To prevent your website from being loaded in an iframe on another website, you can use the X-Frame-Options header in .NET 4.5 or Angular to control if and how your web page should be displayed within an iframe. Here's how you can achieve this in both technologies:

For .NET 4.5:

1. In your .NET 4.5 application, you can configure the response headers to include the X-Frame-Options header to protect your website from being displayed within an iframe on another domain.
2. You can set the X-Frame-Options header to either "DENY" or "SAMEORIGIN" to prevent your website from being loaded in an iframe. Setting it to "DENY" will ensure that your website cannot be loaded in an iframe on any domain, while "SAMEORIGIN" will restrict it to being loaded in an iframe on the same domain.

In your ASP.NET application, you can achieve this by adding the following code to your web.config file within the system.webServer section:

<httpProtocol>
  <customHeaders>
    <add name="X-Frame-Options" value="DENY" />
  </customHeaders>
</httpProtocol>

For Angular:

1. In your Angular application, you can implement the X-Frame-Options header using HTTP Interceptors to intercept outgoing requests and set the X-Frame-Options header as part of the response.
2. Create an HTTP Interceptor to modify the response headers before they are returned to the client. In the interceptor, add the X-Frame-Options header with the desired value to prevent your website from being loaded in an iframe.

Here's an example of how you can create an HTTP Interceptor in Angular to add the X-Frame-Options header:

import { Injectable } from '@angular/core';
import { HttpInterceptor, HttpRequest, HttpHandler, HttpEvent, HttpResponse } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable()
export class XFrameOptionsInterceptor implements HttpInterceptor {
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    req = req.clone({
      setHeaders: {
        'X-Frame-Options': 'DENY'
      }
    });
    return next.handle(req);
  }
}

You would then need to add the interceptor to your Angular module providers so that it is used when making HTTP requests.

Once you have implemented the X-Frame-Options header in either .NET 4.5 or Angular, the browser will enforce the specified restrictions on how your website can be displayed in iframes on other domains.

To enhance the security of your application based on the suggestions provided, you can implement the following codes for your .NET 4.5 and Angular application:

.NET .5 (Server Side)

You need to add the following security headers in your web.config file inside the system.webServer section.

<httpProtocol>
  <customHeaders>
    <add name="Strict-Transport-Security" value="max-age=31536000; includeSubDomains" />
    <add name="X-Frame-Options" value="DENY" />
    <add name="Content-Security-Policy value="script-src 'self'" />
  </customHeaders>
</httpProtocol>

This server side configuration will apply the recommended headers to every HTTP response.

Angular (Client Side)

In Angular, you typically don't set these headers at the client side as they are response headers, which should be set at the server side. However, in the case that you have complete control over the request, you can use HttpInterceptor to modify the headers.

But remember, this may be unnecessary and even redundant, as these headers are ultimately set and managed server-side.

Here's an example of a simple HttpInterceptor:

import { Injectable } from '@angular/core';
import { HttpInterceptor, HttpRequest, HttpHandler, HttpEvent } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable()
export class SecurityHeadersInterceptor implements HttpInterceptor {
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    req = req.clone({
      setHeaders: {
        'Strict-Transport-Security': 'max-age=31536000; includeSubDomains',
        'X-Frame-Options': 'DENY',
        '-Security-Policy': "script-src 'self'"
      }
    });
    return next.handle(req);
  }
}

Again, these headers are typically set at server side (in this case, your .NET backend), so you not might need to set them at the Angular client side.

Finally, remember to register your interceptor in your module's providers array:

import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';

@NgModule({
  ...
  providers: [
    { provide: HTTP_INTERCEPTORS, useClass: SecurityHeadersInterceptor, multi: true },
    ...
  ],
  ...
export class AppModule { }

Important note: Be careful when using the 'Content-Security-Policy' header. The 'script-src 'self'' directive could break your application if you are loading scripts from a CDN or using inline scripts. You need specify them properly in the CSP header based on your application needs.

Adding security headers like 'Strict-Transport-Security,' 'X-Frame-Options,' and 'Content-Security-Policy' is typically done on the server-side and not at the client-side. The server sets the headers while responding to the request and the browser enforces the rules defined by the headers.

HttpInterceptor in Angular is primarily used to intercept HTTP requests (or responses) to transform or handle them before passing them along. While you could theoretically use them to amend headers, it would generally not be the right tool for adding server-side response security headers, and would likely not have the desired result.

For a .NET 4.5 application, you should set these headers at the server level. Here's how you can add these headers in the Web.config file:

<system.webServer>
    <httpProtocol>
      <customHeaders>
        <add name="Strict-Transport-Security" value="max-age=31536000; includeSubDomains"/>
        <add name="X-Frame-Options" value="DENY"/>
        <add name="Content-Security-Policy" value="script-src 'self'"/>
      </customHeaders>
    </httpProtocol>
</system.webServer>

Once these headers are set on the server-side, all responses from the server will include these headers. These will guide the user's web browser to adhere to the specific security policies.

This method only requires changes to your server configuration and no alteration of your client-side Angular application - a more simple and appropriate solution for your needs.