Testing a AWS S3 Presigned Url returns 403 Forbidden (Nodejs)

Question

I have a Lambda Nodejs function behind an API Gateway which successfully returns a Presigned URL:

const AWS = require('aws-sdk');
const S3 = new AWS.S3({
  apiVersion: '2006-03-01',
  signatureVersion: 'v4'
});

function getSignedUrl(id, type) {
  const key = `uploads/${id}.${type}`;
  return S3.getSignedUrl('putObject', {
    Bucket: 'example-bucket-name',
    Key: key,
    Expires: 300
  });
}

The Presigned URL may look like this:

https://example-bucket-name.s3.eu-central-1.amazonaws.com/uploads/489eb7115d0c479eaf9c3b6a01eb1893.png?Content-Type=image%2Fpng&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=ASIARTVN4TPKUACY5POZ%2F20200616%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20200616T104031Z&X-Amz-Expires=300&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEEMaDGV1LWNlbnRyYWwtMSJHMEUCIQCDd%2B5hFjcBd%2FA6TEV7Se6L%2B6V8VtgCrMg0%2FbOkoGKy1wIgL20u20i%2B80rnBf49MfU1T3MQK2RQdoyQF6SwGQiYgeMq7gEIvP%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FARABGgwxMTA5NjAwOTAwNjkiDIcy2z8%2FpQIhMOOaZirCAUFhV6uGF%2Ff44lDl%2BaFxIt9D302gcuPaxlrgZWlRMHb%2FEdrKFJsWP%2FG7%2B6ovilKh9WmcBX1fzuVa%2BHQ6rv6OaCueMEnDOBEj%2FvJ1hrI%2FwMDF1RLVlqq7pTDp6h6hmUxPfbqXu1k8sjcFotVzXZTzR0dX6kmWl41uEvaglXjrGG3ApvviH%2BSFLdUdvK9PBgrgSlamGIhxdJN75xxBzQMELfdpPJ6QanhLEwIa%2FuMliHPliXC2fasMzFEheA3Xmik43McnMJ3DovcFOuABdae1G7uUXOSaQzGZ7IjPLLZnMFfow4SzosQHlMUurlqQATPbieC9W3McsMVwggwzZX6BcN9OJb%2B0Ag3x9pS5eLnLsEio%2FyAPZJfXzoGBH5AdZ6TAZtC5cgKy0TEebH%2F3bF4%2FiamoTQ6YcZ4f48NefoNFHcRPXl3VF%2FdINmuTSG1cNlh2svT9jAUfOgaeK7tnFAW79L38Nv7xnnFMYFpyxoUx8XVkffCXmq15dyG7rLIR0FHkJ7p4C8eEqbQzOj%2Fsj1ELFFAWPtq38ZgFnWF%2BYf6W4UrkHD9AGdUucD1qvAA%3D&X-Amz-Signature=e11f346296a979e586b8f81a9db2ef2ce58c9f7a13a4f3c31f9a0bb9997b8b81&X-Amz-SignedHeaders=host

However when testing said URL in the browser I get a SignatureDoesNotMatch. Which I guess seems fair since I want to only use this with a PUT from the application later.

Using curl or postman I however get 403 Forbidden:

curl -v -X PUT -T 489eb7115d0c479eaf9c3b6a01eb1893.png "https://example-bucket-name.s3.eu-central-1.amazonaws.com/uploads/489eb7115d0c479eaf9c3b6a01eb1893.png?Content-Type=image%2Fpng&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=ASIARTVN4TPKUACY5POZ%2F20200616%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20200616T104031Z&X-Amz-Expires=300&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEEMaDGV1LWNlbnRyYWwtMSJHMEUCIQCDd%2B5hFjcBd%2FA6TEV7Se6L%2B6V8VtgCrMg0%2FbOkoGKy1wIgL20u20i%2B80rnBf49MfU1T3MQK2RQdoyQF6SwGQiYgeMq7gEIvP%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FARABGgwxMTA5NjAwOTAwNjkiDIcy2z8%2FpQIhMOOaZirCAUFhV6uGF%2Ff44lDl%2BaFxIt9D302gcuPaxlrgZWlRMHb%2FEdrKFJsWP%2FG7%2B6ovilKh9WmcBX1fzuVa%2BHQ6rv6OaCueMEnDOBEj%2FvJ1hrI%2FwMDF1RLVlqq7pTDp6h6hmUxPfbqXu1k8sjcFotVzXZTzR0dX6kmWl41uEvaglXjrGG3ApvviH%2BSFLdUdvK9PBgrgSlamGIhxdJN75xxBzQMELfdpPJ6QanhLEwIa%2FuMliHPliXC2fasMzFEheA3Xmik43McnMJ3DovcFOuABdae1G7uUXOSaQzGZ7IjPLLZnMFfow4SzosQHlMUurlqQATPbieC9W3McsMVwggwzZX6BcN9OJb%2B0Ag3x9pS5eLnLsEio%2FyAPZJfXzoGBH5AdZ6TAZtC5cgKy0TEebH%2F3bF4%2FiamoTQ6YcZ4f48NefoNFHcRPXl3VF%2FdINmuTSG1cNlh2svT9jAUfOgaeK7tnFAW79L38Nv7xnnFMYFpyxoUx8XVkffCXmq15dyG7rLIR0FHkJ7p4C8eEqbQzOj%2Fsj1ELFFAWPtq38ZgFnWF%2BYf6W4UrkHD9AGdUucD1qvAA%3D&X-Amz-Signature=e11f346296a979e586b8f81a9db2ef2ce58c9f7a13a4f3c31f9a0bb9997b8b81&X-Amz-SignedHeaders=host"

The Lambda function has the following Permissions:

s3:ListBucket          Allow: arn:aws:s3:::example-bucket-name
s3:GetBucketLocation   Allow: arn:aws:s3:::example-bucket-name
s3:PutObject           Allow: arn:aws:s3:::example-bucket-name/uploads/*

The S3 Bucket has the following CORS Rules:

<?xml version="1.0" encoding="UTF-8"?>
<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
<CORSRule>
    <AllowedOrigin>*</AllowedOrigin>
    <AllowedMethod>HEAD</AllowedMethod>
    <AllowedMethod>GET</AllowedMethod>
    <AllowedMethod>PUT</AllowedMethod>
    <AllowedMethod>POST</AllowedMethod>
    <MaxAgeSeconds>3000</MaxAgeSeconds>
    <ExposeHeader>ETag</ExposeHeader>
    <AllowedHeader>*</AllowedHeader>
</CORSRule>
</CORSConfiguration>

Here is the Bucket ACL:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AWSConfigBucketPermissionsCheck",
            "Effect": "Allow",
            "Principal": {
                "Service": "config.amazonaws.com"
            },
            "Action": "s3:GetBucketAcl",
            "Resource": "arn:aws:s3:::example-bucket-name"
        },
        {
            "Sid": "DenyUnEncryptedTraffic",
            "Effect": "Deny",
            "Principal": {
                "AWS": "*"
            },
            "Action": "*",
            "Resource": "arn:aws:s3:::example-bucket-name/*",
            "Condition": {
                "Bool": {
                    "aws:SecureTransport": "false"
                }
            }
        }
    ]
}

Could it be that the above DenyUnEncryptedTraffic Rule is causing the 403? I tested it by removing said rule but I still get a 403.

Block all public access is On!

The bucket owner has full access to the bucket!

I have been wasting too much time on this already and really need some help!

NJones NJones · Accepted Answer · 2020-06-16T11:44:47

Ok now I feel stupid:

Just tested said Presigned PUT URL with Postman and somehow it works:

Make sure you enter the Presigned URL, Select PUT and then select binary and add a file.

I will leave this up in case someone finds this useful.

Testing a AWS S3 Presigned Url returns 403 Forbidden (Nodejs)

4 Answers