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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Microsoft 365 Potential ransomware activity

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Microsoft 365 Potential ransomware activity

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Identifies when Microsoft Cloud App Security reports that a user has uploaded files to the cloud that might be infected with ransomware.

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: 5 (version history)

Added (Elastic Stack release): 7.16.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Austin Songer

Rule license: Elastic License v2

Potential false positives

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If Cloud App Security identifies, for example, a high rate of file uploads or file deletion activities it may represent an adverse encryption process.

Investigation guide

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Rule query

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event.dataset:o365.audit and event.provider:SecurityComplianceCenter
and event.category:web and event.action:"Potential ransomware
activity" 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 Encrypted for Impact
- ID: T1486
- Reference URL: https://attack.mitre.org/techniques/T1486/

Rule version history

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Version 5 (8.4.0 release)

Formatting only

Version 3 (8.1.0 release)

Formatting only

Version 2 (8.0.0 release)

Formatting only

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