Detection rules › Splunk
GCP Multiple Failed MFA Requests For User
The following analytic detects multiple failed multi-factor authentication (MFA) requests for a single user within a Google Cloud Platform (GCP) tenant. It triggers when 10 or more MFA prompts fail within a 5-minute window, using Google Workspace login failure events. This behavior is significant as it may indicate an adversary attempting to bypass MFA by bombarding the user with repeated authentication requests. If confirmed malicious, this activity could lead to unauthorized access, allowing attackers to compromise accounts and potentially escalate privileges 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 Multiple Failed MFA Requests For User
id: cbb3cb84-c06f-4393-adcc-5cb6195621f1
version: 12
creation_date: '2022-08-25'
modification_date: '2026-05-13'
author: Mauricio Velazco, Splunk
status: production
type: TTP
description: The following analytic detects multiple failed multi-factor authentication (MFA) requests for a single user within a Google Cloud Platform (GCP) tenant. It triggers when 10 or more MFA prompts fail within a 5-minute window, using Google Workspace login failure events. This behavior is significant as it may indicate an adversary attempting to bypass MFA by bombarding the user with repeated authentication requests. If confirmed malicious, this activity could lead to unauthorized access, allowing attackers to compromise accounts and potentially escalate privileges within the GCP environment.
data_source:
- Google Workspace
search: |-
`gws_reports_login` event.name=login_failure `gws_login_mfa_methods`
| bucket span=5m _time
| stats dc(_raw) AS mfa_prompts values(user) AS user
BY src_ip, login_challenge_method, _time
| where mfa_prompts >= 10
| `gcp_multiple_failed_mfa_requests_for_user_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. We would also recommend tuning the detection by adjusting the window `span` and `mfa_prompts` threshold values according to your environment. Specifically, this analytic leverages the User log events.
known_false_positives: Multiple Failed MFA requests may also be a sign of authentication or application issues. Filter as needed.
references:
- https://www.mandiant.com/resources/blog/russian-targeting-gov-business
- https://arstechnica.com/information-technology/2022/03/lapsus-and-solar-winds-hackers-both-use-the-same-old-trick-to-bypass-mfa/
- https://therecord.media/russian-hackers-bypass-2fa-by-annoying-victims-with-repeated-push-notifications/
- 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: Multiple Failed MFA requests for user $user$
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/multiple_failed_mfa_gws/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: bucket
| bucket span=5m _time
Stage 3: stats
| stats dc(_raw) AS mfa_prompts values(user) AS user
BY src_ip, login_challenge_method, _time
Stage 4: where
| where mfa_prompts >= 10
Stage 5: search
| `gcp_multiple_failed_mfa_requests_for_user_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 |
|
mfa_prompts | ge |
|
sourcetype | eq |
|