If you own a website, there’s a high chance (82.9% according to W3Techs) that it is based on PHP.
As a programing language, PHP is incredibly popular for its ability to create dynamic websites, not to mention that it is free and requires no licensing fee, so anyone (with some programming knowledge) can use it.
However, PHP is not bulletproof, and you may see some vulnerability here and there. Hackers and bots will try to exploit these weaknesses and gain access to your website, so it’s important to first know what these are.
Most Common PHP Vulnerabilities
There are five most common PHP vulnerabilities, and these are:
- Cross-Site Request Forgery (CSRF)
Cross-Site Request Forgery, or CSRF, happens when the hacker manages to create a link and get someone with a privileged access (like an administrator) to click on this link. A typical CSRF attack is when this link manages to create a new “admin” user with an already existing password.
- SQL Injection (SQLi)
SQL Injection, or SQLi, occurs when the hacker sends his own instructions to your database and it executes them. The blame here usually falls on the PHP developer, who has not checked the input from a visitor for malicious code before passing it on to the database.
- Authentication Bypass
PHP developers sometimes mistakenly validate that a visitor has the proper access level. This usually happens with the function “is_admin(), which makes some developers think the user is an admin, when in fact, they are just viewing an admin page and are not an actual administrator. The result of this mistake is that non-admin users now have access to features only admins should be able to see.
- Remote and Local File Inclusion (RFI and LFI)
Remote File Inclusion (RFI) and Local File Inclusion (LFI) are two more common PHP vulnerabilities.
RFI happens when a PHP application receives input such as an URL, and passes it to a function designed to load a file. For example, this function may load a code from a malicious website this way and be executed on your site when the attacker wants to.
If we are talking about a local file that was passed on, then this is a Local File Inclusion (LFI). This way, for instance, the attacker can get access to the wp-config.php file.
- Remote Code Execution (RCE)
If a hacker manages to upload a code to your website and execute it, we are effectively talking about a Remote Code Execution, or RCE. One way an attacker might use RCE is to instruct the website to create a file containing a code that grants it the full access to your site.
How to Defend Against Security Vulnerabilities
So how can you defend or minimize these and other security vulnerabilities? Without going too much into the code, here are seven PHP development techniques that can help you with this:
- Test Your Code as You Develop it
Instead of testing your code AFTER finishing the entire code block, you should do it IN ADVANCE. This will give the opportunity to spot many of the vulnerabilities in your code that you weren’t able to if you would test the code as a whole.
Let’s say, you are developing a method within a permissions class that performs account verification tests. If you test the code as a whole, some bugs may slip through and you may end up with a bad conditional statement. If you test the entire code, you may not reach that faulty conditional statement because you missed another error that you could have spotted if you tested as you developed the code.
- Be Consistent with Your Code and Methods
Being consistent with your code and methods is a 101 of PHP development. Yet, many inexperienced PHP devs tend to make messy and inconsistent codes. Inconsistent codes are not only difficult to work with, but this inconsistent method can also create a code that is confusing to the developer and a security liability.
- Front-end Tests
You don’t always have to look under the hood to see what’s wrong with your car. Same with codes, you don’t always have to search for the vulnerabilities in the back-end when you can simply perform a front-end test.
While these types of tests may take some time to run manually, you can use some nice software that will do the test for you and do it quickly and meticulously.
- Unit Testing
Another type of testing you should perform to reduce security vulnerabilities on your website is unit testing. This will allow you to perform tests on different functionalities of your code snippets and see whether your code works as you want it or not. Plus, since you can use unit testing for several applications at once, you can use it to test user permission-related codes and see if these are followed or not.
- Sanitization Handlers and Form Handlers
These two types of handlers are an excellent way to automatically perform some basic sanitization.
For instance, sanitization handlers work against variables and superglobals and sanitize them before they get to you. On the other hand, form handlers will lead the data through some basic sanitization prior to letting you manipulate it.
Think of these two as airport security checkpoints. Sanitization handlers check for metals (data), and form handlers check if there’s anything dangerous in your bag (forms).
- Database Handler Classes
Developing a database handler class can allow you to identify and minimize some security liabilities that would have otherwise went unnoticed. For instance, you can develop your database handler class to pass the incoming data through a sanitization handler.
- Framework Usage
If you don’t want to create your own database handler class, you can use a PHP framework. These are basically complete cores with already developed sanitization handlers that you can build upon. This is very useful if you forgot to perform sanitization on some data.
Few websites, if any, are completely free of security vulnerabilities. More and more are getting hacked every year. According to Symantec’s Internet Security Report (ISTR) for 2016, 78% websites they scanned had some vulnerability, which was an increase of 2% compared to the previous year. However, with the 7 PHP development techniques described above, you can be one step ahead of them and keep your system safe.
Finally, if you are still uncertain in your abilities as a developer, you can take advantage of PHP development services by Iflexion for added piece of mind.
Do you have any comments or questions about these PHP development techniques? Do you know some other techniques? Let us know below and don’t forget to share this post if you found it useful.