Web Security Essentials Every Developer Should Know

Security is Not Optional

As developers, we have a responsibility to protect our users. Let's explore the most common vulnerabilities and how to prevent them.

SQL Injection

Never concatenate user input into SQL queries. Always use prepared statements:

// Bad
$sql = "SELECT * FROM users WHERE id = " . $_GET["id"];

// Good
$stmt = $pdo->prepare("SELECT * FROM users WHERE id = ?");
$stmt->execute([$_GET["id"]]);

Cross-Site Scripting (XSS)

Always escape output:

echo htmlspecialchars($userInput, ENT_QUOTES, "UTF-8");

CSRF Protection

Use CSRF tokens for all state-changing operations:

<input type="hidden" name="csrf_token" value="<?php echo $token; ?>">

Additional Tips

• Use HTTPS everywhere
• Hash passwords with bcrypt
• Implement rate limiting
• Keep dependencies updated

Security is an ongoing process. Stay informed and always assume user input is malicious.