CVE-2020-8017 in Linux Enterprise Module for Desktop Applications
Summary
by MITRE
A Race Condition Enabling Link Following vulnerability in the cron job shipped with texlive-filesystem of SUSE Linux Enterprise Module for Desktop Applications 15-SP1, SUSE Linux Enterprise Software Development Kit 12-SP4, SUSE Linux Enterprise Software Development Kit 12-SP5; openSUSE Leap 15.1 allows local users in group mktex to delete arbitrary files on the system This issue affects: SUSE Linux Enterprise Module for Desktop Applications 15-SP1 texlive-filesystem versions prior to 2017.135-9.5.1. SUSE Linux Enterprise Software Development Kit 12-SP4 texlive-filesystem versions prior to 2013.74-16.5.1. SUSE Linux Enterprise Software Development Kit 12-SP5 texlive-filesystem versions prior to 2013.74-16.5.1. openSUSE Leap 15.1 texlive-filesystem versions prior to 2017.135-lp151.8.3.1.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 05/13/2024
The vulnerability identified as CVE-2020-8017 represents a race condition flaw within the cron job implementation of the texlive-filesystem package across multiple SUSE and openSUSE distributions. This race condition specifically enables link following capabilities that can be exploited by local users who belong to the mktex group, creating a significant security risk for system integrity and file access control. The flaw exists in the timing-sensitive operations of the cron job that manages LaTeX-related filesystem components, where improper synchronization allows malicious users to manipulate file system operations during execution windows. The vulnerability manifests when the cron job processes symbolic links without adequate temporal safeguards, enabling attackers to substitute or manipulate target files during the processing window. This issue falls under the CWE-367 weakness category, specifically addressing time-of-check to time-of-use race conditions that occur when system resources are accessed between verification and actual use phases. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, as local users can leverage group membership to gain unauthorized file deletion capabilities. The affected systems include SUSE Linux Enterprise Module for Desktop Applications 15-SP1, SUSE Linux Enterprise Software Development Kit 12-SP4 and 12-SP5, and openSUSE Leap 15.1, all of which utilize the vulnerable texlive-filesystem package versions prior to their respective patched releases. The race condition vulnerability allows attackers to delete arbitrary files on the system because the cron job does not properly validate file paths or implement atomic operations when handling symbolic links. When the mktex group members execute the cron job, they can manipulate the filesystem during the window between when file access permissions are checked and when the actual file operations are performed, enabling them to target any file accessible to the system. This creates a persistent threat vector that can be exploited repeatedly, as the cron job executes automatically on schedule, providing attackers with regular opportunities to exploit the timing gap. The vulnerability demonstrates a fundamental flaw in how the system manages concurrent file operations and symbolic link resolution within scheduled tasks, which can be particularly dangerous in enterprise environments where LaTeX document processing is common. The impact extends beyond simple file deletion, as attackers can potentially manipulate system configuration files or critical components that rely on the LaTeX filesystem structure. The patch versions provided in the affected releases address the race condition by implementing proper synchronization mechanisms, atomic file operations, and enhanced validation of symbolic link targets during cron job execution. System administrators should immediately apply the patched versions to mitigate this vulnerability and prevent potential exploitation by local users with mktex group membership. The vulnerability underscores the importance of proper race condition handling in system cron jobs and highlights the need for comprehensive security reviews of scheduled tasks that interact with file system resources, particularly those that involve symbolic link manipulation or file path resolution. Organizations should also implement additional monitoring for unauthorized file deletion activities and ensure that group membership policies are properly enforced to limit access to potentially vulnerable system components.