Protect Amazon S3 Buckets from Unauthorized Access

Amazon S3 Bucket Security Overview

Many Amazon S3 users have received security notifications from Amazon about bucket security settings:

This means that one or more buckets may allow anonymous users to list their contents.

Fortunately, public access can be disabled for the affected buckets. CS Browser includes the Security Scan Tool to find potentially unprotected buckets and fix the discovered issues.

How to Find Unprotected Buckets

1. Click Tools > Security Scan..

   

2. The Security Scan Tool dialog opens and the scan starts automatically.

   

   CS Browser retrieves the bucket list and checks the security settings for each bucket. The scan detects public access granted through bucket ACLs to All Users or Authenticated Users, as well as public bucket policies that are not blocked by the current Amazon S3 Block Public Access settings. All discovered issues are displayed in the table.

How to Fix Bucket Security Issues

Review each issue before applying the fix. Some buckets are intentionally public, for example, buckets that host public downloads. The fix blocks public access to every selected bucket.

1. Select the buckets whose security settings you want to fix, then click Fix selected issues.

   

2. CS Browser enables all four bucket-level Amazon S3 Block Public Access settings and marks the processed buckets in green.

   

   Existing ACL grants and bucket policies are not deleted. They remain configured, but cannot grant public access while the corresponding Block Public Access settings remain enabled.