TLDR: Instructions were written as hex into fragments. You found the right order and inserted them back to get the program running. The correct order was 8, 7, 1, 5, 6, 2, 3, 4. The flag was welcOOOme.
Original writeup (https://www.serraabak.com/notes/DefconCTFQuals-RE-ELF-Crumble).
