The detection rule identifies the execution of the `Get-AdUser` PowerShell cmdlet, particularly when it includes a filter, by analyzing PowerShell Script Block Logging (specifically EventCode=4104). This command is commonly used to enumerate domain users and can be a precursor to more aggressive actions by attackers, such as information gathering for reconnaissance of Active Directory environments. By monitoring for instances where `Get-AdUser` is invoked with filter criteria, security teams can quickly identify potential misuse of this cmdlet, which may indicate an attempt to compromise user accounts or gather intelligence on the organization's user structure. This rule is applicable in detecting not just malicious activities from external threats, but also potentially internally from compromised accounts or users with elevated privileges who are performing unauthorized reconnaissance activities on the network.