Sigma rule: Suspicious Inbox Forwarding

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-ca50c54e1fee, updated 2022-10-09T00:00:00.000Z.

Rule

Title
Suspicious Inbox Forwarding
Status
test
Level
low
Author
Austin Songer @austinsonger
Date
2021-08-22
Modified
2022-10-09
File
rules/cloud/m365/threat_management/microsoft365_susp_inbox_forwarding.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects when a Microsoft Cloud App Security reported suspicious email forwarding rules, for example, if a user created an inbox rule that forwards a copy of all emails to an external address.

Log source

product
m365
service
threat_management

Detection

selection:
    eventSource: SecurityComplianceCenter
    eventName: 'Suspicious inbox forwarding'
    status: success
condition: selection

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.exfiltration
  • attack.t1020

MITRE ATT&CK ids this rule names

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/cloud/m365/threat_management/microsoft365_susp_inbox_forwarding.yml

Sources and licences

  • SigmaHQ

    "Suspicious Inbox Forwarding" by Austin Songer @austinsonger (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/cloud/m365/threat_management/microsoft365_susp_inbox_forwarding.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Suspicious Inbox Forwarding",
entity page, dataset version ref-ca50c54e1fee, updated 2022-10-09T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/6c220477-0b5b-4b25-bb90-66183b4089e8 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 6c220477-0b5b-4b25-bb90-66183b4089e8, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.