A shellcode is a small piece of code used as the payload in the exploitation of a software vulnerability.
Shellcodes get that name because they typically start a command shell from which the attacker can control the compromised machine. Shellcode is commonly written in machine code, but any piece of code that performs a similar task can be called shellcode. Because the function of a payload is not limited to merely spawning a shell, some have suggested that the name shellcode is insufficient.
Shellcode can either be local or remote, depending on whether it gives an attacker control over the machine it runs on (local) or over another machine through a network (remote).
