Hint: Use gdb peda

Thanks! This was a fun challenge to create.

I'm new to RE and took me a while to figure it out, even though it is pretty simple. Thanks for this challenge, learned a lot.

sorry guys, I can't get the file to execute and also not to debug with gdb. I get stuff like "zsh: exec format error: ./Reykjavik" or ".................... ............. sh: ./Reykjavik: not found" or (gdb) run Starting program: /code/Reykjavik /bin/sh: exec: line 1: /code/Reykjavik: not found During startup program exited with code 127. .... -bash: ./Reykjavik: cannot execute binary file: Exec format error

What's up with that file ?!?

or do you just want to trick me, ej ?

ok it runs on ubuntu ... not on alpine docker, not on raspian

Sorry for the problems... I created on Ubuntu and didn't test on any other platforms.

A smart challenge for beginners, with more than one way to be solved. Nice job, kcbowhunter!

Got me reconciled with RE, thanks

Yeah, after long time learning Assembly (i learn slowly) and watching liveoverflow I did it :D Great challenge!! Deserve the 5 *

Congrats! Unfortunately these reversing challenges have a steep learning curve; C, assembly, GDB / Ghira etc. Congrats on hanging in there!

the real resource that may help you a little bit :-) https://www.youtube.com/watch?v=nLp3hr6Jf2M

This problem is loosely based on this example from LiveOverflow on YouTube: https://www.youtube.com/watch?v=VroEiMOJPm8

do not try to get the flag in a few minutes, take your time to know what is happening... step by step

This was my first ever RE challenge and it was awesome thank you!

Glad you liked it... I tried to design it for people new to Reversing. Thanks for solving it!

You're welcome :-)

It's was good RE challenge. Myself being a beginner, I found this interesting. As for the tools, I found the interface of ghidra a little overwhelming and I stumbled upon a new tool "Cutter"while googling. It also uses ghidra and radare2 in the background but it much better to use.

Thanks for the feedback, sounds interesting.

I have recompiled and uploaded without the AVX instructions to make it a little easier to solve.