CVE-2020-7621
📋 TL;DR
CVE-2020-7621 is a command injection vulnerability in strong-nginx-controller that allows attackers to execute arbitrary commands on the server. This affects systems running vulnerable versions of the strong-nginx-controller package. The vulnerability exists in the _nginxCmd() function where user input is not properly sanitized before being passed to shell commands.
💻 Affected Systems
- strong-nginx-controller
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root-level access, allowing attackers to install malware, exfiltrate data, or pivot to other systems.
Likely Case
Remote code execution leading to service disruption, data theft, or deployment of cryptocurrency miners.
If Mitigated
Limited impact with proper input validation and least privilege configurations in place.
🎯 Exploit Status
The vulnerability is straightforward to exploit with publicly available proof-of-concept code.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.3 and later
Vendor Advisory: https://github.com/strongloop/strong-nginx-controller/security/advisories
Restart Required: Yes
Instructions:
1. Update strong-nginx-controller to version 1.0.3 or later using npm update strong-nginx-controller. 2. Restart the application. 3. Verify the fix by checking the package version.
🔧 Temporary Workarounds
Input Validation Sanitization
allImplement strict input validation and sanitization for all parameters passed to _nginxCmd() function.
// Add input validation in server.js before _nginxCmd() calls
Network Segmentation
linuxRestrict network access to the strong-nginx-controller service to trusted IPs only.
iptables -A INPUT -p tcp --dport [PORT] -s [TRUSTED_IP] -j ACCEPT
iptables -A INPUT -p tcp --dport [PORT] -j DROP
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure
- Monitor for suspicious command execution patterns and implement application-level input validation
🔍 How to Verify
Check if Vulnerable:
Check package.json or run npm list strong-nginx-controller to see if version is 1.0.2 or earlier.Check Version:
npm list strong-nginx-controller | grep strong-nginx-controllerVerify Fix Applied:
Verify strong-nginx-controller version is 1.0.3 or later using npm list strong-nginx-controller.📡 Detection & Monitoring
Log Indicators:
- Unusual command execution patterns in system logs
- Unexpected nginx configuration changes
- Suspicious process creation from Node.js
Network Indicators:
- Unexpected outbound connections from the server
- Traffic to known malicious IPs
SIEM Query:
process.name: "sh" OR process.name: "bash" AND parent.name: "node" AND command_line: "*nginx*"