CVE-2024-1329 in Nomad
Summary
by MITRE • 02/08/2024
HashiCorp Nomad and Nomad Enterprise 1.5.13 up to 1.6.6, and 1.7.3 template renderer is vulnerable to arbitrary file write on the host as the Nomad client user through symlink attacks. Fixed in Nomad 1.7.4, 1.6.7, 1.5.14.
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Analysis
by VulDB Data Team • 09/26/2024
HashiCorp Nomad and Nomad Enterprise versions 1.5.13 through 1.6.6 and 1.7.3 contain a critical vulnerability that allows attackers to perform arbitrary file writes on the host system as the Nomad client user through symlink manipulation attacks. This vulnerability stems from insufficient validation of symbolic links during template rendering operations within the Nomad client component. The flaw specifically affects the template renderer which processes configuration templates and generates files on the host filesystem. When Nomad processes templates that contain symbolic links, it fails to properly verify the target paths of these links, allowing an attacker to create malicious symlinks that point to sensitive system files or directories. This vulnerability directly maps to CWE-59, which describes improper handling of symbolic links, and represents a privilege escalation vector that can be exploited to compromise the host system. The attack requires an attacker to have the ability to influence template content or the environment in which templates are processed, typically through compromised jobs or access to the Nomad client configuration.
The operational impact of this vulnerability is significant as it enables attackers to modify critical system files, potentially leading to persistent access, data exfiltration, or complete system compromise. When exploited, the vulnerability allows an attacker to write arbitrary content to files on the host system, including configuration files, binaries, or other sensitive resources that the Nomad client process has write permissions to. The vulnerability affects Nomad clients running on Linux systems where the Nomad process operates with elevated privileges. Attackers can leverage this weakness to overwrite system binaries, modify configuration files, or inject malicious code that persists across system reboots. The exploitation requires careful manipulation of the template rendering process to ensure that the symbolic links point to desired target locations, making this a sophisticated attack vector that requires understanding of both Nomad's template system and the target host filesystem structure.
The vulnerability is addressed through patches released in Nomad versions 1.7.4, 1.6.7, and 1.5.14, which implement proper validation of symbolic links during template processing. These fixes ensure that the template renderer performs additional checks to verify that symbolic links do not point to sensitive locations or that they are properly resolved before file operations are performed. The remediation follows established security principles for preventing symlink attacks by implementing proper path validation and ensuring that file operations occur in controlled environments. Organizations running affected versions should immediately upgrade to the patched releases to mitigate this risk. The vulnerability also aligns with ATT&CK technique T1059.007, which describes the use of template injection techniques to execute arbitrary code, and T1546.001, which covers changes to system binaries through the modification of configuration files. System administrators should monitor for unusual file modifications on hosts where Nomad clients are running and implement additional controls such as file integrity monitoring to detect potential exploitation attempts.
The fix implemented in the patched versions enforces strict validation of symbolic links by ensuring that all paths referenced in templates are properly resolved and validated against a whitelist of allowed locations. This approach prevents attackers from creating symlinks that point to system-critical files or directories. The implementation follows security best practices for preventing path traversal and symlink-based attacks, ensuring that the template rendering process operates in a secure context where file operations are restricted to predefined safe locations. Organizations should also consider implementing additional security controls such as mandatory access controls, file system permissions, and process isolation to further reduce the impact of any potential exploitation attempts. The vulnerability serves as a reminder of the importance of proper input validation and path resolution in systems that process user-supplied templates or configuration data, particularly in container orchestration and infrastructure management platforms.