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The first and often easiest method is to simply run the process or program to the point where the UAC prompt appears. In the lower left-hand corner is the "Show Details" link (or in this case the "Hide Details" link as Show Details was already clicked on). Select that and then in the details section in the top of the page will be expanded and show the file which is attempting to be initiated and which is causing the UAC prompt [See the detail "Program location" surrounded by the Orange box in the image below.]. This is then almost always the file which needs to be managed by ACS with an Application Initiation policy.
Note: UAC windows may have different coloring or size than this example, but the layout is generally the same with the Show/Hide details at the bottom left side, and the details in the upper middle section.
Option 2
If the UAC prompt page does not give enough information then a more extensive investigation may need to be undertaken.
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