The 'Hidden User Creation' detection rule is designed to identify the creation of hidden user accounts on macOS systems. This includes accounts with User IDs less than 500, which typically indicates a system or service account rather than a regular user. The rule utilizes the `dscl` command, particularly looking for instances where the command is used to create a new user while also inspecting the command line for specific flags that indicate the account is hidden (e.g., the 'IsHidden' option). The detection criterion stipulates that the event must either reflect the creation of such an account with a User ID under 500 or the explicit use of the 'IsHidden' option in conjunction with its confirmation. This detection rule serves a dual purpose, helping to uncover both overt attempts to create unauthorized hidden accounts as well as possibly legitimate administrative actions that could be misused for evading detection.