What is FUD Crypter?

What Is FUD Crypter?
FUD is acronym for fully undetectable.It is a software that can be used to encrypt your exe files.
What is the use of FUD Crypter?
FUD crypters can be used to encrypt viruses,RAT,keyloggers,spywares etc to make them undetectable from antiviruses.When these exe files are encrypted with Fud crypters they become undetectable with antiviruses

How Does FUD Crypter Work?
The Basic Working Of FUD Crypter is explained below
The Crypter takes the original binary file of you exe and applies many encryption on it and stores on the end of file(EOF).So a new crypted executable file is created.
Original Exe Crypted Exe
001————- 010                                      101————-110
100|Original File|000->  Cryptor  ->010|Original File|110
010————- 111                                        110————-010
The new exe is not detected by antiviruses because its code is scrambled by the crypter.When executed the new .exe file decrypts the binary file into small the data small pieces at a time and injects them into another already existing process or a new empty one, OR it drops the code into multiple chunks in alternative data streams(not scanned by most a/v) then executes it as a .txt or .mp3 file.
Why Most FUD Crypters Donot Work?
As a FUD crypter becomes popular it also get the eyes of antivirus companies.The antivirus companies update their software and employ detection mechanism that detect the encryption’s by the crypter.So, most of the popular FUD crypter are easily detected by antiviruses.
Where can I test Whether my Crypter is FUD or not?
To test you crypter encrypt any virus with it and test it on http://scanner.novirusthanks.org and make sure you check the box Do not distribute the sample .