Or they can just take the executable and change the extension. Extension-based blocking doesn't really work. However, these types of files generally have magic

Or they can just take the executable and change the extension. Extension-based blocking doesn't really work. However, these types of files generally have magic numbers in their headers that you could inspect to determine what they are. Also, it'd be rather inconvenient if you couldn't upload a compressed archive to a file-sharing site.