Figure 3: Log Window Clicking on the Log Alt+L option will bring up the Log Window. Final Note 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. By attempting to defeat the copy protection of your application, we can learn a great deal about how robust the protection mechanism is. In order to explain reverse engineering, we have downloaded the beta version of software from the Internet that is operative for 30 days. Now view the call stack by pressing the Alt+ K. The modified text appears in red letters in the Dump, as shown below.
We are going to patch the jump that returns the invalid registration box. Yes it is, we did found a real serial number and we can find a serial for any name we enter by following the procedure of this tutorial. Scroll down until you find RegQueryValueExA. In order to fill the gap, x64dbg was developed. A new window opens up with a list of all strings found in the file.
It's a great site, but you can utilize the internet too! I have simple my own CrackMe application written with Visual C 2010 Express. It is still asking for a serial. By hitting F9 to run the debugger, we should encounter the error message as seen in Figure 16. Some time we need extra plugin to make debugging easy you can check Ollydbg Plugin section of this blog. Clicking Copy to Executable, and then clicking All Modifications.
For several years, he has been researching Reverse Engineering, Secure Source Coding, Advance Software Debugging, Vulnerability Assessment, System Programming and Exploit Development. His spare time activity includes tourism, movies and meditation. He can be reached at om. Running Putty in Ollydbg In Ollydbg, from the menu bar, click Debug, Run. There are usually two places a serial is stored! It allow you to easily navigate to code that refers to a selected line of code as shown; Up till now, we have identified the actual line code that is responsible for producing the error message. When you are ready press the Go button.
I am able to disassemble and crack my application using IlSpy which is too easy, it's translated almost to source code. The software is about 8 years old, I can download it but cannot purchase it as the company went out of business. That information is found at the bottom of the w32dasm window. By doing this testing before the product becomes publically available, we can modify the code to make circumvention of copy protection more difficult before its release. After configuring like this you have to change Driver name in ollydbg. We will need to rely on OllyDbg. Thanks for you comment, I really appreciate it!!! Ollydbg finds another line of code that uses this string, as shown below.
This is to verify that we can come up with the keys. If you liked this post, feel free to share it with others who may be interested in learning the art of reverse engineering. Now you can find the time limit code. I means we have to know what is ollydbg and Its Feature So OllyDbg is a 32-bit assembler level analysing debugger for Microsoft ®Windows ®. Lets take a look at the next one: Oh! Surprisingly, the target is not packed or protected. To do this click on the String References button at the top of w32dasm. How to reverse engineer In here, we are taking a keygen.
The beginner will notice that the interface looks very much like a text editor with some advanced features. The copy protection mechanism often involves a process in which the software checks whether it should run and, if should, which functionality should be exposed. The first thing I usually do in these cases is to check if the executable is compressed or not. One of the tests consisted of getting the serial key of a simple program. Resume the program and enter any software key you feel like. It is only a game to get more reversing engineer skills to research malware. Here, the red box showing, the entry point instructions of the program referred to as 00401204.
Note that many of the view menu items have hot-key commands. Next press F12 to pause the debugging execution. The vendor stipulates a time restrictions condition over the beta software in order to be license misuse and permitting the product to run only in a reduced-functionality mode until the user registers. Post Views: 1,851 In order to remove bugs from a program or to modify an app with or without having the source code, a process called debugging is used. Right-click in the Code window of Olly and choose Search For, select All Intermodular Calls.
He is a regular contributor to programming journal and assistance developer community with blogs, research articles, tutorials, training material and books on sophisticated technology. Typically in copy protection, the user is obligatory to register first for the product before use. Your ultimate objective is to prevent the program from hitting the error code path. Bans are handed out at moderator discretion. Step 1: Run the crackme and you will see that it needs a name and a serial number, enter some fake info. Now it is time to do some modification to the binary code. While the error dialog box is still displayed, start debugging by pressing F9 or from Debug menu.