CVE-2020-6836
📋 TL;DR
CVE-2020-6836 is a critical remote code execution vulnerability in the hot-formula-parser Node.js package. It allows attackers to inject arbitrary code through unsanitized user input that gets executed via eval(). Any Node.js application using vulnerable versions of this package for parsing formulas from untrusted sources is affected.
💻 Affected Systems
- hot-formula-parser (Node.js package)
📦 What is this software?
Hot Formula Parser by Hot Formula Parser Project
⚠️ Risk & Real-World Impact
Worst Case
Full server compromise allowing attackers to execute arbitrary commands, steal data, deploy ransomware, or pivot to other systems.
Likely Case
Remote code execution leading to data exfiltration, cryptocurrency mining, or botnet enrollment.
If Mitigated
Limited impact if input validation prevents malicious payloads from reaching the parser.
🎯 Exploit Status
Exploitation is trivial with public proof-of-concept code available. No authentication required if the vulnerable endpoint is exposed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.0.1
Vendor Advisory: https://www.npmjs.com/advisories/1439
Restart Required: Yes
Instructions:
1. Update package.json to require 'hot-formula-parser': '^3.0.1'. 2. Run 'npm update hot-formula-parser'. 3. Restart your Node.js application.
🔧 Temporary Workarounds
Input Validation and Sanitization
allImplement strict input validation to reject any formula containing suspicious characters or patterns before passing to the parser.
Network Isolation
allRestrict network access to affected services using firewalls or network policies.
🧯 If You Can't Patch
- Implement strict input validation to reject any formula containing parentheses, quotes, semicolons, or backticks.
- Run the service with minimal privileges and in a containerized/sandboxed environment.
🔍 How to Verify
Check if Vulnerable:
Check package.json or node_modules/hot-formula-parser/package.json for version <3.0.1.Check Version:
npm list hot-formula-parserVerify Fix Applied:
Confirm package version is 3.0.1 or higher and test with known malicious payloads.📡 Detection & Monitoring
Log Indicators:
- Unusual process spawns from Node.js
- Suspicious eval() calls in application logs
- Error logs containing malformed formula syntax
Network Indicators:
- Unexpected outbound connections from Node.js process
- Traffic to known malicious IPs/domains
SIEM Query:
process.name:node AND (process.cmdline:*eval* OR process.cmdline:*child_process*)🔗 References
- https://blog.truesec.com/2020/01/17/reverse-shell-through-a-node-js-math-parser/
- https://github.com/handsontable/formula-parser/commit/396b089738d4bf30eb570a4fe6a188affa95cd5e
- https://www.npmjs.com/advisories/1439
- https://blog.truesec.com/2020/01/17/reverse-shell-through-a-node-js-math-parser/
- https://github.com/handsontable/formula-parser/commit/396b089738d4bf30eb570a4fe6a188affa95cd5e
- https://www.npmjs.com/advisories/1439
