What is a Content Security Policy?

Content Security Policy (CSP) is a critical security standard that helps protect websites from various attacks, particularly Cross-Site Scripting (XSS) and data injection attacks. By implementing a CSP, you can specify which dynamic resources are allowed to load on your website.

A properly configured CSP works as an additional security layer that helps detect and mitigate certain types of attacks, including:

Cross-site Scripting (XSS): Prevents attackers from injecting malicious scripts into your pages
Clickjacking: Controls whether your site can be framed by other sites
Unwanted Resource Loading: Restricts which external resources can be loaded
Data Exfiltration: Limits where data can be sent from your website
Malicious Code Execution: Defines which scripts can execute on your pages

By defining approved sources of content, CSP significantly reduces the attack surface of your website and helps keep your users safe from common security threats.

How Our CSP Generator Works

The BrowseSafe CSP Generator provides an intuitive interface to create customized Content Security Policies for your website. Our tool allows you to:

Select Required Directives: Choose which CSP directives you need based on your website's functionality
Define Trusted Sources: Specify which domains are allowed to serve various types of content
Set Fallback Options: Configure default behavior when trusted sources are unavailable
Implement Reporting: Set up violation reporting to monitor potential attacks
Test Your Policy: Generate both testing (report-only) and production-ready policies
Format for Implementation: Get your policy formatted as HTTP headers, meta tags, or nginx/Apache configuration

Our tool generates policies that follow best practices while being tailored to your specific website needs, helping you find the right balance between security and functionality.

Key CSP Directives Explained

default-src: The fallback directive for other resource types not specified
script-src: Controls which scripts can be executed on your site
style-src: Specifies valid sources for stylesheets
img-src: Defines which image sources are allowed
connect-src: Restricts URLs for fetch, WebSocket, and EventSource connections
font-src: Controls which sources can serve fonts
media-src: Limits sources for audio and video
frame-src: Specifies valid sources for frames
object-src: Controls sources for plugins like <object>, <embed>, and <applet>
base-uri: Restricts URLs that can appear in a <base> element
form-action: Lists valid endpoints for form submissions
frame-ancestors: Specifies valid parents that may embed your page in frames
report-uri: Defines where CSP violation reports should be sent

Each directive can accept various values, including 'self' (same origin), specific domains, 'none' (no sources), and special keywords like 'unsafe-inline' or 'unsafe-eval' (though these should be avoided when possible).

Implementing CSP on Your Website

There are two primary methods to implement a Content Security Policy on your website:

HTTP Header

The most robust implementation method is by adding the CSP as an HTTP header in your server configuration. This is typically done in:

Apache: Using the Header directive in .htaccess or server config
Nginx: Adding it to the add_header directive in your site configuration
Express (Node.js): Using middleware like helmet
PHP: Using the header() function
ASP.NET: Adding it to the HTTP response headers

Meta Tag

Alternatively, you can implement CSP using a meta tag in the <head> section of your HTML documents:

<meta http-equiv="Content-Security-Policy" content="default-src 'self';">

While easier to implement, this method doesn't support all CSP features, such as frame-ancestors and report-uri directives.

Testing Your CSP

Before fully implementing a restrictive CSP, it's recommended to use Content-Security-Policy-Report-Only mode, which reports violations without blocking content. This helps you identify and fix issues before enforcing the policy.

Our CSP Generator can create both enforcement and report-only versions of your policy. We recommend the following testing approach:

Start with a report-only policy and a reporting endpoint
Monitor violations in a test environment for at least a week
Adjust your policy to address legitimate needs
Gradually implement the enforcement policy in stages
Continue monitoring for new violations as your site evolves

This careful approach ensures you don't accidentally break functionality while still achieving the security benefits of CSP.

CSP Best Practices

Avoid 'unsafe-inline' and 'unsafe-eval': These bypass key protections
Use nonces or hashes for inline scripts: Rather than allowing all inline scripts
Start strict and loosen as needed: Begin with restrictive policies and make exceptions only when necessary
Implement report-uri/report-to: Monitor violations to catch issues early
Use HTTPS for all resources: Ensure resources are loaded securely
Regularly audit and update: Review and adjust your CSP as your site evolves
Consider subresource integrity: Use integrity attributes with your CSP
Test across browsers: Ensure compatibility with all major browsers

Following these practices will help you create effective policies that maximize security without compromising functionality.

Content Security Policy (CSP) Generator

Create Custom Security Headers to Protect Your Website