Microsoft 365 User Restricted from Sending Email

Identifies when a user has been restricted from sending email due to exceeding sending limits of the service policies per the Security Compliance Center.

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:

Tags:

Elastic
Cloud
Microsoft 365
Continuous Monitoring
SecOps
Configuration Audit

Version: 1

Added (Elastic Stack release): 7.16.0

Rule authors: Austin Songer

Rule license: Elastic License v2

Potential false positives

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A user sending emails using personal distribution folders may trigger the event.

Investigation guide

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## Config

The Microsoft 365 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:SecurityComplianceCenter
and event.category:web and event.action:"User restricted from sending
email" and event.outcome:success

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
Technique:
- Name: Valid Accounts
- ID: T1078
- Reference URL: https://attack.mitre.org/techniques/T1078/

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