This rule is designed to detect the addition of a user to privileged groups within Active Directory, which is a serious security concern. Privileged groups have elevated rights that allow members to perform significant actions within Active Directory and on domain-joined systems. Attackers can exploit the ability to add users to these groups to maintain access and control over the environment. The rule operates using logs from Windows event logging and specifically detects any 'added-member-to-group' actions for groups such as 'Domain Admins', 'Administrators', and others with high privileges. The investigation process includes identifying who performed the action, confirming if it was legitimate, and reviewing associated alerts from the past 48 hours. It is essential to validate if the administrator had the authority to make such changes and respond appropriately to prevent potential misuse.