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Microsoft 365 Exchange DKIM Signing Configuration Disabled

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Microsoft 365 Exchange DKIM Signing Configuration Disabled

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Identifies when a DomainKeys Identified Mail (DKIM) signing configuration is disabled in Microsoft 365. With DKIM in Microsoft 365, messages that are sent from Exchange Online will be cryptographically signed. This will allow the receiving email system to validate that the messages were generated by a server that the organization authorized and were not spoofed.

Rule type: query

Rule indices:

filebeat-*
logs-o365*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-30m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://docs.microsoft.com/en-us/powershell/module/exchange/set-dkimsigningconfig?view=exchange-ps

Tags:

Elastic
Cloud
Microsoft 365
Continuous Monitoring
SecOps
Data Protection
Persistence

Version: 101 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 8.6.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Disabling a DKIM configuration may be done by a system or network administrator. Verify that the configuration change was expected. Exceptions can be added to this rule to filter expected behavior.

Investigation guide

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Rule query

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event.dataset:o365.audit and event.provider:Exchange and
event.category:web and event.action:"Set-DkimSigningConfig" and
o365.audit.Parameters.Enabled:False and event.outcome:success

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
Technique:
- Name: Modify Authentication Process
- ID: T1556
- Reference URL: https://attack.mitre.org/techniques/T1556/

Rule version history

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Version 101 (8.6.0 release)

Formatting only

Version 100 (8.5.0 release)

Formatting only

Version 8 (8.4.0 release)

Formatting only

Version 6 (8.2.0 release)

Formatting only

Version 5 (8.1.0 release)

Formatting only

Version 4 (7.13.0 release)

Formatting only

Version 3 (7.12.0 release)

Formatting only

Version 2 (7.11.2 release)

Formatting only

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