I would like to introduce you now to a more advanced and professional cracking technique, cracking using a debugger. What is a debugger? In few words, a debugger is a software that will let us look in the asm code before and after the code is executed by the cpu. The debugger will pause the the execution of the code and will allow us to trace it step by step as the cpu executes it. All crackers uses a debugger, even W32Dasm has a debugger built in but is not very confortable. The most advanced debugger for cracking used by all crackers is OllyDBG, this tool will become your friend, your partner, it will be for you the tool number one! Configurations of your OllyDbg.

Please read this before download! Registration How to crack winrar using ollydbg. This software is a shareware. To use this program on a permanent basis or for. Unpacking, Reversing, Patching. This article is an introduction of packing, how to unpack, to reverse an exe and finally patching it. I have chosen to show reversing. Jun 05, 2015 ollydbg, how to crack software using ollydbg, ollydbg crack software, ollydbg reverse engineering.

Let's do some configurations, press alt+o to access options and go to the CPU menu. Woolf A Sketch Of The Past Pdf. Make you settings look like in this picture: After this go to EXCEPTIONS menu and make your settings look like in this other picture: Ok, we are done for now. We will use olly for everything, like patching, finding serial keys, unpacking, studing, etc. We will start our first lesson with olly by finding the serial key of a crackme, during tracing the code it will be very easy to understand where we should patch if needed. Our mission in this lesson is to find a serial key for our entered name. Run the crackme and you will see that it needs a name and a serial number, enter some fake info. Click on check serial.:?

Nothing happens Lets find a real serial for our name now! Disassemble our target with w32dasm then click on the imports button. See the picture below: On the dialog box that shows up find this: USER32.GetDlgItemTextA like in the picture below: Select it like in picture above and double click on it, you will land at the address: 004011DF (write down this address), just a bit below this we have an other reference to USER32.GetDlgItemTextA at the address 004011F0 (write this address down too).

Close W32Dasm, we don't need it anymore. Run OllyDBG and click on file, open, browse to our crackme and open it.

Cool, you should see the asm code now. Press F9 button from your keyboard then the crackme should show up. Enter your name and any serial number but don't click on 'check serial' button yet. I will enter MiStEr_X as name and 12345 as serial. Return to OllyDBG then click on 'Go to Address' button. This button is indicated in the picture below: picture5: On the blank box enter the first address we did found on w32dasm, 4011DF then click ok! You will be here: PUSH 019h PUSH 0403096h PUSH 066h PUSH DWORD PTR SS:[EBP+8] 004011DF CALL GetDlgItemTextA;read the entered name PUSH 01Eh PUSH 0403078h PUSH 065h PUSH DWORD PTR SS:[EBP+8] 004011F0 CALL GetDlgItemTextA;read the entered serial CMP EAX,4; compare entered name with 4 JB @crackme__00401245; jump if below (if our entered name is smaller than 4 digits then jump) GetDlgItemTextA is used in asm to retrive the information entered by users in blank boxes!

Now, put the selector line on '004011DF Call GetDlgItemTextA' then press the F2 button from your keyboard to set a breakpoint. Go to the second address to and set a breakpoint there too by pressing F2. See the picture below to see my breakpoints. The addresses highlighted with white means that there is set a breakpoint. Picture6: Bring up the crackme from the taskbar and click on 'check serial' Olly will break on the first breakpoint, now press F9 (run) and Olly will break on the other breakpoint we did set.