1. Introduction

1.1 Brief Explanation of the Tutorial's Goal

Web attacks are a constant threat to any web application. This tutorial aims to provide you with a fundamental understanding of some of the most common web attacks and techniques to prevent them.

1.2 What the User Will Learn

By the end of this tutorial, you will learn:
- Common types of web attacks.
- How to use secure headers.
- The importance of validating and sanitizing user input.
- An introductory understanding of common attack vectors.

1.3 Prerequisites

Basic knowledge of web development and HTTP (Hypertext Transfer Protocol) is required. Familiarity with any server-side programming language like Node.js, Python, or PHP will be beneficial.

2. Step-by-Step Guide

2.1 Using Secure Headers

HTTP response headers can have a significant impact on your web application's security. They can prevent or mitigate various types of attacks.

For example, the X-XSS-Protection header can prevent cross-site scripting attacks:

app.use(function(req, res, next) {
  res.setHeader("X-XSS-Protection", "1; mode=block");
  next();
});

2.2 Validating and Sanitizing User Input

User input is a common source of web attacks. Always validate and sanitize input to ensure it's safe:

var sanitizeHtml = require('sanitize-html');

app.post('/submit', function(req, res) {
  var clean = sanitizeHtml(req.body.userInput);
  // now `clean` is safe to use
});

2.3 Understanding Common Attack Vectors

Common attack vectors include SQL Injection, Cross-Site Scripting (XSS), and Cross-Site Request Forgery (CSRF). Understand these and use appropriate techniques to prevent them.

3. Code Examples

3.1 Preventing SQL Injection

var mysql = require('mysql');
var connection = mysql.createConnection({
  host     : 'localhost',
  user     : 'me',
  password : 'secret',
  database : 'my_db'
});

app.get('/users/:id', function(req, res) {
  var id = req.params.id;
  connection.query('SELECT * FROM users WHERE id = ?', [id], function(error, results, fields) {
    if (error) throw error;
    res.json(results);
  });
});

3.2 Preventing XSS

app.use(function(req, res, next) {
  res.setHeader("X-XSS-Protection", "1; mode=block");
  next();
});

4. Summary

In this tutorial, we covered various techniques to prevent common web attacks. We discussed the use of secure headers, the importance of validating and sanitizing user input, and common attack vectors.

For further learning, consider exploring other security measures like HTTPS, CSP, and more.

5. Practice Exercises

5.1 Exercise 1: Secure Headers

Implement the HTTP Strict Transport Security (HSTS) header in your application.

5.2 Exercise 2: User Input

Create a form that accepts user input, validates it, and sanitizes it before use.

5.3 Exercise 3: SQL Injection

Create a mock database and implement a measure to prevent SQL injection.

Solutions to these exercises can be found on the official OWASP (Open Web Application Security Project) website. Keep practicing and stay secure!