HackTheBox Ancient Encodings Writeup

Explore the basics of cybersecurity in the Ancient Encodings 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.

Provided Script

source.py

from Crypto.Util.number import bytes_to_long
from base64 import b64encode
from secret import FLAG

def encode(message):
    return hex(bytes_to_long(b64encode(message)))

def main():
    encoded_flag = encode(FLAG)
    with open("output.txt", "w") as f:
        f.write(encoded_flag)

if __name__ == "__main__":
    main()

Provided Output

output.txt

0x53465243657a51784d56383361444e664d32356a4d475178626a6c664e44497a5832677a4d6a4e664e7a42664e5463306558303d

Proof of Concept (PoC)

from Crypto.Util.number import long_to_bytes
from base64 import b64decode

def decode(encoded_hex):
    encoded_int = int(encoded_hex, 16)
    encoded_base64 = long_to_bytes(encoded_int)
    return b64decode(encoded_base64)

def main():
    with open("output.txt", "r") as f:
        encoded_hex = f.read().strip()
    flag = decode(encoded_hex)
    print(f"Recovered FLAG: {flag.decode()}")

if __name__ == "__main__":
    main()

Summary

Ancient Encodings on Hack The Box is a very easy-level challenge focused on reversing layered encodings to retrieve a hidden flag. The challenge involves analyzing a script that encodes the flag using Base64 and hex-encoded integer conversion. By reversing the process with tools like Python’s Crypto.Util and Base64, participants decode the output file to recover the flag. This challenge introduces basic encryption reversal concepts, making it ideal for beginners in cybersecurity.