CVE-2021-25297
📋 TL;DR
This vulnerability allows authenticated attackers to execute arbitrary operating system commands on Nagios XI servers through improper input sanitization in a configuration wizard. It affects Nagios XI version 5.7.5 specifically. Attackers with valid credentials can achieve remote code execution on the server.
💻 Affected Systems
- Nagios XI
📦 What is this software?
Nagios Xi by Nagios
⚠️ Risk & Real-World Impact
Worst Case
Full compromise of the Nagios XI server leading to lateral movement within the network, data exfiltration, and persistent backdoor installation.
Likely Case
Unauthorized command execution leading to service disruption, configuration changes, or credential harvesting from the Nagios server.
If Mitigated
Limited impact due to network segmentation, minimal privileges, and proper input validation controls.
🎯 Exploit Status
Multiple public exploit scripts exist, and exploitation requires valid user credentials.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.8.0 and later
Vendor Advisory: https://assets.nagios.com/downloads/nagiosxi/versions.php
Restart Required: Yes
Instructions:
1. Backup current configuration. 2. Download latest Nagios XI version from official site. 3. Follow upgrade instructions at /usr/local/nagiosxi/scripts/upgrade_to_latest.sh. 4. Restart Nagios services.
🔧 Temporary Workarounds
Remove vulnerable file
linuxTemporarily disable the vulnerable configuration wizard by removing or restricting access to the affected file.
sudo rm /usr/local/nagiosxi/html/includes/configwizards/switch/switch.inc.php
Restrict file permissions
linuxChange file permissions to prevent execution while maintaining audit trail.
sudo chmod 000 /usr/local/nagiosxi/html/includes/configwizards/switch/switch.inc.php
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Nagios XI from critical systems
- Enforce strong authentication controls and monitor for suspicious user activity
🔍 How to Verify
Check if Vulnerable:
Check if file /usr/local/nagiosxi/html/includes/configwizards/switch/switch.inc.php exists and Nagios version is 5.7.5.Check Version:
cat /usr/local/nagiosxi/var/xiversionVerify Fix Applied:
Verify Nagios XI version is 5.8.0 or later and the vulnerable file has been patched or removed.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /includes/configwizards/switch/switch.inc.php
- Suspicious command execution in system logs from nagios user
Network Indicators:
- Unexpected outbound connections from Nagios server
- Traffic to unusual ports from Nagios host
SIEM Query:
source="nagios_access.log" AND uri="/includes/configwizards/switch/switch.inc.php" AND method="POST"🔗 References
- http://nagios.com
- http://packetstormsecurity.com/files/161561/Nagios-XI-5.7.5-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/170924/Nagios-XI-5.7.5-Remote-Code-Execution.html
- https://assets.nagios.com/downloads/nagiosxi/versions.php
- https://github.com/fs0c-sh/nagios-xi-5.7.5-bugs/blob/main/README.md
- https://www.fastly.com/blog/anatomy-of-a-command-injection-cve-2021-25296-7-8-with-metasploit-module-and
- http://nagios.com
- http://packetstormsecurity.com/files/161561/Nagios-XI-5.7.5-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/170924/Nagios-XI-5.7.5-Remote-Code-Execution.html
- https://assets.nagios.com/downloads/nagiosxi/versions.php
- https://github.com/fs0c-sh/nagios-xi-5.7.5-bugs/blob/main/README.md
- https://www.fastly.com/blog/anatomy-of-a-command-injection-cve-2021-25296-7-8-with-metasploit-module-and
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-25297
