CrackMe5
A gui-based crackme written in visual studio 2017 win32 api, which creates a serial key based on user name.
Objectives:
- Enter your first name.
- Crack the software to find a valid serial key for your firstname
Link: https://crackinglessons.com/crackme-5/
Software
It was a simple software which asks for your first name and a serial key.
Detect It Easy (die)
Using DIE software I found the entry point.
EntryPoint = ImageBase + AddressOfEntryPoint --> 0x0040143f
x32dbg
Using x32dbg, I applied call stack method. I entered wrong serial key, clicked checked then paused the program. And found an entry of MessageBox.
Logic was simple it creates a serial key according to the first name entered then compares the serial key you entered. If not equal it jumps.
I simply updated the logic to first bypass some checks with JMP and secondly, instead of or eax, 1 I wrote xor eax,eax to make eax register always zero and with this way program can always pass the test and zero flag will be set to 1.
And this is it.