CVE-2009-5080 in groff
Summary
by MITRE
The (1) contrib/eqn2graph/eqn2graph.sh, (2) contrib/grap2graph/grap2graph.sh, and (3) contrib/pic2graph/pic2graph.sh scripts in GNU troff (aka groff) 1.21 and earlier do not properly handle certain failed attempts to create temporary directories, which might allow local users to overwrite arbitrary files via a symlink attack on a file in a temporary directory, a different vulnerability than CVE-2004-1296.
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Analysis
by VulDB Data Team • 11/13/2021
The vulnerability described in CVE-2009-5080 affects GNU troff version 1.21 and earlier, specifically targeting three shell scripts within the contrib directory: eqn2graph.sh, grap2graph.sh, and pic2graph.sh. These scripts serve as utilities for converting mathematical equations, graphs, and figures into graphical representations. The flaw stems from inadequate error handling during temporary directory creation processes, creating a path traversal vulnerability that can be exploited through symbolic link attacks. This issue represents a distinct vulnerability from CVE-2004-1296, indicating that while both involve temporary file handling, they manifest through different attack vectors and system weaknesses.
The technical implementation of this vulnerability occurs when the shell scripts attempt to create temporary directories for processing graphical conversions. When these operations fail, the scripts do not properly validate or handle the error conditions, leaving temporary files in a state where they can be manipulated through symlink attacks. An attacker with local access can exploit this by creating symbolic links in the temporary directory path that point to arbitrary files on the system. When the script subsequently attempts to write to what it believes is a temporary file, it actually overwrites the targeted file, potentially leading to privilege escalation or arbitrary code execution depending on the target file's permissions and location. This type of vulnerability maps directly to CWE-354 and CWE-362, as it involves improper handling of temporary files and race conditions.
The operational impact of CVE-2009-5080 extends beyond simple file overwrites, as it can be leveraged for more sophisticated attacks within local environments. Attackers can use this vulnerability to overwrite system configuration files, binaries, or other critical components, potentially gaining elevated privileges or causing system instability. The vulnerability is particularly concerning in multi-user environments where local users might not have direct access to critical system files but could manipulate temporary directories through shared resources. This attack vector aligns with ATT&CK technique T1059.007 for shell scripting and T1068 for local privilege escalation, as the vulnerability can be used to gain higher system privileges through file manipulation attacks. The attack requires local system access and can be executed by any user who can influence the temporary directory creation process, making it a persistent threat in environments where users have shell access.
Mitigation strategies for CVE-2009-5080 should focus on both immediate patching and defensive system hardening measures. The primary solution involves upgrading to GNU troff version 1.22 or later, where the temporary directory handling has been properly addressed. Organizations should also implement proper file permissions and directory ownership controls to prevent unauthorized symbolic link creation in temporary directories. System administrators can apply restrictive permissions to temporary directories and ensure that scripts are run with minimal necessary privileges. Additional defensive measures include implementing proper input validation and error handling within shell scripts, using absolute paths for temporary files, and monitoring for unusual file access patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of secure temporary file handling practices and proper error condition management in shell scripting environments.