Rule: S3 Public Access Block at Account Level
This rule ensures blocking S3 public access at account level.
| Rule | S3 public access should be blocked at account level |
| Framework | NIST 800-53 Revision 5 |
| Severity | ✔ Medium |
Rule Description
The rule is to ensure that public access to Amazon S3 (Simple Storage Service) buckets is blocked at the account level in compliance with the NIST 800-53 Revision 5 security standard. By blocking public access, we can prevent unauthorized access to sensitive data stored in S3 buckets and minimize the risk of data breaches.
Troubleshooting Steps
If there are any issues with implementing or enforcing the S3 public access block at the account level, you can follow these troubleshooting steps:
- 1.
Check IAM Permissions: Verify that the IAM (Identity and Access Management) policies associated with your AWS (Amazon Web Services) account have the necessary permissions to implement the S3 public access block. Ensure that the account has adequate IAM privileges to manage S3 bucket policies and access controls.
- 2.
Bucket Policy Evaluation: Review the bucket policies associated with your S3 buckets. Ensure that there are no conflicting policies that allow public access to any of the buckets. Verify that the bucket policies explicitly deny public access.
- 3.
Access Control Lists (ACLs): Check the ACLs of your S3 buckets and objects. Make sure that there are no permissions granted to the "Everyone" group or any other public entity. Remove public access permissions from the ACLs if found.
- 4.
Block Public Access Settings: Confirm that the block public access settings are enabled at the account level. To do this:
a. Log in to the AWS Management Console. b. Navigate to the S3 service. c. Click on "Account settings" in the top-right corner. d. Ensure that all the block public access settings are enabled.
- 5.
Logging and Monitoring: Enable S3 access logging and set up alerts to monitor any potential access control policy violations. This will help identify and address any misconfigurations or unauthorized access attempts.
Necessary Codes
There are no specific codes needed to implement the S3 public access block at the account level. However, you can use the AWS Command Line Interface (CLI) to manage and check the configuration for block public access settings.
Step-by-Step Guide for Remediation
Follow these steps to remediate and block public access at the account level for S3 buckets:
- 1.
Open the AWS Management Console and navigate to the S3 service.
- 2.
Click on "Account settings" in the top-right corner of the S3 dashboard.
- 3.
Ensure that the following block public access settings are enabled:
- Block public access to buckets and objects granted through new access control lists (ACLs)
- Block public access to buckets and objects granted through any new bucket policies
- Block public and cross-account access to buckets and objects through any public bucket policies
- Restrict access to S3 buckets only from the specified AWS accounts, IAM users, or roles
- 4.
Review the existing bucket policies for all S3 buckets associated with your account.
- 5.
Update bucket policies to explicitly deny public access. Sample bucket policy for blocking public access:
{ "Version": "2012-10-17", "Statement": [ { "Sid": "BlockPublicAccess", "Effect": "Deny", "Principal": "*", "Action": [ "s3:GetObject", "s3:PutObject", "s3:ListBucket" ], "Resource": [ "arn:aws:s3:::example-bucket/*", "arn:aws:s3:::example-bucket" ] } ] } - 6.
Review and update the Access Control Lists (ACLs) of S3 buckets. Remove any public access permissions and ensure that permissions are only granted to authorized entities.
- 7.
Enable S3 access logging for all buckets and set up appropriate monitoring and alerting mechanisms for access control violations.
- 8.
Regularly audit and review the S3 bucket configurations and access controls to ensure continued compliance with the S3 public access blocking policy.
Following these steps will help ensure that public access to S3 buckets at the account level is blocked, meeting the requirements of the NIST 800-53 Revision 5 standard.