Detection: O365 Email Reported By User Found Malicious

Updated Date: 2024-04-01 ID: 7698b945-238e-4bb9-b172-81f5ca1685a1 Author: Steven Dick Type: TTP Product: Splunk Enterprise Security

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.

Search

 1`o365_management_activity` Workload=SecurityComplianceCenter  Operation=AlertEntityGenerated Name="Email reported by user as*" 
 2| fromjson Data 
 3| rename _raw AS temp etps AS _raw 
 4| extract pairdelim=";" kvdelim=":" 
 5| rename _raw AS etps temp AS _raw 
 6| search RescanVerdict IN (Phish,Malware) 
 7| rex field=tsd "\<(?<src_user>.+)\>" 
 8| eval src_user = case(isnull(src_user),tsd,true(),src_user) 
 9| stats count min(_time) as firstTime max(_time) as lastTime values(ms) as subject values(RescanVerdict) as result values(tsd) as sender values(src_user) as src_user by AlertId,AlertEntityId,Operation,Name 
10| rename Name as signature, AlertId as signature_id, AlertEntityId as user 
11| `security_content_ctime(firstTime)` 
12| `security_content_ctime(lastTime)` 
13| `o365_email_reported_by_user_found_malicious_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
N/A	N/A	N/A	N/A	N/A

Macros Used

Name	Value
o365_management_activity	`sourcetype=o365:management:activity`
o365_email_reported_by_user_found_malicious_filter	`search *`

o365_email_reported_by_user_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

KillChainPhase.DELIVERY

NistCategory.DE_CM

Cis18Value.CIS_10

Axiom

GOLD SOUTHFIELD

APT-C-36

APT1

APT12

APT19

APT28

APT29

APT30

APT32

APT33

APT37

APT38

APT39

APT41

Ajax Security Team

Andariel

BITTER

BRONZE BUTLER

BlackTech

Cobalt Group

Confucius

DarkHydrus

Darkhotel

Dragonfly

EXOTIC LILY

Elderwood

Ember Bear

FIN4

FIN6

FIN7

FIN8

Ferocious Kitten

Gallmaker

Gamaredon Group

Gorgon Group

Higaisa

Inception

IndigoZebra

Kimsuky

Lazarus Group

LazyScripter

Leviathan

Machete

Malteiro

Mofang

Molerats

MuddyWater

Mustang Panda

Naikon

Nomadic Octopus

OilRig

PLATINUM

Patchwork

RTM

Rancor

Sandworm Team

SideCopy

Sidewinder

Silence

TA2541

TA459

TA505

TA551

The White Company

Threat Group-3390

Tonto Team

Transparent Tribe

Tropic Trooper

WIRTE

Windshift

Wizard Spider

admin@338

menuPass

APT1

APT28

APT29

APT3

APT32

APT33

APT39

BlackTech

Cobalt Group

Confucius

EXOTIC LILY

Earth Lusca

Elderwood

Ember Bear

Evilnum

FIN4

FIN7

FIN8

Kimsuky

Lazarus Group

LazyScripter

Leviathan

LuminousMoth

Machete

Magic Hound

Mofang

Molerats

MuddyWater

Mustang Panda

Mustard Tempest

OilRig

Patchwork

Sandworm Team

Sidewinder

TA2541

TA505

Transparent Tribe

Turla

Windshift

Wizard Spider

ZIRCONIUM

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 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

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
The user $user$ reported an email classified as $result$ from $src_user$	75	75	100

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/submissions-outlook-report-messages?view=o365-worldwide

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: 1