CVE-2020-7781
📋 TL;DR
CVE-2020-7781 is an OS command injection vulnerability in the connection-tester npm package that allows attackers to execute arbitrary commands on the host system. This affects any application using vulnerable versions of connection-tester before 0.2.1. The vulnerability is particularly dangerous because it can be exploited without authentication.
💻 Affected Systems
- connection-tester npm package
📦 What is this software?
Connection Tester by Connection Tester Project
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise allowing complete control over the affected server, data exfiltration, lateral movement, and persistent backdoor installation.
Likely Case
Remote code execution leading to application compromise, data theft, and potential privilege escalation on the host system.
If Mitigated
Limited impact with proper input validation and sandboxing, potentially only affecting the application's own data and processes.
🎯 Exploit Status
The vulnerability is in line 15 of index.js where user input is directly passed to exec() without proper sanitization. Public PoC demonstrates command injection via the host parameter.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.2.1
Vendor Advisory: https://github.com/skoranga/node-connection-tester/pull/10
Restart Required: Yes
Instructions:
1. Update package.json to specify 'connection-tester': '^0.2.1'. 2. Run 'npm update connection-tester'. 3. Restart your Node.js application. 4. Verify the update with 'npm list connection-tester'.
🔧 Temporary Workarounds
Input Validation Wrapper
allCreate a wrapper function that validates and sanitizes all inputs before passing to connection-tester functions
// Implement input validation for host, port parameters
// Reject any input containing shell metacharacters: ; & | ` $ ( )
Network Segmentation
linuxRestrict network access to applications using vulnerable versions
iptables -A INPUT -p tcp --dport [APP_PORT] -s [TRUSTED_NETWORK] -j ACCEPT
iptables -A INPUT -p tcp --dport [APP_PORT] -j DROP
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all user inputs passed to connection-tester functions
- Run the application with minimal privileges and in a containerized/sandboxed environment
🔍 How to Verify
Check if Vulnerable:
Check package.json or run: npm list connection-tester | grep connection-testerCheck Version:
npm list connection-tester | grep connection-testerVerify Fix Applied:
Verify installed version is 0.2.1 or higher with: npm list connection-tester📡 Detection & Monitoring
Log Indicators:
- Unusual command execution patterns in system logs
- Suspicious child process spawns from Node.js applications
- Failed connection attempts with malformed host parameters
Network Indicators:
- Unexpected outbound connections from Node.js applications
- Traffic to unusual ports or external IPs
SIEM Query:
process.name: 'node' AND (process.args: '*;*' OR process.args: '*&*' OR process.args: '*|*' OR process.args: '*`*' OR process.args: '*$(*')