CVE-2024-23721
📋 TL;DR
CVE-2024-23721 is a directory traversal vulnerability in Draytek Vigor3910 devices that allows attackers to access sensitive system files by manipulating POST requests. This affects organizations using Draytek Vigor3910 routers with firmware version 4.3.2.5. Attackers can exploit this to read arbitrary files from the device's filesystem.
💻 Affected Systems
- Draytek Vigor3910
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through credential theft, configuration extraction, and potential lateral movement to connected networks.
Likely Case
Sensitive information disclosure including configuration files, credentials, and system logs.
If Mitigated
Limited impact with proper network segmentation and access controls preventing external exploitation.
🎯 Exploit Status
Public proof-of-concept demonstrates exploitation via crafted POST requests without authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://draytek.com
Restart Required: Yes
Instructions:
1. Check Draytek website for security advisories
2. Download latest firmware if available
3. Backup current configuration
4. Upload and install new firmware
5. Restart device
6. Restore configuration if needed
🔧 Temporary Workarounds
Restrict Management Interface Access
allLimit access to the router's web management interface to trusted IP addresses only.
Configure firewall rules to restrict access to management ports (typically 80/443)
Disable Unnecessary Services
allTurn off any unnecessary web services or management interfaces.
Disable remote management if not required
🧯 If You Can't Patch
- Implement strict network segmentation to isolate the router from sensitive networks
- Deploy network monitoring and intrusion detection for suspicious POST requests to the management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version in web interface: System Maintenance > Firmware InformationCheck Version:
Check via web interface or SSH: show versionVerify Fix Applied:
Verify firmware version is no longer 4.3.2.5 after update📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to management interface
- Multiple failed file access attempts
- Requests with directory traversal patterns (../)
Network Indicators:
- HTTP POST requests with path traversal payloads to router management IP
- Unusual traffic patterns to router management ports
SIEM Query:
source="router_logs" AND (http_method="POST" AND (uri="*../*" OR uri="*..\\*"))