CVE-2019-3922
📋 TL;DR
This vulnerability allows remote unauthenticated attackers to execute arbitrary code on Alcatel Lucent I-240W-Q GPON ONT devices by sending a specially crafted HTTP POST request. The stack buffer overflow occurs in the web interface's fsetup_Form handler, potentially giving attackers full control of affected devices. Organizations using these specific GPON ONT devices with vulnerable firmware are affected.
💻 Affected Systems
- Alcatel Lucent I-240W-Q GPON ONT
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent malware, intercept network traffic, pivot to internal networks, or brick devices.
Likely Case
Device takeover enabling traffic interception, credential theft, and use as a foothold for further network attacks.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
The vulnerability is well-documented with public proof-of-concept code available. Remote exploitation requires no authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Later firmware versions from Alcatel Lucent
Vendor Advisory: https://www.al-enterprise.com/en/support/security-advisories
Restart Required: Yes
Instructions:
1. Contact your ISP or Alcatel Lucent for updated firmware. 2. Download the firmware update. 3. Access device web interface. 4. Navigate to firmware update section. 5. Upload and apply the new firmware. 6. Reboot the device.
🔧 Temporary Workarounds
Disable web interface access
linuxBlock external access to the device's web management interface
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Network segmentation
allIsolate GPON devices on separate VLANs with strict firewall rules
🧯 If You Can't Patch
- Deploy network-based intrusion prevention systems (IPS) to detect and block exploit attempts
- Implement strict firewall rules to block all inbound HTTP/HTTPS traffic to affected devices from untrusted networks
🔍 How to Verify
Check if Vulnerable:
Check firmware version via device web interface or CLI. If version is 3FE54567BOZJ19, device is vulnerable.Check Version:
Check via web interface at http://device-ip/ or via telnet/ssh if enabledVerify Fix Applied:
Verify firmware version has been updated to a version later than 3FE54567BOZJ19.📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /GponForm/fsetup_Form with unusual payloads
- Device reboot logs after suspicious requests
Network Indicators:
- HTTP traffic to port 80/443 containing buffer overflow patterns
- Unusual outbound connections from GPON devices
SIEM Query:
source="firewall" AND dest_port=80 AND uri_path="/GponForm/fsetup_Form" AND http_method="POST"