Identity and access management in AWS Control Tower

• AWS account root user – When you first create an AWS account, you begin with an identity that has complete access to all AWS services and resources in the account. This identity is called the AWS account root user. You have access to this identity when you sign in with the email address and password that you used to create the account. We strongly recommend that you do not use the root user for your everyday tasks, even the administrative ones. Instead, adhere to the best practice of using the root user only to create your first IAM Identity Center user (recommended) or IAM user (not a best practice in most use cases). Then securely lock away the root user credentials and use them to perform only a few account and service management tasks. For more information, see When to sign in as a root user.

• IAM user – An IAM user is an identity within your AWS account that has specific, customized permissions. You can use the IAM user credentials to sign in to secure AWS webpages such as the AWS Management Console, AWS Discussion Forums, or the AWS Support Center. AWS best practices recommend that you create an IAM Identity Center user instead of an IAM user, because there is more security risk when you create an IAM user that has long-term credentials.

  If you must create an IAM user for a certain purpose, in addition to sign-in credentials, you can generate access keys for each IAM user. You can use these keys when you call AWS services programmatically, either through one of the several SDKs or by using the AWS Command Line Interface (CLI). The SDK and CLI tools use the access keys to cryptographically sign your request. If you don’t use AWS tools, you must sign the request yourself. AWS Control Tower supports Signature Version 4, a protocol for authenticating inbound API requests. For more information about authenticating requests, see Signature Version 4 Signing Process in the AWS General Reference.

• IAM role – An IAM role is an IAM identity that you can create in your account that has specific permissions. An IAM role is similar to an IAM user in that it is an AWS identity, and it has permissions policies that determine what the identity can and cannot do in AWS. However, instead of being uniquely associated with one person, a role is intended to be assumable by anyone who needs it. Also, a role does not have standard long-term credentials such as a password or access keys associated with it. Instead, when you assume a role, it provides you with temporary security credentials for your role session. IAM roles with temporary credentials are useful in the following situations:

  • Federated user access – Instead of creating an IAM user, you can use existing identities from AWS Directory Service, your enterprise user directory, or a web identity provider. These are known as federated users. AWS assigns a role to a federated user when access is requested through an identity provider. For more information about federated users, see Federated Users and Roles in the IAM User Guide.

  • AWS service access – A service role is an IAM role that a service assumes to perform actions in your account on your behalf. When you set up some AWS service environments, you must define a role for the service to assume. This service role must include all the permissions that are required for the service to access the AWS resources that it needs. Service roles vary from service to service, but many allow you to choose your permissions as long as you meet the documented requirements for that service. Service roles provide access only within your account and cannot be used to grant access to services in other accounts. You can create, modify, and delete a service role from within IAM. For example, you can create a role that allows Amazon Redshift to access an Amazon S3 bucket on your behalf and then load data from that bucket into an Amazon Redshift cluster. For more information, see Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide.

  • Applications running on Amazon EC2 – You can use an IAM role to manage temporary credentials for applications that are running on an Amazon EC2 instance and making AWS CLI or AWS API requests. This is preferable to storing access keys within the Amazon EC2 instance. To assign an AWS role to an Amazon EC2 instance and make it available to all of its applications, you create an instance profile that is attached to the instance. An instance profile contains the role and enables programs that are running on the Amazon EC2 instance to get temporary credentials. For more information, see Using an IAM Role to Grant Permissions to Applications Running on Amazon EC2 Instances in the IAM User Guide.

• IAM Identity Center user Authentication to the IAM Identity Center user portal is controlled by the directory that you have connected to IAM Identity Center. However, authorization to the AWS accounts that are available to end users from within the user portal is determined by two factors:

  • Who has been assigned access to those AWS accounts in the AWS IAM Identity Center console. For more information, see Single Sign-On Access in the AWS IAM Identity Center User Guide.

  • What level of permissions have been granted to the end-users in the AWS IAM Identity Center console to allow them the appropriate access to those AWS accounts. For more information, see Permission Sets in the AWS IAM Identity Center User Guide.

Topics

• Overview of managing access permissions to your AWS Control Tower resources

• Using identity-based policies (IAM policies) for AWS Control Tower