Demonstrating the code_inject tool

As we can see, our program injects and executes a shellcode that creates an executable memory mapping, where the payload program is then injected and executed:

1. Run the host program (the one that you want to infect):

   ryan@elfmaster:~$ ./host &
   [1] 29656
   I am but a simple program, please don't infect me.
   

2. Run code_inject and tell it to inject the program named payload into the process for the host:

   ryan@elfmaster:~$ ./code_inject `pidof host` payload
   I am the payload who has hijacked your process!
   [1]+ Done ./host
   

You may have noticed that there appears to be no traditional shellcode (byte code) in code_inject.c. That's because the uint64_t injection_code(void *) function is our shellcode. Since it is already compiled into machine instructions, we just calculated its length and passed its address to pid_write() in order to inject it into the process. This, in my opinion, is a more elegant way of doing things than the more common method of including an array...