Microsoft 365 Exchange Transport Rule Creation

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: 206

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

edit

Setup

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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&CK^TM

Tactic:
- Name: Exfiltration
- ID: TA0010
- Reference URL: https://attack.mitre.org/tactics/TA0010/
Technique:
- Name: Transfer Data to Cloud Account
- ID: T1537
- Reference URL: https://attack.mitre.org/techniques/T1537/

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