>My main application requires periodically starting and using a (local) COM EXE. My app should be the only thing that ever calls/starts this COM EXE.
>
>Is there accepted best practice to prevent, say, someone in Windows Explorer double-clicking on the COM EXE and starting it manually?
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>My first thought is to pass in a parameter with the CREATEOBJECT( ) call that invokes the COM EXE. If it doesn't get a parameter (or the right value of the parameter), it closes itself - maybe after popping up an explanatory message.
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>This is really to deal with curious users, or those who click on the COM EXE by mistake when they should be starting up the main app EXE. It doesn't have to be battle-hardened and able to thwart determined hackers.

If you make the exe hidden, you will still be able to run it. But your users won't see it.