Elastic Security Detection Rules

M365 Potential AiTM UserLoggedIn via Office App (Tycoon2FA)

Last updated 6 days ago on 2026-05-14
Created 6 days ago on 2026-05-14

About

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.
Tags
Domain: CloudDomain: IdentityDomain: SaaSData Source: Microsoft 365Data Source: Microsoft 365 Audit LogsUse Case: Threat DetectionThreat: Tycoon2FATactic: Initial AccessTactic: Credential AccessLanguage: kuery
Severity
high
Risk Score
73
MITRE ATT&CK™

Initial Access (TA0001)(external, opens in a new tab or window)

↳ Phishing (T1566)(external, opens in a new tab or window)

Credential Access (TA0006)(external, opens in a new tab or window)

↳ Steal Web Session Cookie (T1539)(external, opens in a new tab or window)

False Positive Examples
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.
License
Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type
Query (Kibana Query Language)
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
logs-o365.audit-*
Related Integrations

o365(external, opens in a new tab or window)

Query
text code block:
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)

Install detection rules in Elastic Security

Detect M365 Potential AiTM UserLoggedIn via Office App (Tycoon2FA) in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).