Yes, that is likely. It is my understanding that SCORM files are uploaded this way, but that is all. The file itself is it an entire course file or just a single page of text, text and images, text, images and multimedia files?
If it is just a text file, unzip it, then upload it or copy and paste. If it is text and images, or text, images and multimedia, can't help you there. Unless you want to, in your course, create a page, add an image and/or multimedia files, back it up and then download it. Change the download file type to zip and unzip it. Use this file as a shell, changing the xml code as required. Zip it up and change the file type to mbz, then restore. (This used to be simple but since v2.0, it is not as easy as it used to be but the security restrictions should be able to be gotten around, look for the patterns for file linking.) If it is an entire course, and it has all the Moodle required xml files, in place, change the file type to mbz and upload it as a restore.
There is probably an easier way of doing this, but I don't know it, based on the little information provided.