Table of Contents PHP Security
Scope of Article
In the open source world, PHP programming is often the first choice due to its availability and flexibility. It is a powerful server-side scripting language that provides a robust framework to create versatile web applications. However, recent virus attacks on PHP-based websites have shown that this power can be diminished if programmers ignore important security measures. This article highlights key challenges in PHP security and provides solutions to mitigate those risks.
How PHP Works
PHP typically runs on Apache web servers but can also run on commercial platforms like Microsoft IIS. It is a set of libraries installed on the server, enabling backend database connectivity, web service calls, and dynamic HTML generation. While PHP handles server-side scripting, HTML, CSS, and JavaScript are processed on the client side by the browser.
Website Security: The Bigger Picture
Website security requires a holistic approach, including:
- Properly configured firewalls
- Hardened operating systems
- Locked-down web servers
- Secure backend databases
While PHP is versatile, it does not inherently secure your code—it is the programmer’s responsibility to address vulnerabilities. Exploits generally fall into two categories:
- Local exploits – caused by misconfigured servers or OS vulnerabilities.
- Remote exploits – caused by insecure code that attackers manipulate to access sensitive data.
Typical PHP Security Problem Areas
| Problem Area | Possible Exploit |
|---|---|
| Forms Processing | Form Submit Spoofing |
| Sessions | Session Hijacking |
| Databases | SQL Injection |
| Shared Hosts | File System Exposure |
Forms Processing Security
Forms like contact pages or newsletter sign-ups are common attack vectors. Without proper validation:
- Malicious JavaScript or HTML can be submitted.
- Databases can store bogus or blank entries, creating email server issues.
- Attackers can manipulate date ranges in queries to overload databases.
PHP provides the $_POST method to handle submitted form data. Always validate inputs before processing or storing them.
Database Security and SQL Injection
One of the most dangerous exploits is SQL Injection. A common mistake is using unsanitized form data in queries:
<?php
$sql = "INSERT INTO users (username) VALUES ('{$_POST['username']}')";
?>
If a hacker enters DROP TABLE users; instead of a username, it could cause catastrophic data loss. Always use prepared statements or parameterized queries to prevent SQL injection.
Session Security
Sessions help PHP preserve data across user interactions. However, if not handled securely, they can be guessed, stolen, or destroyed. Always validate session data on every request using $_SESSION variables, and regenerate session IDs to prevent hijacking.
Summary
PHP security is not a built-in feature—it requires coordinated efforts across servers, operating systems, and programming practices. Developers must:
- Validate and sanitize all user input.
- Secure database queries with prepared statements.
- Manage sessions carefully to prevent hijacking.
- Implement proper server and OS hardening for layered defense.
By following these best practices, developers can significantly reduce risks and build secure PHP web applications.
About the Author
Supriya Awati is a PHP developer who loves web programming and server/client-side scripting. She works at Valency Networks as a cyber security product designer and can be reached at supriya@valencynetworks.com.
