Home/CVE-2021-25983/Sigma rules
Sigma

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.

Detection rules

4 of 4
direct high
Disabling Multi Factor Authentication
Detects disabling of Multi Factor Authentication.
status test author Splunk Threat Research Team (original rule), Harjot Singh @cyb3rjy0t (sigma rule) id 60de9b57-dc4d-48b9-a6a0-b39e0469f876 license Sigma · DRL-1.1
view Sigma YAML
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
direct medium
Authentications To Important Apps Using Single Factor Authentication
Detect when authentications to important application(s) only required single-factor authentication
status test author MikeDuddington, '@dudders1' id f272fb46-25f2-422c-b667-45837994980f license Sigma · DRL-1.1
view Sigma YAML
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
direct medium
Multi Factor Authentication Disabled For User Account
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.
status test author Harjot Singh (@cyb3rjy0t) id b18454c8-0be3-41f7-86bc-9c614611b839 license Sigma · DRL-1.1
view Sigma YAML
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
direct low
Azure AD Only Single Factor Authentication Required
Detect when users are authenticating without MFA being required.
status test author MikeDuddington, '@dudders1' id 28eea407-28d7-4e42-b0be-575d5ba60b2c license Sigma · DRL-1.1
view Sigma YAML
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
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