The CIS Benchmark recommends the use of Multi-Factor Authentication (MFA) on accounts with a console password (Section 1.2) and root accounts (1.14). Enabling MFA helps secure accounts, so conversely, the lack of MFA may result in accounts that are more easily compromised. You want to see if users are logging in without MFA.
How to use Splunk software for this use case
To deploy this use case, make sure that you have the Splunk ES Content Updates installed on your Splunk Enterprise Security deployment. This extensive content library empowers you to deploy out-of-the-box security detections and analytic stories to enhance your investigations and improve your security posture. If you do not have Splunk Enterprise Security, these detections will still give you an idea of what you can accomplish with SPL in the Splunk platform or with the free app, Splunk Security Essentials.
Some of the detections that can help you with this use case include: