Anti virus softwares are the last and only defense against malwares in most of the personal computers. So getting through them or evading them is one of the most important thing in penetrating such systems. Payload encoding is one of the method used by attackers to evade detection. You can use metasploit built-in encoders to encode your payloads, but most of the anti virus solutions will detect these payloads. So we need alternatives to evade the detection. Shellter is one of the available solution.
Shellter is able to re-encode windows 32 bit application packages after including the payload or the shell codes so that anti virus softwares will not be able to detect it.
Shellter is not built into Kali Linux, so you have to install it manually. You can either download Shellter from here or use the command apt-get install shellter