CVE-2005-3126 in antiword
Summary
by MITRE
The (1) kantiword (kantiword.sh) and (2) gantiword (gantiword.sh) scripts in antiword 0.35 and earlier allow local users to overwrite arbitrary files via a symlink attack on temporary (a) output and (b) error files.
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Analysis
by VulDB Data Team • 08/04/2019
The vulnerability identified as CVE-2005-3126 affects the antiword document conversion utility version 0.35 and earlier, specifically targeting two shell scripts named kantiword.sh and gantiword.sh. This represents a classic symlink attack scenario that exploits insecure temporary file handling within the script execution environment. The flaw occurs when these scripts create temporary files during their operation without proper validation of file existence or ownership, creating opportunities for malicious users to manipulate the system through symbolic link manipulation. The vulnerability falls under the category of insecure temporary file handling as defined by CWE-377, which specifically addresses the creation of temporary files with insecure permissions or predictable names. The attack vector involves a local user who can create symbolic links that point to sensitive system files, allowing them to overwrite or modify critical data during the execution of these scripts.
The technical implementation of this vulnerability stems from the scripts' failure to properly secure temporary file creation processes. When kantiword.sh and gantiword.sh execute, they generate temporary output and error files in predictable locations without verifying whether these files already exist or are symbolic links. This insecure practice allows an attacker to establish symbolic links with the same names as the temporary files before the scripts execute, effectively redirecting file operations to arbitrary locations on the filesystem. The vulnerability specifically targets the race condition that occurs between file creation and access, where the window between when a temporary file is created and when it is accessed by the script provides an opportunity for manipulation. The attack requires local system access but can result in significant privilege escalation or data compromise depending on the target files being overwritten.
The operational impact of this vulnerability extends beyond simple file overwrite capabilities, as it can potentially enable privilege escalation when the affected scripts are executed with elevated privileges. If these scripts are installed with setuid permissions or run under a privileged context, an attacker could leverage the symlink attack to modify system-critical files such as configuration files, binaries, or even system libraries. The vulnerability affects the integrity and confidentiality of the system by allowing unauthorized modification of files that should remain protected. From an attacker's perspective, this represents a low-effort, high-impact attack that can be executed without requiring network access or complex exploitation techniques. The vulnerability's persistence in older versions of antiword demonstrates the importance of secure coding practices and proper temporary file handling in shell scripts, which aligns with ATT&CK technique T1059.004 for executing shell commands and T1068 for privilege escalation through insecure file operations.
Mitigation strategies for this vulnerability should focus on implementing secure temporary file creation practices that prevent symbolic link manipulation. The most effective approach involves using secure file creation methods that check for existing files and ensure proper permissions are set during file creation. System administrators should immediately update to antiword versions 0.36 and later where this vulnerability has been patched. Additionally, implementing proper file system permissions and using tools like the umask command can help prevent unauthorized file creation. The vulnerability also highlights the importance of regular security audits of shell scripts and system utilities, particularly those that handle temporary files or operate with elevated privileges. Organizations should consider implementing file integrity monitoring solutions and regular vulnerability scanning to identify similar insecure temporary file handling patterns in other software components. The fix typically involves modifying the scripts to use secure temporary file creation functions or to verify that temporary files are not symbolic links before proceeding with file operations.