HTTP Security Headers

Node RASP intercepts each HTTP response from the server. For each response specific security-related HTTP headers are set automatically, based on the content type of the body and personal preferences. This ensures a safe client-server communication.

Usage

The security headers are added to every request by default. If you want to change the default settings you can either set an environment variable, add a variable to your package.json or change the variable directly on the OutogingMessage prototype itself.

For instance, you can add the environment variable securityHeader like following:

 export SECURITYHEADER="{ \"addHeaders\": true,
  \"headers\":
  { \"x-powered-by\": true,
    \"expect-ct\": true,
    \"strict-transport-security\": true,
    \"referrer-policy\": true,
    \"x-dns-prefatch-control\": true,
    \"x-permitted-cross-domain-policies\": true,
    \"x-content-type-options\": true,
    \"content-security-policy\": true,
    \"x-download-options\": true,
    \"x-frame-options\": true,
    \"x-xss-protection\": true,
    \"feature-policy\": false,
    \"public-key-pins\": false,
    \"cache-control\": false
   }
}"

This option works for node.js without having to use npm. However, a variable defined in the package.json or directly on the OutgoingMessage prototype overwrite the options in an environment variable.

Your package.json for configuring the security headers looks like this:

{ "name": "application",
  "securityHeader":
  { "addHeaders": true,
    "headers":
    { "x-powered-by": true,
      "expect-ct": true,
      "strict-transport-security": true,
      "referrer-policy": true,
      "x-dns-prefatch-control": true,
      "x-permitted-cross-domain-policies": true,
      "x-content-type-options": true,
      "content-security-policy": true,
      "x-download-options": true,
      "x-frame-options": true,
      "x-xss-protection": true,
      "feature-policy": false,
      "public-key-pins": false,
      "cache-control": false
    }
  },
  "scripts": { "start": "node index.js" }
}

One can either turn off the whole feature by setting the addHeaders variable or change the settings for specific headers. Run your server with npm start, otherwise the package.json won't be loaded.

You can also change the default options for the security header directly on the OutgoingMessage prototype. For instance, disabling all security headers would work like follows:

OutgoingMessage.prototype.setSecurityHeaders({ 'addHeaders': false });

Security Headers

There are multiple security headers for HTTP communication. Some are useful for a broad variety of content types. Others are only applicable for HTML-based communication. In the following table, different security headers are listed. For each security header a short description is presented and its usage for different content types is shown. The presented configuration is a trade-off between compatibility and security.

Header	Value	Description	All HTTP	HTML
Expect-CT	max-age=86400; enforce	Browsers expects certificate transparency.	X	X
Strict-Transport-Security (HSTS)	max-age=31536000; includeSubdomains	Keep users on HTTPS.	X	X
Referrer-Policy	same-origin	Restrict referrer headers.	X	X
X-Content-Type-Options	nosniff	Prevents browsers from sniffing the content-type.	X	X
X-DNS-Prefatch-Control	off	Disable browsers’ DNS prefetching.	X	X
X-Powered-By	delete	Indicates what technology powers the server.	X	X
X-Download-Options	noopen	Prevent from executing downloads in site’s context.		X
X-Frame-Options	deny	Prevents your webpage from being put in an iframe.		X
X-XSS-Protection	1; mode=block	Basic protection against XSS.		X
X-Permitted-Cross-Domain-Policies	e.g. none	Permission to handle data across domains.
Content-Security-Policy	e.g. script-src 'self'; object-src 'self'	Whitelist of things that are allowed on the webpage.
Feature-Policy	e.g. vibrate 'none'; geolocation 'none'	Deny the use of browser features.
Public-Key-Pins	e.g. pin-sha256="klO23nT2ehFDXCfx 3eHTDRESMz3asj1muO+4aIdjiuY="; max-age=2592000; includeSubDomains	Prevent person-in-the-middle attacks.
Cache-Control Surrogate-Control Pragma Expires	e.g. nocache	Disables browser caching.