Do you know most the security vulnerabilities can be fixed by implementing necessary headers in the response header?

Security is as essential as content and SEO of your website, and thousands of website get hacked due to misconfiguration or lack of protection.

If you are a website owner or security engineer and looking to protect your websitefrom Clickjacking, code injection, MIME types, XSS, etc. attacks then this guide will help you.

In this article, I will talk about various HTTP Header to implement in multiple web servers, network edge & CDN provider for better website protection.

Notes:

• You are advised to take a backup of configuration file prior making changes

• Some of the headers may not be supported on all the browsers, so check out the compatibility before the implementation.

• Mod_headers must be enabled in Apache to implement these headers. Ensure the following line uncommented in httpd.conf file.

LoadModule headers_module modules/mod_headers.so

• Post-implementation, you can use secure headers online tool to verify the results.

If you are using SUCURI Cloud WAF, then you don’t have to worry about adding these manually on your web server as most of them are automatically enabled.

X-XSS-Protection

X-XSS-Protection header can prevent some level of XSS (cross-site-scripting) attacks, and this is compatible with IE 8+, Chrome, Opera, Safari & Android.

Google, Facebook, Github use this header, and most of the penetration testing consultancy will ask you to implement this.

There are four possible ways you can configure this header.

Let’s implement 1;mode=block in the following web servers.

Apache HTTP Server

Add the following entry in httpd.conf of your Apache webserver

Header set X-XSS-Protection "1; mode=block"

Restart the apache to verify

Nginx

Add the following in nginx.conf under http block

add_header X-XSS-Protection "1; mode=block";

Nginx restart is needed to get this reflected on your web page response header.

MaxCDN

If you are using MaxCDN, then adding header is easy and on-the-fly.

Go to Edge Rules >> click “New Rule” and select “Add X-XSS-Protection Header” from the drop-down.

Microsoft IIS

• Open IIS Manager

• Select the Site you need to enable the header for

• Go to “HTTP Response Headers.”

• Click “Add” under actions

• Enter name, value and click Ok

• Restart IIS to see the results

HTTP Strict Transport Security

HSTS (HTTP Strict Transport Security) header to ensure all communication from a browser is sent over HTTPS (HTTP Secure). This prevents HTTPS click through prompts and redirects HTTP requests to HTTPS.

Before implementing this header, you must ensure all your website page is accessible over HTTPS else they will be blocked.

HSTS header is supported on all the major latest version of a browser like IE, Firefox, Opera, Safari, and Chrome. There are three parameters configuration.

So let’s take an example of having HSTS configured for one year including preload for domain and sub-domain.

Apache HTTP Server

You can implement HSTS in Apache by adding the following entry in httpd.conf file

Header set Strict-Transport-Security "max-age=31536000; includeSubDomains; preload"

Restart apache to see the results

Nginx

To configure HSTS in Nginx, add the next entry in nginx.conf under server (SSL) directive

add_header Strict-Transport-Security 'max-age=31536000; includeSubDomains; preload';

As usual, you will need to restart Nginx to verify

Cloud Flare

If you are using Cloud Flare, then you can enable HSTS in just a few clicks.

• Log in to Cloud Flare and select the site

• Go to the “Crypto” tab and click “Enable HSTS.”

Select the settings the one you need and changes will be applied on the fly.

Microsoft IIS

Launch the IIS Manager and add the header by going to “HTTP Response Headers” for the respective site.

Restart the site

X-Frame-Options

Use the X-Frame-Options header to prevent Clickjacking vulnerability on your website. By implementing this header, you instruct the browser not to embed your web page in frame/iframe. This has some limitation in browser support, so you got to check before implementing it.

You can configure the following three parameters.

Let’s take a look at how to implement “DENY” so no domain embeds the web page.

Apache

Add the following line in httpd.conf and restart the webserver to verify the results.

Header always append X-Frame-Options DENY

Nginx

Add the following in nginx.conf under server directive/block.

add_header X-Frame-Options “DENY”;

Restart to verify the results

F5 LTM

Create an iRule with the following and associated with the respective virtual server.

when HTTP_RESPONSE {

HTTP::header insert "X-FRAME-OPTIONS" "DENY"

}

You don’t need to restart anything, changes are reflected in the air.

WordPress

You can get this header implemented through WordPress too. Add the following in a wp-config.php file

header('X-Frame-Options: DENY);

If you are not comfortable editing the file, then you can use a plugin as explained here.

Microsoft IIS

Add the header by going to “HTTP Response Headers” for the respective site.

Restart the site to see the results.

X-Content-Type-Options

Prevent MIME types security risk by adding this header to your web page’s HTTP response. Having this header instruct browser to consider files types as defined and disallow content sniffing. There is only one parameter you got to add “nosniff”.

Let’s see how to advertise this header.

Apache

You can do this by adding the below line in httpd.conf file

Header set X-Content-Type-Options nosniff

Don’t forget to restart the Apache webserver to get the configuration active.

Nginx

Add the following line in nginx.conf file under server block.

add_header X-Content-Type-Options nosniff;

As usual, you got to restart the Nginx to check the results.

WordPress

If you are using WordPress, then you may consider using Security Headers plugin to implement this header.

Microsoft IIS

Open IIS and go to HTTP Response Headers

Click on Add and enter the Name and Value

Click OK and restart the IIS to verify the results.

HTTP Public Key Pinning

Minimize the man-in-the-middle (MITM) attacks risk by pinning certificate. This is possible with HPKP (HTTP Public Key Pinning) header.

You can pin the root certificate public key or immediate certificate. At the time of writing, HPKP currently works in Firefox and Chrome and support SHA-256 hash algorithm.

There are four possible parameter configurations.

Let’s see HPKP header example from facebook.com

public-key-pins-report-only:max-age=500; pin-sha256="WoiWRyIOVNa9ihaBciRSC7XHjliYS9VwUGOIud4PB18="; pin-sha256="r/mIkG3eEpVdm+u/ko/cwxzOMo1bk4TyHIlByibiA5E="; pin-sha256="q4PO2G2cbkZhZ82+JgmRUyGMoAeozA+BSXVXQWB8XWQ="; report-uri=http://reports.fb.com/hpkp/

If this is something you need to implement on your website, then head to implementation guide written by Scott Helme.

Content Security Policy

Prevent XSS, clickjacking, code injection attacks by implementing the Content Security Policy (CSP) header in your web page HTTP response. CSP instruct browser to load allowed content to load on the website.

All browsers don’t support CSP, so you got to verify before implementing it. There are three ways you can achieve CSP headers.

1. Content-Security-Policy – Level 2/1.0

2. X-Content-Security-Policy – Deprecated

3. X-Webkit-CSP – Deprecated

If you are still using deprecated one, then you may consider upgrading to the latest one.

There are multiple parameters possible to implement CSP, and you can refer OWASP for an idea. However, let’s go through two most used parameters.

The following example of loading everything from the same origin in various web servers.

Apache

Get the following added in httpd.conf file and restart the webserver to get effective.

Header set Content-Security-Policy "default-src 'self';"

Nginx

Add the following in server block in nginx.conf file

add_header Content-Security-Policy "default-src 'self';";

Microsoft IIS

Go to HTTP Response Headers for your respective site in IIS Manager and add the following

X-Permitted-Cross-Domain-Policies

Using Adobe products like PDF, Flash, etc.? You can implement this header to instruct the browser how to handle the requests over a cross-domain. By implementing this header, you restrict loading your site’s assets from other domain to avoid resource abuse.

There are a few options available.

Apache

If you don’t want to allow any policy.

Header set X-Permitted-Cross-Domain-Policies "none"

You should see the header like the following.

Nginx

And, let’s say you need to implement master-only then add the following in nginx.conf under server block.

add_header X-Permitted-Cross-Domain-Policies master-only;

And the result.

Referrer Policy

Looking to control the referrer-policy of your site? There are certain privacy and security benefits. However, not all the options are supported by all the browsers, so review your requirement before the implementation.

Referrer-Policy supports the following syntax.

Apache

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