ID | Technique | Tactic |
---|---|---|
T1586 | Compromise Accounts | Resource Development |
T1586.003 | Cloud Accounts | Resource Development |
T1078 | Valid Accounts | Defense Evasion |
T1078.004 | Cloud Accounts | Initial Access |
T1621 | Multi-Factor Authentication Request Generation | Persistence |
Detection: GCP Authentication Failed During MFA Challenge
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.
Search
1`gws_reports_login` event.name=login_failure `gws_login_mfa_methods`
2| stats count min(_time) as firstTime max(_time) as lastTime by user, src_ip, login_challenge_method
3| `gcp_authentication_failed_during_mfa_challenge_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
Google Workspace login_failure | N/A | 'gws:reports:admin' |
'gws:reports:admin' |
Macros Used
Name | Value |
---|---|
gws_login_mfa_methods | event.parameters{}.multiValue{} IN ("backup_code", "google_authenticator", "google_prompt", "idv_any_phone", "idv_preregistered_phone", "internal_two_factor", "knowledge_employee_id", "knowledge_preregistered_email", "login_location", "knowledge_preregistered_phone", "offline_otp", "security_key", "security_key_otp") |
gcp_authentication_failed_during_mfa_challenge_filter | search * |
gcp_authentication_failed_during_mfa_challenge_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 Notable | Yes |
Rule Title | %name% |
Rule Description | %description% |
Notable Event Fields | user, dest |
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. 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.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
User $user$ failed to pass MFA challenge | 54 | 60 | 90 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | gws:reports:login |
gws:reports:login |
Integration | ✅ Passing | Dataset | gws:reports: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: 5