Level - Medium
Description:
I love assembly so much, I decided to make my own!
[vm.py] [instructions.bin]
The nice-looking version of vm.py is found in vm_orig.py, not provided to the participants. Custom opcodes and a stack are defined in the Python file. I used create.py to create my instructions to check the flag. The first byte of instructions.bin is the length of the flag, and the rest are opcodes.
The solution is to figure out what each opcode does and print debugging statements as vm.py processes the instructions.bin file, showing what each of the values should be in the flag.
Flag - byuctf{vms_just_1mplem3nt_0pcodes_&_instruct10n5}