How to Prevent SQL Injection Attacks on WordPress

WordPress is one of the most used website building platforms because of its wide range of potential applications. You can build an online store, host a blog about your favorite hobby, create a community through forums, or represent a large corporation.

But however you use it, a primary responsibility is keeping your site safe from hackers. That’s why it’s important to understand how to prevent Structured Query Language (SQL) injection attacks. 

The good news is that there are plenty of steps you can take to protect your WordPress site from this malicious code. Learning how to detect, remove, and prevent SQL injections can help you effectively secure your valuable data and make you less susceptible to attack.

What is an SQL injection and how does it work?

To understand how the injections work, it’s helpful to first learn what SQL is. This is a common language used in database development.

Your website uses it to retrieve critical information from your database and generate dynamic content. Some of the SQL databases include MySQL (WordPress sites), MongoDB, and SQL Server.

Your WordPress website uses a database to manage your site’s essential data and content, like your pages, posts, and comments. It arranges this information in tables.

view of the tables in a WordPress database

Your database is where your most sensitive data is stored. Therefore, any attack that exposes it can have severe consequences. 

SQL injection (SQLI) is a type of hacking method cybercriminals use to infiltrate and manipulate WordPress databases. Essentially, hackers can exploit loopholes in the backend coding of websites and insert malicious code into data entry fields. 

This code allows nefarious actors to execute SQL commands to the database servers via web requests using query strings, cookies, and <input> elements. This means that they can create, access, change, and eliminate data from your WordPress database. 

There are many different entry points where this can occur. The most commonly-used entry fields include signup, login, and contact forms, as well as search bars and shopping carts.

Let’s say you have a form on your website where visitors can enter their phone number. Cybercriminals can use that entry field to insert malicious code that requests the admin username and password.

Types of SQL injections

There are several different types of SQL injections. One category is what’s known as “in-band.” This is the simplest type of injection and includes error-based attacks.

With this technique, hackers use the injection to gain details about the database structure and table names. For instance, an error message may provide the table name included in a query. Then the hacker can use this information to create new attacks. 

Another type is what’s referred to as “blind SQL injection.” This is when the attacker sends a variety of queries to the database to find out how the site analyzes the responses. Doing so can help them probe responses to SQL queries to identify potential vulnerabilities, and request the database to transmit data to an external source. 

How common are SQL injection attacks?

Unfortunately, SQL injection attacks are prevalent. In fact, according to a report published by Akamai, between 2017 and 2019, around two-thirds of attacks on software applications were attributed to SQL injections.

A separate 2020 Vulnerability Stats Report also revealed that SQL injections made up 42 percent of the most common critical vulnerabilities.

SQL injections are a possibility for any website using SQL databases, like WordPress-based sites, especially those that have input fields like contact forms and search boxes.

Why SQL injections are dangerous

SQL injections are dangerous for a handful of reasons. First, they give hackers the opportunity to steal sensitive information, like your login credentials or customer data.

Not only can hackers use SQL injection to procure and steal data, but they can also use it to delete that data. This means you’re at risk of losing private and essential information used to run your website. 

In addition, there’s a risk of reputation damage and loss of revenue. A data breach can hurt your business, and you might lose the trust of your customers or fans.

Plus, these attacks can lead to Google blocklisting your site. If you end up on this list, many potential visitors will receive a warning that your site is unsafe. Most of these folks will turn back and may never return. Plus, Google will also significantly demote your search rankings — which could lead to a major, long-term loss of organic traffic that’s difficult to recover from. 

How to detect SQL injections

There are a few signs that might indicate that you’ve fallen victim to an SQL injection attack. One is that you’re suddenly receiving an influx of emails via your site’s contact form. Another indicator is if you’re receiving strange popups, ads, and error messages, especially if they’re redirecting you to seemingly sketchy websites. 

Unfortunately, the signs of an SQL injection attack are not always so obvious. As we mentioned earlier, sometimes hackers want to use injections to steal information rather than damage your website. Therefore, they may use more subtle methods that make detection more difficult. 

SQL injection detection and scanning tools

The only way to know for sure if you’ve been targeted is to conduct a scan on your website. Fortunately, there are a variety of online tools that can help you detect SQL injections on your WordPress site.  

For example, you can use Pentest Tools to conduct two free scans of your website.

PenTest tools homepage

There are two options: a Light scan or a Full scan. For the latter, you’ll need to upgrade to a paid plan. Simply enter your website’s URL and click on the Scan target button. If there are any vulnerabilities present, the scan will reveal them. 

How to remove SQL injections from your WordPress website

1. Restore a backup

Your best option to remove SQL injections is to restore a backup of your site. If you’re using Jetpack Backup, all you have to do is use the activity log to determine when the attack happened, then restore a backup from before that point. Your site will be returned to the state it was in before the hack.

However, it is important to note that, in some cases, SQL injections are done little by little, over time. You may need to go back pretty far to find a clean backup, which could result in data loss. 

And though restoring a backup may get your site up and running again, if sensitive data was stolen, you’ll still have to deal with the ramifications of the breach.

2. Use a website cleaning service

Another option is to use a third-party website cleaning service to scan your site and fix any SQL injections. Sucuri is one option — simply submit your website to their team and let them take care of everything else. Since they’re experts, they can remove malware from your database more effectively than the average developer.

3. Remove the injections yourself

Finally, if you have experience managing and working with MySQL, you can manually clean up your database. Note, though, that this is an advanced technique and if you don’t know what you’re doing, making any changes can lead to issues. 

How to prevent SQL injection attacks in the future

There’s no way to ensure that your site is ever 100 percent secure, but there are measures you can take to minimize your risk of attack. Let’s take a look at eight methods you can use to prevent SQL injections in WordPress.

1. Validate (or sanitize) your data

The key to preventing SQL injections in WordPress is to secure any entry field that can be used to enter data or content on your website. This includes comment sections and forms. Therefore, it’s important to validate and sanitize data entered into these fields upon submission.

Input validation and sanitization let you check the commands submitted by users. Sanitization even lets you change the commands. It’s an effective way to ensure that these commands don’t contain malicious code or strings of characters. 

Validation ensures that the information entered in a form matches the requested format before processing the request. For example, if you had an entry field for an email address, the data wouldn’t be validated if the ‘@’ symbol wasn’t present. 

The easiest way to create validation for your form data is by establishing rules for your forms. The process for doing so will depend on the specific plugin you’re using. For instance, if you use the premium version of Formidable Forms, you can add your own custom Input Mask Format for text fields.

adding validation to form fields in WordPress

Adding input format requirements can limit the risk of SQL injection. Sanitization can help ensure that the data entered is safe to process once it’s been validated.

Most WordPress form plugins automatically sanitize form data. However, you can add additional security measures. Rather than open-ended answers, consider using drop-down menus and multiple choice options. You could also restrict the use of special characters.

2. Install a WordPress security tool

Jetpack’s WordPress security plugin can monitor your site for vulnerabilities that could lead to SQL injections. This gives you the opportunity to fix them before someone takes advantage. 

With downtime monitoring, you’ll know the second your site goes down so you can react quickly. And with real-time backups, you can restore your site in full.

As one of the best security plugins on WordPress, it also provides security tools like:

3. Keep your website and database updated at all times

Using outdated software and tools can introduce a whole range of vulnerabilities on your site for hackers to exploit. This is why it’s important to make sure that you keep your WordPress website updated at all times.

Currently, nearly half of WordPress installations aren’t using the most updated version. Therefore, you may want to consider enabling automatic updates to ensure that you’re always running the most recent version of WordPress. 

To do this for Core updates, you can navigate to the wp-config.php file in the root directory of your website. Next, copy and paste the following code snippet to the file:

define( 'WP_AUTO_UPDATE_CORE', true );

You can enable automatic updates for your plugins by navigating to the Plugins screen from your admin dashboard. Then, click on Enable Automatic Updates from the far-right column.

enabling auto-updates in WordPress

To minimize vulnerabilities, we recommend removing any unused plugins or themes from your site. It’s also wise to update your SQL version. If you’re using cPanel for your hosting control panel, you can update your MySQL software from your dashboard. Depending on your hosting provider, you may be able to enable automatic SQL updates. 

4. Change your WordPress database prefix

By default, every time you install WordPress, the CMS uses “wp_” as its database prefix. We highly recommend changing this to something else, since hackers can use it to exploit vulnerabilities via SQL injection.

Before getting started, you should back up your database. This way, if anything goes wrong, you have a safe version to restore.

Next, connect to your site via FTP client or your host’s File Manager and browse to the wp-config.php file, which is located in the root directory of your site. In the file, look for the table_prefix line, then change “wp_” to something else:

$table_prefix  = 'wp_a12345_';

When you’re done, save the file. That’s it!

5. Use a firewall

Another strategy you can use to protect against SQL injection is to install a firewall. This is a network security system that helps you monitor and control the data coming into your WordPress site. This can catch and filter out malicious code, including those from SQL injection attacks.

There is a wide variety of WordPress firewall tools you can use. Some popular options include Wordfence and Sucuri. These tools won’t prevent attackers from submitting commands, but they can help block them from actually accessing your site. 

6. Hide the version of WordPress you’re using

Having the version of your WordPress site publicly available can make it easier for attackers to exploit known vulnerabilities, as each version comes with its own set. Therefore, to safeguard your site, we recommend hiding the version you’re using.

Doing so is quick and easy. To get started, simply copy the following code snippet:

remove_action(‘wp_head’, ‘wp_generator’);

Next, navigate to the functions.php file of your current WordPress theme. You can do this directly from the Theme Editor in WordPress, using an FTP client, or using your host’s File Manager. Paste the code within the file, then save your changes. 

7. Eliminate unnecessary database functionality

The more functionality that your WordPress database has, the more susceptible it is to attack. To minimize your risk of SQL injection, consider normalizing your database and eliminating any unnecessary functions and content. 

In a nutshell, database normalization refers to the process of organizing your data. The purpose of doing this is to eliminate any redundant data in your database and make sure that all data dependencies make sense. You can do this by putting your database in First Normal Form.

If you want a more beginner-friendly option to cleaning up your WordPress database, you can use a plugin. There are a handful of solid options to choose from, like WP-Optimize.

This freemium plugin helps you clean your database without needing to manually run SQL commands through phpMyAdmin. Instead, you can use it to optimize your database directly from your WordPress dashboard.

database table optimization options

It removes all unnecessary information from your database, including trash and unapproved comments. WP-Optimize also lets you defragment your MySQL database tables with a single click. 

8. Limit user access and permissions

You can assign various roles for WordPress users on your website. These can range anywhere from a subscriber to an administrator. With each role, you can control how much access is granted and which “capabilities” they’re given.

To help strengthen your security, it’s best to limit the number of roles with full admin access and user permissions. The fewer people who are able to change and enter data, the less likely you are to face an SQL injection attack.

To customize the user roles and permissions in WordPress, you can navigate to Users → All Users.

WordPress users in the dashboard

Then, click on the Edit link below the name of the user you want to limit access and permissions for. On the next screen, you can change their role using the dropdown Role menu.

When managing your WordPress user roles, we also recommend deleting any accounts that are no longer in use. Eliminating roles that are outdated can minimize your vulnerabilities. 

9. Avoid using nulled plugins

Nulled plugins are premium tools that have been stolen and are offered for free. While they may seem like a great deal, not only are you hurting the original developer by not paying them for their work, you’re also risking a hack. 

Nulled plugins are very often full of malicious code and backdoors that give hackers an easy gateway into your site. Avoid them at all costs and, instead, use plugins from reputable sources. 

Safeguard your WordPress site from SQL injections

To protect your WordPress site and data from the threat of cybercriminals, it’s important to be aware of some of the most common methods used to gain access to your site. When it comes to strengthening the security of your database, this means being well-versed in SQL injections. 

As we discussed in this post, an SQL injection can have damaging effects on your WordPress site, from exposure of sensitive data to the loss of content and revenue. Fortunately, there are a handful of steps you can take to detect, remove, and prevent injection attacks.

No website is ever entirely safe, but by following the above tips and techniques, you can significantly reduce your chances of falling victim to SQL injections. 

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Simon Keating profile
Simon Keating

Simon has worked in marketing and product development for over 10 years, previously at HubSpot, Workday, and now Automattic (Jetpack). He has a varied education, with a degree in chemical engineering and a masters in computer science to his name. His passion is helping people and their businesses grow.

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