Centralized IAM management

For expansive organizations with numerous AWS accounts, centralizing IAM management is not just beneficial – it is essential. It fosters consistency, trims administrative tasks, and bolsters security. With AWS Organizations providing the structural backbone, we now turn to the mechanisms of IAM Identity Center and SCPs to enhance the management of access across multiple accounts.

Managing access to multiple accounts

IAM Identity Center (formerly AWS SSO) offers a consolidated management of all identity-centric data spanning multiple AWS accounts. This centralized platform empowers administrators with insights into IAM role usage patterns, frequently accessed permissions, and unused permissions. By discerning active permissions, administrators can fine-tune IAM policies, ensuring they are both robust and efficient.

Users can be integrated into IAM Identity Center from an external IdP, such as Microsoft AD or any SAML 2.0 compliant IdP, or they can be defined within the Identity Center directory itself. This flexibility allows organizations to leverage their existing identity management infrastructure or to use IAM Identity Center as a standalone solution for managing access to AWS resources across multiple accounts.

Unlike traditional IAM federation, which requires setting up trust relationships in each account, IAM Identity Center offers a centralized solution with features such as SSO. For users, the experience is significantly simplified. Once authenticated through IAM Identity Center, they gain the ability to seamlessly navigate across accounts, accessing the necessary resources without the need for repeated logins. The SSO mechanism not only improves user productivity but also strengthens security by minimizing the need for multiple credentials and reducing the potential attack surface.

Restricting permissions across the organization

SCPs are a powerful feature of AWS Organizations. They allow administrators to set permission restrictions that apply to all or a selected set of accounts within an organization. Unlike IAM policies, which grant permissions, SCPs primarily function to deny specific actions, setting the upper bounds of what IAM identities are not allowed to do, thereby ensuring uniform security postures across all accounts. This capability is crucial in maintaining a controlled environment where SCPs, by design, override any locally defined IAM policies with more permissive settings. The hierarchical structure of SCPs allows for the mitigation of overly permissive policies in individual accounts through SCP-imposed restrictions. A prime example includes universally blocking the deletion of S3 buckets and objects to protect data integrity. This framework highlights the significance of a strategically layered IAM architecture, where SCPs enforce organization-wide restrictions and local policies tailor finer-grained access controls.