What is hardened PHP?

PHP (Hypertext Preprocessor) is one of the most commonly used scripting languages for web development. It offers a user-friendly syntax and can run on various platforms and operating systems. Although PHP is a powerful language, it is also vulnerable to security risks and attacks. Attackers can exploit vulnerabilities in the programming to access the system, steal data, or carry out other malicious activities.

For this reason, it is important for developers to harden their PHP applications to minimise potential security risks. This article discusses the basics of PHP hardening, various techniques and best practices for implementation, as well as tools to support hardening. A guide to implementation is also provided. The aim of this article is to help developers make their PHP applications more secure and resilient against attacks.

Basics of PHP Hardening

First, familiarise yourself with the basics of PHP and PHP Hardening:

What is PHP?

PHP (Hypertext Preprocessor) is a server-side scripting language used for creating dynamic web applications. It was developed in 1994 by Rasmus Lerdorf and has since been constantly evolving. PHP is used by many well-known websites such as Facebook, Wikipedia, and WordPress because it is easy to learn and user-friendly. PHP is also platform-independent and can run on various operating systems like Windows, Linux, and Mac OS.

Why is PHP Hardening Important?

PHP applications are vulnerable to security risks due to the nature of their usage. Inadequate security measures can allow attackers to exploit vulnerabilities in the programming to access the system, steal data, or carry out other malicious activities. Therefore, it is important for developers to harden their PHP applications to minimise potential security risks. PHP hardening involves a range of techniques, best practices, and tools that can be applied to enhance the security of PHP applications.

How Does PHP Hardening Work?

PHP hardening can be achieved through secure PHP configuration, the use of secure functions, the implementation of security checks, and the use of encryption. Best practices for PHP hardening include validating user inputs, avoiding inadequate validation, using parameter binding for database queries, and employing secure password storage techniques. PHP hardening tools can help identify and fix vulnerabilities before they can be exploited.

Techniques for PHP Hardening

Here is an overview of various techniques in the field of PHP Hardening:

• Secure Configuration Options

Secure PHP configuration can help minimise potential security risks. This can be achieved by disabling unnecessary functions and modules. For example, functions like "eval" and "exec" should be disabled as they can be used to execute malicious code.

• Using Secure Functions

Secure functions should be used to ensure that no malicious inputs enter the system. For example, the use of "preg_replace()" should be avoided as it has a security vulnerability that can lead to the execution of malicious code. Instead, "preg_replace_callback()" should be used to avoid malicious inputs.

• Implementing Security Checks

Security checks should be implemented to ensure that user inputs and data are validated and sanitized before entering the application. For example, all user inputs should be validated for their validity before entering the application. It is also important for all database queries to use parameter binding to avoid SQL injections.

• Using Encryption

Encryption should be used to ensure that sensitive data such as passwords and credit card information are securely transmitted and stored. For example, data should be transmitted over HTTPS to ensure that it is encrypted during transmission. It is also important to securely store passwords by hashing and salting them.

Best Practices for PHP Hardening

Find out about the best practices for PHP hardening here:

• Checking User Inputs

All user inputs should be checked for validity and integrity to ensure they match the expected formats and patterns. This includes inputs such as usernames, email addresses, phone numbers, and other information. It is important to sanitize all inputs to remove unwanted characters before processing them in the application.

• Avoiding Inadequate Validation

Inadequate validation can allow malicious code to enter the system. It is important to validate all data for its validity and integrity before entering the application. This can be achieved through the use of regular expressions and other validation techniques.

• Using Parameter Binding in Database Queries

Parameter bindings should be used in all database queries to prevent SQL injections. Parameter bindings ensure that user inputs are passed as parameters to the database query, rather than integrating them directly into the query. This prevents malicious code from being injected into the query.

• Use of Secure Password Storage Techniques

Passwords should be securely stored by hashing and salting them. It is also important to store passwords in the database encrypted or hashed. Additionally, passwords should be changed regularly to minimise the risk of compromises. It is also a best practice to avoid using passwords with low complexity and length, and to promote the use of password managers to generate and store strong and secure passwords.

What tools can be used for PHP hardening?

The right tools can make the work easier in the area of hardened PHP:

• PHP Scanners

PHP scanners are special tools that look for known vulnerabilities in PHP applications. These scanners can automatically check code and identify security holes before they can be exploited by attackers. Some common PHP scanners include OWASP ZAP, Nikto, Acunetix, Qualys, and Nessus.

• PHP Security Packages

PHP security packages contain special PHP modules that help enhance the security of PHP applications. These modules provide additional security features such as authentication, encryption, validation, access control, and more. Some common PHP security packages include Suhosin, Hardening-Patch, PHPIDS, PHPSecLib, and Libsodium.

• PHP Code Analysis Tools

PHP code analysis tools can be used to inspect an application's code and uncover vulnerabilities. These tools can automatically search for errors and weaknesses that could potentially be exploited by attackers. Some common PHP code analysis tools include SonarQube, Scrutinizer, PHP_CodeSniffer, PHPStan, and PHPMD.

Using tools for PHP hardening can help identify and eliminate potential vulnerabilities in PHP applications before they can be exploited by attackers. However, it is important to note that none of these tools can automatically solve all security issues. Thorough manual inspection of the application and careful implementation of PHP hardening best practices remain essential to ensure the security of PHP applications.

Implementation of PHP Hardening

Here is a guide on implementing PHP hardening:

Implementing PHP hardening can be a complex task that may vary depending on the type of application. However, here are some general steps that can be followed when implementing PHP hardening:

• Updating PHP version to the latest stable version
• Disabling unnecessary PHP modules and functions
• Configuring PHP settings for maximum security
• Using secure programming practices in application development
• Checking the application for known vulnerabilities and security flaws
• Utilising tools to check the security of the application and server

Using Frameworks to Facilitate Implementation

Using PHP frameworks can facilitate the implementation of PHP hardening as many of these frameworks provide specific security features. Some of the popular PHP frameworks known for developing secure applications include Laravel, Symfony, CodeIgniter, and CakePHP.

These frameworks offer developers features such as authentication, validation, encryption, and access control. They can also help prevent SQL injection attacks, cross-site scripting (XSS), and other vulnerabilities.

However, using a framework for application development is not a guarantee of a secure application. It is important to continue following best practices for PHP hardening and conduct additional security checks to identify and address potential vulnerabilities.

Conclusion

PHP hardening is an important process to ensure that PHP-based applications and servers are secure and protected. Unhardened PHP applications are vulnerable to various attacks such as SQL injection, cross-site scripting, and remote code execution.

It is important to note that PHP hardening is an ongoing process that needs to be regularly reviewed and updated. Only by doing so can PHP applications and servers remain protected against new threats. With the right techniques and tools, along with continuous monitoring, PHP hardening can be successfully implemented to enhance the security of PHP applications and servers.

Our article is based on our own experiences and research as well as information from external sources.

Sources & further links on the topic:
http://www.hardened-php.net/ (Website of the Hardened PHP Project)

Image credit:
Edgar Oliver on Pixabay