Detection: Azure AD User Consent Blocked for Risky Application

Description

The following analytic detects instances where Azure AD has blocked a user's attempt to grant consent to a risky or potentially malicious application. This detection leverages Azure AD audit logs, focusing on user consent actions and system-driven blocks. Monitoring these blocked consent attempts is crucial as it highlights potential threats early on, indicating that a user might be targeted or that malicious applications are attempting to infiltrate the organization. If confirmed malicious, this activity suggests that Azure's security measures successfully prevented a harmful application from accessing organizational data, warranting immediate investigation to understand the context and take preventive measures.

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

Data Source

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

Macros Used

Name Value
azure_monitor_aad sourcetype=azure:monitor:aad
azure_ad_user_consent_blocked_for_risky_application_filter search *
azure_ad_user_consent_blocked_for_risky_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 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

UPDATE_KNOWN_FALSE_POSITIVES

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Azure AD has blocked $user$ attempt to grant to consent to an application deemed risky. 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 Azure AD azure:monitor:aad
Integration ✅ Passing Dataset Azure AD azure:monitor:aad

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