Hack-the-Box: Racecar PWN challenge flag decoder

flag_decoder.py

#!/usr/bin/env python3
import re
import sys

def main(payload=None):
    if payload is None:
        payload = input("Enter exfiltrated memory addresses: ")

    raw_flag = payload.split()

	  # Split into two character substrings:  '0x48656c6c6f' into ['0x', '48', '65', '6c', '6c', '6f']
	  # as part of 2d-list.
    raw_flag = [re.findall('..', item) for item in raw_flag]
    
	  # Iterate the characters in reverse order since we're popping off the stack.  
    # Ignore the the '0x' signififier for the memory address.  
    # Each two character hexadecimal (base16) string is converted to the corresponding ASCII leter. 
    flag_list = [''.join(chr(int(char, 16)) for char in chars[::-1] if char != '0x') for chars in raw_flag]
    flag = ''.join(flag_list)

    # Using regex to extract the substring starting with HTB{ and ending with }
    match = re.search(r'HTB\{.*?\}', flag)
    if match:
        print(match.group())
    else:
        print("Flag with format HTB{***} not found:  We have this:  " + flag)

if __name__ == "__main__":
    if len(sys.argv) > 1:
        main(sys.argv[1])
    else:
        main()