CVE-2020-5791
📋 TL;DR
This vulnerability allows remote authenticated admin users in Nagios XI 5.7.3 to execute arbitrary operating system commands with apache user privileges. It's an OS command injection flaw that enables attackers to run commands on the underlying system. Only Nagios XI installations with admin users are affected.
💻 Affected Systems
- Nagios XI
📦 What is this software?
Nagios Xi by Nagios
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through privilege escalation from apache user to root, leading to data theft, lateral movement, or ransomware deployment.
Likely Case
Unauthorized command execution allowing data exfiltration, backdoor installation, or monitoring system manipulation.
If Mitigated
Limited impact if proper network segmentation, least privilege, and monitoring are in place, potentially containing damage to the Nagios server.
🎯 Exploit Status
Multiple public exploit scripts available; requires admin credentials but exploitation is straightforward once authenticated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.7.4 and later
Vendor Advisory: https://www.nagios.com/downloads/nagios-xi/change-log/
Restart Required: Yes
Instructions:
1. Backup current Nagios XI configuration and data. 2. Download Nagios XI 5.7.4 or later from Nagios website. 3. Follow Nagios XI upgrade documentation. 4. Restart Nagios services after upgrade.
🔧 Temporary Workarounds
Remove Admin Access
linuxTemporarily disable or remove admin user accounts until patching can be completed.
# Edit Nagios XI user configuration to remove admin privileges
Network Segmentation
linuxRestrict access to Nagios XI admin interface to trusted IP addresses only.
iptables -A INPUT -p tcp --dport 80 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Implement strict network access controls to limit Nagios XI admin interface access
- Enable detailed logging and monitoring for command execution attempts
🔍 How to Verify
Check if Vulnerable:
Check Nagios XI version via web interface or command: grep 'product_version' /usr/local/nagiosxi/html/config.inc.phpCheck Version:
grep 'product_version' /usr/local/nagiosxi/html/config.inc.phpVerify Fix Applied:
Verify version is 5.7.4 or higher and test admin interface functionality📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in Apache logs
- Suspicious admin login patterns
- Unexpected system commands in Nagios logs
Network Indicators:
- Unusual outbound connections from Nagios server
- Command injection patterns in HTTP requests
SIEM Query:
source="apache" AND (url="*admin*" AND (cmd="*|*" OR cmd="*;*" OR cmd="*`*"))🔗 References
- http://packetstormsecurity.com/files/159743/Nagios-XI-5.7.3-Remote-Command-Injection.html
- http://packetstormsecurity.com/files/162235/Nagios-XI-5.7.3-Remote-Code-Execution.html
- https://www.tenable.com/security/research/tra-2020-58
- http://packetstormsecurity.com/files/159743/Nagios-XI-5.7.3-Remote-Command-Injection.html
- http://packetstormsecurity.com/files/162235/Nagios-XI-5.7.3-Remote-Code-Execution.html
- https://www.tenable.com/security/research/tra-2020-58
