The patching or editing assembly code features are normally invisible in the IDA Pro. You can double check it from the Edit menu that none of the Patch program options appeared. Thus, in order to make this option visible, open the idagui.
So, make the following changes and save this file. After saving this file, re-launch the IDA PRO and the movement you change the submenu option in the configuration file, you can notice that Patch program option becomes visible in the Edit menu as:. The target file will be loaded into the IDA Pro but we could still not modify the byte sequence of the binary file even if enabling the Patch program option in the Edit menu earlier.
So here, the role of special IDA script files came into light as they are able to modify the byte like OllyDbg as well as writing the changes into the executable to make the effect permanent. When downloaded, extract the files in a separate folder on the file system of your machine.
There are couple of scripts files provided but mainly; two script files are significant as follows:. After successful completion of such aforesaid operations, we can modify as well as write the byte sequence into binary file.
We have only the binary executable and so it is almost impossible to know about the logic implementation without the source code. But we can disassemble the source code of any binary by employing IDA Pro because unless we are aware with logic flow, how can we subvert any security mechanism. As we can consider the following image, IDA Pro disassembles the binary into raw assembly instruction sets. The comparison happens via string class strcmp method and if the value is 0, then the entered value is corrected otherwise incorrect.
The program intimates us that we have entered the correct password as follows:. We can easily anticipate that Jump instruction determines either the password is correct or incorrect.
As we are implying from execution flow, everything depends on jnz instruction. So, the reverse engineer would surely be interested in this instruction because manipulation of this instruction can produce different results. However, all we have to do is to change the corresponding jnz statement related bytes. So, right click on the current location of this statement and synchronize it with Hex Editor View in order to examine this statement byte sequence as:.
The hex view offers a 16 bytes of sequence in one line and each two bytes represent only one assembly instruction set such that the hex value 75 35 belongs to. Before we begin debugging, lets navigate around the code to find some interesting landmarks. According to the Microsoft Developers Network documentation , this function determines if the calling process, i. It sets EAX to 1 if the calling process is being debugged.
It sets EAX to 0 if the calling process is not being debugged. So we will have to deal with this common anti-debugging technique. Scrolling down a little ways, we see what looks to be a command prompt asking for the passphrase and then some sort of comparison routine. Note the hard-coded string that is moved into the ECX register:. Just by static examination, we managed to extract the passphrase. That is one way to defeat this example.
But suppose we did not see the passphrase, perhaps it was obfuscated or encrypted, or buried in thousands of thousands of lines of code.
But first, we are going to have to deal with the IsDebuggerPresent check at the start of this code. First, lets set a break point at the very start of the program, like in the screenshot below hit the F2 key and you will see a red band indicating the break point is set :. It is important to have the kernel32 and the underscore along with the IsDebuggerPresent :. Next click OK:. This will take us back to our current break point, that is, to where the current instruction pointer is pointing to:.
Next, we are going to want to navigate to that crucial decision point we saw earlier during our static analysis:. Now after hitting F9 again, the debugger runs to this break point we just set. After typing any phassphrase, we hit the breakpoint. Note the value in the EAX register.
Since it is 1, the JNZ command will jump us to the incorrect password message. Virtual DJ pro is very suitable for club, studio and home use. May you like to download duplicate photo cleaner license key.
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