CthulhuJs 🐙

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CthulhuJs is a powerful framework for browser fingerprint obfuscation and masquerading. By hooking low-level browser APIs, it allows for customized modification or randomization of various hardware and software fingerprints. It is designed to protect user privacy, bypass anti-bot detections, or be used in automated testing environments.

📦 Extension Link

✨ Core Features

CthulhuJs provides comprehensive browser environment simulation and fingerprint obfuscation, covering dimensions from low-level rendering to high-level interaction.

🎨 Graphics & Rendering

• Canvas Fingerprinting: Dynamically interferes with HTMLCanvasElement and CanvasRenderingContext2D data (toDataURL/getImageData) while maintaining visual consistency.
• WebGL & WebGPU: Obfuscates GPU renderer info (Vendor/Renderer), parameters, and WebGL context. Supports the latest WebGPU fingerprint protection.
• DOM Rects (ClientRects): Introduces micro-perturbations to getBoundingClientRect and getClientRects to counter geometric measurement fingerprinting.
• Font Metrics: Obfuscates the system font list and measurement results (width/height) of font rendering to prevent tracking via font enumeration.
• Screen & Window: Customizes screen resolution, color depth, Device Pixel Ratio (DPR), and window dimensions.
• CSS Media: Spoofs matchMedia query results (e.g., dark mode, high contrast).

🔊 Media & Network

• Audio Context: Interferes with the audio processing pipeline (DynamicsCompressor/Oscillator) and modifies the audio fingerprint hash.
• WebRTC: Intercepts WebRTC connections to prevent IP leaks and spoofs or hides ICE Candidates.
• Voice/Speech: Handles fingerprints related to the SpeechSynthesis API.

🛡️ Evasion & Protection

• Native Masquerading: Core Feature. Based on Proxy hijacking, it ensures that all hooked functions possess the same characteristics as native functions.
• Object Trace & Hijack: Intercepts and tracks access to sensitive objects, allowing for custom logic when specific conditions are triggered.
• Iframe Injection: Recursive injection mechanism that automatically identifies and handles dynamically created Iframes, ensuring fingerprint consistency between subframes and the main frame.
• Worker Interception: Intercepts and handles communication within Web Workers to ensure fingerprint synchronization in worker threads.

🆔 Identity & Environment

• Navigator: Deeply customizes UserAgent, Platform, HardwareConcurrency, DeviceMemory, Languages, and other basic attributes.
• Plugins & MimeTypes: Spoofs navigator.plugins and navigator.mimeTypes with support for custom plugin data.
• Geolocation: Simulates Geolocation APIs with custom latitude and longitude coordinates.
• Date & Timezone: Spoofs system timezone offset and Date object behavior to align with the target geographic location.

🤖 Behavior & Automation Evasion

• Human-Like Behavior:
  • Event Trust: Fixes the isTrusted property for events triggered by automation scripts.
  • WebDriver Hiding: Removes or spoofs the navigator.webdriver property.
  • Visibility: Simulates normal page visibility states (Page Visibility API).
• Driver Evasion ⚠️ Experimental:
  • Attempts to hide low-level driver traces (e.g., CDC_ variables) left by Selenium, Puppeteer, or Playwright.
  • Note: This feature is experimental and may cause instability in some environments.
• Feature Alignment ⚠️ Experimental:
  • Automatically adjusts browser API features (Blink/Gecko differences) based on the UserAgent version.
  • Note: It is recommended to ignore this when Safe Mode is enabled to avoid logic conflicts.

🛠 Development & Build

Requirements

• Node.js (v14+ recommended)
• npm

Installation

npm install

Build

The project provides build commands for development and production. Compiled files will be generated in public/dev or public/build.

# Development Mode (uncompressed code for debugging)
npm run "script dev"

# Production Mode (compressed and obfuscated code)
npm run "script build"

Build Artifacts

Filename	Description
window.js	Core Engine. Provides the SCOPE_CHEATER object responsible for receiving configuration and executing injection.
generator.js	Config Generator. Provides the generateBrowser function to generate config objects based on UserAgent or Seed.
randomTest.js	Auto-test Script. Integrates generation and injection logic for quick randomization of the current environment.

🚀 Usage Guide / Injection Methods

⚠️ Core Principle: Scripts must be executed before the webpage loads (Document Start). If using Puppeteer/Playwright, use page.evaluateOnNewDocument. If using a Chrome Extension, inject at the run_at: document_start stage in content_scripts.

Method 1: Quick Random Fingerprint (Recommended for Testing)

Inject randomTest.js directly. The script will automatically generate and apply a random fingerprint.

// Puppeteer Example
const fs = require('fs');
const randomTestScript = fs.readFileSync('./public/build/randomTest.js', 'utf8');

await page.evaluateOnNewDocument(randomTestScript);

Method 2: Customizing via Generator

This method allows for consistency (via Seed) or specifying a particular UserAgent.

1. Inject Generator (generator.js).
2. Generate Config: Call BROWSER_GENERATOR.
3. Inject Engine (window.js).
4. Apply Config: Call SCOPE_CHEATER.run().

// Pseudocode Flow
const generatorCode = fs.readFileSync('./public/build/generator.js', 'utf8');
const windowCode = fs.readFileSync('./public/build/window.js', 'utf8');

// 1. Inject generator code
await page.evaluateOnNewDocument(generatorCode);
// 2. Inject engine code
await page.evaluateOnNewDocument(windowCode);

await page.evaluateOnNewDocument(() => {
    // 3. Generate fingerprint config (supports UA, seed, safeMode, etc.)
    const config = self.BROWSER_GENERATOR({
        userAgent: "Mozilla/5.0 (Windows NT 10.0; Win64; x64)...",
        seed: 123456, // Same seed generates the same fingerprint
        safeMode: true
    });
    // 4. Pass config to global variable
    self.SCOPE_BROWSER = config;
    // 5. Start obfuscation
    self.SCOPE_CHEATER.run();
});

Method 3: Fully Manual Parameters

If you have your own fingerprint library (JSON data), you can skip the generator and inject window.js directly.

const windowCode = fs.readFileSync('./public/build/window.js', 'utf8');
const myFingerprintData = { ... }; // JSON object matching the generator structure

await page.evaluateOnNewDocument(windowCode);
await page.evaluateOnNewDocument((data) => {
    self.SCOPE_BROWSER = data; // Assign data
    self.SCOPE_CHEATER.run(); // Run engine
}, myFingerprintData);

📂 Project Structure

CthulhuJs/
├── src/
│   ├── cheaters/          # 🎭 [Core] Obfuscation modules
│   │   ├── audioCheater.js
│   │   ├── canvasCheater.js
│   │   ├── navigatorCheater.js
│   │   └── ... (more modules)
│   ├── generate/            # 🎲 Generation logic & databases
│   │   ├── devices.json     #    - Real device UA & screen database
│   │   ├── webglInfos.json  #    - Real WebGL renderer/vendor database
│   │   ├── types.js         #    - Type definitions
│   │   └── index.js         #    - Generator entry
│   ├── jsons/               # 🗃️ Browser engine feature libraries
│   │   ├── blink.features.json
│   │   └── gecko.features.json
│   ├── kits/                # 🛠️ Utilities
│   │   ├── objects.js       #    - Object manipulation
│   │   ├── proxy.js         #    - Core Proxy hijacking & Native Masquerading
│   │   └── utils.js         #    - Helper functions
│   ├── browserFill.js       # 🧩 Browser environment polyfills
│   ├── const.js             # 📌 Constants
│   ├── generator.js         # ⚙️ [Entry] Fingerprint generator
│   ├── randomTest.js        # 🧪 [Entry] Random test script
│   ├── window.js            # 🚪 [Entry] Main window injection (Window Scope)
│   └── worker.js            # 👷 [Entry] Worker thread injection (Worker Scope)
├── public/                  # 📦 (GitIgnored) Build output (dev/build)
├── webpack.config.js        # 🏗️ Webpack configuration
├── babel.config.js          # 🧬 Babel configuration
├── type.d.ts                # 📝 TypeScript type definitions
└── package.json             # 📦 Dependencies & scripts

⚖️ Disclaimer

This project (CthulhuJs) is for security research, academic exchange, and defensive testing only.

• The developer is not responsible for any legal consequences or service interruptions caused by the use of this project.
• Do not use this project for any illegal purposes (e.g., malicious attacks, fraud, bypassing legitimate access controls).
• By using this project, you agree to comply with all applicable laws and regulations.

📄 License

MIT License.