Detection: O365 Block User Consent For Risky Apps Disabled

Updated Date: 2024-05-26 ID: 12a23592-e3da-4344-8545-205d3290647c Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects when the "risk-based step-up consent" security setting in Microsoft 365 is disabled. It monitors Azure Active Directory logs for the "Update authorization policy" operation, specifically changes to the "AllowUserConsentForRiskyApps" setting. This activity is significant because disabling this feature can expose the organization to OAuth phishing threats, allowing users to grant consent to malicious applications. If confirmed malicious, attackers could gain unauthorized access to user data and sensitive information, leading to data breaches and further compromise within the organization.

1`o365_management_activity` Workload=AzureActiveDirectory Operation="Update authorization policy." 
2| eval index_number = if(mvfind('ModifiedProperties{}.Name', "AllowUserConsentForRiskyApps") >= 0, mvfind('ModifiedProperties{}.Name', "AllowUserConsentForRiskyApps"), -1) 
3| search index_number >= 0  
4| eval AllowUserConsentForRiskyApps = mvindex('ModifiedProperties{}.NewValue',index_number) 
5| where AllowUserConsentForRiskyApps like "%true%" 
6| stats count min(_time) as firstTime max(_time) as lastTime by user, Operation, AllowUserConsentForRiskyApps, user_agent 
7| `security_content_ctime(firstTime)` 
8| `security_content_ctime(lastTime)` 
9| `o365_block_user_consent_for_risky_apps_disabled_filter`

Data Source

Name Platform Sourcetype Source Supported App
O365 Update authorization policy. N/A 'o365:management:activity' 'o365' N/A

Macros Used

Name Value
o365_management_activity sourcetype=o365:management:activity
o365_block_user_consent_for_risky_apps_disabled_filter search *
o365_block_user_consent_for_risky_apps_disabled_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
T1562 Impair Defenses Defense Evasion
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
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

Legitimate changes to the 'risk-based step-up consent' setting by administrators, perhaps as part of a policy update or security assessment, may trigger this alert, necessitating verification of the change's intent and authorization.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Risk-based step-up consent security setting was disabled by $user$ 30 60 50
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