Microsoft 365 Incident Investigation Decision Tree

Corpus Roadmap — Planned Publication

This dossier is part of the Hermes Codex Microsoft 365 DFIR corpus (Bloc XI — Référentiels). Detailed forensic analysis, detection rules, and field investigation procedures for this topic are integrated with the foundational architecture established in Phase 1.

Overview & Investigation Context

This reference card details the technical mechanics, log artifacts, and forensic methodology for Microsoft 365 Incident Investigation Decision Tree.

During Microsoft 365 incident response engagements, investigators must navigate the identity plane, workload activity records, and cloud telemetry while maintaining strict adherence to the evidentiary threshold:

Possible → Configured → Authorized → Accessible → Utilized → Observed → Proven

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Key Cross-References & Prerequisites

01. M365 DFIR Fundamentals Understand the core tenant architecture, identity boundaries, and workload interactions.

02. Microsoft Entra ID: The Identity Plane Explore user, group, device, and service principal authentication pipelines.

04. Preparing a Tenant for DFIR CSIRT onboarding protocol, credential sanitization, and emergency tenant access.

06. M365 DFIR Access Matrix Operational role, license, portal, and log retention lookup table.