Detection: Azure AD OAuth Application Consent Granted By User

Description

The following analytic detects when a user in an Azure AD environment grants consent to an OAuth application. It leverages Azure AD audit logs to identify events where users approve application consents. This activity is significant as it can expose organizational data to third-party applications, a common tactic used by malicious actors to gain unauthorized access. If confirmed malicious, this could lead to unauthorized access to sensitive information and resources. Immediate investigation is required to validate the application's legitimacy, review permissions, and mitigate potential risks.

Search

1`azure_monitor_aad` operationName="Consent to application" properties.result=success 
2| rename properties.* as *  
3| eval permissions_index = if(mvfind('targetResources{}.modifiedProperties{}.displayName', "ConsentAction.Permissions") >= 0, mvfind('targetResources{}.modifiedProperties{}.displayName', "ConsentAction.Permissions"), -1) 
4| eval permissions = mvindex('targetResources{}.modifiedProperties{}.newValue',permissions_index) 
5| rex field=permissions "Scope: (?<Scope>[^,]+)" 
6| stats count min(_time) as firstTime max(_time) as lastTime by operationName, user, Scope 
7| `security_content_ctime(firstTime)` 
8| `security_content_ctime(lastTime)` 
9| `azure_ad_oauth_application_consent_granted_by_user_filter`

Data Source

Name	Platform	Sourcetype	Source
Azure Active Directory Consent to application	Azure	'azure:monitor:aad'	'Azure AD'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

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 AuditLog log category.

Known False Positives

False positives may occur if users are granting consents as part of legitimate application integrations or setups. It is crucial to review the application and the permissions it requests to ensure they align with organizational policies and security best practices.

Associated Analytic Story

• Azure Active Directory Account Takeover

Risk Based Analytics (RBA)

References

• https://attack.mitre.org/techniques/T1528/

• https://www.microsoft.com/en-us/security/blog/2022/09/22/malicious-oauth-applications-used-to-compromise-email-servers-and-spread-spam/

• https://learn.microsoft.com/en-us/azure/active-directory/manage-apps/protect-against-consent-phishing

• https://learn.microsoft.com/en-us/defender-cloud-apps/investigate-risky-oauth

• https://www.alteredsecurity.com/post/introduction-to-365-stealer

• https://github.com/AlteredSecurity/365-Stealer

Detection Testing

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: 4