O365 File Permissioned Application Consent Granted by User

SPLUNK detection rule by Mauricio Velazco, Splunk · Apache-2.0

The following analytic identifies instances where a user in the Office 365 environment grants consent to an application requesting file permissions for OneDrive or SharePoint. It leverages O365 audit logs, focusing on OAuth application consent events. This activity is significant because granting such permissions can allow applications to access, modify, or delete files, posing a risk if the application is malicious or overly permissive. If confirmed malicious, this could lead to data breaches, data loss, or unauthorized data manipulation, necessitating immediate investigation to validate the application's legitimacy and assess potential risks.

name: O365 File Permissioned Application Consent Granted by User
id: 6c382336-22b8-4023-9b80-1689e799f21f
version: 9
creation_date: '2023-12-06'
modification_date: '2026-05-13'
author: Mauricio Velazco, Splunk
status: production
type: TTP
description: The following analytic identifies instances where a user in the Office 365 environment grants consent to an application requesting file permissions for OneDrive or SharePoint. It leverages O365 audit logs, focusing on OAuth application consent events. This activity is significant because granting such permissions can allow applications to access, modify, or delete files, posing a risk if the application is malicious or overly permissive. If confirmed malicious, this could lead to data breaches, data loss, or unauthorized data manipulation, necessitating immediate investigation to validate the application's legitimacy and assess potential risks.
data_source:
    - O365 Consent to application.
search: "`o365_management_activity` Workload=AzureActiveDirectory Operation=\"Consent to application.\" ResultStatus=Success | eval admin_consent =mvindex('ModifiedProperties{}.NewValue',0) | search admin_consent=False | eval permissions =mvindex('ModifiedProperties{}.NewValue',4) | rex field=permissions \"Scope:(?<Scope>[^,]+)\" | makemv delim=\" \" Scope | search Scope IN (\"Files.Read\", \"Files.Read.All\", \"Files.ReadWrite\", \"Files.ReadWrite.All\", \"Files.ReadWrite.AppFolder\") | fillnull | stats count min(_time) as firstTime max(_time) as lastTime values(Scope) as Scope by signature dest user src vendor_account vendor_product object ObjectId | `security_content_ctime(lastTime)` | `o365_file_permissioned_application_consent_granted_by_user_filter`"
how_to_implement: You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events.
known_false_positives: OAuth applications that require file permissions may be legitimate, investigate and filter as needed.
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/defender-cloud-apps/investigate-risky-oauth
    - https://www.alteredsecurity.com/post/introduction-to-365-stealer
    - https://github.com/AlteredSecurity/365-Stealer
drilldown_searches:
    - name: View the detection results for - "$user$"
      search: '%original_detection_search% | search  user = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: User $user$ consented an OAuth application that requests file-related permissions.
    entity:
        field: user
        type: user
        score: 50
analytic_story:
    - Office 365 Account Takeover
asset_type: O365 Tenant
mitre_attack_id:
    - T1528
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: identity
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1528/o365_user_consent_file_permissions/o365_user_consent_file_permissions.log
          source: o365
          sourcetype: o365:management:activity
      test_type: unit

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

89da0fe0-3d6e-4d99-b189-2f17a572eb9a

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