CVE-2020-23309
📋 TL;DR
CVE-2020-23309 is a denial-of-service vulnerability in JerryScript's JavaScript parser where an assertion failure can be triggered by specially crafted JavaScript code, causing the interpreter to crash. This affects applications using JerryScript 2.2.0 for embedded JavaScript execution. The vulnerability allows attackers to crash affected systems but does not typically lead to remote code execution.
💻 Affected Systems
- JerryScript
📦 What is this software?
Jerryscript by Jerryscript
⚠️ Risk & Real-World Impact
Worst Case
Complete denial of service causing application/system crash, potentially disrupting critical embedded systems or IoT devices.
Likely Case
Application crash requiring restart, leading to service disruption and potential data loss in active sessions.
If Mitigated
Minimal impact if systems are properly segmented and have crash recovery mechanisms in place.
🎯 Exploit Status
Proof of concept available in GitHub issue #3820. Exploitation requires ability to inject JavaScript into JerryScript parser, which could be achieved through various input vectors.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 2.2.0 (2.3.0 and later)
Vendor Advisory: https://github.com/jerryscript-project/jerryscript/issues/3820
Restart Required: Yes
Instructions:
1. Upgrade JerryScript to version 2.3.0 or later. 2. Recompile any applications using JerryScript. 3. Restart affected services or devices.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict validation of JavaScript input to prevent malicious code from reaching JerryScript parser
Process isolation
allRun JerryScript in isolated processes with crash recovery mechanisms
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable systems from untrusted networks
- Deploy monitoring for process crashes and implement automated restart mechanisms
🔍 How to Verify
Check if Vulnerable:
Check JerryScript version: if using 2.2.0, system is vulnerable. Test with proof-of-concept JavaScript from GitHub issue #3820.Check Version:
Check application documentation or build configuration for JerryScript version. For compiled applications, use strings command or check version headers.Verify Fix Applied:
Verify JerryScript version is 2.3.0 or later. Test with same proof-of-concept to confirm no crash occurs.📡 Detection & Monitoring
Log Indicators:
- JerryScript process crashes
- Assertion failure messages containing 'js-parser-statm.c:2756'
- Unexpected application restarts
Network Indicators:
- Unusual JavaScript payloads sent to applications using JerryScript
SIEM Query:
Process:jerryscript AND (EventID:1000 OR "assertion failed" OR "stack_depth")