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unbuned

Extract JavaScript from Bun-compiled executables

Reverse engineer, analyze, and learn from Bun applications

Features • Installation • Usage • Examples • How It Works

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What is unbuned?

unbuned is a powerful Python tool that extracts pure JavaScript source code from Bun-compiled executables. Whether you're reverse engineering an application, conducting security research, or learning how a Bun app works, unbuned gives you access to the bundled JavaScript code.

Why unbuned?

• Zero Dependencies: Pure Python 3.6+ stdlib only
• Universal: Works with any Bun-compiled executable
• Clean Output: 100% ASCII JavaScript, no binary contamination
• Fast: Extracts megabytes of code in seconds
• Accurate: Smart boundary detection ensures complete extraction

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Features

• Parse PE headers to locate .bun section
• Find JavaScript start marker (// @bun)
• Intelligent JavaScript/binary boundary detection
• Refine boundaries using end markers (debugId, sourceMappingURL, })();)
• Extract and save pure, readable JavaScript
• Support for Windows, Linux, and macOS executables

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Installation

git clone https://github.com/vibheksoni/unbuned.git
cd unbuned

No dependencies required! Just Python 3.6+

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Usage

python unbuned.py <path-to-bun-executable>

Example

python unbuned.py droid.exe

Output:

Extracted: output/droid/droid.js
Size: 14,234,567 bytes

The extracted JavaScript will be saved to output/<executable-name>/<executable-name>.js

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Examples

We've included two real-world examples in the output/ directory:

1. Factory Droid CLI (droid.exe)

• Extracted: 14MB of JavaScript
• Contains: AI agent logic, model configurations, Factory-specific code
• Location: output/droid/droid.js

2. Claude Code (claude.exe)

• Extracted: 11MB of JavaScript
• Contains: AWS Code implementation, Anthropic SDK, tool definitions
• Location: output/claude/claude.js

Both examples demonstrate unbuned's ability to extract massive amounts of clean, readable JavaScript from production Bun executables.

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How It Works

unbuned uses a multi-stage extraction process:

1. PE Header Parsing: Locates the .bun section in Windows PE executables
2. Magic Byte Detection: Falls back to magic byte search (\xe5\x02\x80\x01) if needed
3. JavaScript Marker: Finds the // @bun comment marking the start of JS code
4. Boundary Detection: Analyzes byte patterns to detect where JavaScript ends
5. Refinement: Uses source map markers and code patterns to refine the boundary
6. Extraction: Decodes and saves pure UTF-8 JavaScript

Boundary Detection Algorithm

The tool uses a sophisticated heuristic to detect where JavaScript ends:

• Analyzes chunks for non-printable character ratios
• Looks for source map comments (//# sourceMappingURL=)
• Detects debug markers (//# debugId=)
• Identifies IIFE closures (})();)
• Validates binary data after potential boundaries

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Use Cases

• Reverse Engineering: Understand how a Bun application works
• Security Research: Analyze executables for vulnerabilities or malicious code
• Learning: Study real-world Bun bundling and code structure
• Recovery: Extract source code when original files are lost
• Analysis: Examine dependencies and third-party libraries

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Requirements

• Python 3.6 or higher
• No external dependencies

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Limitations

• Extracts bundled JavaScript only (not native modules or assets)
• Minified code remains minified (use a beautifier for readability)
• Some obfuscated code may be harder to analyze

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Contributing

Contributions are welcome! Feel free to:

• Report bugs
• Suggest features
• Submit pull requests
• Share your extraction results

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License

MIT License - see LICENSE for details

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Disclaimer

This tool is intended for educational purposes, security research, and legitimate reverse engineering. Always respect software licenses and intellectual property rights. Use responsibly.

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Related Projects

• asar - Extract Electron app.asar archives
• pkg - Package Node.js apps into executables
• nexe - Create standalone Node.js executables

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Made for the reverse engineering community

Star this repo if you find it useful!

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Author

vibheksoni

Currently open to work. If you're looking for someone with security research, reverse engineering, malware analysis, or full-stack development experience - hit me up.

• X/Twitter: @ImVibhek
• Website: vibheksoni.com
• Security Blog: opendoors.wtf
• GitHub: vibheksoni

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Remember: With great power comes great responsibility. Use this tool ethically and legally.