CVE-2021-31164
📋 TL;DR
Apache Unomi versions before 1.5.5 are vulnerable to CRLF log injection due to improper escaping in log statements. This allows attackers to inject malicious content into log files, potentially leading to log poisoning or log-based attacks. Organizations running vulnerable Apache Unomi instances are affected.
💻 Affected Systems
- Apache Unomi
📦 What is this software?
Unomi by Apache
⚠️ Risk & Real-World Impact
Worst Case
Attackers could inject malicious content into log files, potentially enabling log poisoning attacks, log-based injection attacks, or manipulation of log analysis systems.
Likely Case
Log file corruption or injection of misleading log entries that could disrupt monitoring, auditing, or forensic analysis.
If Mitigated
Limited impact with proper log validation and monitoring in place, though log integrity could still be compromised.
🎯 Exploit Status
Exploitation requires the ability to influence log statements, typically through user input that gets logged.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.5.5
Vendor Advisory: http://unomi.apache.org/security/cve-2021-31164
Restart Required: Yes
Instructions:
1. Download Apache Unomi version 1.5.5 or later from the official Apache website. 2. Stop the current Unomi service. 3. Replace the existing Unomi installation with the patched version. 4. Restart the Unomi service. 5. Verify the update was successful.
🔧 Temporary Workarounds
Implement Log Sanitization
allAdd input validation and sanitization for all user inputs that may be logged to prevent CRLF injection.
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all user inputs that are logged.
- Monitor log files for unusual patterns or unexpected CRLF sequences and implement alerting.
🔍 How to Verify
Check if Vulnerable:
Check the Apache Unomi version. If it is earlier than 1.5.5, it is vulnerable.Check Version:
Check the Unomi version via the web interface or configuration files, or run: java -jar unomi.jar --version (if applicable).Verify Fix Applied:
Verify that the Apache Unomi version is 1.5.5 or later after applying the patch.📡 Detection & Monitoring
Log Indicators:
- Unexpected CRLF sequences in log entries
- Malformed log lines
- Suspicious patterns in log data
SIEM Query:
Search for log entries containing CRLF sequences (\r\n) in Apache Unomi logs.