CVE-2023-30602
📋 TL;DR
The Hitron CODA-5310 router's Telnet service transmits sensitive data like user credentials in plaintext without encryption. Unauthenticated remote attackers can intercept this traffic to steal administrator and user credentials. This affects all users of vulnerable CODA-5310 routers with Telnet enabled.
💻 Affected Systems
- Hitron Technologies CODA-5310
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of router administration, credential theft leading to network takeover, lateral movement to connected devices, and persistent backdoor installation.
Likely Case
Credential harvesting leading to unauthorized router access, configuration changes, and potential man-in-the-middle attacks on network traffic.
If Mitigated
Limited to credential exposure if Telnet is disabled or network segmentation prevents access to Telnet service.
🎯 Exploit Status
Exploitation requires only network access to Telnet port and packet capture tools. No authentication needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check with Hitron for latest firmware
Vendor Advisory: https://www.twcert.org.tw/tw/cp-132-7084-74e83-1.html
Restart Required: Yes
Instructions:
1. Log into router admin interface. 2. Navigate to firmware update section. 3. Download latest firmware from Hitron support site. 4. Upload and apply firmware update. 5. Reboot router.
🔧 Temporary Workarounds
Disable Telnet Service
allCompletely disable Telnet access and use SSH or web interface instead.
Login to router admin > Advanced Settings > Remote Management > Disable Telnet
Network Segmentation
allRestrict access to Telnet port (23) using firewall rules.
iptables -A INPUT -p tcp --dport 23 -j DROP (Linux)
netsh advfirewall firewall add rule name="Block Telnet" dir=in action=block protocol=TCP localport=23 (Windows)
🧯 If You Can't Patch
- Disable Telnet service immediately via admin interface
- Implement network segmentation to restrict Telnet port access to trusted management networks only
🔍 How to Verify
Check if Vulnerable:
Use packet capture tool (Wireshark/tcpdump) on network segment with router, connect to Telnet port, check if credentials appear in plaintext.Check Version:
Login to router web interface > Status > Firmware Version or telnet to router and check bannerVerify Fix Applied:
After patch, verify Telnet traffic is encrypted or service is disabled. Check firmware version matches patched release.📡 Detection & Monitoring
Log Indicators:
- Multiple failed Telnet authentication attempts
- Successful Telnet logins from unusual IPs
- Configuration changes via Telnet
Network Indicators:
- Unencrypted Telnet traffic containing login credentials
- Port 23 scans from external IPs
- Telnet sessions to router from non-management networks
SIEM Query:
source="router_logs" (protocol="telnet" AND (event="login" OR event="authentication")) | stats count by src_ip