2.1.4. Multi-Account Strategies for IAM (Organizations, Control Tower)
First Principle: Multi-account strategies fundamentally isolate workloads, simplify billing, and enforce consistent security policies across an organization's AWS environment, preventing broad impact from breaches.
For security specialists, using multiple AWS accounts is a critical best practice for isolating workloads, managing permissions, and achieving robust governance. A single AWS account creates a large "blast radius" if compromised.
Key Services for Multi-Account Strategies and IAM Governance:
- AWS Organizations: A service that helps you centrally manage and govern your AWS environment as you grow and scale your AWS resources.
- Purpose: Consolidates multiple AWS accounts into a single organization, allowing for consolidated billing and centralized management.
- Organizational Units (OUs): Create a hierarchical structure to group accounts (e.g., by department, environment like Dev/Test/Prod).
- Service Control Policies (SCPs): A powerful type of policy within AWS Organizations that defines the maximum available permissions for all IAM users and roles in affected accounts. Act as preventative "guardrails" at the organizational level, ensuring accounts adhere to corporate security policies.
- AWS Control Tower: A service that simplifies setting up and governing a secure, compliant multi-account AWS environment.
- Purpose: Automates the creation of a well-architected multi-account landing zone.
- Benefits: Establishes a baseline of security and compliance best practices through pre-configured guardrails (preventative and detective controls). Simplifies new account provisioning.
Scenario: A large enterprise operates dozens of AWS accounts across multiple business units. They need to ensure strict security isolation between these accounts, enforce company-wide security policies (e.g., prevent public S3 buckets), and streamline the creation of new, secure accounts.
Reflection Question: How do multi-account strategies (managed by AWS Organizations) and AWS Control Tower (for automated landing zone/guardrails), along with Service Control Policies (SCPs), fundamentally ensure that workloads are isolated, simplify billing, and enforce consistent security policies across an organization's AWS environment at scale?