IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.
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Elastic Docs ›Elastic Security Solution [8.9] ›Detections and alerts ›Prebuilt rule reference

Suspicious Microsoft 365 Mail Access by ClientAppId

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Suspicious Microsoft 365 Mail Access by ClientAppId

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Identifies when a Microsoft 365 Mailbox is accessed by a ClientAppId that was observed for the fist time during the last 10 days.

Rule type: new_terms

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: Initial Access

Version: 1

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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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:MailItemsAccessed and event.outcome:success

Framework: MITRE ATT&CKTM

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