CVE-2019-1010161
📋 TL;DR
This vulnerability in perl-Crypt-JWT allows attackers to bypass authentication by crafting malicious JWT tokens. It affects any application using perl-Crypt-JWT version 0.022 or earlier for JWT-based authentication. Attackers can forge valid tokens without proper cryptographic verification.
💻 Affected Systems
- perl-Crypt-JWT
📦 What is this software?
Perl Crypt Jwt by Perl Crypt Jwt Project
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through unauthorized access to protected resources, data exfiltration, and privilege escalation across all services using JWT authentication.
Likely Case
Unauthorized access to protected API endpoints, user data exposure, and session hijacking in applications relying on JWT for authentication.
If Mitigated
Limited impact with proper network segmentation, additional authentication layers, and monitoring for anomalous token usage.
🎯 Exploit Status
Exploitation requires crafting JWT tokens with specific malformed signatures; public GitHub issue demonstrates the technique.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.023
Vendor Advisory: https://github.com/DCIT/perl-Crypt-JWT/issues/3
Restart Required: No
Instructions:
1. Update perl-Crypt-JWT using CPAN: 'cpan Crypt::JWT' 2. Verify installation with 'perl -MCrypt::JWT -e "print $Crypt::JWT::VERSION"' 3. Ensure version is 0.023 or higher
🔧 Temporary Workarounds
Input Validation Filter
allImplement custom JWT token validation to reject malformed signatures before processing.
# Perl code snippet to validate token structure
# Check token has proper format before passing to Crypt::JWT
🧯 If You Can't Patch
- Implement network-level controls to restrict access to JWT-protected endpoints
- Add secondary authentication factor or session validation
🔍 How to Verify
Check if Vulnerable:
Check installed version: 'perl -MCrypt::JWT -e "print $Crypt::JWT::VERSION"' - if output is 0.022 or lower, system is vulnerable.Check Version:
perl -MCrypt::JWT -e "print $Crypt::JWT::VERSION"Verify Fix Applied:
After update, run same command and confirm version is 0.023 or higher.📡 Detection & Monitoring
Log Indicators:
- Failed authentication attempts with malformed JWT tokens
- Successful authentications with unusual token patterns
Network Indicators:
- HTTP requests with crafted JWT tokens to authentication endpoints
- Unusual token payload sizes or structures
SIEM Query:
source="application.log" AND ("JWT" OR "token") AND ("malformed" OR "invalid" OR "bypass")