mcp-hayabusa

MCP server that wraps the Hayabusa CLI for EVTX (Windows Event Log) analysis, exposing scan_evtx and get_hayabusa_rules tools.

Prerequisites

• Python 3.10+ (this machine's default python/py is 3.8 — use py -3.13 explicitly; see below)
• The Hayabusa binary — download_hayabusa.py (below) fetches it into ./hayabusa/, which server.py finds automatically. Alternatively, set HAYABUSA_PATH or put hayabusa on PATH.

Setup

py -3.13 -m pip install -r requirements.txt
py -3.13 download_hayabusa.py   # downloads Hayabusa for this platform into ./hayabusa/

server.py finds the downloaded binary automatically — no env var needed. On Linux, set HAYABUSA_LIBC=musl at download time if you need the musl build instead of the glibc default.

Run

py -3.13 server.py

This starts the server on stdio, for use with an MCP client (e.g. Claude Code, Claude Desktop).

Tool: scan_evtx

Argument	Type	Default	Description
evtx_path	str	required	Path to a single .evtx file to scan
min_severity	str	medium	Minimum severity to include: informational, low, medium, high, critical

Returns a formatted JSON string (total_detections + a detections array), or {"error": ...} on failure (missing file, missing Hayabusa binary, non-zero exit, timeout, locked/inaccessible file, invalid min_severity).

Tool: get_hayabusa_rules

Argument	Type	Default	Description
keyword	str	""	Case-insensitive substring matched against each rule's title/id/tags/category. Empty = all rules.
limit	int	50	Max rules returned, clamped to [1, 500] (there are ~5000 rule files total)

Returns a formatted JSON string: total_rules_scanned, total_matches, returned, truncated, and a rules array (each with title, id, level, status, category, tags, source, path), sorted highest-severity-first. The first call per server process takes a few seconds (parsing ~5000 YAML rule files); results are cached in memory afterward, so subsequent calls are near-instant regardless of keyword/limit.

Status

Verified against a real, locally downloaded Hayabusa v3.10.0 and real EVTX data (including a locked live Windows event log, to confirm error handling). See CLAUDE.md for architecture notes and known gaps.