CVE-2021-21889
📋 TL;DR
This vulnerability allows authenticated attackers to execute arbitrary code on Lantronix PremierWave 2050 devices by exploiting a stack-based buffer overflow in the Web Manager Ping functionality. Attackers can achieve remote code execution through specially crafted HTTP requests. Organizations using affected Lantronix PremierWave 2050 devices are at risk.
💻 Affected Systems
- Lantronix PremierWave 2050
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining root privileges, persistent backdoor installation, lateral movement to other network devices, and complete data exfiltration.
Likely Case
Unauthorized remote code execution leading to device takeover, network reconnaissance, and potential pivot point for attacking other systems.
If Mitigated
Limited impact due to network segmentation, strong authentication controls, and monitoring preventing successful exploitation.
🎯 Exploit Status
Exploitation requires authentication but is straightforward once credentials are obtained. Public proof-of-concept exists in Talos disclosure.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 8.9.0.0R5 or later
Vendor Advisory: https://www.lantronix.com/support/software-downloads/
Restart Required: Yes
Instructions:
1. Download latest firmware from Lantronix support portal. 2. Backup current configuration. 3. Upload firmware via web interface. 4. Apply firmware update. 5. Reboot device. 6. Restore configuration if needed.
🔧 Temporary Workarounds
Disable Web Manager Ping
allDisable the vulnerable Ping functionality in the web interface if not required.
Restrict Web Interface Access
linuxLimit access to the web interface using firewall rules to only trusted IP addresses.
iptables -A INPUT -p tcp --dport 80 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to isolate PremierWave devices from critical systems
- Enforce strong authentication policies and monitor for credential compromise
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: System > About. Version 8.9.0.0R4 indicates vulnerability.Check Version:
curl -k https://device-ip/system/about | grep 'Firmware Version'Verify Fix Applied:
Verify firmware version is 8.9.0.0R5 or later in System > About page.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to /ping endpoint
- Multiple failed authentication attempts followed by successful login
- Unexpected process execution or system reboots
Network Indicators:
- HTTP traffic to device on port 80/443 with unusual payload sizes
- Outbound connections from device to unknown external IPs
SIEM Query:
source="premierwave.log" AND (url="/ping" OR method="POST") AND size>1024