muhannad-hash/mcp-shield

> A security scanner for MCP servers — detect backdoors, exfiltration, prompt injection, and supply chain risks before they reach your AI.
The MCP ecosystem is growing fast. Not every server on npm is safe. mcp-shield lets Claude audit any MCP server — local or from npm — before you trust it with your files, keys, and context.
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What it detects
| Category | Examples |
|----------|---------|
| **Exfiltration** | process.env sent over network, SSH key access, AWS credential reads |
| **Code execution** | eval(), new Function(), child_process.exec(), dynamic require() |
| **Obfuscation** | Base64 runtime decoding, hex-encoded payloads, char-code arrays |
| **Sensitive file access** | .env, id_rsa, browser cookies, ~/.gitconfig |
| **Prompt injection** | Hidden instructions, zero-width characters, role-switch attacks, jailbreak patterns |
| **Supply chain** | Package age, download count, maintainer count, CVEs in dependencies |
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Demo
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How it works
**Static analysis** — scans JavaScript/TypeScript source files with a library of regex patterns covering 20+ attack signatures across 5 categories.
**Supply chain audit** — queries the npm registry for package metadata, then runs npm audit to surface known CVEs in the dependency tree.
**Prompt injection detection** — checks tool descriptions and responses for zero-width characters, instruction overrides, role-switch attacks, and other LLM-targeting techniques.
**--ignore-scripts installation** — when scanning npm packages, installs with --ignore-scripts so no malicious postinstall hooks run during analysis.
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Contributing
PRs welcome. Detection patterns live in src/patterns.ts — adding new signatures is a single object.
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