![]() The following block is the disassembled code of the validate function. Analyze it to get an impression of what the function is doing. Of course the more unique a string you search is, the more precise your results will be and you will get to the "juice" a lot quicker. If you remember the message of the failed serial check "Error!" (Title), "The serial is not valid." (Message) and "Try again" (Button) you can also try to search the disassebly for this strings. It's a fairly small executable and you won't have much troubles finding the validate:(void*)arg2 function. If you couldn't run the app - don't worry just carry on and continue reading!Ĭranck up the disassembler of your choice (I use the recent Hopper demo version - but you can also use IDA free) and analyze the Sandwich crackme app. We already have gathered some interessting informations by running the app and trying to validate a test serial. So let's start!Īfter trying to launch and examining the app is to disassemble the executable with a decompiler and try to find the serial validate function. ![]() What we want to do now is to find the validation function for the serial check. It's time now to dig in and visit the code of this app. ![]() Here you can see the main (only) screen of the macOS / OSX Sandwich crackme app ( 1-Sandwich) from /crackmes/ - with some numbers entered by me to test the serial validation function:Īfter clicking on the "Validate" button the app calls a function to check the entered serial. As excpected the validation of my test-serial fails and the crackme shows the following message: Don't worry if it's not starting on your device - also if it has a blocked icon in the finder which says that the app is not compatible with your os version. Even if it's not running on your system, you can generate a keygen just fine by decompiling it and analyzing the machO (assembler) and / or pseudo code. used and so you may find yourself comfortable a lot quicker in the disassebly of the app which you're going to examine later on in the reverse engineering process.Ĭheck if it's running on your OS version - I didn't manage to get it to run on macOS BigSur - but on macOS High Sierra the app runs very well. You also may get hints to texts, buttons, menus, labels etc. You can gather a lot of information just by clicking around the app and test it's functionalities. The first thing you always should do when attempting to reverse engineer, crack or patch an app is - Launch it and examine its functions! It's the only way to get a real feeling of the app and get to know how it works and how the workflow is.
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