Rule: S3 Public Access Blocked at Bucket Levels
Ensure S3 public access is blocked at bucket levels to maintain data security.
| Rule | S3 public access should be blocked at bucket levels |
| Framework | CISA-cyber-essentials |
| Severity | ✔ High |
Rule Description: S3 Public Access Blocking for CISA-Cyber Essentials
Overview:
This rule enforces the blocking of public access at the bucket level in Amazon S3 (Simple Storage Service) for compliance with CISA-Cyber Essentials standards. By default, S3 buckets are private to the AWS account owner only. However, this rule ensures that public access, which may lead to potential security vulnerabilities, is explicitly denied for all buckets within the AWS account.
Rule Implementation:
To implement this rule, follow the steps below:
- 1.
Sign in to the AWS Management Console.
- 2.
Navigate to the S3 service.
- 3.
Locate and select the bucket for which you want to block public access.
- 4.
Click on the "Permissions" tab.
- 5.
Under the "Public access settings" section, click on the "Edit" button.
- 6.
Ensure that all four options ("Block all public access", "Settings for ACLs", "Settings for bucket policies", and "Settings for CORS") are checked.
- 7.
Scroll down and review the changes and ensure the changes reflect "Block all public access" for all options.
- 8.
Click on the "Save changes" button.
Troubleshooting Steps:
If you encounter any issues while implementing this rule, follow these troubleshooting steps:
- 1.
Verify the correct AWS account credentials are used for accessing the S3 service.
- 2.
Double-check that you have the necessary permissions to modify the bucket settings.
- 3.
Ensure that the selected bucket exists within the AWS account and is spelled correctly.
- 4.
Confirm that the "Block all public access" options are enabled for all settings mentioned in the rule implementation steps.
- 5.
Check if there are any conflicting bucket policies or ACLs that might override the public access blocking settings.
- 6.
Verify if any other services or AWS resources, such as CloudFront or EC2 instances, are still allowing public access to the S3 bucket.
- 7.
If the issue persists, consider reaching out to AWS Support for further assistance.
Related Monitoring and Compliance Checks:
To monitor and ensure ongoing compliance with this rule, you can:
- 1.
Set up AWS Config Rules or use AWS CloudTrail to monitor changes related to public access settings for S3 buckets.
- 2.
Regularly review the configurations and permissions of your S3 buckets to validate no public access is inadvertently granted.
Compliance:
This rule ensures compliance with CISA-Cyber Essentials standards by blocking public access to S3 buckets, reducing the risk of unauthorized access or data exposure.
Additional Recommendations:
In addition to blocking public access at the bucket level, consider implementing the following security best practices to further enhance the security of your S3 buckets:
- 1.
Implement proper access controls using AWS Identity and Access Management (IAM) policies and IAM roles to manage access to S3 buckets.
- 2.
Enable versioning for your S3 buckets to protect against accidental overwrites and enabling easier recovery from data loss.
- 3.
Regularly scan your S3 buckets for any exposed or leaked data using AWS tools like Amazon Macie, or third-party security solutions.
- 4.
Implement encryption for your S3 data using AWS Key Management Service (KMS) or SSE-S3 (Server-Side Encryption).
- 5.
Enable S3 bucket logging, which helps in monitoring and auditing access and activities performed on the S3 bucket.
Remember to follow AWS' security best practices and stay updated with the latest recommendations to ensure the highest level of security for your AWS resources.