Microsoft 365 Exchange Transport Rule Modification

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Microsoft 365 Exchange Transport Rule Modification

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Identifies when a transport rule has been disabled or deleted in Microsoft 365. Mail flow rules (also known as transport rules) are used to identify and take action on messages that flow through your organization. An adversary or insider threat may modify a transport rule to exfiltrate data or evade defenses.

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:("Remove-TransportRule" or "Disable-TransportRule") and event.outcome:success

Framework: MITRE ATT&CKTM