Generating Forensic Timelines with Hayabusa

Overview

Hayabusa (隼, Japanese for "peregrine falcon") is a Sigma-based threat-hunting and fast-forensics timeline generator for Windows event logs, developed by Yamato Security in Rust. It parses .evtx files (offline or via live analysis of a local host), applies a large built-in library of Sigma detection rules plus Hayabusa-specific rules, and produces a single, readable, chronological timeline of high-signal events with severity levels, MITRE ATT&CK tactics, and rule references. This collapses thousands of raw event-log records into a prioritized incident timeline that an analyst can review quickly.

Hayabusa is purpose-built for DFIR triage. Instead of loading EVTX into a SIEM, an investigator runs a single binary against a directory of collected logs and gets a CSV or JSON timeline plus metrics (events per computer, per Event ID, per channel). Because detections are Sigma-based, coverage tracks the open detection-engineering community, and rules can be updated on demand with update-rules. The tool's output integrates with downstream analysis: CSV opens in Timeline Explorer, JSONL feeds into jq, and timesketch-* profiles export directly into Timesketch.

A frequent finding in Hayabusa timelines is malicious PowerShell — MITRE ATT&CK T1059.001 (Command and Scripting Interpreter: PowerShell) — surfaced via Sigma rules over Event ID 4104 (script-block logging), 4103, and Sysmon process creation. This skill maps to NIST CSF RS.AN-03 (analysis is performed to establish what has taken place during an incident).

When to Use

• During incident-response triage, to turn a pile of collected .evtx files into a prioritized timeline.
• When you need fast, SIEM-free detection over Windows event logs with community Sigma coverage.
• To enumerate suspicious activity (PowerShell, account changes, lateral movement) across many hosts' logs.
• To produce metrics (events per computer/Event ID/channel) and pivot keywords for deeper hunting.
• To export an incident timeline into Timesketch or Timeline Explorer for collaborative analysis.