Elastic high stable kql

M365 Potential AiTM UserLoggedIn via Office App (Tycoon2FA)

Detects Microsoft 365 audit "UserLoggedIn" events consistent with Tycoon 2FA phishing-as-a-service (PhaaS) adversary-in-the-middle (AiTM) activity: the Microsoft Authentication Broker requesting access where the object identifier matches Microsoft Graph or Exchange Online, or the Office web client application authenticating to itself, combined with Node.js-style user agents (node, axios, undici). Tycoon 2FA bypasses MFA by relaying authentication and capturing session material, often targeting Microsoft 365 and Gmail. Baseline legitimate automation and developer tooling before tuning.

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Detection Logic

data_stream.dataset:"o365.audit" and event.category:"authentication" and event.action:"UserLoggedIn" and
(
    (
        o365.audit.ApplicationId:"29d9ed98-a469-4536-ade2-f981bc1d605e" and
        o365.audit.ObjectId:(
            "00000002-0000-0ff1-ce00-000000000000" or "00000003-0000-0000-c000-000000000000"
        )
    ) or
    (
        o365.audit.ApplicationId:"4765445b-32c6-49b0-83e6-1d93765276ca" and
        o365.audit.ObjectId:"4765445b-32c6-49b0-83e6-1d93765276ca"
    )
) and user_agent.original:(node or axios* or undici)

False Positives

⚠ Legitimate Node.js or undici-based automation, health checks, or internal services that use the Microsoft Authentication Broker or the same first-party application IDs against Graph or Exchange may match. Developers using axios or undici with delegated flows can also resemble this pattern.

Field Validations

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