CVE-2020-23302
📋 TL;DR
This is a critical heap-use-after-free vulnerability in JerryScript's string handling that allows memory corruption. Attackers can exploit this to execute arbitrary code or cause denial of service. Any system running vulnerable JerryScript versions is affected.
💻 Affected Systems
- JerryScript JavaScript engine
📦 What is this software?
Jerryscript by Jerryscript
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment
Likely Case
Application crash causing denial of service, potentially leading to memory corruption and instability
If Mitigated
Contained crash within sandboxed environment with minimal impact
🎯 Exploit Status
Proof-of-concept exists in GitHub issue #3748. Exploitation requires crafting specific JavaScript to trigger the use-after-free condition.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: JerryScript 2.3.0 or later
Vendor Advisory: https://github.com/jerryscript-project/jerryscript/issues/3748
Restart Required: Yes
Instructions:
1. Update JerryScript to version 2.3.0 or later. 2. Recompile any applications using JerryScript. 3. Restart affected services or devices.
🔧 Temporary Workarounds
Disable JavaScript execution
allTemporarily disable JavaScript processing in affected applications if possible
Input validation and sanitization
allImplement strict input validation for JavaScript code processed by JerryScript
🧯 If You Can't Patch
- Isolate affected systems from untrusted networks and internet access
- Implement strict network segmentation and monitor for abnormal memory usage patterns
🔍 How to Verify
Check if Vulnerable:
Check JerryScript version: jerry --version. If version is 2.2.0 or earlier, system is vulnerable.Check Version:
jerry --versionVerify Fix Applied:
Verify JerryScript version is 2.3.0 or later: jerry --version📡 Detection & Monitoring
Log Indicators:
- Segmentation faults
- Memory corruption errors
- Unexpected JerryScript process termination
Network Indicators:
- Unusual JavaScript payloads sent to JerryScript endpoints
- Repeated connection attempts to JerryScript services
SIEM Query:
Process:jerry AND (EventID:1000 OR EventID:1001) OR Memory:corruption