CVE-2021-3583
📋 TL;DR
CVE-2021-3583 is a template injection vulnerability in Ansible that allows attackers to execute arbitrary commands through specially crafted facts in multi-line YAML strings. This can lead to sensitive information disclosure and system compromise. Users running vulnerable Ansible versions with template processing are affected.
💻 Affected Systems
- Ansible
- Red Hat Ansible Automation Platform
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining shell access, exfiltrating sensitive data, and pivoting to other systems in the environment.
Likely Case
Limited command execution leading to disclosure of configuration files, credentials, or other sensitive information from the controller system.
If Mitigated
Minimal impact with proper input validation and restricted user permissions preventing template injection.
🎯 Exploit Status
Exploitation requires access to modify facts or playbooks. Public proof-of-concept demonstrates template injection through crafted YAML.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Ansible 2.9.27, 2.10.7, 2.11.3, 2.12.0 and later
Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1968412
Restart Required: No
Instructions:
1. Update Ansible using pip: 'pip install --upgrade ansible>=2.9.27' or appropriate version. 2. For Red Hat systems: 'yum update ansible'. 3. Verify installation with 'ansible --version'.
🔧 Temporary Workarounds
Restrict template processing
allAvoid using user-controlled facts in templates and sanitize all template inputs.
Implement strict permissions
allLimit who can create or modify playbooks and restrict Ansible controller access.
🧯 If You Can't Patch
- Implement network segmentation to isolate Ansible controllers from sensitive systems
- Enable detailed logging and monitoring for template processing activities
🔍 How to Verify
Check if Vulnerable:
Run 'ansible --version' and check if version is below 2.9.27, 2.10.7, 2.11.3, or 2.12.0Check Version:
ansible --versionVerify Fix Applied:
After update, run 'ansible --version' to confirm version is patched. Test template processing with known safe inputs.📡 Detection & Monitoring
Log Indicators:
- Unusual template processing errors
- Unexpected command execution in Ansible logs
- Multiple failed template rendering attempts
Network Indicators:
- Anomalous outbound connections from Ansible controllers
- Unexpected data exfiltration patterns
SIEM Query:
source="ansible.log" AND ("template error" OR "command injection" OR "unexpected variable")