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Photo by Maik Jonietz on Unsplash

4. X-Frame-Options

The x-frame-options header provides click jacking protection by not allowing iframes to load on your website. It is supported by IE 8+, Chrome 4.1+, Firefox 3.6.9+, Opera 10.5+, Safari 4+. Here is an example of what the header looks like:

x-frame-options: SAMEORIGIN

Enable in Nginx

add_header x-frame-options "SAMEORIGIN" always;

Enable in Apache

header always set x-frame-options "SAMEORIGIN"

5. Expect-CT

The expect-ct header prevents miss used certificates from being used by allowing websites to report and optionally enforce Certificate Transparency requirements. When this header is enabled the website is requesting the browser to verify whether or not the certificate appears in the public CT logs. Here is an example of what the header looks like:

expect-ct: max-age=604800, enforce, report-uri=”https://www.example.com/report”

Enable in Nginx

add_header expect-ct "max-age=604800, enforce, report-uri='https://www.example.com/report' always;

Enable in Apache

header always set expect-ct "max-age=604800, enforce, report-uri="https://www.example.com/report"

6. X-Content-Type-Options

The x-content-type-options header prevents Internet Explorer and Google Chrome from sniffing a response away from the declared content-type. This helps reduce the danger of drive-by downloads and helps treat the content the right way. Here is an example of what the header looks like:

x-content-type-options: nosniff

Enable in Nginx

add_header x-content-type-options "nosniff" always;

Enable in Apache

header always set x-content-type-options "nosniff"

7. Feature-Policy

The feature-policy header grants the ability to allow or deny browser features, whether in its own frame or content within an inline frame element (<iframe>). Here is an example of what the header looks like:

feature-policy: autoplay 'none'; camera 'none'

Enable in Nginx

add_header feature-policy "autoplay 'none'; camera 'none'" always;

Enable in Apache

header always set feature-policy "autoplay 'none'; camera 'none'"

Photo by Markus Spiske on Unsplash

There are a lot of things to consider when securing your website or web application, but a good place to start is to explore your HTTP security headers and ensure you are keeping up with best practices. In many cases, they are very easy to implement and only require a slight web server configuration change. HTTP security headers provide yet another layer of security by helping to mitigate attacks and security vulnerabilities. In this post, we will explore some of them to help you better understand their purpose and how to implement them.

What Are HTTP Security Headers?

Whenever a browser requests a page from a web server, the server responds with the content along with HTTP response headers. Some of these headers contain content metadata such as the content-encoding, cache-control, status error codes, etc.

Along with these are also HTTP security headers that tell your browser how to behave when handling your website’s content. For example, by using the strict-transport-security you can force the browser to communicate solely over HTTPS. There are six different HTTP security headers that we will explore below (in no particular order) that you should be aware of and we recommend implementing if possible.

1. Content Security Policy

The content-security-policy the header provides an additional layer of security. This policy helps prevent attacks such as Cross-Site Scripting (XSS) and other code injection attacks by defining content sources that are approved and thus allowing the browser to load them.

All major browsers currently offer full or partial support for content security policy. And it won’t break the delivery of the content if it does happen to be delivered to an older browser, it will simply not be executed.

There are many directives which you can use with content security policy. This example below allows scripts from both the current domain (defined by ‘self’) as well as google-analytics.com.

content-security-policy: script-src ‘self’ https://www.google-analytics.com

To explore all of the directives, and to see implementation on Nginx and Apache, make sure to check out our in-depth post on Content Security Policy.

2. X-XSS-Protection

The x-xss-protection the header is designed to enable the cross-site scripting (XSS) filter built into modern web browsers. This is usually enabled by default, but using it will enforce it. It is supported by Internet Explorer 8+, Chrome, and Safari. Here is an example of what the header looks like:

x-xss-protection: 1; mode=block

Enable in Nginx

add_header x-xss-protection “1; mode=block” always;

Enable in Apache

header always set x-xss-protection “1; mode=block”

3. HTTP Strict Transport Security (HSTS)

The strict-transport-security header is a security enhancement that restricts web browsers to access web servers solely over HTTPS. This ensures the connection cannot be established through an insecure HTTP connection which could be susceptible to attacks.

All major modern browsers currently support HTTP strict transport security except for Opera Mini and versions previous of Internet Explorer.

Here is an example of what the header looks like: You can include the max-age, subdomains, and preload.

strict-transport-security: max-age=31536000; includeSubDomains; preload

To read more about this header and see implementation on Nginx and Apache, make sure to check out our in-depth post on HTTP Strict Transport Security.