Here a small puzzle
for you to enjoy.In this file, there are 16
short poems to be found.Joy is had not by grepping
or wanton scanning,but by careful parsing, and
attention to detail.Such will be rewarded
by small joys of wonder.With kindest regards,
– Sijmen
Download
(7 MB download, 1.5 GB extracted)
With its support for multiple overlaying filesystems, redundant fields and optional extensions, the ISO 9660 format (used for CD-ROMs and .iso disc images) is notoriously suited for smuggling data.
In this crafted file, I have hidden 16 poems for you to discover by careful reading of its ISO file structure and some deduction. A fun challenge for the CTF-minded and curious tech enthusiast alike.
If you’re new to the file format, there’s a good overview of the format on the OSDev wiki. Start with the Primary Volume Descriptor at address 0x8000 and go from there.
Should you get stuck, want to chat about the puzzle, or anything else, drop me an email or a message on Mastodon. I’m also especially keen to hear from people who do solve it, and how they found it.
Good luck, have fun!