I'm experimenting very much ATM. - I had several problems with the permissions... but as I only want to extract some sort of files I don't care for my proof of concept. (took ownership and so on). One Change that has to be made is that the uncompressed Manifest files get included in the cab files. Not the encrypted ones like in the current situation. I checked on Win81 updates they are provided uncompressed. With uncompressed manifest files it is also possible to look into the packages like with CBS package inspector - compressed manifest cabed files will fail.