UAC and elevation prompt pattern

Question

I've read several questions regarding UAC and privilege elevation but I've not found a satisfactory/comprehensive answer.

I have this scenario: on Windows 6 or above, when the user opens a configuration window I have to show the shield (BCM_SETSHIELD) on the OK button only if privilege elevation will be required to complete the task. -- I do know that in the Windows UI the shield is always visualized for "administrative tasks", even if UAC is disabled, but the customer had this specific request.

I have draft this condition in order to show the icon:

1. The user has not administrative rights
   OR
2. The current process has TOKEN_ELEVATION_TYPE == TokenElevationTypeLimited

The condition #1 is simple: if the user hasn't administrative rights elevation is always required regardless of UAC. The #2 implies that the user has administrative rights, and any other value of TOKEN_ELEVATION_TYPE means that elevation is not needed.

Is really that simple? I am missing something? And - there's a documented or well-known pattern regarding this topic?

Answer 1

You are right. Most people just put the shield on if the button will be running elevated, but the right thing to do is to put the shield on if the button will cause elevation (ie suppress it if you are already elevated, since everything you launch will remain elevated unless you go to some trouble to launch a non elevated process, and suppress it if UAC is off.)

The good news is that if someone in the Administrators group runs (under UAC) an application non-elevated, you'll get back false when you ask if they are an admin or not. So I think you might be ok with just that one test.