O365 Admin Consent Bypassed by Service Principal

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Description

This detection targets situations where a service principal in Office 365 Azure Active Directory assigns app roles without the standard admin consent, a potential security breach. Using o365_management_activity logs, it examines the 'Add app role assignment to service principal' operation, focusing on service principals and extracting details like role ID and description. This is critical for SOCs to detect potential bypassing of crucial administrative controls, which could lead to unauthorized access or privilege escalation. A true positive implies a service principal might be misusing automated processes to assign sensitive permissions.

• Type: TTP

• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

• Last Updated: 2024-02-09
• Author: Mauricio Velazco, Splunk
• ID: 8a1b22eb-50ce-4e26-a691-97ff52349569

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1098.003	Additional Cloud Roles	Persistence, Privilege Escalation

Kill Chain Phase

• Installation
• Exploitation

NIST

• DE.CM

CIS20

• CIS 10

CVE

Search

`o365_management_activity` Workload=AzureActiveDirectory Operation="Add app role assignment to service principal." 
| eval len=mvcount('Actor{}.ID') 
| eval userType = mvindex('Actor{}.ID',len-1) 
| eval roleId = mvindex('ModifiedProperties{}.NewValue', 0) 
| eval roleValue = mvindex('ModifiedProperties{}.NewValue', 1) 
| eval roleDescription = mvindex('ModifiedProperties{}.NewValue', 2) 
| eval dest_user = mvindex('Target{}.ID', 0) 
| search userType = "ServicePrincipal" 
| eval src_user = user 
| stats count earliest(_time) as firstTime latest(_time) as lastTime by src_user dest_user roleId roleValue roleDescription 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)`  
| `o365_admin_consent_bypassed_by_service_principal_filter`

Macros

The SPL above uses the following Macros:

• o365_management_activity
• security_content_ctime

o365_admin_consent_bypassed_by_service_principal_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

• _time
• Workload
• Operation
• Actor{}.ID
• ModifiedProperties{}.NewValue
• src_user
• dest_user

How To Implement

You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events.

Known False Positives

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

Associated Analytic Story

• Office 365 Persistence Mechanisms

RBA

Risk Score	Impact	Confidence	Message
54.0	90	60	Service principal $src_user$ bypassed the admin consent process and granted permissions to $dest_user$

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

Reference

• https://attack.mitre.org/techniques/T1098/003/
• https://msrc.microsoft.com/blog/2024/01/microsoft-actions-following-attack-by-nation-state-actor-midnight-blizzard/
• https://www.microsoft.com/en-us/security/blog/2024/01/25/midnight-blizzard-guidance-for-responders-on-nation-state-attack/
• https://attack.mitre.org/techniques/T1098/002/
• https://www.microsoft.com/en-us/security/blog/2024/01/25/midnight-blizzard-guidance-for-responders-on-nation-state-attack/
• https://winsmarts.com/how-to-grant-admin-consent-to-an-api-programmatically-e32f4a100e9d

Test Dataset

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

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