CVE-2020-28908
📋 TL;DR
CVE-2020-28908 is a command injection vulnerability in Nagios Fusion 4.1.8 and earlier that allows attackers to execute arbitrary commands with elevated privileges. This can lead to complete system compromise of Nagios monitoring servers. Organizations using vulnerable Nagios Fusion installations are affected.
💻 Affected Systems
- Nagios Fusion
📦 What is this software?
Fusion by Nagios
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with root-level access, allowing installation of persistent backdoors, data exfiltration, and lateral movement across the network.
Likely Case
Privilege escalation to nagios user leading to unauthorized access to monitoring data, configuration modification, and potential further exploitation.
If Mitigated
Limited impact with proper network segmentation, minimal privileges, and intrusion detection systems in place.
🎯 Exploit Status
Exploit requires authentication but is well-documented in public sources. The vulnerability allows command injection through crafted HTTP requests.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Nagios Fusion 4.1.9 and later
Vendor Advisory: https://www.nagios.com/downloads/nagios-xi/change-log/
Restart Required: Yes
Instructions:
1. Backup current configuration. 2. Download Nagios Fusion 4.1.9 or later from Nagios website. 3. Follow official upgrade documentation. 4. Restart Nagios Fusion services. 5. Verify upgrade completed successfully.
🔧 Temporary Workarounds
Network Segmentation
linuxRestrict access to Nagios Fusion web 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
Web Application Firewall
allImplement WAF rules to block command injection patterns
# Configure WAF to block patterns like ;, |, &, $(), `, >, < in HTTP parameters
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach the Nagios Fusion interface
- Enable detailed logging and monitoring for suspicious command execution patterns
🔍 How to Verify
Check if Vulnerable:
Check Nagios Fusion version via web interface or command line: grep 'fusion_version' /usr/local/nagiosfusion/html/config.inc.phpCheck Version:
grep 'fusion_version' /usr/local/nagiosfusion/html/config.inc.phpVerify Fix Applied:
Verify version is 4.1.9 or higher and test that command injection attempts are properly sanitized📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Multiple failed authentication attempts followed by successful login
- Suspicious HTTP requests containing shell metacharacters
Network Indicators:
- Unusual outbound connections from Nagios server
- HTTP requests with command injection patterns to Nagios Fusion endpoints
SIEM Query:
source="nagios.log" AND ("command injection" OR "shell metacharacter" OR ";" OR "|" OR "&" OR "`" OR "$(")🔗 References
- http://packetstormsecurity.com/files/162783/Nagios-XI-Fusion-Privilege-Escalation-Cross-Site-Scripting-Code-Execution.html
- https://skylightcyber.com/2021/05/20/13-nagios-vulnerabilities-7-will-shock-you/
- https://www.nagios.com/downloads/nagios-xi/change-log/
- http://packetstormsecurity.com/files/162783/Nagios-XI-Fusion-Privilege-Escalation-Cross-Site-Scripting-Code-Execution.html
- https://skylightcyber.com/2021/05/20/13-nagios-vulnerabilities-7-will-shock-you/
- https://www.nagios.com/downloads/nagios-xi/change-log/
