SQL Injection is one of the most common and dangerous vulnerabilities in web applications. It occurs when an attacker is able to insert or manipulate SQL queries that are executed by the application. Protecting against SQL Injection is crucial to ensuring data security and system integrity. Here are some best practices for protecting your web applications against SQL Injection: ### <br>1. Use of Prepared Statements ### php ```php $stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username AND password = :password"); $stmt->execute(['username' => $username, 'password' => $password]); ``` ### python with SQLAlchemy ```py stmt = text("SELECT * FROM users WHERE username = :username AND password = :password") result = connection.execute(stmt, username=username, password=password) ``` ### <br>2. Use of ORM (Object-Relational Mapping) ORMs abstract the database layer and help avoid writing SQL directly, reducing the risk of SQL Injection. Django (Python): ```py user = User.objects.get(username=username, password=password) ``` Hibernate (Java) ```java Query query = session.createQuery("from User where username = :username and password = :password"); query.setParameter("username", username); query.setParameter("password", password); User user = (User) query.uniqueResult(); ``` ### <br>3. Input Validation and Sanitization Validate and sanitize user inputs to ensure they are in the expected format. PHP example using filter_input ```php $username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING); $password = filter_input(INPUT_POST, 'password', FILTER_SANITIZE_STRING); ``` JavaScript example using validator.js ```js const validator = require('validator'); let username = validator.escape(req.body.username); let password = validator.escape(req.body.password); ``` ### <br>4. Main Security Practices + Minimum privileges: Grant only the necessary privileges to the database user used by the application. + Web Application Firewalls (WAF): Use WAFs to monitor and filter HTTP traffic, identifying and blocking attacks. + Updates and Patches: Keep your system, libraries and database up to date with the latest security patches. ### <br>5. Logs and Monitoring Implement detailed logs and monitor suspicious activity, such as unauthorized access attempts and database errors. ### <br>6. Education and Training Educate and train developers on security best practices and how to identify and prevent SQL Injection. Complete PHP Protection Example ```php <?php // Database connection using PDO $dsn = 'mysql:host=localhost;dbname=testdb'; $username = 'dbuser'; $password = 'dbpass'; try { $pdo = new PDO($dsn, $username, $password); $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); // Receives input data $input_username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING); $input_password = filter_input(INPUT_POST, 'password', FILTER_SANITIZE_STRING); // Use of prepared statements $stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username AND password = :password"); $stmt->execute(['username' => $input_username, 'password' => $input_password]); $user = $stmt->fetch(PDO::FETCH_ASSOC); if ($user) { echo "Login successful!"; } else { echo "Invalid credentials."; } } catch (PDOException $e) { echo "Error: " . $e->getMessage(); } ?> ``` Protecting against SQL Injection involves a combination of techniques and good practices. Using prepared statements, ORMs, validating and sanitizing inputs, applying least privilege principles, keeping systems up to date, and educating developers are all essential steps in protecting your web applications against this threat. Have you ever used one of the above practices? Did you get good results? Let us know in the comments