CVE-2020-22874
📋 TL;DR
This integer overflow vulnerability in jsish's Jsi_ObjArraySizer function allows remote attackers to execute arbitrary code by triggering memory corruption. It affects all systems running jsish versions before 3.0.8, potentially leading to complete system compromise.
💻 Affected Systems
- jsish (JavaScript Interpreter SHell)
📦 What is this software?
Jsish by Jsish
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full system compromise, data theft, and persistent backdoor installation
Likely Case
Remote code execution allowing attacker to run arbitrary commands with application privileges
If Mitigated
Denial of service or application crash if exploit fails or is blocked
🎯 Exploit Status
Integer overflow to RCE requires specific memory manipulation but no authentication
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.0.8 and later
Vendor Advisory: https://github.com/pcmacdon/jsish/commit/858da537bde4de9d8c92466d5a866505310bc328
Restart Required: Yes
Instructions:
1. Update jsish to version 3.0.8 or later using package manager or source compilation. 2. Restart any services using jsish. 3. Recompile any applications embedding jsish with the updated version.
🔧 Temporary Workarounds
Disable jsish execution
allRemove or disable jsish interpreter if not required
sudo apt remove jsish
sudo yum remove jsish
chmod -x /usr/bin/jsish
Network isolation
linuxRestrict network access to services using jsish
sudo iptables -A INPUT -p tcp --dport [PORT] -j DROP
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all jsish inputs
- Run jsish in a sandboxed/containerized environment with minimal privileges
🔍 How to Verify
Check if Vulnerable:
Check jsish version: jsish -v | grep -q '^3\.0\.[0-7]\|^[0-2]\..*' && echo 'VULNERABLE'Check Version:
jsish -vVerify Fix Applied:
Verify version is 3.0.8 or later: jsish -v | grep -q '^3\.0\.8\|^3\.[1-9]\|^[4-9]\..*' && echo 'PATCHED'📡 Detection & Monitoring
Log Indicators:
- Unexpected process crashes of jsish
- Memory allocation errors in application logs
- Unusual network connections from jsish processes
Network Indicators:
- Exploit attempts with malformed JavaScript/JSON payloads
- Unexpected outbound connections from jsish hosts
SIEM Query:
process.name:"jsish" AND (event.action:"crash" OR memory.allocation.failed)