I poked at the file a bit to see if I could mount it under Linux, but wasn’t able to – which surprised me, because I’ve managed to mount .dmg files easily enough before. The results, all in all, were kind of weird.
sudo mount -t hfs AbandonThem.dmg /mnt/temp and
sudo mount -t hfsplus AbandonThem.dmg /mnt/temp both give
mount's generic “wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error” error message. The
file command suggests it has an MBR boot sector, plus another partition, which it doesn’t identify beyond saying that it’s type 0xEE, which is apparently a partition type used by GUID-capable software to fool older MBR-related software into not accidentally overwriting a partition they don’t understand. (But the
gparted tools, which should understand GUID-based partitioning, see the image as containing only blank, unallocated space.)
Thinking that maybe it was compressed in an unusual way, I tried using
dmg2img to convert it, but that too just gives an “inflation failed” message, with no further information, on partition one. Running it with increased verbosity suggests that
dmg2img thinks that the file contains eight partitions, seven of which are only 430 bytes in size. (Partition 4 is apparently 4232 bytes. No, these numbers don’t come anywhere near adding up to the file size on disk.)
fdisk on it prints a size warning, “GPT PMBR size mismatch (136507 != 59505) will be corrected by w(rite).”
None of this inherently suggests any trickery of any kind; it might just be that the image was created by software that creates comparatively unusual .dmg files (or maybe just a newer version of macOS that the Linux tools haven’t yet caught up with). It seems weird to me that disk-imaging software would create an image file with multiple partitions and a partition table, but then, I’m not a Mac person, so maybe that’s the way that Apple or third-party software designers are designing imaging software for Macs these days.
7z program managed to decompress it (good ol’ 7-zip!), and it looks like yes, there is no story on there that’s not a Mac-only executable.