Cross-origin resource sharing (CORS) is a security concept implemented by web browsers that restricts web pages from making requests to a different domain than the one it originated from. This is to prevent arbitrary scripts from accessing sensitive information on a different domain.
In Angular, this can cause problems with HTTP requests to APIs from a different origin. To handle this situation, Angular provides a HttpClientModule that includes support for CORS requests. However, simply adding HttpClientModule to the imports array of your app module does not completely solve the problem.
To further protect your app from potential security breaches, you can use the Referrer-Policy header and set it to 'strict-origin-when-cross-origin'. This tells the browser to only send the full URL of the page as the referrer when the request is made from a different origin.
In this article, I will explain how to set the Referrer-Policy header in Angular and provide code examples.
Setting the Referrer-Policy Header
First, we need to add the Referrer-Policy header to our server response. In most cases, this can be done by adding a middleware in your server code. Here is an example of how to set the Referrer-Policy header in an Express server:
const express = require('express')
const app = express()
app.use((req, res, next) => {
res.setHeader('Referrer-Policy', 'strict-origin-when-cross-origin')
next()
})
This middleware will set the Referrer-Policy header to 'strict-origin-when-cross-origin' for all server responses.
Next, we need to configure our Angular app to send requests with the Referrer-Policy header. We can do this by creating an HttpInterceptor that adds the header to all outgoing requests.
Create a file called referrer-policy.interceptor.ts with the following code:
import { Injectable } from '@angular/core';
import { HttpInterceptor, HttpRequest, HttpHandler } from '@angular/common/http';
@Injectable()
export class ReferrerPolicyInterceptor implements HttpInterceptor {
intercept(req: HttpRequest<any>, next: HttpHandler) {
const secureReq = req.clone({
headers: req.headers.set('Referrer-Policy', 'strict-origin-when-cross-origin')
});
return next.handle(secureReq);
}
}
This interceptor adds the Referrer-Policy header to all outgoing HTTP requests.
Finally, we need to provide this interceptor to the HttpClientModule in our app module.
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';
import { ReferrerPolicyInterceptor } from './referrer-policy.interceptor';
@NgModule({
imports: [HttpClientModule],
providers: [
{ provide: HTTP_INTERCEPTORS, useClass: ReferrerPolicyInterceptor, multi: true }
]
})
export class AppModule { }
This code adds our ReferrerPolicyInterceptor to the list of HTTP interceptors used by the HttpClientModule.
Conclusion
In this article, we learned how to set the Referrer-Policy header to 'strict-origin-when-cross-origin' in an Express server and an Angular app. By doing this, we can further protect our app from potential security breaches caused by CORS requests.
Remember, CORS is an important security concept and should not be disabled without good reason. Always make sure to set proper CORS policies and protect your app from potential security breaches.
Sure thing!
To expand on the previous topics, let's first dive deeper into CORS and why it is important.
CORS is a security feature implemented by web browsers that restricts web pages from making requests to a different domain than the one it originated from. This security measure is in place to prevent malicious scripts from accessing sensitive information on a different domain.
For example, imagine you have a website hosted at www.example.com. This website makes an AJAX request to an API hosted on api.example.com. Without CORS, your web browser would block the request due to the different origins.
With CORS, we can set policies on the server hosting the API to allow requests from specific domains. This way, the API can be accessed from www.example.com while still blocking requests from other domains.
In Angular, we can use the HttpClientModule to make CORS requests to APIs hosted on different domains. However, this alone does not guarantee the security of our app. By adding the Referrer-Policy header and setting it to strict-origin-when-cross-origin, we can further protect our app from malicious scripts and potential security breaches.
The Referrer-Policy header tells the browser how much information to include in the 'referer' field of an HTTP request. The 'referer' field is used to tell the server where the request originated from. By setting the header to strict-origin-when-cross-origin, we tell the browser to only send the full origin of the request when the request is made from a different domain.
This helps protect our app from potential security breaches caused by malicious scripts attempting to make requests from a different origin. By limiting the information sent in the referer header, we limit the amount of sensitive information that can be accessed by an attacker.
In summary, CORS is an important security feature in web development that helps prevent malicious scripts from accessing sensitive information on different domains. In Angular, we can use the HttpClientModule to make CORS requests and further protect our app by setting the Referrer-Policy header to strict-origin-when-cross-origin.
Always remember to properly secure your apps with proper CORS policies and other security measures to prevent potential security breaches.
Popular questions
Q: What is the Referrer-Policy header, and why is it used in an Angular app?
A: The Referrer-Policy header is a security header that tells the browser how much information to send in the 'referer' field of an HTTP request. In an Angular app, the Referrer-Policy header is used to protect against potential security breaches caused by malicious scripts attempting to make requests from a different domain.
Q: What does the 'strict-origin-when-cross-origin' value for the Referrer-Policy header do?
A: When the Referrer-Policy header is set to 'strict-origin-when-cross-origin', the browser will only send the full origin of the request in the 'referer' field when the request is made from a different domain. This helps protect against potential security breaches caused by malicious scripts attempting to make requests from a different domain.
Q: How can the Referrer-Policy header be set in an Angular app?
A: The Referrer-Policy header can be set in an Angular app by creating an HttpInterceptor that adds the header to all outgoing HTTP requests. The interceptor can then be provided to the HttpClientModule in the app module.
Q: Why is cross-origin resource sharing (CORS) an important security concept?
A: CORS is an important security concept because it restricts web pages from making requests to a different domain than the one it originated from. This helps prevent malicious scripts from accessing sensitive information on a different domain.
Q: What does the HttpClientModule in Angular do?
A: The HttpClientModule in Angular provides support for making HTTP requests to APIs hosted on different domains. It includes built-in support for handling CORS requests. By adding the Referrer-Policy header and setting it to 'strict-origin-when-cross-origin', we can further protect our app from potential security breaches caused by malicious scripts attempting to make requests from a different domain.
Tag
ReferrerPolicyStrictOriginXCOR (with code examples)
