Content Security Policy (CSP) is a powerful security standard designed to help protect your website from a wide range of threats, including Cross-Site Scripting (XSS), data injection, and other code execution attacks. By specifying which sources of content are trusted and allowed to load on your site, CSP acts as a security layer that prevents malicious scripts and resources from being executed in your users' browsers.
In this article, we will see how to implement the best Content-Security-Policy for your website, ensuring compliance with the latest security standards and best practices for security and easy maintenances.
How to get started with Content-Security-Policy?
The first step when starting to implement the content-security-policy is to understand what is the current state of the policy on your website.
If you already have a CSP policy
You can use CentralCSP's free scanner to audit your current CSP policy.
The content-security-policy is implemented using the Content-Security-Policy header in the HTTP response headers.Depending on the server or framework you are using, the implementation will be different.
Web Servers
This list includes software that directly handles HTTP requests from the internet.
Nginx
A high-performance web server and reverse proxy. The CSP header is added using the add_header directive in your site's configuration file.
A widely used open-source web server. The CSP header is set using the mod_headers module, typically in a .htaccess file or the main server configuration.
This list includes toolkits and libraries used to build web applications. The CSP is typically set within the application's code or configuration.
Nuxt
A framework for building Vue.js applications. You can set the CSP header globally using route rules in your nuxt.config.ts file or by using the dedicated nuxt-security module.
A minimal and flexible back-end web framework for Node.js. The recommended way to set CSP is with the Helmet middleware.
const express =require("express");const app =express();// middleware to set the Content-Security-Policy headerapp.use("/",(req, res, next)=>{// setting the Content-Security-Policy header res.setHeader("Content-Security-Policy","default-src 'self';");// next middleware or route handlernext();});
Django
A high-level Python web framework. While you can create a custom middleware, the standard approach is to use the django-csp library to manage CSP headers.
Django do not provide a built-in CSP middleware, but you can use the django-csp library to implement it.
A PHP web framework with expressive, elegant syntax. The common method is to use a middleware. The spatie/laravel-csp package is a popular and robust solution.
For now we only have a Content-Security-Policy-Report-Only header. This do not block anything and is just used to report the violations whenever something should have been blocked.
As we need to get all the reports, we need to implement a report-only endpoint to collect the reports and build a custom policy.To do so, you can use the report-uri directive in the CSP header.
Once validated, deploy your CSP in production in enforce mode and set up ongoing monitoring.
Conclusion
Deploying a content-security-policy isn't an easy task, but with the right tools and a structured approach, you can achieve robust security without sacrificing functionality. Remember, CSP is not a one-time setup: review and update your policy regularly as your website evolves to maintain the highest level of protection.
Theotime Quere