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InformationalSplunk security contentSteven Dick

O365 Email Send and Hard Delete Exfiltration Behavior

The following analytic identifies when an O365 email account sends and then hard deletes an email to an external recipient within a short period (within 1 hour). This behavior may indicate a compromised account where…

Description

The following analytic identifies when an O365 email account sends and then hard deletes an email to an external recipient within a short period (within 1 hour). This behavior may indicate a compromised account where the threat actor is attempting to remove forensic artifacts or evidence of exfiltration activity. This behavior is often seen when threat actors want to reduce the probability of detection by the compromised account owner.

Detection logic

Detection requirements

Platform
ContainersESXiIaaSLinuxmacOSOffice SuiteWindows

The rule states no platform. This is derived from the 3 ATT&CK techniques it maps to.

Log source category
office_365_reporting_message_traceoffice_365_universal_audit_log

Known benign triggers

  • Users that habitually/proactively cleaning the recoverable items folder may trigger this alert.

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