PHP Hardening: Strategies to Meet Compliance Requirements

PHP hardening against security threats is essential to avoid security breaches, legal penalties, and reputational damage. However, in addition to improving overall security, PHP hardening can also help your team meet strict and increasingly complex compliance requirements, such as guidelines set by CIS benchmarks, GDPR, and others.

In this blog, I look into the connection between PHP hardening and compliance requirements. I also provide insight on potential challenges you may encounter, outline a few application hardening best practices, and recommend services that can help support your team.

PHP Hardening and Compliance Standards: Overview

You never want your business to end up as a security breach or compliance mismanagement statistic. The advantage of compliance requirements is that they create a consistent set of guidelines to help everyone. Here are a few common examples of compliance standards where hardening PHP applications can help to meet requirements.

CIS Security Benchmarks

The Center for Internet Security (CIS) is a nonprofit organization dedicated to creating confidence in the connected world. Their mission has led to dozens of vendors like IBM , Oracle, and Red Hat to lead the charge in securing infrastructure both on prem or in the cloud.

Many open source communities have developed excellent security starting points using CIS benchmarks. For example, when building a PHP hardening strategy, you can use pre-hardened container images of configuration recommendations to launch a secure application. Community members are quite aware of the requirements for hardening, and as with application frameworks, the configurations represent the sum of many years of knowledge and experience.

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GDPR 

The General Data Protection Regulation (GDPR) is an EU law enacted in 2016 that is designed to protect the personal data of EU citizens. The 88-page text sets strict standards required for businesses when handling customer information. 

Many non-EU businesses naively believe that because they are not in the EU, they don't need to follow GDPR regulations. However, this is not the case, as these businesses may have customers, partners, or even employees who are EU citizens, meaning that they are protected under GDPR. As one of the more stringent standards, following GDPR guidelines while working on a PHP hardening strategy will also ensure compliance with many other jurisdictions.

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HIPAA

The Health Insurance Portability and Accountability Act (HIPAA) is a U.S. law requiring any company operating with patient information to meet stringent standards for securing data and maintaining privacy. PHP hardening strategies to meet HIPAA requirements could include implementing access and authorization controls, keeping PHP versions updated to access the latest security protection, and more.

PCI DSS

Payment Card Industry Data Security Standards (PCI DSS) impact anyone processing a financial transaction on the internet. PHP is well-suited to address issues when handling secure transactions on the net and integrates very well with third-party APIs. This helps you to avoid the nuisance of managing credit card information.

PHP Hardening: Challenges and Barriers

As the great Jimmy Dugan once said, "It's supposed to be hard. The hard is what makes it great." While he was referring to baseball, the sentiment also applies to PHP security. There are always things that get in the way of worthwhile processes, and PHP hardening is no exception. Prioritizing security as a part of your development process and building a PHP hardening strategy requires discipline.

While challenges and barriers will still appear, I recommend adding checks for PHP hardening and security in the CI/CD process. As code moves through the pipeline, use tools like Psalm and CodeSniffer to check for deprecations. Seek out and develop best practices to ease implementation. These solutions are also highly configurable, so shop standards can be added to the list of standard checks.

Let's take a look at a few challenges and barriers you may face as you get started.

Legacy Systems

Monolithic code is probably the single greatest impediment to hardening PHP applications against threats. Testing monoliths requires a significant amount of human intervention, and humans are simply not perfect. 

One solution is decomposing large programs into functions and methods that can be unit tested. This will not only benefit your team, but will pay back dividends for years to come. Another approach is to have new developers write tests as soon as they join the team. Not only does this help developers contribute, but they can also learn the application sets while remaining relatively harmless.

Regardless of your plan of attack, monolithic code and legacy systems are a major hurdle and consideration for teams implementing PHP hardening strategies to meet compliance requirements. However, increasing code coverage will ensure there are fewer bugs and fewer attack vectors in the application set.

Lack of Regular Updates

Old code also means out-of-date PHP versions. How old is your PHP, and what stack is it running on? For instance, according to the 2025 PHP Landscape Report, 13.90% of participants were deploying applications using PHP 5.6 or older, with an additional 14.08% deploying PHP 7.0, 7.1, or 7.2. 

Each of these versions have been end of life (EOL) and unsupported by the community for over five years. In that time, dozens of vulnerabilities have been identified by both the community and dedicated third parties like Zend. While these vulnerabilities have been mitigated in current PHP versions, applications using unsupported EOL PHP are left at risk.

How often your PHP stack is updated will seriously impact your security model and PHP hardening efforts, and the longer you delay upgrading, the larger of a challenge it becomes. For example, I've seen organizations work really hard to get to PHP 8, just to leave the stack at 8.1.3. Meanwhile, the community is at version 8.1.32.

Having a regular cadence for keeping pace with the PHP lifecycle is an incredibly strong method for PHP hardening. Auditing this regularly is essential for planning, remediating, and ensuring all compliance standards are satisfied.

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Limited Resources or Lack of Developer Knowledge

A lot of developers like to write code and build incredible new applications. Some of those developers, like me, also have the desire to a little administration work. However, I started my career as a system administrator in a large corporate data center, which instilled some good habits. Not all developers have or want this ability.

It is best to identify the lack of these skills and aptitudes early on so the appropriate people can be added to the team and fill in the gaps. Projecting that a developer "should" do certain things is not the same as ensuring things get done. With IT resources already stretched, subjecting team members to tasks they are not ready for can result in even fewer developers to get the job done.

Another option is to pursue professional development and education courses for your team. However, it is critical that these training opportunities are effectively delivered, measured, and led by experts. For instance, Zend offers a full suite of PHP training courses created and led by proven PHP professionals. Each course is designed to help set a standardized knowledge base for your team, and they cover topics ranging from unit testing to boosting website performance and beyond.

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PHP Application Hardening Best Practices

Now that I've gone through some of the challenges that may appear while hardening PHP applications, let's go through a few best practices for your team to follow. Always keep in mind that PHP hardening is a multifaceted process, and you will require buy in and participation from your entire team to create a successful strategy. But, once you've gotten everyone on board, following these steps can help meet compliance requirements.

Follow Secure Coding Practices

I mentioned earlier that implementing tools in the CI/CD pipeline can help enforce strong coding standards and  meet compliance requirements. This is a very good and inexpensive place to start. However, we need to move further up the pipeline. Generally speaking, both experienced and new developers have spent little time on PHP hardening. With most developers seeing four or five programming languages over four years, they don't always have time to develop best practices on their own. 

To ensure your team follows secure coding practices, you can implement ongoing educational opportunities, such as "lunch and learns" or set meeting times for discussion. For instance, say a member of your team discovered an example of SQL injection in some legacy code. They can then use that dedicated time to show the rest of the team a good technique for remediating the issue with proper validation and prepared SQL statements.

Additionally, you can also use third-party services to provide access to skilled engineers who can provide insights and actionable steps for PHP hardening, such as through Zend Black Belt PHP services. 

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Use the Most Up-to-Date PHP Version

Earlier, I talked about how using unsupported EOL PHP versions can be a major challenge in PHP hardening and meeting compliance requirements. It is also important to appreciate that part of the "cost" of community code projects is keeping up with the community. Many times, I work with clients who see PHP as free, and who get upset when they need to modify the code to take a new version.

This is the price of admission for using open source languages. Since PHP is a "perimeter" technology, it is imperative that the code gets updated regularly. A good rule of thumb is to update your PHP stack as often as you update your firewall.

Stay on Top of Dependency Management

Another huge value-add to open source languages like PHP is that they rarely are 100% homegrown. Modules from the PHP community are often integrated into applications to provide flexibility and productivity. For instance, I would not dream of writing PHP code to create a proper spreadsheet as there are wonderful libraries that already do this quite well. However, as helpful as these modules and dependencies are, they also require regular updates and management.

Periodically checking these modules for updates is another cost of doing business and a critical piece of PHP hardening strategies. Making sure your components are up to date is almost as important as the stack itself. Productively using good package management tools like Composer can help identify and remediate issues quickly and easily.

Here's an example. We worked with a legacy application that had fourteen instances of two different PDF tools scattered amongst the code base. By the time we were done, we had refactored the application using Composer to include only one version, and maintenance became a breeze. This also reduced the overall code base significantly.

Use Container Technologies

In addition to providing maximum uptime through horizontal scaling, strong CI/CD implementations leverage containerization. Building a Docker file to compose a prescriptive model that is certified by your team ensures that many aspects of the components of the PHP application are current. While some companies are reluctant to adopt containers, implementation is a lot like unit testing, with the hardest build being the first one. Once on board, teams tend to enjoy the flexibility and ease of maintenance offered by containers.

One of the most significant advantages of the container approach is the ability to update the PHP stack as part of the build process. It can be as easy as changing a line in the config file and just like that, everything is patched.

Another feature is application isolation, which can facilitate separation of concerns via a reduced attack area. The less you expose, the less attackers can target. Implementing a "least access privilege" model can help in PHP hardening to help meet necessary compliance requirements.

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Enforce Strong Authentication and Access Controls

Authentication has come a long way with multi-factor authentication (MFA), hardware-based authentication, and centralized tools such as OAUTH and others. If your application is not leveraging one or more of these technologies, please reconsider, as strong authentication and access controls are key to PHP hardening strategies.

While access is something that can be addressed quickly, the resolution is rarely just setting the authorities properly in the web server or on a directory structure. In this case, education and good processes are the key. Many development teams become paralyzed when they do not have the tools required to work within the hardened network systems. For instance, consider a team that is required to implement new certificates on a server, but the network team refuses to grant access without SSL. To remedy this, companies must invest in clear communication and education across teams to ensure everyone is focused on security and compliance.

Ensure Your Team Is Trained and Updated on Security Strategies

Clear communication and ongoing education cannot be stressed enough. Network teams must zealously protect the infrastructure, but good processes and education will have a significant impact on productivity. Decentralizing applications and leveraging separation of concerns means that there are more nodes relying on the network for communication. Education goes all ways, with the network team needing to educate developers on concepts like port management, and the developer team needing to educate the network team on the architecture of application components.

Make PHP Hardening a Team Sport

PHP hardening is a huge piece of the compliance puzzle. But make sure to always take a holistic approach, and remember that this process is a team sport. While hardening PHP applications, don't neglect other attack vectors such as databases, network web servers, and other parts of your stack. 

For example, one of my favorite questions to ask CIOs when they bring up the subject of security is, "When was the last time you upgraded the software on your central switch?" It is such a basic piece of infrastructure that we all depend on, but that is often ignored. Always make sure to search the perimeter, and get everyone involved.

Final Thoughts

PHP hardening is a great way for your team to meet compliance standards while addressing potential security risks. By addressing vulnerabilities, maintaining up-to-date PHP stacks, and implementing strong coding practices, you can reduce risk and protect your customers from security threats. Communication and cross-team collaboration is key to a successful strategy.

However, despite the many benefits of PHP hardening, the process and initial implementation can often be complex. Perforce Zend can help. We specialize in securing PHP applications through expert guidance, a full suite of Professional Services, and industry-leading products. We provide the tools and support you need to ensure compliance and build a comprehensive PHP hardening strategy.

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Additional Resources

• 101 Guide - PHP Security
• Solution - Zend PHP Security and Consulting Services
• Blog - Why Good PHP Monitoring Matters
• Blog - 6 PHP Security Best Practices
• Blog - Getting Started With Web Application Monitoring
• Blog - Everything You Need to Know About Maintaining PHP Compliance