Ensure that your AWS S3 buckets cannot be publicly accessed for WRITE actions in order to protect your S3 data from unauthorized users. An S3 bucket that allows WRITE (UPLOAD/DELETE) access to everyone (i.e. anonymous users) can provide attackers the capability to add, delete and replace objects within the bucket, which can lead to S3 data loss or unintended charges on your AWS bill.
Granting public "WRITE" access to your AWS S3 buckets can allow anonymous users to upload, modify and delete S3 objects without permission. Cloud Conformity strongly recommends against setting WRITE (UPLOAD/DELETE) permission for the "Everyone" predefined group in production.
To determine if your existing AWS S3 buckets allow public WRITE access, perform the following:
To remove public WRITE access for your S3 buckets, you need to perform the following: