How to Prevent and Detect WordPress Theme Hacks

WordPress themes are a security problem most people don’t talk about until it’s too late. While plugins get all the scrutiny, a compromised theme can be just as destructive – sometimes worse.

Outdated code, sloppy development, and abandoned projects turn themes into easy targets for attackers looking to hijack sites, inject malware, or quietly siphon data.

And because themes are primarily for the frontend, a breach isn’t always obvious. Everything might seem normal as long as your site looks fine, until traffic drops, SEO rankings nosedive, or customers start getting redirected somewhere they definitely didn’t intend to go.

Let’s go over how to spot a compromised WordPress theme and how to lock things down before your homepage becomes a billboard for a sketchy online casino.

Quick ways to detect if your WordPress theme is compromised

The fastest way to know if your WordPress theme has been hacked is to run a security scan. Sure, you can hunt for weird links and broken pages, but modern malware is sneaky – it hides in your code, injects scripts, and sets up backdoors.

A good security tool scans your site, flags suspicious changes, and tells you exactly what’s wrong.

Shield Security PRO is one such tool, and its File Locker feature will detect and notify you of changes to your theme’s functions.php file so you’re not sitting on a ticking time bomb.

Otherwise, here are some indicators to look out for if you suspect your WordPress theme has been hacked:

• Altered theme metadata in the stylesheet can mean that hackers changed header details – such as the theme name, version, or author – to disable automatic updates and obscure their modifications.
• Unexpected external file includes in theme files can mean that hackers inserted PHP functions (like include or require) that load remote scripts, establishing hidden backdoors.
• Hardcoded backdoor access points in theme files can mean that hackers added custom admin functions or login bypasses, ensuring they can regain access even if the breach is detected.
• Injected inline JavaScript or spam links in theme templates can mean that hackers altered the theme to capture user data or redirect visitors to malicious domains, directly compromising the site’s functionality.
• Unauthorised scheduled tasks in functions.php can mean that hackers set up recurring cron jobs to execute periodic malicious actions, keeping the compromise active over time.

What to do if your WordPress theme gets hacked

If you’ve run the checks above and determined that your WordPress theme has been hacked, here’s what you should do immediately:

• Switch to a default WordPress theme to stop the execution of malicious code and help isolate the issue while you troubleshoot further.
• Remove unauthorised files and scrub obfuscated code from the hacked theme to eliminate the hidden backdoors and prevent ongoing exploitation.
• Reset passwords and audit user accounts to close off unauthorised access so compromised credentials are no longer a vulnerability.
• Restore a backup from before the hack to reinstate a secure version of your theme, provided that the backup is verified malware-free.
• Implement additional security measures such as installing a reputable security plugin like Shield Security PRO and scheduling regular scans, to harden your site against future theme compromises.

We can’t stress enough how important it is to be proactive in the situation. You have no guarantee that the theme’s developer will resolve it at all, let alone in a timely manner.

Take BeTheme, which is currently in use across an estimated 236,000 sites. In versions up to and including 27.5.6, it doesn’t fully check user inputs in some of its features, which can allow attackers with certain access to insert harmful code that runs whenever a user views the page.

At the time of writing this, the vulnerability has been publicly known for seven months but remains unpatched.

How confident are you that your theme is free of unreported vulnerabilities? The only way to be certain is to build your own protections. In the next sections, we’ll show you how.

How to choose a secure WordPress theme

Your theme, no matter how good, won’t protect your site, but the wrong one will absolutely put it at risk. The best defense is a solid security plugin and making sure your theme doesn’t come already full of security holes. Here’s how to choose one:

• Use themes from reputable sources that prioritise security and ongoing updates. The Divi Theme by Elegant Themes is a great choice, as are alternatives from marketplaces like ThemeForest, which vet for quality and security.
• Avoid nulled or pirated themes, no matter how tempting. These often come preloaded with backdoors and hidden malware, giving attackers instant access to your site.
• Choose a theme that follows WordPress coding standards by ensuring it’s built with secure code that aligns with best practices.
• Make sure the theme is regularly updated to stay compatible with the latest WordPress version and security patches.
• Check user reviews for security and performance issues before installing a theme. Look for complaints about bugs, poor support, or vulnerabilities that haven’t been fixed.

Reduce the chances of a WordPress theme hack with Shield Security PRO

Shield Security PRO offers multiple layers of protection to keep your theme secure, detecting and blocking threats before they can take hold.

As we’ve already mentioned, File Locker keeps your theme’s functions.php under constant watch. If a hacker – or an overeager admin – tries to modify something they shouldn’t, you’ll get an immediate alert, giving you a chance to react before the damage is done.

Then there’s MAL{ai}, a malware scanner that actually learns from threats. Instead of relying solely on outdated signature-based detection, it spots both known and emerging threats buried inside your theme files. That means it can catch malware that’s been specifically engineered to evade traditional security tools.

And, to prevent bad actors from casually waltzing into your settings, Security Admin restricts access to critical configurations, ensuring only authorised users can make changes.

Best practices for WordPress theme security

If you prefer to take a manual approach to things instead, here’s what you can do to secure your WordPress theme:

• Disable theme file editing in WordPress to prevent hackers from injecting malicious code through the built-in editor. Add define(‘DISALLOW_FILE_EDIT’, true); to your wp-config.php file to block unauthorised modifications.
• Restrict theme upload permissions to limit who can install or modify themes. Only allow a single, trusted admin account to upload or change themes, reducing the risk of unauthorised file injections.
• Regularly review your theme’s functions.php file for unexpected code injections. Hackers often hide malicious scripts here, so check for obfuscated code or functions that alter user roles, settings, or database entries.
• Monitor your theme’s file integrity using checksum verification. If a theme file changes without an official update, investigate immediately to rule out unauthorised modifications.
• Delete unused themes completely instead of leaving them inactive. Even deactivated themes can contain vulnerabilities that hackers exploit to gain access to your site.
• Set strict file permissions on theme directories to prevent unauthorised modifications. Use 755 for directories and 644 for individual files to restrict access while allowing normal functionality.
• Block direct access to theme files to prevent attackers from viewing and exploiting vulnerabilities. Add Options -Indexes to your .htaccess file to stop unauthorised users from listing or accessing theme directories.
• Ensure your child theme follows WordPress coding standards to prevent security loopholes. Poorly written customisations can introduce vulnerabilities, so validate your child theme’s code.

Secure your WordPress themes with Shield Security PRO

WordPress themes are a bigger security risk than most people realise. Attackers don’t need to break your login page if they can slip malicious code into an outdated or poorly coded theme. Once inside, they can inject spam links, redirect visitors, or use your site to spread malware – often without you noticing until the damage is done.

Even well-coded themes aren’t immune, because every theme runs on the same open-source framework, making vulnerabilities inevitable. The best way to stay safe is by using a proactive security plugin like Shield Security PRO.

Its MAL{ai} malware scanner detects both known and emerging threats, while File Locker prevents unauthorised changes to critical theme files, and Security Admin ensures only trusted users can modify key settings. Together, these features make it significantly harder for attackers to exploit your theme as an entry point.No theme will ever be completely secure, but that doesn’t mean your site has to be vulnerable. Check out Shield Security PRO and give your theme the protection it can’t give itself.