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 |
Detection: GCP Unusual Number of Failed Authentications From Ip
Description
The following analytic identifies a single source IP failing to authenticate into Google Workspace with multiple valid users, potentially indicating a Password Spraying attack. It uses Google Workspace login failure events and calculates the standard deviation for source IPs, applying the 3-sigma rule to detect unusual failed authentication attempts. This activity is significant as it may signal an adversary attempting to gain initial access or elevate privileges. If confirmed malicious, this could lead to unauthorized access, data breaches, or further exploitation within the environment.
Search
1`gws_reports_login` event.type = login event.name = login_failure
2| bucket span=5m _time
3| stats dc(user_name) AS unique_accounts values(user_name) as tried_accounts values(authentication_method) AS authentication_method by _time, src
4| eventstats avg(unique_accounts) as ip_avg , stdev(unique_accounts) as ip_std by _time
5| eval upperBound=(ip_avg+ip_std*3)
6| eval isOutlier=if(unique_accounts > 10 and unique_accounts >= upperBound, 1, 0)
7| where isOutlier =1
8| `gcp_unusual_number_of_failed_authentications_from_ip_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Google Workspace login_failure | N/A | 'gws:reports:admin' |
'gws:reports:admin' |
N/A |
Macros Used
Name | Value |
---|---|
gws_reports_login | sourcetype=gws:reports:login |
gcp_unusual_number_of_failed_authentications_from_ip_filter | search * |
gcp_unusual_number_of_failed_authentications_from_ip_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Risk Event | True |
Implementation
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 positives for this detection. Please review this alert
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
Unusual number of failed console login attempts (Count: $unique_accounts$) against users from IP Address - $src$ | 54 | 60 | 90 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | gws_login |
gws:reports:login |
Integration | ✅ Passing | Dataset | gws_login |
gws:reports:login |
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: GitHub | Version: 2