Author:
BitFriends

Language:
C/C++

Upload:
3:54 PM 07/08/2020

Platform
Unix/linux etc.

Difficulty:
1.4

Quality:
5.0

Arch:
x86-64

Description

This is a very simple crackme. The goal is to get "you are logged in as admin". Patching is not allowed. The solution should contain an exact description, how this works. Have fun!

• Comments
• Solutions

jeffli6789 on 2:06 AM 07/14/2020: simple and interesting. Though it relies on certain property of malloc which is not always true

Dynamite on 10:26 PM 07/18/2020: awesome ....i solved it at last without changing any code. Its a nice catch

Arch3m1d35 on 7:43 PM 07/24/2020: So, I figured out "how" to do it. I may be a numbskull tho, because I'm having trouble wrapping my head around "why" it works that way. I have a vague understanding, but when I do the math the numbers don't add up for me.

ObjectivePhP on 7:47 AM 07/28/2020: As far as I know, there's no guarantee that subsequent malloc calls will be in a contiguous block of memory. The overflow attack is simple enough but it seems like static allocation would've worked better here as it's entirely possible that there are n random bytes between the two buffers.

dyingc on 3:34 AM 01/03/2021: Absolutely a newbie in RE and I'm so glad I can finally solve it!

Wolfgang7 on 10:54 AM 08/02/2021: Who can say that malloc puts blocks in this order? Anyway, nice but too easy.

jimsktsmith on 12:26 PM 12/26/2021: passs : type 31 times numer "1"

alxxx on 7:20 AM 04/03/2024: python3 -c 'print("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\x00\x00\x00\x00")' | ./a.out

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