how to break the code of exe file? What is it exactly?

darshan · Post by **darshan** » 14 Mar 2008, 08:10

hi my name is darshan, completely new to all this but really interested
my school teacher said if you are able to break the code of an exe (we are using vb right now) then you get a 5 percent bonus. more than that i want to know what this code is, what does it do, and how you can obtain it

thank you
darshan

Post by **ayu** » 14 Mar 2008, 08:17

I'm not completely sure what you are saying.....but

When you write your code in VB and then compile it, what the computer does is that it basically translates the code into a "language" that the computer understands (machine language) and builds it into an exe (executable) file for later use.

With "obtaining" the code your teacher probably means that you should reverse engineer it.

So my tip would be to read up on how the compiler works, and then how reverse engineering works. Since you apparently already know some VB, you should know some basics of programming.

I can't provide you with links at the moment since i have some stuff that i need to attend to now (cleaning my room). But i suggest that you Google for it =)

Nerdz · Post by **Nerdz** » 14 Mar 2008, 09:42

Hi and welcome on our Forum

First, what you mean by breaking the code? Do you need to retrieve a serial number or a piece of code?

There are some tool to debug an .exe and look at what it does...

As an example, If you take a little program that want you to enter a valid code(12345) there are 2 possibilities for you.

You can open the debugger, make a trace to where it goes and HOW it compare the string(code) you have entered and the correct one. Doing this will require some asm(Assembly) knowlege( Which is alway usefull to understand how the machine work). When you'll read the code, you'll see some binary operation to valid you code. Now all you have to do is build a code that would supply the validator...

so Validate = "12345 -> 1+2+3+4+5 == 15
You could input 96 which will result 15...

The other way, is to simply bypass the validate function using the debugger(You might wanna read about how the stack work on a computer).

Let's say we have this piece of code:

Code: Select all

0-if (key == "abc")
4-RegistrationSuccessfull();
8-else
12-NotValid();

You see, when you press the button to submit the code, the program will call the Validate function and then check if it is == to "abc". Let's say the adress 0. Now that you got the address of the RegistrationSuccessfull, you can jump directly to this adress by changing the "jmp 0" to "jmp 4"

Hope this help.

bubzuru · Post by **bubzuru** » 14 Mar 2008, 10:47

reversing vb code is very easy

here are the tools you will need
1.olly dbg http://www.ollydbg.de/
2.win32dasm Here
3.HxD http://mh-nexus.de/hxd/
4.Hiew http://www.hiew.ru/

check these threads
http://suck-o.com/modules.php?name=Foru ... pic&t=3035
http://suck-o.com/modules.php?name=Foru ... pic&t=3082

rhysh · Post by **rhysh** » 28 Mar 2008, 05:26

also you may find res hacker usefull

winrar has a dialog called reminer_nag or something rather
open winrar.exe in res hacker and delete that dialog
now save as and you have a cracked version of winrar

the dialog is in the section called dialog

thats an easy start for you!!!

i know this cus thats the first soft i ever cracked and i remember it very well