Insomni'hack 2024 - Award Challenge
As I haven't posted for a long time and now participated in the Insomni'hack 2024 CTF, I thought I write about the challenge "award", which I thought was quite interesting. After solving another easy challenge, I spent pretty much the entire night of the CTF on it, but only finished the next day, when the CTF was already over. Given was a binary. If you want to follow-along, you can find the binary here (encoded as base64 with added line breaks). Additionally, there was given an nc command to run that remote, so the binary was only for analysis of what runs on the remote side. So the analysis and decompilation of the binary could be easily done in any of the usual tools. I used Binary Ninja , as I have a license for it and it's not that expensive. I spent quite some time in setting the right variable names etc. The decompiled code looks like this: Decompiled Code Note: There were also stack cookies in the main function added by the compiler, but that code has be