Sigma rules for CVE-2021-25983
4 rules · scoped to cve · back to CVE-2021-25983
Direct rules mention this entity in their title or description. Related rules cover the techniques this entity is known to use.
title: Disabling Multi Factor Authentication
id: 60de9b57-dc4d-48b9-a6a0-b39e0469f876
status: test
description: Detects disabling of Multi Factor Authentication.
references:
- https://research.splunk.com/cloud/c783dd98-c703-4252-9e8a-f19d9f5c949e/
author: Splunk Threat Research Team (original rule), Harjot Singh @cyb3rjy0t (sigma rule)
date: 2023-09-18
tags:
- attack.persistence
- attack.credential-access
- attack.defense-impairment
- attack.t1556.006
logsource:
service: audit
product: m365
detection:
selection:
Operation|contains: 'Disable Strong Authentication.'
condition: selection
falsepositives:
- Unlikely
level: high
title: Authentications To Important Apps Using Single Factor Authentication
id: f272fb46-25f2-422c-b667-45837994980f
status: test
description: Detect when authentications to important application(s) only required single-factor authentication
references:
- https://learn.microsoft.com/en-gb/entra/architecture/security-operations-user-accounts
author: MikeDuddington, '@dudders1'
date: 2022-07-28
tags:
- attack.privilege-escalation
- attack.persistence
- attack.initial-access
- attack.stealth
- attack.t1078
logsource:
product: azure
service: signinlogs
detection:
selection:
Status: 'Success'
AppId: 'Insert Application ID use OR for multiple'
AuthenticationRequirement: 'singleFactorAuthentication'
condition: selection
falsepositives:
- If this was approved by System Administrator.
level: medium
title: Multi Factor Authentication Disabled For User Account
id: b18454c8-0be3-41f7-86bc-9c614611b839
status: test
description: |
Detects changes to the "StrongAuthenticationRequirement" value, where the state is set to "0" or "Disabled".
Threat actors were seen disabling multi factor authentication for users in order to maintain or achieve access to the account. Also see in SIM Swap attacks.
references:
- https://www.sans.org/blog/defending-against-scattered-spider-and-the-com-with-cybercrime-intelligence/
author: Harjot Singh (@cyb3rjy0t)
date: 2024-08-21
tags:
- attack.credential-access
- attack.persistence
logsource:
product: azure
service: auditlogs
definition: 'Requirements: The TargetResources array needs to be mapped accurately in order for this rule to work'
detection:
selection:
LoggedByService: 'Core Directory'
Category: 'UserManagement'
OperationName: 'Update user'
TargetResources.ModifiedProperties.DisplayName: 'StrongAuthenticationRequirement'
TargetResources.ModifiedProperties.NewValue|contains: "State\":0"
condition: selection
falsepositives:
- Legitimate authorized activity.
level: medium
title: Azure AD Only Single Factor Authentication Required
id: 28eea407-28d7-4e42-b0be-575d5ba60b2c
status: test
description: Detect when users are authenticating without MFA being required.
references:
- https://learn.microsoft.com/en-gb/entra/architecture/security-operations-user-accounts
author: MikeDuddington, '@dudders1'
date: 2022-07-27
tags:
- attack.privilege-escalation
- attack.persistence
- attack.initial-access
- attack.credential-access
- attack.stealth
- attack.defense-impairment
- attack.t1078.004
- attack.t1556.006
logsource:
product: azure
service: signinlogs
detection:
selection:
Status: 'Success'
AuthenticationRequirement: 'singleFactorAuthentication'
condition: selection
falsepositives:
- If this was approved by System Administrator.
level: low