O365 User Consent Denied for OAuth Application

name: O365 User Consent Denied for OAuth Application
id: 2d8679ef-b075-46be-8059-c25116cb1072
version: 11
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 has denied consent to an OAuth application seeking permissions within the Office 365 environment. This detection leverages O365 audit logs, focusing on events related to user consent actions. By filtering for denied consent actions associated with OAuth applications, it captures instances where users have actively rejected permission requests. This activity is significant as it may indicate users spotting potentially suspicious or unfamiliar applications. If confirmed malicious, it suggests an attempt by a potentially harmful application to gain unauthorized access, which was proactively blocked by the user.
data_source:
    - O365
search: |-
    `o365_graph` status.errorCode=65004
      | rename userPrincipalName as user
      | rename ipAddress as src_ip
      | stats min(_time) as firstTime max(_time) as lastTime
        BY user src_ip appDisplayName
           status.failureReason
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `o365_user_consent_denied_for_oauth_application_filter`
how_to_implement: You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 events.
known_false_positives: OAuth applications that require mail 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/azure/active-directory/manage-apps/protect-against-consent-phishing
    - 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 $user$ denifed consent for an OAuth application.
    entity:
        field: user
        type: user
        score: 50
threat_objects:
    - field: src_ip
      type: ip_address
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_declined/o365_user_consent_declined.log
          source: o365
          sourcetype: o365:graph:api
      test_type: unit