Nokia GPON Router

Note: Certain credentials and tokens have been partially redacted from this publication for responsible disclosure.

Research Overview

This research involved a comprehensive security analysis of the Nokia G-0425G-B GPON router, focusing on its authentication mechanisms, web application architecture, backend API surface, and management-channel security.

Target

Nokia G-0425G-B GPON Router Firmware Version: 3FE49362IJIK01 Build Date: 2021-10-18

Research Objective

To understand the router’s authentication flow, enumerate its backend APIs, identify security weaknesses, and analyze the overall security posture of its web management interface and remote management channels.

Methodology

The research combined:

• Static analysis — Downloading and analyzing JavaScript files (crypto_page.js, all.min.js, inline page scripts) to understand client-side logic
• Dynamic analysis — Interacting with API endpoints to map functionality and observe request/response patterns
• Network enumeration — Service discovery via Nmap and SSH CLI exploration
• Configuration review — Examining router settings for security-relevant misconfigurations

Technical Analysis

Authentication Flow

The login process uses a hybrid encryption scheme:

1. RSA — The router provides a public key embedded in the login page
2. AES — The client generates a random AES key and IV
3. Payload encryption — Login data is AES-encrypted client-side
4. Key exchange — The AES key is RSA-encrypted and sent alongside the payload
5. Session handling — Successful login returns HTTP 299 with an X-SID header

API Surface

Analysis of the router’s JavaScript and page structure revealed 108+ backend endpoints covering:

• Status reporting (PPP, WAN, LAN, WiFi, GPON optics)
• Configuration management (WAN, LAN, WiFi, DNS, firewall)
• Security features (MAC filter, IP filter, parental controls)
• Maintenance functions (firmware upgrade, backup, reboot, factory reset)
• Diagnostics (ping, port mirroring, logs)

Security Weaknesses Identified

Finding	Detail
Hardcoded CSRF token	Token value LPENM…[redacted] embedded statically in HTML
Legacy SSH	Only ssh-rsa host key algorithm supported
Outdated kernel	Linux 3.18.21 (end-of-life since 2017)
Old Dropbear SSH	Version 2017.75
TR-069 over HTTP	Management channel unencrypted
Shared ACS credentials	TR-069 ACS password appears to be same across devices
No HTTPS enforcement	HTTP serves login page without redirect

Security Impact

The combination of weak CSRF protections, legacy SSH configurations, and unencrypted TR-069 management creates multiple attack surfaces:

• CSRF weaknesses could allow cross-site request forgery if combined with social engineering
• Legacy SSH weakens encryption and exposes the device to downgrade attacks
• TR-069 over HTTP exposes management credentials to anyone on the same network path
• Outdated kernel leaves the device vulnerable to known privilege escalation exploits

Recommendations

1. Implement per-session CSRF tokens for all state-changing API endpoints
2. Enable modern SSH algorithms — support at minimum ssh-ed25519 and ecdsa-sha2-nistp256
3. Upgrade kernel and Dropbear to patched versions
4. Encrypt TR-069 with TLS and use unique per-device credentials
5. Enforce HTTPS and disable plain HTTP access to management interface
6. Reduce API exposure — restrict diagnostic endpoints to authenticated sessions only

Disclosure

Findings were documented with a focus on security impact rather than actionable exploit chains. The research highlights architectural weaknesses rather than providing step-by-step exploitation guidance.