Detection: O365 Added Service Principal

Description

The following analytic detects the addition of new service principal accounts in O365 tenants. It leverages data from the o365_management_activity dataset, specifically monitoring for operations related to adding or creating service principals. This activity is significant because attackers can exploit service principals to gain unauthorized access and perform malicious actions within an organization's environment. If confirmed malicious, this could allow attackers to interact with APIs, access resources, and execute operations on behalf of the organization, potentially leading to data breaches or further compromise.

1`o365_management_activity` Workload=AzureActiveDirectory Operation="*Add service principal*" OR (Operation = "*principal*" AND action = "created") 
2| stats count values(ModifiedProperties{}.NewValue) as new_value by src_user src_user_type action Operation authentication_service Workload 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `o365_added_service_principal_filter`

Data Source

Name Platform Sourcetype Source
O365 N/A 'o365:management:activity' 'o365'

Macros Used

Name Value
o365_management_activity sourcetype=o365:management:activity
o365_added_service_principal_filter search *
o365_added_service_principal_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
T1136.003 Cloud Account Persistence
T1136 Create Account Persistence
KillChainPhase.INSTALLATION
NistCategory.DE_CM
Cis18Value.CIS_10
APT29
LAPSUS$
Indrik Spider
Scattered 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 splunk Microsoft Office 365 add-on. This search works with o365:management:activity

Known False Positives

The creation of a new Federation is not necessarily malicious, however these events need to be followed closely, as it may indicate federated credential abuse or backdoor via federated identities at a different cloud provider.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
User $src_user$ has created new service principal $new_value$ in AzureActiveDirectory 42 70 60
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: 5