Receive AccessDenied when trying to access a page via the full url on my website

Question

For a while, I was simply storing the contents of my website in a s3 bucket and could access all pages via the full url just fine. I wanted to make my website more secure by adding an SSL so I created a CloudFront Distribution to point to my s3 bucket.

The site will load just fine, but if the user tries to refresh the page or if they try to access a page using the full url (i.e., www.example.com/home), they will receive an AccessDenied page.

I have a policy on my s3 bucket that restricts access to only the Origin Access Identity and index.html is set as my domain root object.

I am not understanding what I am missing.

To demo, feel free to visit my site.

You will notice how it redirects you to kurtking.me/home. To reproduce the error, try refreshing the page or access a page via full URL (i.e., kurtking.me/life)

Any help is much appreciated as I have been trying to wrap my head around this and search for answers for a few days now.

8.27.2023 Disclaimer

The solution I marked as the answer worked for me at the time, and held me over as I was developing locally and learning. It has come to my attention that this may not be the best practice.

I have not spent enough time in this area of AWS to have a recommended alternative, but some ideas are floating throughout the Answer section.

Answer 1

I have figured it out and wanted to post my solution in case anyone else runs into this issue.

The issue was due to Angular being a SPA (Single Page App) and me using an S3 bucket to store it. When you try to go to a specific page via url access, CloudFront will take (for example, /about) and go to your S3 bucket looking for that file. Because Angular is a SPA, that file doesn't technically exist in your S3 bucket. This is why I was getting the error.

What I needed to do to fix it

If you open your distribution in Cloudfront, you will see an 'Error Pages' tab. I had to add two 'Custom Error Responses' that handled 400 and 403. The details are the same for 400 and 403, so I only include a photo for 400. See below:

Basically, what is happening is you are telling Cloudfront that regardless of a 400 or 403 error, to redirect back to index.html, thus giving control to Angular to decide if it can go to the path or not. If you would like to serve the client a 400 or 403 error, you need to define these routes in Angular.

After setting up the two custom error responses, I deployed my cloudfront solutions and wallah, it worked!

I used the following article to help guide me to this solution.

Answer 2

The better way to solve this is to allow list bucket permission and add a 404 error custom rule for cloudfront to point to index.html. 403 errors are also returned by WAF, and will cause additional security headaches, if they are added for custom error handling to index.html. Hence, better to avoid getting 403 errors from S3 in the first place for angular apps.

Answer 3

If you have this problem using CDK you need to add this :

MyAmplifyApp.addCustomRule({
  source: '</^[^.]+$|\.(?!(css|gif|ico|jpg|js|png|txt|svg|woff|ttf|map|json)$)([^.]+$)/>',
  target: '/index.html',
  status: amplify.RedirectStatus.REWRITE
});

Answer 4

For those who are trying to achieve this using terraform, you only need to add this to your CloudFront Configuration:

resource "aws_cloudfront_distribution" "cf" {
   ...

   custom_error_response {
   error_code    = 403
   response_code = 200
   response_page_path = "/index.html"
   }
   
   ...
   
}

Answer 5

The accepted answer seems to work but it does not seem like a good practice. Instead check if the cloudfront origin is set to S3 Bucket(in which the static files are) or the actual s3 url endpoint. It should be the s3 url endpoint and not the s3 bucket.

The url after endpoint should be the origin

Answer 6

Add a Cloudfront function to rewrite the requested uri to /index.html if it doesn't match a regex.

For example, if none of your SPA routes contain a "." (dot), you could do something like this:

function handler(event) {
    var request = event.request
    if (/^(?!.*\..*).*$/.test(request.uri)) {
        request.uri = '/index.html'
    }
    return request
}

This gets around any kind of side effects you would get by redirecting 403 -> index.html. For example, if you use a WAF to restrict access by IP address, if you try to navigate to the website from a "bad IP", a 403 will be thrown, but with the previously suggested 403 -> index.html redirect, you'd still see index.html. With a cloudfront function, you wont.

Answer 7

Please check from the console which error are you getting. In my case I was getting a 403 forbidden error, and using the settings which are shown in the screenshot worked for me