Security Best Practices

import express from 'express';
import helmet from 'helmet';
import rateLimit from 'express-rate-limit';

const app = express();

// Helmet: 보안 헤더 자동 설정
app.use(helmet({
  contentSecurityPolicy: {
    directives: {
      defaultSrc: ["'self'"],
      scriptSrc: ["'self'", "'unsafe-inline'", "https://trusted-cdn.com"],
      styleSrc: ["'self'", "'unsafe-inline'"],
      imgSrc: ["'self'", "data:", "https:"],
      connectSrc: ["'self'", "https://api.example.com"],
      fontSrc: ["'self'", "https:", "data:"],
      objectSrc: ["'none'"],
      mediaSrc: ["'self'"],
      frameSrc: ["'none'"],
    },
  },
  hsts: {
    maxAge: 31536000,
    includeSubDomains: true,
    preload: true
  }
}));

// HTTPS 강제
app.use((req, res, next) => {
  if (process.env.NODE_ENV === 'production' && !req.secure) {
    return res.redirect(301, `https://${req.headers.host}${req.url}`);
  }
  next();
});

// Rate Limiting (DDoS 방지)
const limiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15분
  max: 100, // IP당 최대 100 요청
  message: 'Too many requests from this IP, please try again later.',
  standardHeaders: true,
  legacyHeaders: false,
});

app.use('/api/', limiter);

// Auth 엔드포인트는 더 엄격하게
const authLimiter = rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 5, // 15분에 5번만
  skipSuccessfulRequests: true // 성공 요청은 카운트하지 않음
});

app.use('/api/auth/login', authLimiter);

import Joi from 'joi';

const userSchema = Joi.object({
  email: Joi.string().email().required(),
  password: Joi.string().min(8).pattern(/^(?=.*[A-Z])(?=.*[a-z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]/).required(),
  name: Joi.string().min(2).max(50).required()
});

app.post('/api/users', async (req, res) => {
  // 1. Input 검증
  const { error, value } = userSchema.validate(req.body);

  if (error) {
    return res.status(400).json({ error: error.details[0].message });
  }

  // 2. SQL Injection 방지: Parameterized Queries
  // ❌ 나쁜 예
  // db.query(`SELECT * FROM users WHERE email = '${email}'`);

  // ✅ 좋은 예
  const user = await db.query('SELECT * FROM users WHERE email = ?', [value.email]);

  // 3. XSS 방지: Output Encoding
  // React/Vue는 자동으로 escape, 그 외는 라이브러리 사용
  import DOMPurify from 'isomorphic-dompurify';
  const sanitized = DOMPurify.sanitize(userInput);

  res.json({ user: sanitized });
});

import csrf from 'csurf';
import cookieParser from 'cookie-parser';

app.use(cookieParser());

// CSRF protection
const csrfProtection = csrf({ cookie: true });

// CSRF 토큰 제공
app.get('/api/csrf-token', csrfProtection, (req, res) => {
  res.json({ csrfToken: req.csrfToken() });
});

// 모든 POST/PUT/DELETE 요청에 CSRF 검증
app.post('/api/*', csrfProtection, (req, res, next) => {
  next();
});

// 클라이언트에서 사용
// fetch('/api/users', {
//   method: 'POST',
//   headers: {
//     'CSRF-Token': csrfToken
//   },
//   body: JSON.stringify(data)
// });

# Database
DATABASE_URL=postgresql://user:password@localhost:5432/mydb

# JWT
ACCESS_TOKEN_SECRET=your-super-secret-access-token-key-min-32-chars
REFRESH_TOKEN_SECRET=your-super-secret-refresh-token-key-min-32-chars

# API Keys
STRIPE_SECRET_KEY=sk_test_xxx
SENDGRID_API_KEY=SG.xxx

apiVersion: v1
kind: Secret
metadata:
  name: myapp-secrets
type: Opaque
stringData:
  database-url: postgresql://user:password@postgres:5432/mydb
  jwt-secret: your-jwt-secret

// 환경변수에서 읽기
const dbUrl = process.env.DATABASE_URL;
if (!dbUrl) {
  throw new Error('DATABASE_URL environment variable is required');
}

// Access Token 짧게 (15분)
const accessToken = jwt.sign({ userId }, ACCESS_SECRET, { expiresIn: '15m' });

// Refresh Token 길게 (7일), DB에 저장
const refreshToken = jwt.sign({ userId }, REFRESH_SECRET, { expiresIn: '7d' });
await db.refreshToken.create({
  userId,
  token: refreshToken,
  expiresAt: new Date(Date.now() + 7 * 24 * 60 * 60 * 1000)
});

// Refresh Token Rotation: 사용 시마다 새로 발급
app.post('/api/auth/refresh', async (req, res) => {
  const { refreshToken } = req.body;

  const payload = jwt.verify(refreshToken, REFRESH_SECRET);

  // 기존 토큰 무효화
  await db.refreshToken.delete({ where: { token: refreshToken } });

  // 새 토큰 발급
  const newAccessToken = jwt.sign({ userId: payload.userId }, ACCESS_SECRET, { expiresIn: '15m' });
  const newRefreshToken = jwt.sign({ userId: payload.userId }, REFRESH_SECRET, { expiresIn: '7d' });

  await db.refreshToken.create({
    userId: payload.userId,
    token: newRefreshToken,
    expiresAt: new Date(Date.now() + 7 * 24 * 60 * 60 * 1000)
  });

  res.json({ accessToken: newAccessToken, refreshToken: newRefreshToken });
});

- [ ] A01: Broken Access Control - RBAC, 권한 검증
- [ ] A02: Cryptographic Failures - HTTPS, 암호화
- [ ] A03: Injection - Parameterized Queries, Input Validation
- [ ] A04: Insecure Design - Security by Design
- [ ] A05: Security Misconfiguration - Helmet, 기본 비밀번호 변경
- [ ] A06: Vulnerable Components - npm audit, 정기 업데이트
- [ ] A07: Authentication Failures - 강력한 인증, MFA
- [ ] A08: Data Integrity Failures - 서명 검증, CSRF 방지
- [ ] A09: Logging Failures - 보안 이벤트 로깅
- [ ] A10: SSRF - 외부 요청 검증