The "AWS Root Login Without MFA" rule is designed to detect attempts to log in to the AWS root user account without employing multi-factor authentication (MFA), which is a crucial security best practice recommended by Amazon Web Services (AWS). By monitoring AWS CloudTrail logs, this rule identifies any successful login events to the root account where MFA was not used, signaling a potential security risk. The root account holds complete administrative access, and as such, it should be protected with MFA to prevent unauthorized access. The rule helps organizations adhere to best practices by alerting when these sensitive logins occur without the additional MFA layer, which can significantly enhance account security. The investigation process encourages analysts to review other related alerts, user behavior, command actions, and the context surrounding the login attempts. In the event of a detection, the guidance provided includes steps for incident response, remediation actions, and configuring MFA for the root user.