CVE-2001-0906 in teTeX
Summary
by MITRE
teTeX filter before 1.0.7 allows local users to gain privileges via a symlink attack on temporary files that are produced when printing .dvi files using lpr.
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Analysis
by VulDB Data Team • 11/09/2024
The vulnerability described in CVE-2001-0906 represents a classic privilege escalation flaw affecting the teTeX filter system prior to version 1.0.7. This issue specifically manifests when processing .dvi files through the lpr printing system, creating a dangerous race condition scenario that local attackers can exploit to elevate their system privileges. The vulnerability stems from inadequate handling of temporary files generated during the printing process, where the system fails to properly validate file ownership and permissions before processing.
The technical flaw exploits a symlink attack pattern where malicious users can create symbolic links to critical system files in the temporary directory space. When the teTeX filter processes a .dvi file, it generates temporary files that are typically created with predictable names and locations. The vulnerability occurs because the filter does not perform proper validation to ensure that these temporary files are not symbolic links pointing to privileged system files such as /etc/passwd or other sensitive locations. This weakness allows attackers to manipulate the system's file operations and potentially overwrite critical files with malicious content, thereby gaining elevated privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with a reliable method to compromise systems running affected versions of teTeX. The attack requires only local access and can be executed without special privileges, making it particularly dangerous in multi-user environments where users might have legitimate access to the printing system. This vulnerability directly maps to CWE-377, which addresses insecure temporary file handling, and aligns with ATT&CK technique T1068, which covers privilege escalation through local exploits. The vulnerability affects systems where users can submit print jobs through lpr, which was common in many unix-based systems during this era.
Mitigation strategies for CVE-2001-0906 involve several approaches that address the root cause of the vulnerability. The primary solution is updating to teTeX version 1.0.7 or later, which includes proper temporary file handling mechanisms that prevent symlink attacks. Additionally, system administrators should implement proper file permissions and ownership checks for temporary directories used by the printing system. The recommended approach includes setting restrictive permissions on temporary file locations and ensuring that temporary files are created with unique names that cannot be predicted by attackers. Organizations should also consider implementing proper file system monitoring and access controls to detect and prevent unauthorized symbolic link creation in sensitive directories. The vulnerability demonstrates the importance of proper input validation and temporary file management in preventing privilege escalation attacks, reinforcing principles outlined in security frameworks such as the OWASP Top Ten and NIST cybersecurity guidelines for secure coding practices.