Hello and welcome back.
In this lesson, we are going to start our first project, Easiest Crackme.
We are going to fish for the password.
So if we run it, you remember that this message shows up,
asks you to enter the password.
If you enter a wrong password and hit Enter, it shows us a bad message:
Wrong.
Try again.
So now we have to search for this string inside the code.
So what we do is remember this string: wrong,
try again.
So we close this.
Now we use x64dbg.
And we open the crackme, and now we are going to search for the string inside the code.
So right-click on this, Search for, Current module, String references, and search for the string "wrong."
And you will find it here.
So this technique is called the string search method.
So once we find it, we can double-click on it to go to that address where this string is found.
So this is where the string is found,
and you want to see the logic of this.
You can look for the start of this function, which is over here, push -.
So push - starts the function, and return
here ends the function.
So we can put our cursor here and right-click and graph it,
or we can just press G.
So from here we can analyze the control flow logic.
We can see that there is a jump here which will go to the right if your password is correct, to show
it: Correct.
Nice job.
Or it can go to the left and show you: Wrong.
Try again.
So whether or not it goes to the left or to the right depends on this jump,
and this jump depends on this compare.
So it is comparing - with 42.
If it is not the same, if - is not the same as 42, then jump not equal will jump to this address
3163.
That means on the left.
So this suggests that the password is 42.
So what is 42?
We can use the calculator here and enter 42, 42.
And you can see in the decimal it is 1234.
That means the password is 1234.
So we have already fished the password.
So now with that, we can try to stop this and run the program directly and enter the password 1234.
One, two, three, four.
Correct.
Nice job.
All right, so this is how easy it is to solve this using a debugger.
So that's how you can use serial fishing.
Now in the next video, I will show you how to do patching.
So patching is when you want to force it to be correct.
Even though your password is wrong, you still want to show the good message.
Currently, if your password is wrong, it shows you the bad message.
So next,
next video, I will show you how to patch this program so that even though your password is wrong, it
still shows you the good message, not the bad message.
Okay, so that's all for this video.
Thank you for watching.