GCP Authentication Failed During MFA Challenge

name: GCP Authentication Failed During MFA Challenge
id: 345f7e1d-a3fe-4158-abd8-e630f9878323
version: 11
date: '2026-03-10'
author: Bhavin Patel, Mauricio Velazco, Splunk
status: production
type: TTP
description: The following analytic detects failed authentication attempts during the Multi-Factor Authentication (MFA) challenge on a Google Cloud Platform (GCP) tenant. It uses Google Workspace login failure events to identify instances where MFA methods were challenged but not successfully completed. This activity is significant as it may indicate an adversary attempting to access an account with compromised credentials despite MFA protection. If confirmed malicious, this could lead to unauthorized access attempts, potentially compromising sensitive data and resources within the GCP environment.
data_source:
    - Google Workspace login_failure
search: |-
    `gws_reports_login` event.name=login_failure `gws_login_mfa_methods`
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY user, src_ip, login_challenge_method
      | `gcp_authentication_failed_during_mfa_challenge_filter`
how_to_implement: You must install the latest version of Splunk Add-on for Google Workspace from Splunkbase (https://splunkbase.splunk.com/app/5556) which allows Splunk administrators to collect Google Workspace event data in Splunk using Google Workspace APIs. Specifically, this analytic leverages the User log events.
known_false_positives: Legitimate users may miss to reply the MFA challenge within the time window or deny it by mistake.
references:
    - https://attack.mitre.org/techniques/T1621/
    - https://attack.mitre.org/techniques/T1078/004/
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 ("$user$") starthoursago=168  | 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: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: User $user$ failed to pass MFA challenge
    risk_objects:
        - field: user
          type: user
          score: 50
    threat_objects:
        - field: src_ip
          type: ip_address
tags:
    analytic_story:
        - GCP Account Takeover
        - Scattered Lapsus$ Hunters
    asset_type: Google Cloud Platform tenant
    mitre_attack_id:
        - T1078.004
        - T1586.003
        - T1621
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: identity
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1621/gcp_failed_mfa/gws_login.log
          source: gws:reports:login
          sourcetype: gws:reports:login