A simple script that can be used as a Jamf Extension Attribute to check if a file was installed from the Mac App Store or not.

masCheck.sh

#!/bin/bash

APP=""

if [ ! -e "/Applications/${APP}.app" ]
  then
    echo "<result>Not Installed</result>"
elif [ -e "/Applications/${APP}.app/Contents/_MASReceipt" ]
  then
    echo "<result>Mac App Store</result>"
  else
    echo "<result>Self Service</result>"
fi
exit 0