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PHP Security Best Practices

6 min read Quiz at the end

Common PHP security issues include SQL injection, XSS, and CSRF. Use PDO prepared statements, htmlspecialchars() for output, and CSRF tokens for forms. Keep PHP and all Composer packages updated regularly.

PHP Security

SQL Injection — always use PDO prepared statements
XSS — escape output with htmlspecialchars()
CSRF — use CSRF tokens in all forms
Passwords — use password_hash() / password_verify()
File uploads — validate MIME type, not just extension
Sessions — use session_regenerate_id(true) after login
Error messages — never show stack traces to users
HTTPS — redirect all HTTP to HTTPS
Input validation — filter_input() and type casting
Dependencies — run composer audit regularly

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Topic Quiz · 5 questions

Test your understanding before moving on

1. Which attack inserts malicious SQL via user input?

💡 SQL injection occurs when user input is not sanitized before being used in SQL queries.

2. What prevents XSS in PHP output?

💡 htmlspecialchars() converts HTML special chars to entities, preventing script injection.

3. Which function generates a secure random token?

💡 random_bytes() is cryptographically secure; md5/sha1/rand are not.

4. What does a prepared statement prevent?

💡 Prepared statements separate SQL from data, completely preventing SQL injection.

5. Why should you use HTTPS?

💡 HTTPS encrypts all data between browser and server, protecting credentials and sessions.

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PHP Security Best Practices

PHP Security

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