This detection rule targets user accounts that are newly created or renamed with a '$' character in their names on Windows systems. The purpose of using the '$' character in account names is often related to obfuscation techniques employed by attackers seeking to bypass security measures or blend in with legitimate services. User accounts containing this character could indicate potential misuse or an attempt to evade detection, as systems may not properly parse or analyze these variations in account names. The rule leverages specific Windows Security Event IDs to flag these activities: Event ID 4720 captures the creation of new accounts, while Event ID 4781 detects renaming events. The filtering also excludes the legitimate 'HomeGroupUser$' account to minimize false positives. By focusing on the presence of the '$' in the usernames, this rule enhances the detection of suspicious account management activities in an environment, providing an essential layer of security monitoring.