CVE-2007-5940 in TeXLive 2007
Summary
by MITRE
feynmf.pl in feynmf 1.08, as used in TeXLive 2007, allows local users to overwrite arbitrary files and execute arbitrary code via a symlink attack on the feynmf$$.pl temporary file.
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Analysis
by VulDB Data Team • 08/01/2019
The vulnerability identified as CVE-2007-5940 resides within the feynmf.pl script component of the feynmf package version 1.08, which was distributed as part of TeXLive 2007. This issue represents a classic race condition vulnerability that exploits improper temporary file handling mechanisms within the script execution environment. The feynmf package is designed for creating Feynman diagrams within LaTeX documents, but the implementation contains a critical flaw that affects system security through improper file creation and management practices. The vulnerability specifically targets the temporary file naming convention used by feynmf.pl, which creates temporary files with predictable names that can be exploited through symbolic link manipulation.
The technical flaw manifests through a race condition scenario where the feynmf.pl script creates temporary files using a predictable naming pattern that includes the process ID in the filename. This predictable naming scheme allows local attackers to establish symbolic links with the same names before the legitimate script creates them, thereby redirecting the script's file operations to attacker-controlled locations. The vulnerability operates under CWE-367, which categorizes it as a Time-of-Check to Time-of-Use (TOCTOU) flaw, where the system checks for file existence and permissions at one point but the actual file operations occur later, creating an exploitable window. The attack requires the target user to execute the feynmf.pl script, typically through a LaTeX compilation process, which provides the necessary execution context for the malicious symlink to take effect.
The operational impact of this vulnerability extends beyond simple file overwrites to include arbitrary code execution capabilities, making it particularly dangerous in multi-user environments or when scripts run with elevated privileges. When an attacker successfully manipulates the temporary file creation process, they can overwrite existing files with malicious content or create files with execution permissions, potentially leading to privilege escalation scenarios. The vulnerability affects systems where the feynmf.pl script is executed with sufficient privileges to modify system files, and it particularly impacts environments where LaTeX documents containing Feynman diagram commands are processed, such as academic research systems, documentation servers, or automated build environments. This type of vulnerability aligns with ATT&CK technique T1059.007 for execution through script-based attacks and T1078.004 for legitimate program execution with elevated privileges.
Mitigation strategies for CVE-2007-5940 should focus on implementing proper temporary file handling mechanisms that avoid predictable naming schemes and eliminate race conditions. The most effective approach involves modifying the feynmf.pl script to use secure temporary file creation methods such as mkstemp or similar functions that guarantee unique, non-predictable file names and ensure atomic creation. System administrators should also consider restricting execution permissions for the feynmf.pl script and implementing proper file system permissions that prevent unauthorized symbolic link creation in directories where temporary files are generated. Additionally, updating to newer versions of the feynmf package that address this vulnerability through secure temporary file handling practices would provide permanent resolution. Organizations should also implement monitoring for suspicious symbolic link creation patterns and consider sandboxing compilation environments to limit the potential impact of such vulnerabilities in production systems.