CVE-2020-29054
📋 TL;DR
This vulnerability allows attackers to retrieve cleartext TELNET credentials by executing the 'show system infor' command on affected CDATA optical line terminal devices. This exposes administrative credentials that can be used for unauthorized access. Organizations using the listed CDATA OLT devices are affected.
💻 Affected Systems
- CDATA 72408A
- CDATA 9008A
- CDATA 9016A
- CDATA 92408A
- CDATA 92416A
- CDATA 9288
- CDATA 97016
- CDATA 97024P
- CDATA 97028P
- CDATA 97042P
- CDATA 97084P
- CDATA 97168P
- CDATA FD1002S
- CDATA FD1104
- CDATA FD1104B
- CDATA FD1104S
- CDATA FD1104SN
- CDATA FD1108S
- CDATA FD1204S-R2
- CDATA FD1204SN
- CDATA FD1204SN-R2
- CDATA FD1208S-R2
- CDATA FD1216S-R1
- CDATA FD1608GS
- CDATA FD1608SN
- CDATA FD1616GS
- CDATA FD1616SN
- CDATA FD8000
📦 What is this software?
9288 Firmware by Cdatatec
9288 Firmware by Cdatatec
9288 Firmware by Cdatatec
9288 Firmware by Cdatatec
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain full administrative control over network devices, enabling network disruption, data interception, lateral movement, and persistent backdoor installation.
Likely Case
Unauthorized administrative access leading to configuration changes, service disruption, and credential harvesting for further attacks.
If Mitigated
Limited impact if TELNET access is disabled, network segmentation is implemented, and proper access controls are in place.
🎯 Exploit Status
Exploitation requires initial access to execute the command, but the vulnerability itself is simple to exploit once access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Contact CDATA for specific firmware updates
Vendor Advisory: https://pierrekim.github.io/blog/2020-07-07-cdata-olt-0day-vulnerabilities.html
Restart Required: Yes
Instructions:
1. Contact CDATA support for firmware updates
2. Backup current configuration
3. Apply firmware update following vendor instructions
4. Restart device
5. Verify credentials are no longer exposed in cleartext
🔧 Temporary Workarounds
Disable TELNET service
allDisable TELNET access and use secure alternatives like SSH
telnet disable
service telnet stop
Implement network access controls
linuxRestrict access to TELNET ports using firewall rules
iptables -A INPUT -p tcp --dport 23 -j DROP
🧯 If You Can't Patch
- Disable TELNET service immediately and use SSH for management
- Implement strict network segmentation to isolate affected devices from untrusted networks
🔍 How to Verify
Check if Vulnerable:
Connect to device via TELNET or console and execute 'show system infor' command. Check if credentials are displayed in cleartext.Check Version:
show versionVerify Fix Applied:
After patching, execute 'show system infor' command and verify credentials are no longer displayed in cleartext output.📡 Detection & Monitoring
Log Indicators:
- Multiple failed TELNET authentication attempts followed by successful access
- Unusual 'show system infor' command executions from unexpected sources
Network Indicators:
- Unusual TELNET traffic to affected devices
- Traffic from unexpected sources to port 23
SIEM Query:
source_port=23 AND (event_description="show system infor" OR authentication_success=true)