CVE-2024-40453
📋 TL;DR
SquirrellyJS template engine versions 9.0.0 contain a code injection vulnerability in the options.varName component that allows attackers to execute arbitrary JavaScript code. This affects any application using vulnerable SquirrellyJS versions for server-side template rendering. The vulnerability is particularly dangerous in web applications that process user-controlled template variables.
💻 Affected Systems
- squirrellyjs
📦 What is this software?
Squirrelly by Squirrelly
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, and lateral movement within the network.
Likely Case
Server-side JavaScript execution allowing data exfiltration, file system access, and potential privilege escalation.
If Mitigated
Limited impact with proper input validation and sandboxing, potentially reduced to denial of service or information disclosure.
🎯 Exploit Status
Proof of concept available in public references. Exploitation requires the application to process attacker-controlled template variables through the vulnerable component.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v9.0.1
Vendor Advisory: https://github.com/squirrellyjs/squirrelly/pull/262
Restart Required: Yes
Instructions:
1. Check current SquirrellyJS version: npm list squirrelly
2. Update to v9.0.1: npm update squirrelly@9.0.1
3. Restart the application server
4. Verify the update: npm list squirrelly
🔧 Temporary Workarounds
Input Validation and Sanitization
allImplement strict input validation and sanitization for all template variables before passing to SquirrellyJS.
Disable Vulnerable Component
allAvoid using the options.varName component in template rendering if possible.
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all user-controlled template variables.
- Deploy web application firewall (WAF) rules to detect and block template injection attempts.
🔍 How to Verify
Check if Vulnerable:
Check package.json or run: npm list squirrelly | grep squirrellyCheck Version:
npm list squirrelly | grep squirrellyVerify Fix Applied:
Verify installed version is 9.0.1 or higher: npm list squirrelly📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript execution in template rendering logs
- Errors from SquirrellyJS parsing unexpected template syntax
- Suspicious template variable patterns containing JavaScript code
Network Indicators:
- HTTP requests containing JavaScript code in template parameters
- Unusual outbound connections from the application server
SIEM Query:
source="application.logs" AND ("squirrelly" OR "template") AND ("eval" OR "Function" OR "constructor")