Microsoft 365 Inbox Forwarding Rule Creatededit

Identifies when a new inbox forwarding rule is created in Microsoft 365. Inbox rules process messages in the inbox based on conditions and take actions. In this case, the rules will forward the emails to a defined address. Attackers can abuse inbox rules to intercept and exfiltrate email data without making organization-wide configuration changes or having the corresponding privileges.

Rule type: query

Rule indices:

  • filebeat-*
  • logs-o365*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-30m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100



  • Elastic
  • Cloud
  • Microsoft 365
  • Continuous Monitoring
  • SecOps
  • Configuration Audit

Version: 3

Rule authors:

  • Elastic
  • Gary Blackwell
  • Austin Songer

Rule license: Elastic License v2

Investigation guideedit

## Config

The Office 365 Logs Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule.

Rule queryedit

event.dataset:o365.audit and event.provider:Exchange and
event.category:web and event.action:"New-InboxRule" and
        o365audit.Parameters.ForwardTo:* or
        o365audit.Parameters.ForwardAsAttachmentTo:* or
    and event.outcome:success