Crackme writeup by @310hkc41b https://twitter.com/310hkc41b
You can download crackme0x04.exe from this link.
To solve this cackme we will only use static analysis.
Here we see that the _main() function, after asking us for the password, calls another _check() function to check it.
Well, let's see what this _check() function does.
Here we can see that the function what it does is to add the numerical values of each digit until reaching the value 0xF, that is, 15 dec. Any other combination will give wrong password.
Thus, some valid password combinations can be: 87, 96, 555, 663, 4434, 33333, etc. Any combination that the sum of its digits of the value 15.
Let's see ...
As we can see, in this case we will not need to do any dynamic analysis.