SirWardrake's KeygenMe(Second)

Author:
SirWardrake

Language:
C/C++

Upload:
2024-03-04 03:55

Download

Platform:
Windows

Difficulty:
4.0

Quality:
5.0

Arch:
x86-64

Downloads:
15

Size:
11.59 KB

Writeups:
2

Comments:
10

Description

Try to write a keygen

Comments (10)
Writeups (2)

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nightxyz on 2024-03-08 21:22: Found valid usernames/passwords but couldn't solve algorithm yet.

cnathansmith on 2024-03-15 23:14: @nightxyz try entering a repetitive username like AAABBBCCC and look at what password it converts it to, and you should be able to figure out how to extract the information you need to generate passwords for arbitrary usernames

nightxyz on 2024-03-16 00:09: @cnathansmith Thank you. I have already found the password equivalent of usernames such as "AAAAA" or "aa". Later, I thought about making a table for all the letters, but I gave up because it was a long job and I was struggling with cracking the password of the crackme file named Bobby.

a764934018@outlook.com on 2024-03-16 10:57: reversed its keygen code into C++: https://pastebin.com/4iEaxYm8

cnathansmith on 2024-03-16 17:13: @a764934018@outlook.com Nice! I went the lazy route and just used this as a username: !!""##$$%%&&''(())**++,,--..//00112233445566778899::;;??@@AABBCCDDEEFFGGHHIIJJKKLLMMNNOOPPQQRRSSTTUUVVWWXXYYZZ[[\\]]^^__``aabbccddeeffgghhiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz{{||}}~~ Then split up the password it generates in order to get the substitution values for each character (each input char is doubled up because the substitutions are variable length and it would be impossible to know where each begins and ends in the generated password otherwise)

SirWardrake on 2024-03-17 01:05: @a764934018@outlook.com: Good job, that solution works well! Did you use Ida / Ghidra for this?

a764934018@outlook.com on 2024-03-17 01:37: @cnathansmith what a clever method! learned it. :) I am new to RE and want to learn more so I take my time to reverse it.

a764934018@outlook.com on 2024-03-17 01:38: @SirWardrake thanks. great crackme :) and yes, I used ghidra for this.

1337ReverseEngineer on 2024-03-17 10:53: good crackme but the fact it was UPX packed made the unpacking trivial. if your focus is on keygen maybe dont pack it at all

rrookie on 2024-03-22 14:24: My keygen sticks more to the disassembly. https://pastebin.com/Tr2FaT4A

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Solution by cnathansmith on 2024-03-15 23:22:
Straightforward walkthrough that takes advantage of pattern recognition to develop a keygen

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Solution by 1337ReverseEngineer on 2024-03-17 11:10:
contains keygen.py and the writeup itself

Download

crackmes.one

crackmes.one

SirWardrake's KeygenMe(Second)_SWD