Detection: O365 ApplicationImpersonation Role Assigned

Updated Date: 2024-05-23 ID: 49cdce75-f814-4d56-a7a4-c64ec3a481f2 Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the assignment of the ApplicationImpersonation role in Office 365 to a user or application. It uses the Office 365 Management Activity API to monitor Azure Active Directory audit logs for role assignment events. This activity is significant because the ApplicationImpersonation role allows impersonation of any user, enabling access to and modification of their mailbox. If confirmed malicious, an attacker could gain unauthorized access to sensitive information, manipulate mailbox data, and perform actions as a legitimate user, posing a severe security risk to the organization.

1`o365_management_activity` Workload=Exchange Operation="New-ManagementRoleAssignment"  Role=ApplicationImpersonation 
2|  rename User as target_user 
3| stats  max(_time) as lastTime by Operation, user, object, ObjectId, Role, target_user 
4| `security_content_ctime(lastTime)` 
5| `o365_applicationimpersonation_role_assigned_filter`

Data Source

Name Platform Sourcetype Source Supported App
O365 N/A 'o365:management:activity' 'o365' N/A

Macros Used

Name Value
o365_management_activity sourcetype=o365:management:activity
o365_applicationimpersonation_role_assigned_filter search *
o365_applicationimpersonation_role_assigned_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 Account Manipulation Persistence
T1098.002 Additional Email Delegate Permissions Privilege Escalation
KillChainPhase.EXPLOITAITON
KillChainPhase.INSTALLATION
NistCategory.DE_CM
Cis18Value.CIS_10
APT3
APT41
APT5
Dragonfly
FIN13
HAFNIUM
Kimsuky
Lazarus Group
Magic Hound
APT28
APT29
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

While infrequent, the ApplicationImpersonation role may be granted for leigimate reasons, filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
$user$ granted the ApplicationImpersonation role to $target_user$ 56 80 70
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