Protect S3 bucket from malicious requests


Hi! I'm concerned about the security and cost implications related to my private AWS S3 bucket. I've noticed that my AWS account incurs charges for all requests, including those that result in a 403 error. My concern is that if someone discovers the name of my bucket, they could potentially send a large volume of GET requests, leading to a significant increase in my AWS bill. Is there a method to prevent such unauthorized access and potential cost exploitation?

1 Answer

Yes, there are several methods you can use to prevent unauthorized access to your private S3 bucket and mitigate potential cost exploitation:

S3 Block Public Access: This is the easiest and most recommended solution. It allows you to block all public access to your S3 buckets and objects at the account level. This means that even if someone discovers the name of your bucket, they won't be able to access any objects without explicit permission. You can enable S3 Block Public Access from the S3 console or through the AWS CLI. Important Note: This will block all public access, including access through CloudFront distributions.

Bucket Policies: You can create granular bucket policies that explicitly deny access to everyone except authorized users or services. This gives you more fine-grained control over who can access your objects. However, it can be more complex to manage than S3 Block Public Access.

Access Control Lists (ACLs):

You can use ACLs to grant specific permissions to individual users or groups. This can be helpful if you only need to allow access to a limited number of users. However, ACLs can be difficult to manage for large numbers of users.

CloudFront Origin Access Identity (OAI):

If you are using CloudFront to serve content from your S3 bucket, you can use an OAI to restrict access to authorized users only. This can help to prevent unauthorized access from other sources, such as directly through the S3 API.


Amazon S3 Block Public Access: Security best practices for Amazon S3: Preventing unauthorized access and data exfiltration:

answered 3 months ago

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