100 Days of AWS Day 17

 100 Days of AWS Day 17: Securely Sharing Privative S3 Objects with Pre-signed URLs.

Welcome to Day 18! One of the golden rules in regard to AWS security is not to make S3 buckets public unless there is a necessity to do so. Inquired how can we safely share personal material with particular users? One of the strongest security features of S3 is the Pre-signed URLs.

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The Question

An application stores paid video courses in a private S3 bucket. What is the most secure and scalable method to allow a logged-in user to download a single video they have purchased?

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The Correct Answer

The right choice is (C) Create an S3 Pre-signed URL.

Why It's Right: A Time-limited Pass with Security.

The default settings of a private S3 bucket allow the owner of a bucket and authorized identities to access all its objects. Pre-signed URL gives you an opportunity to override this, giving you temporary access to a particular object.

Here's how it works:

The AWS SDK is used to create a special URL with an IAM identity (such as a user or, more popularly, a role taken up by your application) that is authorized with permission to access the private object.

It will contain the original object path and temporary security credentials as query parameters in this URL.

You have an expiration time after which the URL will cease to work.

The viewer who has this URL is free to perform the given action (e.g., to download the object) in the restricted duration of time as though it were he or she who created it.

An Analogy: The Hotel Key Card 🔑

Any form of publicizing a bucket is equivalent to leaving all the doors of hotel rooms open.

It is similar to an IAM user creating one person the hire of a full-time security guard per individual guest. It's not scalable.

Pre-signed URL is a hotel key card. It has been programmed to provide access to a particular room (your S3 object) and within a set time period only (the expiration date). It forms the safest and most effective way.

The Analysis of the Incorrect Options.

(A) Publicize the video file in the short term: This is a huge security threat. It establishes a race condition under which at a temporary time anyone seeking access to the link on the internet could do so and access the file.

(B) Add a new IAM User to that individual: It is not a scalable solution. Thousands of application users cannot be created and managed by thousands of IAM users. Administrators, developers, and services are IAM users and not your end-users.

(D) Public read policy: Add a public read policy to the bucket: The worst-case scenario. It would open up all your paid video classes to the whole internet, which would ruin the point of having one of the buckets.

Keywords

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