Microsoft 365 Unusual Volume of File Deletion

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Microsoft 365 Unusual Volume of File Deletion

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Identifies that a user has deleted an unusually large volume of files as reported by Microsoft Cloud App Security.

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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Users or System Administrator cleaning out folders.

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:"Unusual volume of file
deletion" and event.outcome:success

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Impact
- ID: TA0040
- Reference URL: https://attack.mitre.org/tactics/TA0040/
Technique:
- Name: Data Destruction
- ID: T1485
- Reference URL: https://attack.mitre.org/techniques/T1485/

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