Crypters

Early on in the learning of cryptography, one may come across a very basic and easily decoded method of encryption: ASCII shifts or substitution. Substitution is generally taking a block of characters and replacing one character with another. For example: (I LOVE YOU) if you shifted each letter one step forward in the alphabet, this message would become: (J MPWF ZPV). This is the basic information about crypting or cryptography. Hacker will use a crypter, which will add junk code to our server; of course there is lot of crypting methods for this kind of things.

Crypter is a program that makes other programs UnDetectable (UD) or FullyUnDetectable (FUD).UD can be detected only by a few antiviruses and FUD cannot be detected by any antivirus. It is used to hide viruses, RATs (Remote Administration Tools), or any Keyloggers from antiviruses, so that they are not detected and deleted by antiviruses. Thus a crypter is a program that allows users to crypt the source code of their program. Generally, antivirus work by splitting source code of application and then search for certain string within source code. If antivirus detects any certain malicious strings, it either stops scan or deletes the file as virus from system. The aims of crypter are protect the executables, making difficult to analyze it or reverse engineer it. Actually the malwares are basically distributed as executables; public malwares are generally detected by antiviruses, so crypters are used to make them Fully Undetectable (FUD).