Detection: O365 Mail Permissioned Application Consent Granted by User

Updated Date: 2024-05-14 ID: fddad083-cdf5-419d-83c6-baa85e329595 Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies instances where a user grants consent to an application requesting mail-related permissions within the Office 365 environment. It leverages O365 audit logs, specifically focusing on events related to application permissions and user consent actions. This activity is significant as it can indicate potential security risks, such as data exfiltration or spear phishing, if malicious applications gain access. If confirmed malicious, this could lead to unauthorized data access, email forwarding, or sending malicious emails from the compromised account. Validating the legitimacy of the application and consent context is crucial to prevent data breaches.

Search

 1`o365_management_activity` Workload=AzureActiveDirectory Operation="Consent to application." ResultStatus=Success 
 2| eval admin_consent =mvindex('ModifiedProperties{}.NewValue', 0) 
 3| search admin_consent=False 
 4| eval permissions =mvindex('ModifiedProperties{}.NewValue', 4) 
 5| rex field=permissions "Scope: (?<Scope>[^,]+)" 
 6| makemv delim=" " Scope 
 7| search Scope IN ("Mail.Read", "Mail.ReadBasic", "Mail.ReadWrite", "Mail.Read.Shared", "Mail.ReadWrite.Shared", "Mail.Send", "Mail.Send.Shared") 
 8| stats max(_time) as lastTime values(Scope) by Operation, user, object, ObjectId 
 9| `security_content_ctime(lastTime)` 
10| `o365_mail_permissioned_application_consent_granted_by_user_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_mail_permissioned_application_consent_granted_by_user_filter	`search *`

o365_mail_permissioned_application_consent_granted_by_user_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

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

Associated Analytic Story

Office 365 Account Takeover

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
User $user$ consented an OAuth application that requests mail-related permissions.	40	80	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