HackTheBox Out of Time Writeup

Explore the basics of cybersecurity in the Out of Time Challenge on Hack The Box. This easy-level Challenge introduces encryption reversal and file handling concepts in a clear and accessible way, perfect for beginners.

import sys
import time
import socket
import base64
import numpy as np

VALID_CHARS = [chr(x) for x in range(33, 126)]
THRESHOLD = 100

def b64_decode_trace(leakage):
    return np.frombuffer(base64.b64decode(leakage))

def connect_to_socket(host, port, option, data):
    data = data.encode()
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.connect((host, port))
        s.recv(1024)
        s.sendall(option)
        s.recv(1024)
        s.sendall(data)
        resp_data = b''
        while True:
            tmp = s.recv(8096)
            if not tmp:
                break
            resp_data += tmp
        return resp_data

def testing(host, port, password_guess):
    leakage = connect_to_socket(host, port, b'1', password_guess)
    return b64_decode_trace(leakage)

def main():
    host, port = sys.argv[1].split(":")
    port = int(port)
    guessed_pw = "HTB{"
    while True:
        ref_trace = testing(host, port, guessed_pw + "\x00")
        for c in VALID_CHARS:
            trace = testing(host, port, guessed_pw + c)
            diff = np.sum(np.abs(trace - ref_trace))
            if diff > THRESHOLD:
                guessed_pw += c
                print(guessed_pw)
                break

if __name__ == "__main__":
    main()

Summary

The Out of Time Challenge demonstrates side-channel attacks by analyzing power trace spikes to deduce passwords through brute-forcing, where correct characters cause trace spikes, showcasing hardware security and cryptographic vulnerabilities.