How to Kill Vulnerabilities in Your Node.js App: A Guide to Writing Secure JavaScript Code

Js/Ts와 Node.js는 소프트웨어 엔지니어링 세계에 혁명을 일으켰지만 큰 힘에는 큰 책임이 따릅니다?️. 너무 많은 패키지와 빠른 엔지니어링 속도로 인해 취약점은 몰래 들어올 수 밖에 없습니다. 이 기사에서는 JavaScript 생태계에 숨어 있는 가장 일반적인 취약점을 다루고 안전한 코드 관행으로 이를 "제거"하는 방법을 정확하게 보여 드리겠습니다.

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1. 종속성 취약점

문제: JavaScript 생태계는 npm과 같은 곳의 패키지에 크게 의존합니다. 이러한 패키지를 설치할 때 추가 종속성을 가져오는 경우가 많습니다. 불행하게도 모든 패키지가 보안을 염두에 두고 유지관리되는 것은 아니며, 일부 패키지는 의도적으로 악성 코드를 포함하기도 합니다.

해결책:

• 종속성 감사: npm 감사를 실행하여 종속성에 알려진 취약점이 있는지 확인하세요. 그러면 문제 해결을 위한 보고서와 제안 사항이 제공됩니다.
• 패키지 정기적 업데이트: npm outdated를 사용하여 오래된 패키지, 특히 보안 패치가 있는 패키지를 확인하세요. 최신 상태를 유지하면 취약점을 예방하는 데 도움이 됩니다.
• 보안 중심 도구 사용: Snyk 또는 OWASP 종속성 검사와 같은 도구는 종속성에서 알려진 취약점을 검사합니다.

2. 안전하지 않은 구성

문제: 특히 프로덕션 환경에서 기본 구성을 그대로 유지하면 애플리케이션이 공격자에게 노출될 수 있습니다. 자세한 로깅 활성화, 디버그 모드 켜짐, 모든 원본에 대한 CORS 허용 등의 작업은 보안 허점을 만들 수 있습니다.

해결책:

• 환경별 구성: 개발 및 프로덕션에 대해 서로 다른 구성을 설정합니다. 예를 들어 디버그 모드를 비활성화하고 프로덕션에서 로깅을 줄입니다.
• 환경 변수: 환경 변수에 민감한 정보(예: 데이터베이스 자격 증명, API 키)를 보관하고 dotenv와 같은 라이브러리를 사용하여 안전하게 관리하세요.
• 민감한 데이터에 .env 파일 사용: 자격 증명이나 민감한 데이터를 코드베이스에 저장하지 마세요. .env 파일을 사용하고, .gitignore에 추가하는 것을 잊지 마세요.

3. 인젝션 공격(SQL/NoSQL 인젝션)

문제: 주입 공격은 사용자 입력이 잘못 처리되어 실행 가능한 코드나 데이터베이스 명령으로 처리될 때 발생합니다. 예를 들어, SQL 주입을 통해 공격자는 데이터베이스 쿼리를 조작하고 민감한 데이터에 액세스할 수 있습니다.

해결책:

• Parameterized Queries: Always use parameterized or prepared statements when interacting with databases. Libraries like pg for PostgreSQL or mongoose for MongoDB support these secure methods.
• Sanitize User Input: Use a library like validator to sanitize input, especially when dealing with forms or other sources of user input.

4. Cross-Site Scripting (XSS)

Problem: XSS attacks happen when attackers inject malicious scripts into your application. For example, if your app displays user-generated content without sanitizing it, an attacker could inject JavaScript that gets executed by other users’ browsers.

Solution:

• Escape User Input: Make sure that any user-generated content displayed on the front end is escaped. This way, it’s treated as plain text and not as executable code.
• Content Security Policy (CSP): A CSP allows you to define which scripts, images, and styles are allowed to run on your website. It’s a powerful way to limit XSS attacks. You can set up a CSP header in your server configuration.
• Use a Trusted Library: If you use templating libraries (e.g., Handlebars, EJS), they often have built-in escaping features. Don’t disable them.

5. Cross-Site Request Forgery (CSRF)

Problem: CSRF attacks trick users into executing unwanted actions on a different website where they’re authenticated. For example, a user logged into their bank account could unknowingly transfer money to another account by clicking a link in a malicious email.

Solution:

• Use CSRF Tokens: When using forms, implement CSRF tokens to verify that each request is legitimate. Many frameworks, such as Express, have middleware like csurf to help prevent CSRF attacks.
• Double Submit Cookies: This is another approach where you set a unique token in a cookie and require the same token to be submitted in the request payload.

const express = require('express');
const csurf = require('csurf');
const cookieParser = require('cookie-parser');

const app = express();

// Use cookie parser and csrf middleware
app.use(cookieParser());
app.use(csurf({ cookie: true }));

// Middleware to add CSRF token to all responses
app.use((req, res, next) => {
  res.locals.csrfToken = req.csrfToken();
  next();
});

app.get('/form', (req, res) => {
  // Render a form with the CSRF token
  res.send(`
    <form action="/submit" method="POST">
      <input type="hidden" name="_csrf" value="${res.locals.csrfToken}">
      <input type="text" name="data">
      <button type="submit">Submit</button>
    </form>
  `);
});

app.post('/submit', (req, res) => {
  res.send('Data received securely!');
});

app.listen(3000, () => console.log('Server running on http://localhost:3000'));

6. Insecure Data Storage

Problem: Storing sensitive data, like passwords or personal information, without encryption or secure storage methods can make it easy for attackers to steal this data if they gain access.

Solution:

• Encrypt Sensitive Data: Use encryption for sensitive data at rest. For example, use libraries like bcrypt for hashing passwords.
• Use HTTPS for Data in Transit: Encrypt data in transit by forcing HTTPS connections. Services like Let’s Encrypt offer free SSL certificates to secure your application.

const bcrypt = require('bcrypt');

async function registerUser(password) {
  // Hash the password with a salt round of 10
  const hashedPassword = await bcrypt.hash(password, 10);
  // Save hashedPassword to the database instead of the plain password
  console.log('Hashed Password:', hashedPassword);
}

async function loginUser(enteredPassword, storedHashedPassword) {
  // Compare the entered password with the stored hashed password
  const match = await bcrypt.compare(enteredPassword, storedHashedPassword);
  if (match) {
    console.log('Login successful!');
  } else {
    console.log('Invalid password');
  }
}

// Example usage
registerUser('gokuIsStrong');

7. Server-Side Vulnerabilities

Problem: Since Node.js runs on the server, any unhandled errors or improperly configured server settings can lead to security issues.

Solution:

• Error Handling: Always handle errors gracefully, and avoid exposing sensitive information in error messages. Instead of sending detailed error messages, use generic messages in production.
• Limit Request Size: Large payloads can overload your server, so limit the request body size using middleware like body-parser to prevent attacks like denial of service (DoS).
• Run as Non-Root User: Avoid running your application with root privileges. In the event of a compromise, this can help limit the damage an attacker can do.

Final Tips

Securing your Node.js and JavaScript applications takes time, but it’s a necessary investment. Here are some final quick tips:

• Use HTTPS Everywhere: Encrypting data in transit is critical to protect user data.
• Avoid eval() and similar functions: Functions like eval() can execute arbitrary code, making your app vulnerable to injection attacks. Avoid using them whenever possible.
• Keep Dependencies to a Minimum: Only install packages you really need. Each package introduces a potential vulnerability, so be selective.

By following these tips and regularly updating your knowledge on security practices, you’ll be better equipped to keep your Node.js applications safe. Security is an ongoing process, but with a proactive approach, you can significantly reduce your application’s vulnerability footprint.

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Conclusion

As much as we aim to secure our code, the truth is there's no such thing as a perfectly secure application, and we can’t kill every vulnerability. New vulnerabilities are discovered regularly, libraries are updated, and our code constantly evolves. Security is an ongoing process that requires vigilance, consistent updates, and a proactive reverse engineering mindset.

Here are a few additional ways to keep improving your code security:

1. Regularly Review Code: Conduct code reviews with a focus on security. Peer reviews help catch vulnerabilities that one developer might miss.

2. Automate Security Testing: Use CI/CD pipelines with automated security testing to catch issues early in development. Tools like GitHub Dependabot, Snyk, and npm audit can be integrated into your workflow for continuous scanning.

3. Stay Informed: Security threats evolve, so stay updated with security news, libraries, and practices. Following communities like OWASP and the Node.js security team can keep you informed of the latest threats and mitigation techniques.

4. Least Privilege Principle: Limit permissions and access levels in your app and database. The principle of least privilege ensures that each part of your application only has the access it absolutely needs to function, reducing potential damage from a breach.

5. User Education: Encourage safe practices, especially for teams with access to sensitive code and environments. Developer security training can help avoid common mistakes that lead to vulnerabilities.

By being vigilant and continuously learning, you’ll be better equipped to manage security risks in the fast-paced Node.js ecosystem. Remember: it’s about reducing risk, not achieving perfection. Happy coding, and here’s to safer, more secure applications!

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