HackTheBox FlagCasino Writeup
Explore the basics of cybersecurity in the FlagCasino Challenge on Hack The Box. This very-easy-level Challenge introduces encryption reversal and file handling concepts in a clear and accessible way, perfect for beginners.
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import ctypes
from pwn import *
libc = ctypes.CDLL('libc.so.6')
casino = ELF("./casino", checksec=False)
mapping = {libc.rand(): chr(i) for i in range(255) for _ in [libc.srand(i)]}
flag = "".join([mapping[casino.u32(casino.sym["check"] + b * 4)] for b in range(30)])
print(flag)
Summary
The FlagCasino Challenge on Hack The Box is a very-easy-level challenge that focuses on reversing and analyzing a C-based random number generation (RNG) process. In this challenge, the player must reverse-engineer the rand() function, which is seeded with user input, to predict the output and retrieve a flag. The solution involves using the libc library’s rand() function in Python to generate values that match the expected ones from the check[] array in the binary. By mapping these generated values to their corresponding characters, the flag is reconstructed and printed.