Pretend to be a FAT-formatted mass storage device and see what files are accessed on automount. Possibly also pretend to be ext2 and see if e.g. the mount time

Pretend to be a FAT-formatted mass storage device and see what files are accessed on automount. Possibly also pretend to be ext2 and see if e.g. the mount time in the filesystem superblock is updated. You can probably also learn a bit from the timings of specific actions by the host, but as long as there is any sort of automounting, I suppose that’s the best way to find out your host OS.