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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.

  • Type: Anomaly

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-22
  • Author: Bhavin Patel, Splunk
  • ID: da20828e-d6fb-4ee5-afb7-d0ac200923d5

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1586 Compromise Accounts Resource Development
T1586.003 Cloud Accounts Resource Development
T1110 Brute Force Credential Access
T1110.003 Password Spraying Credential Access
T1110.004 Credential Stuffing Credential Access
Kill Chain Phase
  • Weaponization
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`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`

Macros

The SPL above uses the following Macros:

:information_source: gcp_multiple_users_failing_to_authenticate_from_ip_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • event.name
  • event.type
  • authentication_method
  • app
  • id.applicationName
  • src

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.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
54.0 60 90 Multiple failed login attempts (Count: $unique_accounts$) against users seen from $src$

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 2