Registry: HKEY_CLASSES_ROOT\.ext\PersistentHandler

Apparently, setting the default value of HKEY_CLASSES_ROOT\.ext\PersistentHandler to the CLSID {5e941d80-bf96-11cd-b579-08002b30bfeb} adds the extension .ext (i. e. the value of the parent key) to the indexer (search) service so that the contents of *.exe files can be found.