O365 Application Available To Other Tenants

name: O365 Application Available To Other Tenants
id: 942548a3-0273-47a4-8dbd-e5202437395c
version: 10
creation_date: '2024-04-13'
modification_date: '2026-05-13'
author: Steven Dick
status: production
type: TTP
description: The following analytic identifies the configuration of Azure Active Directory Applications in a manner that allows authentication from external tenants or personal accounts. This configuration can lead to inappropriate or malicious access of any data or capabilities the application is allowed to access. This detection leverages the O365 Universal Audit Log data source.
data_source:
    - Office 365 Universal Audit Log
search: "`o365_management_activity` Workload=AzureActiveDirectory Operation IN (\"Add application.\",\"Update application.\") ModifiedProperties{}.Name=AvailableToOtherTenants | eval result = case(match(mvindex('ModifiedProperties{}.NewValue',mvfind('ModifiedProperties{}.Name',\"AvailableToOtherTenants\")),\"false\"),\"removed\",true(),\"added\"), object_name=mvindex('Target{}.ID', 3), signature=Operation, object_attrs = \"AvailableToOtherTenants\", user = case(match(mvindex('Actor{}.ID',-1),\"User\"),mvindex('Actor{}.ID',0),match(mvindex('Actor{}.ID',-1),\"ServicePrincipal\"),mvindex('Actor{}.ID',3),true(),mvindex('Actor{}.ID',0)) | search result = \"added\" | fillnull | stats count min(_time) as firstTime max(_time) as lastTime by signature dest user src vendor_account vendor_product object_attrs object_name | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `o365_application_available_to_other_tenants_filter`"
how_to_implement: You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events.
known_false_positives: Business approved changes by known administrators.
references:
    - https://attack.mitre.org/techniques/T1098/
    - https://msrc.microsoft.com/blog/2023/03/guidance-on-potential-misconfiguration-of-authorization-of-multi-tenant-applications-that-use-azure-ad/
    - https://www.wiz.io/blog/azure-active-directory-bing-misconfiguration
finding:
    title: An Azure Application [$object_name$] was configured by [$user$] as accessible to external tenants.
    entity:
        field: user
        type: user
        score: 50
threat_objects:
    - field: object_name
      type: service
analytic_story:
    - Azure Active Directory Persistence
    - Azure Active Directory Account Takeover
    - Data Exfiltration
asset_type: O365 Tenant
mitre_attack_id:
    - T1098.003
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: threat