Suspicious Inbox Forwarding (via threat_management)

title: Suspicious Inbox Forwarding (via threat_management)
id: 4afad659-e36d-5a82-95bd-ef384a59f217
status: stable
description: This rule detects when a Microsoft Cloud App Security reported anomalous email forwarding rules, for example, if a user created an inbox rule that forwards a copy of all emails to an external address.
references:
    - https://attack.mitre.org/techniques/T1020/
    - https://learn.microsoft.com/en-us/defender-cloud-apps/anomaly-detection-policy
    - https://learn.microsoft.com/en-us/defender-cloud-apps/policy-template-reference
author: Huntrule Team
date: 2026-02-22
tags:
    - attack.exfiltration
    - attack.t1020
logsource:
    service: threat_management
    product: m365
detection:
    selection:
        eventSource: SecurityComplianceCenter
        eventName: 'Suspicious inbox forwarding'
        status: success
    condition: selection
falsepositives:
    - Unknown
level: low