s3_ensure_buckets_block_public_access

AWS S3 Buckets Without Public Access Blocked

What It Does

This policy template reports any AWS S3 buckets without the necessary settings enabled to block public access. Optionally, it emails this report.

By default, S3 buckets and objects are created with public access disabled. However, an IAM principal with sufficient S3 permissions can enable public access at the bucket and/or object level. While enabled, 'Block Public Access' prevents an individual bucket, and its contained objects, from becoming publicly accessible.

How It Works

S3 buckets with any of the following PublicAccessBlockConfiguration settings set to "false" will be included in the results:

• BlockPublicAcls
• IgnorePublicAcls
• BlockPublicPolicy
• RestrictPublicBuckets

Input Parameters

• Email Addresses - Email addresses of the recipients you wish to notify.
• Account Number - The Account number for use with the AWS STS Cross Account Role. Leave blank when using AWS IAM Access key and secret. It only needs to be passed when the desired AWS account is different than the one associated with the Flexera One credential. More information is available in our documentation.
• Allow/Deny Regions - Whether to treat Allow/Deny Regions List parameter as allow or deny list. Has no effect if Allow/Deny Regions List is left empty.
• Allow/Deny Regions List - A list of regions to allow or deny for an AWS account. Please enter the regions code if SCP is enabled. See Available Regions in AWS; otherwise, the policy may fail on regions that are disabled via SCP. Leave blank to consider all the regions.
• Exclusion Tags - The policy will filter resources containing the specified tags from the results. The following formats are supported:
  • Key - Filter all resources with the specified tag key.
  • Key==Value - Filter all resources with the specified tag key:value pair.
  • Key!=Value - Filter all resources missing the specified tag key:value pair. This will also filter all resources missing the specified tag key.
  • Key=~/Regex/ - Filter all resources where the value for the specified key matches the specified regex string.
  • Key!~/Regex/ - Filter all resources where the value for the specified key does not match the specified regex string. This will also filter all resources missing the specified tag key.
• Exclusion Tags: Any / All - Whether to filter instances containing any of the specified tags or only those that contain all of them. Only applicable if more than one value is entered in the Exclusion Tags field.
• Exclude S3 Buckets - Names of specific S3 buckets to exclude from the results.

Policy Actions

• Sends an email notification.

Prerequisites

This Policy Template uses Credentials for authenticating to datasources -- in order to apply this policy you must have a Credential registered in the system that is compatible with this policy. If there are no Credentials listed when you apply the policy, please contact your Flexera Org Admin and ask them to register a Credential that is compatible with this policy. The information below should be consulted when creating the credential(s).

• AWS Credential (provider=aws) which has the following permissions:

  • sts:GetCallerIdentity
  • s3:ListBuckets
  • s3:GetBucketLocation
  • s3:GetBucketTagging
  • s3:GetPublicAccessBlock

  Example IAM Permission Policy:

  {
      "Version": "2012-10-17",
      "Statement": [
          {
              "Effect": "Allow",
              "Action": [
                  "sts:GetCallerIdentity",
                  "s3:ListBuckets",
                  "s3:GetBucketLocation",
                  "s3:GetBucketTagging",
                  "s3:GetPublicAccessBlock"
              ],
              "Resource": "*"
          }
      ]
  }

• Flexera Credential (provider=flexera) which has the following roles:

  • billing_center_viewer

The Provider-Specific Credentials page in the docs has detailed instructions for setting up Credentials for the most common providers.

Supported Clouds

• AWS

Cost

This policy template does not incur any cloud costs.