Welcome back.
In this lesson, I will show you a shorter way to bypass decryption.
You don't have to do the comparison analysis anymore.
You can just do patching.
So in the—we are just going to restart this.
And then we're going to run—let it hit our breakpoint.
Press G to go into graphical view.
And then now we're going to run to this breakpoint.
So the prompt is out.
Continue stepping until this becomes into a running state.
It is now running state, which means that it is waiting for us to enter something.
So we type any password: 123456, hit Enter, and now control comes back to the debugger. It's paused, so we
can now run all the way to the last part.
Down here, bypass all the encryption and come straight to this critical instruction.
This instruction is going to move the bad message to the good message, as we have seen earlier.
So we don't want this to happen, right?
So we want these two to be the same.
Right.
So there are many ways to bypass the decryption.
We can NOP this instruction.
That's the easiest way.
All we need to do is NOP this,
and then it will not copy - to -.
It will not copy the bad message into the good message to overwrite the good message.
So we just right-click here, patch the command, and say NOP this.
That's all.
That's all we need to do.
NOP this.
So now we can go back.
We just refresh this first, refresh this.
We see the NOP there.
So right-click on this, Assemble.
We right-click this, Binary, Copy.
Let's see.
So we use patching to bypass the decryption.
Now in a—in a real commercial program, this works because you don't have to decrypt the encryption scheme.
You just have to bypass it by copying the result of the encryption.
And then, you know, you just undo all the encryption scheme.
So because in the real commercial program, once the password is correct, you go ahead and call the
activation function to allow you to use the software.
But if the password is wrong, then you will not call the activation function.
So you just need to NOP this single NOP that will do the trick.
Okay.
So now we're going to patch it.
Patch the file.
And then we're going to call it "Ransom One."
Now we can test our "Ransom One" file.
Enter any wrong—zero.
And you see, "Thanks,
Bobby.
Bobby is now cured."
So this is how we can use patching to bypass encryption.
So you don't have to go and figure out how to decrypt.
All you do is find the right place to patch.
That's all for this video.
Thank you for watching.