CVE-2020-7704
📋 TL;DR
CVE-2020-7704 is a prototype pollution vulnerability in the linux-cmdline npm package that allows attackers to inject arbitrary properties into JavaScript objects, potentially leading to remote code execution or denial of service. This affects any application using vulnerable versions of the linux-cmdline package to parse Linux kernel command-line parameters. The vulnerability is particularly dangerous because it can be exploited through user-controlled input.
💻 Affected Systems
- linux-cmdline npm package
📦 What is this software?
Linux Cmdline by Linux Cmdline Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Denial of service through application crashes or privilege escalation by modifying application behavior.
If Mitigated
Limited impact if input validation and sanitization are implemented, though prototype pollution remains dangerous.
🎯 Exploit Status
Exploitation requires user-controlled input to the vulnerable constructor function. Public proof-of-concept code exists demonstrating the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.1 and later
Vendor Advisory: https://github.com/piranna/linux-cmdline/commit/53c61a88bc47eb25d71832205056beaab95cf677
Restart Required: No
Instructions:
1. Update package.json to specify 'linux-cmdline': '>=1.0.1'. 2. Run 'npm update linux-cmdline' or 'npm install linux-cmdline@latest'. 3. Test application functionality after update.
🔧 Temporary Workarounds
Input Validation and Sanitization
allImplement strict input validation to prevent malicious command-line parameters from reaching the vulnerable constructor.
Object.freeze on Object.prototype
allPrevent prototype pollution by freezing Object.prototype, though this may break legitimate functionality.
Object.freeze(Object.prototype)
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all command-line parameters
- Use alternative command-line parsing libraries that are not vulnerable
🔍 How to Verify
Check if Vulnerable:
Check package.json or node_modules/linux-cmdline/package.json for version <1.0.1Check Version:
npm list linux-cmdline | grep linux-cmdlineVerify Fix Applied:
Verify package.json specifies version >=1.0.1 and run 'npm list linux-cmdline' to confirm📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes
- Unusual command-line parameter patterns
- Prototype modification warnings in Node.js logs
Network Indicators:
- HTTP requests containing malicious command-line parameter payloads
SIEM Query:
source='application_logs' AND (message LIKE '%linux-cmdline%' OR message LIKE '%prototype%pollution%')