Editing Shellcode (section)

===Unicode proof shellcode===
Modern programs use [[Unicode]] strings to allow internationalization of text. Often, these programs will convert incoming [[ASCII]] strings to Unicode before processing them. Unicode strings encoded in [[UTF-16]] use two bytes to encode each character (or four bytes for some special characters). When an [[ASCII]] ([[Latin-1]] in general) string is transformed into UTF-16, a zero byte is inserted after each byte in the original string. Obscou proved in [[Phrack]] 61<ref name="Obscou_2003"/> that it is possible to write shellcode that can run successfully after this transformation. Programs that can automatically encode any shellcode into alphanumeric UTF-16-proof shellcode exist, based on the same principle of a small self-modifying decoder that decodes the original shellcode.