About AWS accounts in AWS Control Tower - AWS Control Tower
Considerations for bringing existing security or logging accountsAbout the shared accounts

About AWS accounts in AWS Control Tower

An AWS account is the container for all your owned resources. These resources include the AWS Identity and Access Management (IAM) identities accepted by the account, which determine who has access to that account. IAM identities can include users, groups, roles, and more. For more information about working with IAM, users, roles, and policies in AWS Control Tower, see Identity and access management in AWS Control Tower.

Resources and account creation time

When AWS Control Tower creates or enrolls an account, it deploys the minimum necessary resource configuration for the account, including resources in the form of Account Factory templates and other resources in your landing zone. These resources may include IAM roles, AWS CloudTrail trails, Service Catalog provisioned products, and IAM Identity Center users. AWS Control Tower also deploys resources, as required by the control configuration, for the organizational unit (OU) in which the new account is destined to become a member account.

AWS Control Tower orchestrates the deployment of these resources on your behalf. It may require several minutes per resource to complete the deployment, so consider the total time before you create or enroll an account. For more information about managing resources in your accounts, see Guidance for creating and modifying AWS Control Tower resources.

Considerations for bringing existing security or logging accounts

Before accepting an AWS account as a security or logging account, AWS Control Tower checks the account for resources that conflict with AWS Control Tower requirements. For example, you may have a logging bucket with the same name that AWS Control Tower requires. Also, AWS Control Tower validates that the account can provision resources; for example, by ensuring that AWS Security Token Service (AWS STS) is enabled, that the account is not suspended, and that AWS Control Tower has permission to provision resources within the account.

AWS Control Tower does not remove any existing resources in the logging and security accounts that you provide. However, if you choose to enable the AWS Region deny capability, the Region deny control prevents access to resources in denied Regions.

About the shared accounts

Three special AWS accounts are associated with AWS Control Tower; the management account, the audit account, and the log archive account. These accounts usually are referred to as shared accounts, or sometimes as core accounts.

  • You can select customized names for the audit and log archive accounts when you're setting up your landing zone. For information about changing an account name, see Externally changing AWS Control Tower resource names.

  • You also can specify an existing AWS account as an AWS Control Tower security or logging account, during the initial landing zone setup process. This option eliminates the need for AWS Control Tower to create new, shared accounts. (This is a one-time selection.)

For more information about the shared accounts and their associated resources, see Resources created in the shared accounts.

Management account

This AWS account launches AWS Control Tower. By default, the root user for this account and the IAM user or IAM administrator user for this account have full access to all resources within your landing zone.

Note

As a best practice, we recommend signing in as an IAM Identity Center user with Administrator privileges when performing administrative functions within the AWS Control Tower console, instead of the signing in as the root user or IAM administrator user for this account.

For more information about the roles and resources available in the management account, see Resources created in the shared accounts.

Log archive account

The log archive shared account is set up automatically when you create your landing zone.

This account contains a central Amazon S3 bucket for storing a copy of all AWS CloudTrail and AWS Config log files for all other accounts in your landing zone. As a best practice, we recommend restricting log archive account access to teams responsible for compliance and investigations, and their related security or audit tools. This account can be used for automated security audits, or to host custom AWS Config Rules, such as Lambda functions, to perform remediation actions.

Amazon S3 bucket policy

For AWS Control Tower landing zone version 3.3 and later, accounts must meet an aws:SourceOrgID condition for any write permissions to your Audit bucket. This condition ensures that CloudTrail only can write logs on behalf of accounts within your organization to your S3 bucket; it prevents CloudTrail logs outside your organization from writing to your AWS Control Tower S3 bucket. For more information, see AWS Control Tower landing zone version 3.3.

For more information about the roles and resources available in the log archive account, see Log archive account resources

Note

These logs cannot be changed. All logs are stored for the purposes of audit and compliance investigations related to account activity.

Audit account

This shared account is set up automatically when you create your landing zone.

The audit account should be restricted to security and compliance teams with auditor (read-only) and administrator (full-access) cross-account roles to all accounts in the landing zone. These roles are intended to be used by security and compliance teams to:

  • Perform audits through AWS mechanisms, such as hosting custom AWS Config rule Lambda functions.

  • Perform automated security operations, such as remediation actions.

The audit account also receives notifications through the Amazon Simple Notification Service (Amazon SNS) service. Three categories of notification can be received:

  • All Configuration Events – This topic aggregates all CloudTrail and AWS Config notifications from all accounts in your landing zone.

  • Aggregate Security Notifications – This topic aggregates all security notifications from specific CloudWatch events, AWS Config Rules compliance status change events, and GuardDuty findings.

  • Drift Notifications – This topic aggregates all the drift warnings discovered across all accounts, users, OUs, and SCPs in your landing zone. For more information on drift, see Detect and resolve drift in AWS Control Tower.

Audit notifications that are triggered within a member account also can send alerts to a local Amazon SNS topic. This functionality allows account administrators to subscribe to audit notifications that are specific to an individual member account. As a result, administrators can resolve issues that affect an individual account, while still aggregating all account notifications to your centralized audit account. For more information, see Amazon Simple Notification Service Developer Guide.

For more information about the roles and resources available in the audit account, see Audit account resources.

For more information about programmatic auditing, see Programmatic roles and trust relationships for the AWS Control Tower audit account.

Important

The email address you provide for the audit account receives AWS Notification - Subscription Confirmation emails from every AWS Region supported by AWS Control Tower. To receive compliance emails in your audit account, you must choose the Confirm subscription link within each email from each AWS Region supported by AWS Control Tower.