Defending Against Clickjacking – How to Secure Nginx Sites

Clickjacking is one of the most insidious threats facing web applications today. By tricking users into clicking on hidden, overlaid interface elements, attackers can silently manipulate privileged actions, steal data, install malware and more.

Also known as a UI redress attack, clickjacking exploits the nature of HTML frames and iframes. By nesting your site in a transparent layer on a malicious page, hackers can overlay invisible buttons to steal clicks and perform actions without consent.

In this comprehensive guide, we’ll cover everything you need to know to lock down Nginx against dangerous clickjacking attempts. You’ll learn:

  • Exactly how clickjacking works to exploit sites
  • Step-by-step hardening instructions for Nginx
  • Expert tips for testing and verifying your configuration
  • Additional best practices to further prevent attacks

Securing your site upfront takes a little effort, but prevents disastrous data breaches, account takeovers, and malware infections down the road. Let’s dive in to protecting Nginx!

The Risks of a Clickjacking Attack

To demonstrate exactly why securing against clickjacking is so critical for sites, let’s first detail some real-world examples and statistics on exploitation in the wild:

  • Email harvesting – By overlaying a hidden form on a real page, attackers silently intercept email addresses entered by users. This quickly builds extensive phishing lists.
  • Spreading malware – Clickjacking has distributed ransomware, info-stealing Trojans, and botnet malware by hiding unwanted drive-by downloads.
  • Manipulating votes & polls – Overlaying rigged buttons has gamed website polls and contests by stuffing ballots out of sight.
  • Account takeovers – A multi-step attack could trick users into clicking a hidden password change form then approval button.

Worryingly, clickjacking scripts are readily available and don’t require advanced skills to modify and spread across sites built with common platforms like WordPress and Drupal.

According to research from, over 10% of the top million sites contain some vulnerability to potential clickjacking attacks. As web apps continue to grow in complexity, the threats are also increasing in sophistication.

Now that you have a deeper understanding of why preventing clickjacking should be a top priority, let’s explore how the X-Frame-Options header specifically counters this attack vector.

Mitigating Clickjacking with X-Frame-Options

The X-Frame-Options HTTP header was designed explicitly as an anti-clickjacking tool for websites. When enabled, it signals to browsers whether your web pages are allowed to render inside a frame or iframe. By selectively permitting this behavior, you can disable the frame nesting necessary to conduct clickjacking.

There are two secure values that offer robust protection:

DENY – This completely blocks rendering pages inside any frame, eliminatig clickjacking capabilities:

X-Frame-Options: DENY  

SAMEORIGIN – Pages are only allowed to be framed by web pages originating from the exact same domain. This prevents third-party/malicious nesting while permitting normal usage:

X-Frame-Options: SAMEORIGIN

Now let’s explore browser specifics, secure implementation in Nginx, and how to confirm your configuration is working properly.

Bulletproof Implementation in Nginx

Adding X-Frame-Options only requires a single line, but hardening security in general demands care and testing. Follow these steps to reliably block clickjacking:

1. Edit Config File

Open your domain.conf inside /etc/nginx/conf.d. Add the line below in your server block – choosing either DENY or SAMEORIGIN:

add_header X-Frame-Options "SAMEORIGIN";

2. Syntax Check & Restart

Test your config edits and restart Nginx for changes to take effect:

nginx -t  
systemctl restart nginx

3. Confirm with Browser Tools

In Chrome or Firefox dev tools, verify header is present on all domain pages such as:

X-Frame-Options: SAMEORIGIN

4. Re-check after Code Changes

Include X-Frame-Options testing whenever you modify platform code or upgrade system software.

That’s the complete process – fairly easy but also simple to overlook! Now let‘s cover additional best practices for preventing clickjacking attacks.

Going Beyond Just Configuring Headers

While sending the X-Frame-Options header handles the brunt of clickjacking defense, additional front-end and back-end tactics should be deployed as well:

Frame-Busting Scripts – JS snippets that force site breakout if framed against policy

CSP frame-ancestors – Block unwanted nesting at the browser level

NOFRAMES – Displays visible warnings if nested in frames

SameSite Cookies – Prevents CSRF attacks that might lead to clickjacking

Input Validation – Sanitize any requests to block JS injection

Layering all these techniques establishes robust, overlapping protection from malicious requests across the full application stack.

For even more ways to lock down your Nginx server, review our complete Nginx Hardening Guide.

Conclusion – Prioritize Clickjacking Protection

With damaging real-world cases continuing to emerge, ensuring your website is secured against clickjacking should be a top priority. Fortunately, implementing simple yet effective headers like X-Frame-Options provides a first line of defense.

Beyond just understanding header configurations, site owners also need testing vigilance, browser expertise, and adopting complementary protections to truly minimize risk. But preventing clickjacking ultimately depends on proactive security fundamentals – configure headers properly and respond to threats before an attack!