CVE-2014-9680 in sudo
Summary
by MITRE
sudo before 1.8.12 does not ensure that the TZ environment variable is associated with a zoneinfo file, which allows local users to open arbitrary files for read access (but not view file contents) by running a program within an sudo session, as demonstrated by interfering with terminal output, discarding kernel-log messages, or repositioning tape drives.
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Analysis
by VulDB Data Team • 03/10/2022
The vulnerability identified as CVE-2014-9680 represents a critical security flaw in the sudo command utility affecting versions prior to 1.8.12. This issue stems from insufficient validation of the TZ environment variable during sudo execution, creating a privilege escalation vector that allows local attackers to gain unauthorized file access capabilities. The vulnerability specifically targets the way sudo handles time zone information, which is typically stored in zoneinfo files within the system's time zone database. When sudo processes commands, it fails to properly verify that the TZ environment variable points to a legitimate zoneinfo file, leaving the system exposed to malicious manipulation of this environmental parameter.
The technical exploitation of this vulnerability occurs through the manipulation of the TZ environment variable within a sudo session context. Attackers can craft malicious environment variable settings that point to arbitrary files on the system, enabling them to open these files for read access without being able to view the actual contents. This limitation in file access, while seemingly restrictive, provides attackers with significant operational capabilities. The vulnerability manifests in scenarios where attackers can interfere with terminal output by redirecting the terminal's display to arbitrary files, effectively corrupting or redirecting user interface elements. Additionally, the flaw enables attackers to discard kernel log messages by redirecting system logging to specific files, potentially covering their tracks or disrupting system monitoring. The vulnerability also allows for tape drive repositioning through file access manipulation, demonstrating how attackers can leverage this flaw to manipulate hardware operations indirectly.
The operational impact of CVE-2014-9680 extends beyond simple file access, as it provides attackers with the ability to disrupt system operations and potentially compromise system integrity. The vulnerability operates at the privilege level of the sudo session, meaning that any user who can execute sudo commands can potentially exploit this flaw to gain unauthorized access to files that they would normally not be able to read. This creates a significant risk for systems where sudo is frequently used, as the attack surface expands to include any process that might be executed through sudo with elevated privileges. The vulnerability's impact is particularly concerning because it operates silently, allowing attackers to manipulate system behavior without explicit indication of compromise. The flaw demonstrates a fundamental weakness in environment variable validation within the sudo utility, which is a core component of Unix-like system security models.
This vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and relates to broader concepts in the ATT&CK framework under privilege escalation and persistence techniques. The issue demonstrates how seemingly benign environment variables can become attack vectors when proper validation mechanisms are absent. System administrators should prioritize updating sudo to version 1.8.12 or later, as this release includes proper validation of the TZ environment variable against legitimate zoneinfo files. Additionally, implementing proper environment variable sanitization policies and monitoring for unusual TZ variable usage can help detect potential exploitation attempts. Organizations should also consider implementing automated patch management systems to ensure timely remediation of such vulnerabilities. The vulnerability serves as a reminder of the importance of validating all environmental parameters in security-critical applications and demonstrates how seemingly minor implementation flaws can create significant security risks in privilege management systems.