ollydbg cracking tutorial
Figure 24: Copy to Executable -> All modification, Figure 25: Resulting Dialog Box after Figure 24. In this tutorial, we will look at one of the most widely used and free debuggers, OllyDbg. Choose “Search for text”: and the search for text window opens. Next press F12 to pause the debugging execution. This operation fills all the corresponding instruction for 0x00401055 with NOPs as following. Since we are at the PUSH 10 instruction (indicated by the grey line), we can examine the Hints pane to see the parts of code that references this call: Figure 20: The Hints pane shows two places that jump to this error message box. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. There are several reasons that could cause this; this code changes polymorphically, so our BP is lost, there is a check in the app for a software breakpoint and the app removes it, the breakpoint is in a section that Olly will not track automatically… It happens. Click on the plus sign in front of HKEY_CURRENT_USER. You can right-click on almost anything in OllyDbg to get a context menu to examine your many debugging options. If they are equal, we jump to 9ADC02, which simply returns. This “>” symbol indicates that other parts of code jumps to this location. Posted by Eric Hokanson in Malware RE, Reverse Engineering, OllyDbg Tutorial, Reverse Engineering, Reverse Engineering Malware. You may also call up many of the view menu options by clicking on the corresponding blue buttons (L, E, M, T, etc). You will now be in the regedit window and see a two pane window with a list of folders in the left pane. Although OllyDbg is free, it is NOT open source as we do not have access to the source code. Open the Hardware breakpoints window (“Debug” -> “Hardware breakpoints”) and click the Follow button on our BP. The following section illustrates the steps in the context of removing the copy protection restriction as; Such tasks however, can also be accomplished by one of the powerful tool IDA pro but it is commercialized and not available freely. Scroll to the top and right click. Right click on the instruction at location 0x401060 inside the CPU window and select “Binary” and then click on the “Fill with NOPs” as shown in Figure 22. OpenRCE (www.openrce.org) has OllyDump, Olly Advanced, and many other useful plug-ins to help hide the debugger from malware attacks or to help automate your dynamic analysis process. You will also need the following tools: F7 – the Step Into command. Reversing with Olly. This will bring up the Calls window. It has become habit to first examine a target with PEiD to determine the packer or protector. ( Log Out /  Next click on the CPU tab and make sure the boxes highlighted in Figure 11. This article demonstrates one way to challenge the strength of the copy protection measure using OllyDbg and identify ways to make your software more secure against unauthorized consumption. Choosing the “View names” (Ctrl-N) opens the Names Window. This is a good sign that the program was written in Delphi. For example, many malware will use the API IsDebuggerPresent to check if they are being debugged and attempted to kill the debugger. Here, right-click in this window and choose. Now we can modify those parts of the code. The objective of writing this paper is to manifest, how to crack an executable without peeping its source code by exercising OllyDbg tool. Olly will then break at this same line again, wanting to jump to the bad boy. Double clicking on our new, patched binary should result in: Today we learned our way around OllyDbg and used that information to debug, reverse, and defeat an expiration lock of a “trial” piece of software. Go to target folder in our case c:\program files\worldtv\ and make a quick backup that we can work on without fear of screwing up the file. It is shareware and it is available here. F2 – Set Breakpoint sets a software breakpoint on the currently selected instruction. Now load the modified program, you can that no expiration error message is shown. It looks like as following; Now open the SoftwareExpiration.exe program in OllyDbg IDE from File à open menu and it will decompile that binary file. So if we make sure a 1 is put into that memory location every time this routine is run, then any other routines will check that memory location and see that it is a 1 and think that we’re registered. The first thing we should do is assess the software with CFF explorer to identify the development language used and some other particulars. Click OK and we get to the main screen: Notice it says “unregistered” at the top in the title bar. ( Log Out /  That information is found at the bottom of the w32dasm window. It has an easy-to-use and fairly intuitive GUI making it a relatively quick study. This program has a time restriction, and after this time, it will not work anymore. It is because I tried that first! Our target is a protected program that ask for serial Download Target bellow, http://www.mediafire.com/?oj6982uxr8rzyrz, The Tools that we need: This will take us to the location of our jne 0041B54C. This is a good place to start. The context menu in the previous figure shows that both 00401055 and 00401063 contains JA (jump above) to the PUSH 10 used for message box. With our tour of Olly behind us, we are now ready to start doing some real work: reversing and cracking a “trial” piece of software. We want to change the jne (jump if not equal) to jmp (jump) that way the program will register when you use any serial. To do this, we want to set a hardware breakpoint on this memory location to tell Olly to stop whenever the app writes to this location. The operation overwrites the JNZ instruction with NOPs, thus eliminating that code path (or jump) to the error message. Highlight everything we changed, right-click and select “Copy to executable”. Now click on the first NOP at address 9ADBF4 and hit the space bar. OllyDbg is not as powerful like as IDA pro but useful in some scenario.


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