Detection: O365 User Consent Denied for OAuth Application

Updated Date: 2024-09-24 ID: 2d8679ef-b075-46be-8059-c25116cb1072 Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies instances where a user has denied consent to an OAuth application seeking permissions within the Office 365 environment. This detection leverages O365 audit logs, focusing on events related to user consent actions. By filtering for denied consent actions associated with OAuth applications, it captures instances where users have actively rejected permission requests. This activity is significant as it may indicate users spotting potentially suspicious or unfamiliar applications. If confirmed malicious, it suggests an attempt by a potentially harmful application to gain unauthorized access, which was proactively blocked by the user.

1`o365_graph` status.errorCode=65004 
2| rename userPrincipalName as user 
3| rename ipAddress as src_ip 
4| stats max(_time) as lastTime by user src_ip appDisplayName status.failureReason 
5| `security_content_ctime(lastTime)` 
6| `o365_user_consent_denied_for_oauth_application_filter`

Data Source

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

Macros Used

Name Value
o365_graph sourcetype=o365:graph:api
o365_user_consent_denied_for_oauth_application_filter search *
o365_user_consent_denied_for_oauth_application_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
T1528 Steal Application Access Token Credential Access
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
APT28
APT29

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 events.

Known False Positives

OAuth applications that require mail permissions may be legitimate, investigate and filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
User $user$ denifed consent for an OAuth application. 30 30 100
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:graph:api
Integration ✅ Passing Dataset o365 o365:graph:api

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: 3