CVE-2019-19148
📋 TL;DR
CVE-2019-19148 allows remote attackers to execute arbitrary commands on Tellabs Optical Line Terminal 1150 devices via the -l option in TELNET or SSH connections. This affects organizations using Tellabs OLT 1150 devices before the February 2020 firmware updates. The vulnerability enables complete system compromise.
💻 Affected Systems
- Tellabs Optical Line Terminal 1150
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise allowing attackers to execute arbitrary commands, disrupt telecommunications services, pivot to other network segments, and potentially cause widespread service outages.
Likely Case
Remote command execution leading to device takeover, configuration changes, service disruption, and potential data exfiltration from connected networks.
If Mitigated
Limited impact if devices are patched, network segmentation is implemented, and access controls restrict TELNET/SSH connections to trusted sources only.
🎯 Exploit Status
Public exploit code is available on GitHub. Attack requires network access to TELNET/SSH ports (typically 23/22).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: SR30.1 or SR31.1
Vendor Advisory: https://docs.tellabs.com/articles/#!vulnerability-response/cve-2019-19148
Restart Required: Yes
Instructions:
1. Download SR30.1 or SR31.1 firmware from Tellabs support portal. 2. Backup current configuration. 3. Upload and install new firmware via management interface. 4. Reboot device. 5. Verify firmware version.
🔧 Temporary Workarounds
Disable TELNET/SSH
allDisable vulnerable services if not required for operations
telnet disable
ssh disable
Network Access Control
linuxRestrict access to TELNET/SSH ports using firewall rules
iptables -A INPUT -p tcp --dport 22 -j DROP
iptables -A INPUT -p tcp --dport 23 -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to isolate OLT devices from untrusted networks
- Deploy intrusion detection systems to monitor for exploitation attempts on TELNET/SSH ports
🔍 How to Verify
Check if Vulnerable:
Check firmware version via CLI: 'show version' and verify if below SR30.1/SR31.1Check Version:
show versionVerify Fix Applied:
After patching, run 'show version' to confirm SR30.1/SR31.1 or higher is installed📡 Detection & Monitoring
Log Indicators:
- Unusual TELNET/SSH connections
- Failed authentication attempts followed by successful -l option usage
- Unexpected command execution in system logs
Network Indicators:
- Traffic to port 22/23 with -l parameter in payload
- Unusual outbound connections from OLT devices
SIEM Query:
source_port:22 OR source_port:23 AND (payload_contains:"-l" OR command_contains:"exec")