Elastic high stable eql

Entra ID AiTM Phishing-Kit Chain Detected

Identifies a Microsoft Entra ID identity-compromise chain in which a single user, within a 10-minute window, authenticates to the Device Registration Service through the Microsoft Authentication Broker (MAB) client, registers a device, and then uses the resulting Primary Refresh Token (PRT) to access a resource other than the Device Registration Service. This sequence is the core post-adversary-in-the-middle (AiTM) persistence pattern used by phishing kits such as Tycoon2FA and Kali365: after capturing a victim session, the kit registers an Azure AD-joined device to obtain a device-bound PRT, which survives user-level session revocation and password resets and grants trusted, MFA-free access. Correlating the broker sign-in, the device-registration audit event, and the follow-on PRT sign-in for the same user within a short window is a high-fidelity indicator of active account takeover.

View Source

Detection Logic

sequence with maxspan=3m
  [authentication where
    data_stream.dataset == "azure.signinlogs" and
    azure.signinlogs.category == "NonInteractiveUserSignInLogs" and
    azure.signinlogs.properties.app_id == "29d9ed98-a469-4536-ade2-f981bc1d605e" and
    azure.signinlogs.properties.resource_display_name == "Device Registration Service" and
    azure.signinlogs.properties.incoming_token_type == "refreshToken" and
    azure.signinlogs.properties.token_protection_status_details.sign_in_session_status == "unbound" and
    azure.signinlogs.properties.user_type == "Member" and
    azure.signinlogs.result_signature == "SUCCESS"
  ] by azure.signinlogs.properties.user_id
  [any where
    data_stream.dataset == "azure.auditlogs" and
    azure.auditlogs.operation_name == "Register device" and
    azure.auditlogs.properties.initiated_by.user.id != null and
    azure.auditlogs.properties.target_resources.`0`.display_name like "DESKTOP-*" and
    event.outcome == "success"
  ] by azure.auditlogs.properties.initiated_by.user.id
  [authentication where
    data_stream.dataset == "azure.signinlogs" and
    azure.signinlogs.properties.incoming_token_type == "primaryRefreshToken" and
    azure.signinlogs.properties.original_transfer_method == "deviceCodeFlow" and
    azure.signinlogs.properties.is_interactive == true and
    azure.signinlogs.properties.resource_display_name != "Device Registration Service" and
    azure.signinlogs.properties.device_detail.is_managed != true and
    azure.signinlogs.result_signature == "SUCCESS"
  ] by azure.signinlogs.properties.user_id

False Positives

  • ⚠ Legitimate device onboarding (for example a user enrolling a new corporate device through Azure AD join) can produce a broker authentication to the Device Registration Service followed by PRT issuance. Validate that the device, source IP/ASN, and user agent are expected, and that the device is managed/compliant.
  • ⚠ Authorized red team or penetration testing engagements that register devices and exercise PRTs will match this sequence. Document the engagement and add scoped exceptions for the involved principals or source addresses.

Field Validations

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