Detection: O365 Email Security Feature Changed

Updated Date: 2024-04-01 ID: 4d28013d-3a0f-4d65-a33f-4e8009fee0ae Author: Steven Dick Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies when specific O365 advanced security settings are altered within the Office 365 tenant. If an attacker successfully disables O365 security settings, they can operate within the tenant with reduced risk of detection. This can lead to unauthorized data access, data exfiltration, account compromise, or other malicious activities without leaving a detailed audit trail.

1`o365_management_activity` Workload=Exchange AND Operation IN ("Set-*","Disable-*","New-*","Remove-*") Operation IN ("*AntiPhish*","*SafeLink*","*SafeAttachment*","*Malware*") 
2| stats values(ObjectId) as object, min(_time) as firstTime, max(_time) as lastTime, count  by Id, UserId, Operation 
3| rename Id as object_id, UserId as user, Operation as signature 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `o365_email_security_feature_changed_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_security_feature_changed_filter search *
o365_email_security_feature_changed_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
T1562 Impair Defenses Defense Evasion
T1562.008 Disable or Modify Cloud Logs Defense Evasion
T1562.001 Disable or Modify Tools Defense Evasion
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
Magic Hound
APT29
Aquatic Panda
BRONZE BUTLER
Ember Bear
FIN6
Gamaredon Group
Gorgon Group
Indrik Spider
Kimsuky
Lazarus Group
Magic Hound
MuddyWater
Putter Panda
Rocke
TA2541
TA505
TeamTNT
Turla
Wizard Spider

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.

Known False Positives

Administrators might alter features for troubleshooting, performance reasons, or other administrative tasks. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
An O365 security object [$object$] was altered by user $user$ using $signature$ 25 100 25
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

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