Azure AD FullAccessAsApp Permission Assigned

name: Azure AD FullAccessAsApp Permission Assigned
id: ae286126-f2ad-421c-b240-4ea83bd1c43a
version: 10
creation_date: '2024-02-14'
modification_date: '2026-05-13'
author: Mauricio Velazco, Splunk
status: production
type: TTP
description: The following analytic detects the assignment of the 'full_access_as_app' permission to an application within Office 365 Exchange Online. This is identified by the GUID 'dc890d15-9560-4a4c-9b7f-a736ec74ec40' and the ResourceAppId '00000002-0000-0ff1-ce00-000000000000'. The detection leverages the azure_monitor_aad data source, focusing on AuditLogs with the operation name 'Update application'. This activity is significant as it grants broad control over Office 365 operations, including full access to all mailboxes and the ability to send emails as any user. If malicious, this could lead to unauthorized access and data exfiltration.
data_source:
    - Azure Active Directory Update application
search: "`azure_monitor_aad` category=AuditLogs operationName=\"Update application\" | eval newvalue = mvindex('properties.targetResources{}.modifiedProperties{}.newValue',0) | spath input=newvalue | search \"{}.ResourceAppId\"=\"00000002-0000-0ff1-ce00-000000000000\" \"{}.RequiredAppPermissions{}.EntitlementId\"=\"dc890d15-9560-4a4c-9b7f-a736ec74ec40\" | eval Permissions = '{}.RequiredAppPermissions{}.EntitlementId' | rename properties.userAgent as user_agent | fillnull | stats count min(_time) as firstTime max(_time) as lastTime by dest user src vendor_account vendor_product user_agent Permissions object signature | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `azure_ad_fullaccessasapp_permission_assigned_filter`"
how_to_implement: 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 through an EventHub. This analytic was written to be used with the azure:monitor:aad sourcetype leveraging the AuditLogs log category.
known_false_positives: The full_access_as_app API permission may be assigned to legitimate applications. Filter as needed.
references:
    - 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/
finding:
    title: User $user$ assigned the full_access_as_app permission to the app registration $object$
    entity:
        field: user
        type: user
        score: 50
analytic_story:
    - Azure Active Directory Persistence
    - NOBELIUM Group
asset_type: Azure Active Directory
mitre_attack_id:
    - T1098.002
    - T1098.003
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: threat