Detection: O365 User Consent Blocked for Risky Application

Updated Date: 2024-05-26 ID: 242e4d30-cb59-4051-b0cf-58895e218f40 Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies instances where Office 365 has blocked a user's attempt to grant consent to an application deemed risky or potentially malicious. This detection leverages O365 audit logs, specifically focusing on failed user consent actions due to 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 O365's security measures successfully prevented a harmful application from accessing organizational data, warranting immediate investigation.

Search

1`o365_management_activity` Workload=AzureActiveDirectory Operation="Consent to application." ResultStatus=Failure 
2| eval permissions =mvindex('ModifiedProperties{}.NewValue', 4) 
3| eval reason =mvindex('ModifiedProperties{}.NewValue', 5) 
4|  search reason = "Risky application detected" 
5| rex field=permissions "Scope: (?<Scope>[^,]+)" 
6|  stats max(_time) as lastTime by Operation, user, reason, object, Scope 
7| `security_content_ctime(lastTime)` 
8| `o365_user_consent_blocked_for_risky_application_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
O365 Consent to application.	N/A	`'o365:management:activity'`	`'o365'`	N/A

Macros Used

Name	Value
o365_management_activity	`sourcetype=o365:management:activity`
o365_user_consent_blocked_for_risky_application_filter	`search *`

o365_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 Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events.

Known False Positives

Microsofts algorithm to identify risky applications is unknown and may flag legitimate applications.

Associated Analytic Story

Office 365 Account Takeover

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
O365 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	`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