GCP Multiple Users Failing To Authenticate From Ip

Description

The following analytic detects a single source IP address failing to authenticate into more than 20 unique Google Workspace user accounts within a 5-minute window. It leverages Google Workspace login failure events to identify potential password spraying attacks. This activity is significant as it may indicate an adversary attempting to gain unauthorized access or elevate privileges within the Google Cloud Platform. If confirmed malicious, this behavior could lead to unauthorized access to sensitive resources, data breaches, or further exploitation within the environment.

Query · spl

`gws_reports_login` event.type = login event.name = login_failure
  | bucket span=5m _time
  | stats count dc(user) AS unique_accounts values(user) as tried_accounts values(authentication_method) AS authentication_method earliest(_time) as firstTime latest(_time) as lastTime
    BY _time event.name src
       app id.applicationName
  | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)`
  | where unique_accounts > 20
  | `gcp_multiple_users_failing_to_authenticate_from_ip_filter`

Implementation guide

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 unique_accounts threshold values according to your environment. Specifically, this analytic leverages the User log events.

Known false positives

  • No known false postives for this detection. Please review this alert.

Analyst notes

Known false positives: No known false postives for this detection. Please review this alert.

Raw source GCP Multiple Users Failing To Authenticate From Ip · SPL
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Published by splunk/security_content ↗, licensed under Apache 2.0 ↗. Reproduced here unmodified. 
name: GCP Multiple Users Failing To Authenticate From Ip
id: da20828e-d6fb-4ee5-afb7-d0ac200923d5
version: 11
creation_date: '2022-10-12'
modification_date: '2026-05-13'
author: Bhavin Patel, Splunk
status: production
type: Anomaly
description: The following analytic detects a single source IP address failing to authenticate into more than 20 unique Google Workspace user accounts within a 5-minute window. It leverages Google Workspace login failure events to identify potential password spraying attacks. This activity is significant as it may indicate an adversary attempting to gain unauthorized access or elevate privileges within the Google Cloud Platform. If confirmed malicious, this behavior could lead to unauthorized access to sensitive resources, data breaches, or further exploitation within the environment.
data_source:
    - Google Workspace
search: |-
    `gws_reports_login` event.type = login event.name = login_failure
      | bucket span=5m _time
      | stats count dc(user) AS unique_accounts values(user) as tried_accounts values(authentication_method) AS authentication_method earliest(_time) as firstTime latest(_time) as lastTime
        BY _time event.name src
           app id.applicationName
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | where unique_accounts > 20
      | `gcp_multiple_users_failing_to_authenticate_from_ip_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 `unique_accounts` threshold values according to your environment. Specifically, this analytic leverages the User log events.
known_false_positives: No known false postives for this detection. Please review this alert.
references:
    - https://cloud.google.com/blog/products/identity-security/how-google-cloud-can-help-stop-credential-stuffing-attacks
    - https://www.slideshare.net/dafthack/ok-google-how-do-i-red-team-gsuite
    - https://attack.mitre.org/techniques/T1110/003/
    - https://www.blackhillsinfosec.com/wp-content/uploads/2020/05/Breaching-the-Cloud-Perimeter-Slides.pdf
drilldown_searches:
    - name: View the detection results for - "$tried_accounts$"
      search: '%original_detection_search% | search  tried_accounts = "$tried_accounts$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$tried_accounts$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$tried_accounts$") | 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"
intermediate_findings:
    entities:
        - field: tried_accounts
          type: user
          score: 20
          message: 'Multiple failed login attempts (Count: $unique_accounts$) against users seen from $src$'
threat_objects:
    - field: src
      type: ip_address
analytic_story:
    - GCP Account Takeover
asset_type: Google Cloud Platform tenant
mitre_attack_id:
    - T1110.003
    - T1110.004
    - T1586.003
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: threat
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1110.003/gcp_gws_multiple_login_failure/gws_login.json
          source: gws_login
          sourcetype: gws:reports:login
      test_type: unit

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