HackTheBox yoU ART Writeup
Explore the basics of cybersecurity in the yoU ART 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.
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from pwn import remote, sys
def get_process():
try:
host, port = sys.argv[1].split(':')
return remote(host, int(port))
except IndexError:
print(f'Usage: python {sys.argv[0]} <ip:port>')
exit(1)
class UARTReceiver:
def __init__(self, connection, baud_rate=100, data_bits=8, parity=True):
self.connection = connection
self.baud_rate = baud_rate
self.data_bits = data_bits
self.parity = parity
def receive_bit(self):
bit = self.connection.recv(1).decode('utf-8')
return int(bit)
def calculate_parity(self, data_bits):
return sum([int(bit) for bit in data_bits]) % 2 == 0
def receive_byte(self):
bit = self.receive_bit()
while bit != 0:
bit = self.receive_bit()
data_bits = []
for _ in range(self.data_bits):
bit = self.receive_bit()
data_bits.append(str(bit))
binary_data = ''.join(data_bits[::-1])
char = chr(int(binary_data, 2))
if self.parity:
parity_bit = self.receive_bit()
expected_parity = 0 if self.calculate_parity(data_bits) else 1
if parity_bit != expected_parity:
print("Error: Parity bit mismatch")
stop_bit = self.receive_bit()
if stop_bit != 1:
print("Error: Stop bit missing or incorrect")
return char
def pwn(connection):
receiver = UARTReceiver(connection, baud_rate=100, data_bits=8, parity=True)
while True:
print(receiver.receive_byte(), end='')
if __name__ == "__main__":
connection = get_process()
pwn(connection)
Summary
yoU ART on Hack The Box is an easy-level challenge focused on decoding data transmitted via a simulated UART (Universal Asynchronous Receiver-Transmitter) protocol. Participants interact with a remote service, implementing UART-specific features like start/stop bits, data bits, and parity checks to decode transmitted bytes. Using a Python-based solution, the challenge highlights key concepts in serial communication, error detection, and binary decoding, offering a practical introduction to hardware-level data transmission in cybersecurity.