The following analytic identifies an attempt to disable multi-factor authentication for a GCP user. An adversary who has obtained access to an GCP tenant may disable multi-factor authentication as a way to plant a backdoor and maintain persistence using a valid account. This way the attackers can keep persistance in the environment without adding new users.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-10-12
- Author: Mauricio Velazco, Splunk
- ID: b9bc5513-6fc1-4821-85a3-e1d81e451c83
Kill Chain Phase
- CIS 10
1 2 3 `gws_reports_admin` command=UNENROLL_USER_FROM_STRONG_AUTH | stats values(user) by _time, command, actor.email, status | `gcp_multi_factor_authentication_disabled_filter`
The SPL above uses the following Macros:
gcp_multi-factor_authentication_disabled_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
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. Specifically, this analytic leverages the Admin log events.
Known False Positives
Legitimate use case may require for users to disable MFA. Filter as needed.
Associated Analytic Story
|45.0||50||90||MFA disabled for User $user$ initiated by $actor.email$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 1