AssemblyLine MCP

A Model Context Protocol (MCP) server for AssemblyLine 4 — the Canadian Centre for Cyber Security's open-source file triage and malware analysis platform. It lets MCP-compatible AI clients (Claude Desktop, Claude Code, Cursor, VS Code, …) submit files, hashes, and URLs for analysis, retrieve results, search across AssemblyLine indices, and triage alerts.

Features

• Built for agents, not just API parity — al_analyze submits and waits, then returns a concise verdict digest (verdict, flagged services, heuristics, AV hits, network IOCs, children) instead of a raw blob; al_submission_iocs and al_find_related cover IOC extraction and pivoting. Guided MCP prompts (triage_file, investigate_hash, review_alert) ship the AssemblyLine triage workflow and scoring semantics inside the server — no skill install required.

• Full AssemblyLine 4 coverage — submit/ingest, inspect submissions and per-file results, Lucene search across every index, alert triage, and system metadata, built on the official assemblyline-client.

• Safe by default — destructive/admin operations (deletes, workflow runs, user/service/system management) are not even registered unless you opt in with AL_ALLOW_ADMIN=true, and every tool carries MCP readOnlyHint / destructiveHint annotations so clients can prompt before risky actions.

• Two transports — stdio for local desktop clients and streamable HTTP for networked/containerized deployments (with optional admin-scope auth).

• Built-in end-to-end self-test — assemblyline-mcp selftest boots an in-process mock AssemblyLine, exercises every tool, and prints a PASS/FAIL report. No live server, no pytest, any architecture.

• Production-ready packaging — uvx-installable, typed (py.typed), multi-arch Docker image, and a published MCP registry manifest.

Related MCP server: MISP MCP Server

Available tools

All tools are prefixed al_. Read-only tools are always available; write tools change state but are non-destructive; admin tools require AL_ALLOW_ADMIN=true.

Guided workflows (MCP prompts — no skill required)

The server registers MCP prompts that encode the AssemblyLine triage workflow and scoring semantics, so the agent interprets results correctly out of the box. These surface natively in any MCP client (Claude Desktop/Code, Cursor, …):

• triage_file — triage a file/hash and report a verdict.

• investigate_hash — known results, IOCs, and related activity for a hash.

• review_alert — assess an alert as true/false positive.

A richer, Claude-specific Agent Skill is also available under skills/assemblyline-triage/ — but it's optional; the server is fully usable without installing anything.

Installation

You need a running AssemblyLine 4 instance and an API key (or username/password).

# Run without installing (recommended)
uvx assemblyline-mcp

# Or with pipx / pip
pipx install assemblyline-mcp
pip install assemblyline-mcp

Docker

docker run --rm -i \
  -e AL_URL=https://al.example.org \
  -e AL_APIKEY_USER=analyst \
  -e AL_APIKEY=your-keyname:secret \
  ghcr.io/SauceTaster/assemblyline-mcp:latest

Configuration

Configuration is via AL_-prefixed environment variables (or a .env file).

¹ Provide either AL_APIKEY_USER + AL_APIKEY or AL_USERNAME + AL_PASSWORD.

Claude Code

claude mcp add assemblyline \
  --env AL_URL=https://al.example.org \
  --env AL_APIKEY_USER=analyst \
  --env AL_APIKEY=your-keyname:secret \
  -- uvx assemblyline-mcp

Claude Desktop

Add to claude_desktop_config.json (see example):

{
  "mcpServers": {
    "assemblyline": {
      "command": "uvx",
      "args": ["assemblyline-mcp"],
      "env": {
        "AL_URL": "https://al.example.org",
        "AL_APIKEY_USER": "analyst",
        "AL_APIKEY": "your-keyname:secret"
      }
    }
  }
}

VS Code

See examples/vscode_mcp.json.

Usage

assemblyline-mcp                    # serve over stdio (default)
assemblyline-mcp serve -t http -p 8000   # serve over streamable HTTP
assemblyline-mcp selftest          # run the built-in end-to-end self-test
assemblyline-mcp doctor            # validate config + connectivity to a real AL
assemblyline-mcp version

doctor performs the AssemblyLine connection handshake and reports the authenticated user — useful as a container HEALTHCHECK and for first-run setup.

Development

git clone https://github.com/SauceTaster/assemblyline-mcp
cd assemblyline-mcp
uv sync                       # creates .venv with Python 3.12 and all dev deps

uv run ruff check .           # lint
uv run ruff format --check .  # formatting
uv run mypy                   # type-check
uv run pytest                 # full test suite (unit + integration + e2e, mock-backed)
uv run assemblyline-mcp selftest   # the shippable e2e diagnostic

The whole test suite runs against an in-process mock AssemblyLine server, so no live instance is required and it works on any architecture (including Apple Silicon). An opt-in suite exercises a real instance — see CONTRIBUTING.md.

Debugging with the MCP Inspector

uv run fastmcp dev src/assemblyline_mcp/server.py

End-to-end with Docker Compose

docker compose -f docker-compose.e2e.yml up --build
# MCP server (http) on http://localhost:8000/mcp/, backed by the mock AssemblyLine

Security

• Credentials are read only from the environment and never logged.

• Destructive tools are gated behind AL_ALLOW_ADMIN; on the HTTP transport they additionally require an admin-scoped token.

• al_file_download returns base64 bytes only — samples are never executed; oversized files (AL_MAX_DOWNLOAD_BYTES) are refused without being fetched.

• The HTTP transport ships with no built-in authentication for read/write tools. It refuses to bind a non-loopback address unless you set AL_ALLOW_INSECURE_BIND=true; before exposing it, front the server with an auth-enforcing reverse proxy or a FastMCP AuthProvider.

See SECURITY.md for the disclosure policy.

Acknowledgements

• AssemblyLine 4 and the assemblyline-client by the Canadian Centre for Cyber Security.

• Built with FastMCP.

License

MIT