Detection: O365 Application Available To Other Tenants

Updated Date: 2024-09-24 ID: 942548a3-0273-47a4-8dbd-e5202437395c Author: Steven Dick Type: TTP Product: Splunk Enterprise Security

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.

1`o365_management_activity` Workload=AzureActiveDirectory Operation IN ("Add application.","Update application.") ModifiedProperties{}.Name=AvailableToOtherTenants 
2| 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)) 
3| search result = "added" 
4| stats values(ActorIpAddress) as src, count, min(_time) as firstTime, max(_time) as lastTime by signature, user, object, object_name, object_attrs, result 
5| `security_content_ctime(firstTime)`  
6| `security_content_ctime(lastTime)` 
7| `o365_application_available_to_other_tenants_filter`

Data Source

Name Platform Sourcetype Source Supported App
N/A N/A N/A N/A N/A

Macros Used

Name Value
o365_management_activity sourcetype=o365:management:activity
o365_application_available_to_other_tenants_filter search *
o365_application_available_to_other_tenants_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
T1098 Account Manipulation Privilege Escalation
KillChainPhase.EXPLOITAITON
KillChainPhase.INSTALLATION
NistCategory.DE_CM
Cis18Value.CIS_10
LAPSUS$
Scattered Spider
APT3
APT41
APT5
Dragonfly
FIN13
HAFNIUM
Kimsuky
Lazarus Group
Magic Hound

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 Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events.

Known False Positives

Business approved changes by known administrators.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
An Azure Application [$object_name$] was configured by [$user$] as accessible to external tenants. 50 50 100
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: 2