Lasso claude-hooks

Claude Hooks

A collection of security and utility hooks for [Claude Code](https://docs.anthropic.com/en/docs/claude-code). Hooks allow you to extend Claude Code's behavior by running custom scripts at key points during execution.

**Research Paper**: For detailed analysis of indirect prompt injection vulnerabilities in Claude Code, see: [The Hidden Backdoor in Claude Coding Assistant](https://www.lasso.security/blog/the-hidden-backdoor-in-claude-coding-assistant)

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Available Hooks

🛡️ Prompt Injection Defender

Defense against **indirect prompt injection** attacks. Scans tool outputs (files, web pages, command results) for injection attempts and warns Claude about suspicious content via PostToolUse hooks.

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Quick Start

Option 1: Interactive Installation (Recommended)

If you have this repo added as a Claude Code skill, simply tell Claude:

"install the prompt injection defender"

Claude will handle the entire installation process for you.

Option 2: Install Script

# Clone this repo, then run the installer pointing to your project
git clone https://github.com/lasso-security/claude-hooks.git
cd claude-hooks
./install.sh /path/to/your-project

What gets installed

The installer copies hook files to your project and configures Claude Code:

your-project/
└── .claude/
    ├── hooks/
    │   └── prompt-injection-defender/
    │       ├── post-tool-defender.py
    │       └── patterns.yaml
    └── settings.local.json  ← hook configuration

📖 **For manual installation and more options, see [INSTALLATION.md](INSTALLATION.md)**

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Understanding Prompt Injection

The Problem: Indirect Prompt Injection

When Claude Code reads files, fetches web pages, or runs commands, malicious instructions can be hidden in that content:

# README.md (looks innocent)
Welcome to our project!

## Installation
...

...