Suspicious Entra ID Auth Broker Sign-In With Node.js User Agent via Tycoon 2FA

ATT&CK techniques

Defense Evasion → Collection

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1550.001Application Access Token
Cred Access
- T1557Adversary-in-the-Middle
Discovery
Lateral Movement
- T1550.001Application Access Token
Collection
- T1557Adversary-in-the-Middle
C2
Exfiltration
Impact

What it detects

This rule detects Entra ID sign ins against the Microsoft Authentication Broker application from Node.js based clients such as axios undici and node-fetch as characteristic of Tycoon 2FA adversary in the middle attacks in Elastic research. Automated Node runtimes replaying stolen tokens through the Auth Broker indicate token theft and primary refresh token abuse rather than genuine user interaction.

Reporting behind it

Related detections9 linkedT1550.001 — drag to rearrange

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Suspicious Entra ID Auth Broker Sign-In With Node.js User Agent via Tycoon 2FA

Pivot detection · T1550.001 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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