Following is some code in fasm that can load dll from memory. Though loading a exe is a bit sufisticated than loading a dll because dll has a '.reloc' section which helps to fix the addresses, you can make the ImageBase of your 'host' PE different with the memory PE to avoid address conflict.



This code is from a chinese virus researcher named 'xfish', who has written a series of articles about writting virus in fasm. To see more, visit here: http://bbs.pediy.com/showthread.php?t=90441 (If you can read chinese or use a translating tool )

LiuGouHua(Chinese)
I have done it with EXE files too, but EXE needs to add reloc section also.

Overflowz

Well done! With the reloc section, you can just treat a exe like dll. If the exe is written by other one and you don't have the source code, you will have to change the ImageBase of the host exe.