Microsoft 365 Exchange Transport Rule Creation

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Microsoft 365 Exchange Transport Rule Creation

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Identifies a transport rule creation in Microsoft 365. Exchange Online mail transport rules should be set to not forward email to domains outside of your organization as a best practice. An adversary may create transport rules to exfiltrate data.

Rule type: query

Rule indices:

  • filebeat-*
  • logs-o365*

Severity: medium

Risk score: 47

Runs every: 5m

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

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Cloud
  • Microsoft 365
  • Continuous Monitoring
  • SecOps
  • Configuration Audit

Version: 5

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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## Config

The Office 365 Logs Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule.

Rule query

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event.dataset:o365.audit and event.provider:Exchange and event.category:web and event.action:"New-TransportRule" and event.outcome:success

Framework: MITRE ATT&CKTM