WMI and Security
WMI supports security by identifying each user before access to WMI and checking the user's permissions. Each user with access permission then has access to all classes and name spaces. WMI does not differentiate between the different classes, instances or name spaces.
On Windows NT/Windows 2000/Windows XP platforms there is no difference between local access or network access to another computer. For network access, you can identify an account for access. For local access, you cannot overwrite the local user.
Even if it is not necessary in general, administrators can issue WMI permissions for WMI user (with the Wbemperm.exe tool). Wbemperm.exe is also installed by WMI.