O365 Email Reported By User Found Malicious

Original Source: [splunk source]
Name:O365 Email Reported By User Found Malicious
id:7698b945-238e-4bb9-b172-81f5ca1685a1
version:6
date:2025-03-25
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:unknown
References:
  -https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/submissions-outlook-report-messages?view=o365-worldwide
drilldown_searches:
name:'View the detection results for - "$src_user$" and "$user$"'
search:'%original_detection_search% | search src_user = "$src_user$" user = "$user$"'
earliest_offset:'$info_min_time$'
latest_offset:'$info_max_time$'
name:'View risk events for the last 7 days for - "$src_user$" and "$user$"'
search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$src_user$", "$user$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
earliest_offset:'$info_min_time$'
latest_offset:'$info_max_time$'
tags:
  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'
  security_domain:threat

tests:
name:'True Positive Test'
 attack_data:
  data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1566/o365_various_alerts/o365_various_alerts.log
  sourcetype: o365:management:activity
  source: o365
manual_test:None