Detection: O365 Email Reported By Admin Found Malicious

Updated Date: 2024-11-14 ID: 94396c3e-7728-422a-9956-e4b77b53dbdf Author: Steven Dick Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects when an email manually submitted to Microsoft through the Security & Compliance portal is found to be malicious. This capability is an enhanced protection feature that can be used within o365 tenants by administrative users to report potentially malicious emails. This correlation looks for any submission that returns a Phish or Malware verdict upon submission.

1`o365_management_activity` Workload=SecurityComplianceCenter Operation=AdminSubmission 
2| search RescanVerdict IN (Phish,Malware) 
3| stats values(Subject) as subject, values(RescanVerdict) as result, values(SenderIP) as src, values(P2Sender) as sender, values(P1Sender) as src_user, values(Recipients{}) as user, count min(_time) as firstTime, max(_time) as lastTime, by Id,Operation,UserId 
4| rename Name as signature, Id as signature_id, UserId as o365_adminuser 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)` 
7| `o365_email_reported_by_admin_found_malicious_filter`

Data Source

No data sources specified for this detection.

Macros Used

Name Value
o365_management_activity sourcetype=o365:management:activity
o365_email_reported_by_admin_found_malicious_filter search *
o365_email_reported_by_admin_found_malicious_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1566 Phishing Initial Access
T1566.001 Spearphishing Attachment Initial Access
T1566.002 Spearphishing Link Initial Access
Delivery
DE.CM
CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

You must install splunk Microsoft Office 365 add-on. This search works with o365:management:activity

Known False Positives

Administrators that submit known phishing training exercises.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

O365 security admin $o365_adminuser$ manually reported a suspicious email from $src_user$

Risk Object Risk Object Type Risk Score Threat Objects
src_user user 50 subject
user user 50 subject

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset o365 o365:management:activity
Integration ✅ Passing Dataset o365 o365:management:activity

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 3