modification, privilege escalation, or even complete system compromise depending on the target files and permissions involved. The attack vector is particularly concerning because it requires only local system access, making it accessible to any user with login privileges on the affected system. The vulnerability aligns with CWE-377: Insecure Temporary File and CWE-378: Creation of Temporary File With Insecure Permissions, both of which are commonly exploited in privilege escalation scenarios.
The security implications extend beyond simple file manipulation as this vulnerability can be leveraged as a foothold for more sophisticated attacks within a compromised system. Attackers can use this technique to plant malicious code in system locations, modify configuration files, or establish persistent access mechanisms. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: Shell Script) and T1068 (Exploitation for Privilege Escalation) as it enables attackers to manipulate shell environments and potentially escalate privileges through file system manipulation. Organizations should consider this vulnerability as part of their broader security posture assessment, particularly in environments where multiple users have local access to systems running affected fish shell versions.
Mitigation strategies should focus on immediate patching to version 2.1.1 or later, which addresses the insecure temporary file handling through proper file validation and secure creation practices. System administrators should also implement monitoring for suspicious symlink creation patterns in temporary directories and consider restricting write permissions to critical temporary locations. Additionally, organizations should conduct vulnerability assessments to identify systems running vulnerable versions of fish shell and ensure proper access controls are in place to limit the potential impact of such vulnerabilities. The fix typically involves implementing proper file existence checks and using secure temporary file creation methods that prevent symbolic link attacks from succeeding.