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Entra ID User Signed In from Unusual Device

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Entra ID User Signed In from Unusual Device

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Identifies when a Microsoft Entra ID user signs in from a device that is not typically used by the user, which may indicate potential compromise or unauthorized access attempts. This rule detects unusual sign-in activity by comparing the device used for the sign-in against the user’s typical device usage patterns. Adversaries may create and register a new device to obtain a Primary Refresh Token (PRT) and maintain persistent access.

Rule type: new_terms

Rule indices:

  • filebeat-*
  • logs-azure.signinlogs-*

Severity: low

Risk score: 21

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

  • Domain: Cloud
  • Domain: Identity
  • Use Case: Threat Detection
  • Tactic: Persistence
  • Data Source: Azure
  • Data Source: Microsoft Entra ID
  • Data Source: Microsoft Entra ID Sign-in Logs
  • Resources: Investigation Guide

Version: 1

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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Triage and analysis

Investigating Entra ID User Signed In from Unusual Device

This rule detects when a Microsoft Entra ID user signs in from a device that is not typically used by the user, which may indicate potential compromise or unauthorized access attempts. This rule detects unusual sign-in activity by comparing the device used for the sign-in against the user’s typical device usage patterns. Adversaries may create and register a new device to obtain a Primary Refresh Token (PRT) and maintain persistent access.

Possible investigation steps

  • Review the azure.signinlogs.properties.user_principal_name field to identify the user associated with the sign-in.
  • Check the azure.signinlogs.properties.device_detail.device_id field to identify the device used for the sign-in.
  • Review azure.signinlogs.properties.incoming_token_type to determine what tpe of security token was used for the sign-in, such as a Primary Refresh Token (PRT).
  • Examine azure.signinlogs.category to determine if these were non-interactive or interactive sign-ins.
  • Check the geolocation of the sign-in by reviewing source.geo.country_name and source.geo.city_name to identify the location of the device used for the sign-in. If these are unusual for the user, it may indicate a potential compromise.
  • Review azure.signinlogs.properties.app_id to determine which client application was used for the sign-in. If the application is not recognized or expected, it may indicate unauthorized access. Adversaries use first-party client IDs to blend in with legitimate traffic.
  • Examine azure.signinlogs.properties.resource_id to determine what resource the security token has in scope and/or is requesting access to. If the resource is not recognized or expected, it may indicate unauthorized access. Excessive access to Graph API is common post-compromise behavior.
  • Review the identity protection risk status by checking azure.signinlogs.properties.risk_level and azure.signinlogs.properties.risk_detail to determine if the sign-in was flagged as risky by Entra ID Protection.

False positive analysis

  • Legitimate users may sign in from new devices, such as when using a new laptop or mobile device. If this is expected behavior, consider adjusting the rule or adding exceptions for specific users or device IDs.
  • Environments where users frequently change devices, such as in a corporate setting with rotating hardware, may generate false positives.
  • Users may use both an endpoint and mobile device for sign-ins, which could trigger this rule.

Response and remediation

  • If the sign-in is confirmed to be suspicious or unauthorized, take immediate action to revoke the access token and prevent further access.
  • Disable the user account temporarily to prevent any potential compromise or unauthorized access.
  • Review the user’s recent sign-in activity and access patterns to identify any potential compromise or unauthorized access.
  • If the user account is compromised, initiate a password reset and enforce multi-factor authentication (MFA) for the user.
  • Review the conditional access policies in place to ensure they are sufficient to prevent unauthorized access to sensitive resources.
  • Identify the registered Entra ID device by reviewing azure.signinlogs.properties.device_detail.display_name and confirm it is expected for the user or organization. If it is not expected, consider removing the device registration.
  • Consider adding exceptions for verified devices that are known to be used by the user to reduce false-positives.

Setup

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Required Microsoft Entra ID Sign-In Logs

This rule requires the Azure integration with Microsoft Entra ID Sign-In logs to be enabled and configured to collect audit and activity logs via Azure Event Hub.

Rule query

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event.dataset: "azure.signinlogs" and
    event.category: "authentication" and
    azure.signinlogs.properties.user_type: "Member" and
    azure.signinlogs.properties.token_protection_status_details.sign_in_session_status: "unbound" and
    not azure.signinlogs.properties.device_detail.device_id: "" and
    azure.signinlogs.properties.user_principal_name: *

Framework: MITRE ATT&CKTM

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