CVE-2023-30603
📋 TL;DR
The Hitron CODA-5310 router has a critical vulnerability where Telnet service uses default credentials with no password change prompt. Unauthenticated attackers can gain administrator privileges, allowing complete system compromise. All users with affected devices using default configurations are vulnerable.
💻 Affected Systems
- Hitron Technologies CODA-5310
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device takeover allowing attackers to intercept all network traffic, install persistent malware, modify DNS settings, disable security features, and use the device as a pivot point into the internal network.
Likely Case
Attackers gain administrative access to modify router settings, redirect traffic, capture credentials, and disrupt network connectivity for all connected devices.
If Mitigated
No impact if default credentials are changed or Telnet service is disabled.
🎯 Exploit Status
Exploitation requires only Telnet access and knowledge of default credentials. No special tools or skills needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://www.twcert.org.tw/tw/cp-132-7085-13321-1.html
Restart Required: No
Instructions:
No official patch available. Follow workarounds to mitigate risk.
🔧 Temporary Workarounds
Change Telnet Credentials
allChange default Telnet username and password to strong, unique credentials
Login to router admin interface > Security/Administration > Change Telnet credentials
Disable Telnet Service
allCompletely disable Telnet service if not required
Login to router admin interface > Services > Disable Telnet
Restrict Telnet Access
allLimit Telnet access to specific IP addresses if service must remain enabled
Login to router admin interface > Firewall/Rules > Restrict Telnet port 23 to trusted IPs
🧯 If You Can't Patch
- Change all default credentials immediately using router admin interface
- Disable Telnet entirely and use SSH with key authentication if remote access needed
🔍 How to Verify
Check if Vulnerable:
Attempt Telnet connection to router on port 23 using default credentials. If login succeeds, device is vulnerable.Check Version:
Check router web interface or use 'telnet [router_ip]' and check banner for version infoVerify Fix Applied:
Attempt Telnet connection with default credentials - should fail. Test with new credentials if Telnet remains enabled.📡 Detection & Monitoring
Log Indicators:
- Multiple failed Telnet login attempts followed by successful login
- Telnet connections from unexpected IP addresses
- Configuration changes via Telnet session
Network Indicators:
- Telnet traffic (port 23) to router from external IPs
- Unusual outbound connections from router after Telnet access
SIEM Query:
source="router_logs" AND (event="telnet_login" AND result="success") OR (port=23 AND dest_ip="[router_ip]")