CVE-2020-7703
📋 TL;DR
CVE-2020-7703 is a prototype pollution vulnerability in the nis-utils npm package that allows attackers to inject arbitrary properties into JavaScript objects. This can lead to denial of service, remote code execution, or privilege escalation. Any application using nis-utils is affected.
💻 Affected Systems
- nis-utils npm package
📦 What is this software?
Nis Utils by Nis Utils 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 remote code execution in Node.js environments.
If Mitigated
Limited impact if proper input validation and sandboxing are implemented.
🎯 Exploit Status
Exploitation requires attacker-controlled input to the setValue function.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in available references - package appears abandoned
Vendor Advisory: https://snyk.io/vuln/SNYK-JS-NISUTILS-598799
Restart Required: Yes
Instructions:
1. Remove nis-utils from package.json. 2. Run npm uninstall nis-utils. 3. Find alternative package or implement custom functionality. 4. Restart all affected services.
🔧 Temporary Workarounds
Input validation wrapper
allWrap setValue calls with strict input validation to prevent prototype pollution
// JavaScript code to validate inputs before calling setValue
function safeSetValue(obj, path, value) {
if (typeof path !== 'string' || path.includes('__proto__') || path.includes('constructor')) {
throw new Error('Invalid path');
}
return setValue(obj, path, value);
}
🧯 If You Can't Patch
- Implement strict input validation for all user inputs passed to setValue function
- Isolate the vulnerable component in a sandboxed environment with limited permissions
🔍 How to Verify
Check if Vulnerable:
Check package.json for nis-utils dependency or run: npm list nis-utilsCheck Version:
npm list nis-utilsVerify Fix Applied:
Confirm nis-utils is removed from package.json and node_modules, then test application functionality📡 Detection & Monitoring
Log Indicators:
- Unusual application crashes
- Unexpected property modifications in objects
- Error logs mentioning prototype pollution
Network Indicators:
- Unusual outbound connections from Node.js processes
- Suspicious payloads containing __proto__ or constructor in requests
SIEM Query:
source="application.logs" AND ("__proto__" OR "constructor.prototype" OR "prototype pollution")