Guest Users Invited To Tenant By Non Approved Inviters — Sigma Rule

Rule metadata and linked tags

Author: MikeDuddington, '@dudders1'. Source status: test; severity: medium. Source dates: 2022-07-28 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: a5c536d0358e86a0e8dd5cde423eba29be7e4ddbdbc2cec232b1dba7957a26a0

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: Guest Users Invited To Tenant By Non Approved Inviters
id: 4ad97bf5-a514-41a4-abd3-4f3455ad4865
status: test
description: Detects guest users being invited to tenant by non-approved inviters
references:
    - https://learn.microsoft.com/en-gb/entra/architecture/security-operations-user-accounts#monitoring-external-user-sign-ins
author: MikeDuddington, '@dudders1'
date: 2022-07-28
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.initial-access
    - attack.stealth
    - attack.t1078
logsource:
    product: azure
    service: auditlogs
detection:
    selection:
        Category: 'UserManagement'
        OperationName: 'Invite external user'
    filter:
        InitiatedBy|contains: '<approved guest inviter use OR for multiple>'
    condition: selection and not filter
falsepositives:
    - If this was approved by System Administrator.
level: medium

Original YAML and metadata in JSON

False positives

• If this was approved by System Administrator.

Source references

• https://learn.microsoft.com/en-gb/entra/architecture/security-operations-user-accounts#monitoring-external-user-sign-ins