Detection rules › Splunk
GCP Authentication Failed During MFA Challenge
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.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Resource Development | T1586.003 Compromise Accounts: Cloud Accounts |
| Initial Access | T1078.004 Valid Accounts: Cloud Accounts |
| Persistence | T1078.004 Valid Accounts: Cloud Accounts |
| Privilege Escalation | T1078.004 Valid Accounts: Cloud Accounts |
| Stealth | T1078.004 Valid Accounts: Cloud Accounts |
| Credential Access | T1621 Multi-Factor Authentication Request Generation |
Rules detecting the same action
Other rules on this platform that filter on the same API call or operation.
Rule body splunk
name: GCP Authentication Failed During MFA Challenge
id: 345f7e1d-a3fe-4158-abd8-e630f9878323
version: 13
creation_date: '2022-10-14'
modification_date: '2026-05-13'
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 ("$user$") | 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 $user$ failed to pass MFA challenge
entity:
field: user
type: user
score: 50
threat_objects:
- field: src_ip
type: ip_address
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
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/T1621/gcp_failed_mfa/gws_login.log
source: gws:reports:login
sourcetype: gws:reports:login
test_type: unit
Stages and Predicates
Stage 1: search
`gws_reports_login` event.name=login_failure `gws_login_mfa_methods`
Stage 2: stats
| stats count min(_time) as firstTime max(_time) as lastTime
BY user, src_ip, login_challenge_method
Stage 3: search
| `gcp_authentication_failed_during_mfa_challenge_filter`
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
event.name | eq |
|
event.parameters{}.multiValue{} | in |
|
sourcetype | eq |
|