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Elastic Docs ›Elastic Security Solution [8.16] ›Detections and alerts ›Prebuilt rule reference

Google Workspace Custom Gmail Route Created or Modified

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Google Workspace Custom Gmail Route Created or Modified

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Detects when a custom Gmail route is added or modified in Google Workspace. Adversaries can add a custom e-mail route for outbound mail to route these e-mails to their own inbox of choice for data gathering. This allows adversaries to capture sensitive information from e-mail and potential attachments, such as invoices or payment documents. By default, all email from current Google Workspace users with accounts are routed through a domain’s mail server for inbound and outbound mail.

Rule type: query

Rule indices:

  • filebeat-*
  • logs-google_workspace*

Severity: medium

Risk score: 47

Runs every: 10 minutes

Searches indices from: now-130m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Cloud
  • Google Workspace
  • Continuous Monitoring
  • SecOps
  • Collection

Version: 2 (version history)

Added (Elastic Stack release): 8.5.0

Last modified (Elastic Stack release): 8.6.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Administrators may create custom email routes in Google Workspace based on organizational policies, administrative preference or for security purposes regarding spam.

Investigation guide

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### Important Information Regarding Google Workspace Event Lag Times
- As per Google's documentation, Google Workspace administrators may observe lag times ranging from minutes up to 3 days between the time of an event's occurrence and the event being visible in the Google Workspace admin/audit logs.
- This rule is configured to run every 10 minutes with a lookback time of 130 minutes.
- To reduce the risk of false negatives, consider reducing the interval that the Google Workspace (formerly G Suite) Filebeat module polls Google's reporting API for new events.
- By default, `var.interval` is set to 2 hours (2h). Consider changing this interval to a lower value, such as 10 minutes (10m).
- See the following references for further information:
  - https://support.google.com/a/answer/7061566
  - https://www.elastic.co/guide/en/beats/filebeat/current/filebeat-module-google_workspace.html

Rule query

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event.dataset:"google_workspace.admin" and
event.action:("CREATE_GMAIL_SETTING" or "CHANGE_GMAIL_SETTING") and
google_workspace.event.type:"EMAIL_SETTINGS" and
google_workspace.admin.setting.name:("EMAIL_ROUTE" or
"MESSAGE_SECURITY_RULE")

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 2 (8.6.0 release)
  • Formatting only
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