Sigma rule: Google Workspace Out Of Domain Email Forwarding

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-2d0aa5e53f4f, updated 2026-04-28T00:00:00.000Z.

Rule

Title
Google Workspace Out Of Domain Email Forwarding
Status
experimental
Level
medium
Author
Tom kluter
Date
2026-04-28
File
rules/cloud/gcp/gworkspace/login/gcp_gworkspace_out_of_domain_email_forwarding.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects automatic email forwarding to external domains in Google Workspace, which may indicate data leakage or misuse.

Log source

product
gcp
service
google_workspace.login

Detection

selection:
    protoPayload.serviceName: 'login.googleapis.com'
    protoPayload.metadata.event.eventName: 'email_forwarding_out_of_domain'
condition: selection

False positives (as the rule lists them)

  • Legitimate forwarding

Tags

  • attack.t1114.003
  • attack.collection

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/gcp/gworkspace/login/gcp_gworkspace_out_of_domain_email_forwarding.yml

Sources and licences

  • SigmaHQ

    "Google Workspace Out Of Domain Email Forwarding" by Tom kluter (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/cloud/gcp/gworkspace/login/gcp_gworkspace_out_of_domain_email_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: Google Workspace Out Of Domain Email Forwarding",
entity page, dataset version ref-2d0aa5e53f4f, updated 2026-04-28T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/2a0bb2dd-eb5f-4517-8cb9-404f8ba764a5 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 2a0bb2dd-eb5f-4517-8cb9-404f8ba764a5, 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.