User State Changed From Guest To Member

Detects the change of user type from "Guest" to "Member" for potential elevation of privilege.

Sigma rule (View on GitHub)

 1title: User State Changed From Guest To Member
 2id: 8dee7a0d-43fd-4b3c-8cd1-605e189d195e
 3status: test
 4description: Detects the change of user type from "Guest" to "Member" for potential elevation of privilege.
 5references:
 6    - https://learn.microsoft.com/en-gb/entra/architecture/security-operations-user-accounts#monitoring-external-user-sign-ins
 7author: MikeDuddington, '@dudders1'
 8date: 2022/06/30
 9tags:
10    - attack.privilege_escalation
11    - attack.initial_access
12    - attack.t1078.004
13logsource:
14    product: azure
15    service: auditlogs
16detection:
17    selection:
18        Category: 'UserManagement'
19        OperationName: 'Update user'
20        properties.message: '"displayName":"UserType","oldValue":"[\"Guest\"]","newValue":"[\"Member\"]"'
21    condition: selection
22falsepositives:
23    - If this was approved by System Administrator.
24level: medium

References

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