Unfamiliar Sign-In Properties — Sigma Rule

Rule metadata and linked tags

Author: Mark Morowczynski '@markmorow', Gloria Lee, '@gleeiamglo'. Source status: test; severity: high. Source dates: 2023-09-03 / not supplied.

{
  "product": "azure",
  "service": "riskdetection"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: e5d5bbd8c29e96b0e78a357dd9471f7c13d276ff2bea6a31aae33739a309c2b2

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Unfamiliar Sign-In Properties
id: 128faeef-79dd-44ca-b43c-a9e236a60f49
status: test
description: Detects sign-in with properties that are unfamiliar to the user. The detection considers past sign-in history to look for anomalous sign-ins.
references:
    - https://learn.microsoft.com/en-us/entra/id-protection/concept-identity-protection-risks#unfamiliar-sign-in-properties
    - https://learn.microsoft.com/en-us/entra/architecture/security-operations-user-accounts#unusual-sign-ins
author: Mark Morowczynski '@markmorow', Gloria Lee, '@gleeiamglo'
date: 2023-09-03
tags:
    - attack.stealth
    - attack.t1078
    - attack.persistence
    - attack.privilege-escalation
    - attack.initial-access
logsource:
    product: azure
    service: riskdetection
detection:
    selection:
        riskEventType: 'unfamiliarFeatures'
    condition: selection
falsepositives:
    - User changing to a new device, location, browser, etc.
level: high

Original YAML and metadata in JSON

False positives

• User changing to a new device, location, browser, etc.

Source references

• https://learn.microsoft.com/en-us/entra/id-protection/concept-identity-protection-risks#unfamiliar-sign-in-properties
• https://learn.microsoft.com/en-us/entra/architecture/security-operations-user-accounts#unusual-sign-ins