O365 Email Reported By User Found Malicious

name: O365 Email Reported By User Found Malicious
id: 7698b945-238e-4bb9-b172-81f5ca1685a1
version: 12
creation_date: '2024-04-07'
modification_date: '2026-05-13'
author: Steven Dick
status: production
type: TTP
description: The following analytic detects when an email submitted to Microsoft using the built-in report button in Outlook is found to be malicious. This capability is an enhanced protection feature that can be used within o365 tenants by users to report potentially malicious emails. This correlation looks for any submission that returns a Phish or Malware verdict upon submission.
data_source:
    - Office 365 Universal Audit Log
search: |-
    `o365_management_activity` Workload=SecurityComplianceCenter Operation=AlertEntityGenerated Name="Email reported by user as*"
      | fromjson Data
      | rename _raw AS temp etps AS _raw
      | extract pairdelim=";" kvdelim=":"
      | rename _raw AS etps temp AS _raw
      | search RescanVerdict IN (Phish,Malware)
      | rex field=tsd "\<(?<src_user>.+)\>"
      | eval src_user = case(isnull(src_user),tsd,true(),src_user)
      | rename Name as signature, AlertId as signature_id, AlertEntityId as user, tsd as sender, ms as subject
      | fillnull
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY dest user src
           vendor_account vendor_product signature
           signature_id src_user sender
           subject
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `o365_email_reported_by_user_found_malicious_filter`
how_to_implement: You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events. You must deploy/allow the usage of the Microsoft Office Report A Message function.
known_false_positives: No false positives have been identified at this time.
references:
    - https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/submissions-outlook-report-messages?view=o365-worldwide
finding:
    title: The user $user$ reported an email classified from $src_user$
    entity:
        field: src_user
        type: user
        score: 50
threat_objects:
    - field: subject
      type: email_subject
analytic_story:
    - Spearphishing Attachments
    - Suspicious Emails
asset_type: O365 Tenant
mitre_attack_id:
    - T1566.001
    - T1566.002
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: threat