Minute

Description

Challenge

Solution

minute-1

The website is nothing special, in the header there's weird collection of headers.

<div class="color-container">
    <!--                                             XXXXXX                                                                           -->
    <div class="color-box" style="background-color: #89504e;"></div>
    <div class="color-box" style="background-color: #470d0a;"></div>
    <div class="color-box" style="background-color: #1a0a00;"></div>
    <div class="color-box" style="background-color: #00000d;"></div>
...

Hex colors seemed suspicious so I parsed all the hex colors, passed it into xxd and got a QR code.

The trickiest part of the challenge was identifing changing colors, every minute colors changed (hence challenge name) meaning different QR codes.

import requests
from bs4 import BeautifulSoup as BS
from PIL import Image
from pyzbar.pyzbar import decode
import os
import re
from datetime import datetime
from time import sleep
 
URL = 'https://minute.ctf.cert.unlp.edu.ar'

filename = "out.png"
while True:
    resp = requests.get(URL)
    colors = BS(resp.text, 'html.parser').find_all('div', {'class': 'color-box'})
    colors = re.findall(r"#(.*?);", resp.text)
    with open(filename, 'wb') as f:
        for color in colors:
            f.write(bytes.fromhex(color))
    
    qr_data = decode(Image.open(filename))
    print(datetime.now(), '|', qr_data[0].data.decode())
    os.remove(filename)
    sleep(55)
    
'''
2023-10-26 01:23:12.129176 | Marty McFly: "Doc, you don't just walk into a store and-and buy plutonium. Did you rip that off?" Dr. Emmett Brown: "Of course. From a group 
of Libyan nationalists. They wanted me to build them a bomb, so I took their plutonium and, in turn, gave them a shiny bomb-casing full of used pinball machine parts!"     
2023-10-26 01:24:12.412898 | Dr. Emmett Brown: "The time-traveling is just too dangerous. Better that I devote myself to study the other great mystery of the universe: women!" Marty McFly: "The future, Unbelievable."
2023-10-26 01:25:12.104980 | Biff Tannen: "What are you looking at, butthead?" Marty McFly: "Chicken?"
2023-10-26 01:26:12.137556 | Griff Tannen: "What's wrong, McFly. Chicken?" Marty McFly: "Nobody calls me chicken."
2023-10-26 01:27:12.063561 | "I guess you guys aren't ready for that, yet. But your kids are gonna love it." - Marty McFly
2023-10-26 01:28:13.300715 | "I foresee two possibilities. One, coming face to face with herself 30 years older would put her into shock and she'd simply pass out. Or two, the encounter could create a time paradox, the results of which could cause a chain reaction that would unravel the very fabric of the space time continuum, and destroy the entire universe! Granted, that's a worse case scenario. The destruction might in fact be very localized, limited to merely our own galaxy." - Dr. Emmett Brown
2023-10-26 01:29:13.253370 | "Then tell me, future boy, who's President of the United States in 1985?" - Dr. Emmett Brown
2023-10-26 01:30:13.096751 | flag{T1emp0=00_aLT1EmP0_My_Fr13nd}
'''

Flag: flag{T1emp0=00_aLT1EmP0_My_Fr13nd}