Detection: Azure AD Admin Consent Bypassed by Service Principal

Updated Date: 2024-07-02 ID: 9d4fea43-9182-4c5a-ada8-13701fd5615d Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies instances where a service principal in Azure Active Directory assigns app roles without standard admin consent. It uses Entra ID logs from the azure_monitor_aad data source, focusing on the "Add app role assignment to service principal" operation. This detection is significant as it highlights potential bypasses of critical administrative consent processes, which could lead to unauthorized privileges being granted. If confirmed malicious, this activity could allow attackers to exploit automation to assign sensitive permissions without proper oversight, potentially compromising the security of the Azure AD environment.

 1`azure_monitor_aad` (operationName="Add app role assignment to service principal" OR operationName="Add member to role*") src_user_type=servicePrincipal  
 2| rename properties.* as *   
 3| eval roleId = mvindex('targetResources{}.modifiedProperties{}.newValue', 0)  
 4| eval roleValue = mvindex('targetResources{}.modifiedProperties{}.newValue', 1)  
 5| eval roleDescription = mvindex('targetResources{}.modifiedProperties{}.newValue', 2)  
 6| eval user_id = mvindex('targetResources{}.id', 0), user=coalesce(user,mvindex('targetResources{}.displayName', 0)) 
 7| rename initiatedBy.app.displayName as src_user  
 8| stats count earliest(_time) as firstTime latest(_time) as lastTime by src_user user user_id roleId roleValue roleDescription 
 9| `security_content_ctime(firstTime)` 
10| `security_content_ctime(lastTime)`  
11| `azure_ad_admin_consent_bypassed_by_service_principal_filter`

Data Source

Name Platform Sourcetype Source Supported App
Azure Active Directory Add app role assignment to service principal Azure icon Azure 'azure:monitor:aad' 'Azure AD' N/A

Macros Used

Name Value
azure_monitor_aad sourcetype=azure:monitor:aad
azure_ad_admin_consent_bypassed_by_service_principal_filter search *
azure_ad_admin_consent_bypassed_by_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
T1098.003 Additional Cloud Roles Persistence
KillChainPhase.EXPLOITAITON
KillChainPhase.INSTALLATION
NistCategory.DE_CM
Cis18Value.CIS_10
LAPSUS$
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 the latest version of Splunk Add-on for Microsoft Cloud Services from Splunkbase(https://splunkbase.splunk.com/app/3110/#/details). You must be ingesting Azure Active Directory events into your Splunk environment. This analytic was written to be used with the azure:monitor:aad sourcetype leveraging the Auditlog log category

Known False Positives

Service Principals are sometimes configured to legitimately bypass the consent process for purposes of automation. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Service principal $src_user$ bypassed the admin consent process and granted permissions to $user$ 54 90 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 Azure AD azure:monitor:aad
Integration ✅ Passing Dataset Azure AD azure:monitor:aad

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