CVE-2024-9902: Ansible Core Privilege Escalation Flaw

CVE-2024-9902 Overview

A security flaw was discovered in Ansible that allows unauthorized file manipulation through the ansible-core user module. The vulnerability enables an unprivileged user to silently create or replace the contents of any file on any system path and take ownership of it when a privileged user executes the user module against the unprivileged user's home directory. If the unprivileged user has traversal permissions on the directory containing the exploited target file, they retain full control over the contents of the file as its owner.

Critical Impact

This improper authorization vulnerability (CWE-863) could allow local privilege escalation and arbitrary file manipulation on systems managed by Ansible, potentially compromising system integrity and confidentiality.

Affected Products

• ansible-core user module
• Red Hat Ansible Automation Platform
• Debian-based systems running vulnerable ansible-core versions

Discovery Timeline

• 2024-11-06 - CVE-2024-9902 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2024-9902

Vulnerability Analysis

The vulnerability exists in the ansible-core user module, which is responsible for managing user accounts on target systems. The flaw stems from improper authorization checks (CWE-863) when the module operates on a user's home directory. When a privileged user (such as root or an automation account with elevated privileges) executes the user module to manage an unprivileged user's account, the module fails to properly validate symbolic links and directory traversal scenarios within the unprivileged user's home directory.

This creates a race condition scenario where the unprivileged user can prepare malicious symbolic links or directory structures in their home directory before the privileged Ansible execution occurs. The privileged execution will then follow these links and create or overwrite files at arbitrary system locations with the elevated privileges, while setting ownership to the unprivileged user.

Root Cause

The root cause is an improper authorization vulnerability (CWE-863) in the ansible-core user module. The module does not adequately validate file paths and symbolic links when operating within a user's home directory context. This allows an attacker to exploit the trust boundary between the unprivileged user's controllable home directory and the privileged execution context of the Ansible automation.

Attack Vector

The attack requires local access and involves the following conditions:

1. An unprivileged user must have a home directory that will be targeted by Ansible's user module
2. A privileged user or automation process must execute the user module against the unprivileged user's account
3. The unprivileged user must have traversal permissions on directories containing target files

The attacker can plant symbolic links in their home directory pointing to sensitive system files. When the privileged Ansible execution processes the home directory, it follows these links and creates/modifies files at the linked locations with the attacker as the owner. This enables the attacker to gain persistent access to sensitive system files or inject malicious content into configuration files.

Detection Methods for CVE-2024-9902

Indicators of Compromise

• Unexpected symbolic links in user home directories pointing to system files like /etc/passwd, /etc/shadow, or configuration files
• Files in sensitive system locations with unexpected ownership by unprivileged users
• Ansible execution logs showing user module operations followed by suspicious file creation events
• Unauthorized modifications to system configuration files coinciding with Ansible playbook executions

Detection Strategies

• Monitor Ansible execution logs for user module invocations and correlate with file system changes
• Implement file integrity monitoring on critical system files to detect unauthorized ownership changes
• Audit symbolic links in user home directories for references to system paths outside the home directory
• Configure SentinelOne endpoint protection to detect privilege escalation patterns and unusual file ownership changes

Monitoring Recommendations

• Enable detailed Ansible logging to capture all module executions and their parameters
• Implement real-time alerting for file ownership changes on sensitive system paths
• Monitor for the creation of symbolic links in user home directories that target system locations
• Use SentinelOne's behavioral AI to detect anomalous file system operations during privileged automation processes

How to Mitigate CVE-2024-9902

Immediate Actions Required

• Apply the latest security patches from Red Hat or Debian as appropriate for your environment
• Review and audit all Ansible playbooks that use the user module to ensure proper input validation
• Restrict which users can have their accounts managed via Ansible automation
• Implement the principle of least privilege for Ansible execution accounts

Patch Information

Security patches have been released to address this vulnerability. Organizations should apply the appropriate updates based on their distribution:

• Red Hat Security Advisory RHSA-2024:8969
• Red Hat Security Advisory RHSA-2024:9894
• Red Hat Security Advisory RHSA-2024:10762
• Red Hat Security Advisory RHSA-2025:1861
• Debian LTS Security Announcement

For additional details, refer to Red Hat CVE Report CVE-2024-9902 and Red Hat Bugzilla Report #2318271.

Workarounds

• Avoid running the user module with elevated privileges against untrusted user accounts until patches are applied
• Implement pre-execution validation scripts that check for symbolic links in user home directories before running Ansible playbooks
• Use dedicated service accounts with minimal privileges for Ansible automation tasks
• Consider implementing additional filesystem restrictions such as nosymfollow mount options where applicable

# Configuration example - Audit symlinks in user home directories before Ansible execution
# Add to pre-flight checks in Ansible playbooks
find /home -type l -exec ls -la {} \; | grep -E "^l.*-> /(etc|var|usr|root)"
# If any results appear, investigate before proceeding with user module operations