Amazon S3 可公开读取的存储桶是否损坏

Question

I have an S3 bucket defined with the following policy -

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AllowReading",
            "Effect": "Allow",
            "Principal": "*",
            "Action": "s3:GetObject",
            "Resource": "arn:aws:s3:::BUCKETNAME/*"
        },
        {
            "Sid": "AllowWriting",
            "Effect": "Allow",
            "Principal": {
                "AWS": "arn:aws:iam::000000000000:user/USERNAME"
            },
            "Action": "s3:PutObject",
            "Resource": "arn:aws:s3:::BUCKETNAME/*"
        }
    ]
}

This bucket is to hold user uploads, and its contents currently needs to be accessible via a standard URL. Each file is stored as a GUID (eg. 64a5e486-e73a-4310-85ff-327f4618a176.jpg ).

AWS seems to warn me over and over that my current policy of having a publicly accessible bucket is extremely bad, but as far as I can see, the only public aspect is reading, which I don't see as a problem. Directory listing is denied to the public, and only a specific IAM user I have set up can write files to the bucket.

My question is, should I be setting up the bucket differently (from a security standpoint) or is AWS simply being overly cautious in its warnings to me?

Answer 1

Over the past year, AWS has been proactively helping customers err on the side of safety by blocking public access by default and by providing clear warnings when buckets are publicly accessible.

If your intention is to allow any objects to be read by anyone (if they know the filename), then your policy is fine and you can be comfortable with the warning that has been provided.

The only way to make it more secure would be to have users login to an application, which then grants access to objects via Amazon S3 pre-signed URLs .