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. As a best practice, Exchange Online mail transport rules should not be set to forward email to domains outside of your organization. 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:

  • Domain: Cloud
  • Data Source: Microsoft 365
  • Use Case: Configuration Audit
  • Tactic: Exfiltration

Version: 102

Rule authors:

  • Elastic

Rule license: Elastic License v2

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:"New-TransportRule" and event.outcome:success

Framework: MITRE ATT&CKTM