AWS Organizations is a service that allows you to consolidate multiple AWS accounts into an organizational structure that you can manage centrally. This capability is essential for businesses with multiple accounts, enabling better governance, cost management, and security. One of the key features of AWS Organizations is Service Control Policies (SCPs), which provide fine-grained control over the actions that users and roles can perform across accounts within your organization. This knowledge base offers a comprehensive guide to AWS Organizations and SCPs, detailing their setup, management, and best practices.

What is AWS Organizations?

AWS Organizations is a service that helps you manage multiple AWS accounts from a single interface. It allows you to create a hierarchical structure of accounts, referred to as an organization, which can include multiple organizational units (OUs). Each OU can contain accounts, and you can apply policies to control access and permissions for those accounts.

Key Features of AWS Organizations

1. Centralized Management: Manage billing, access, and policies across multiple AWS accounts from a single interface.
2. Hierarchical Structure: Create organizational units (OUs) to group accounts and apply policies at different levels.
3. Cost Management: Consolidate billing to take advantage of volume pricing discounts and better understand spending across accounts.
4. Service Control Policies (SCPs): Implement policies to restrict or allow actions across accounts, enhancing security and compliance.
5. Automated Account Creation: Use the API or CLI to programmatically create and manage accounts within your organization.

Setting Up AWS Organizations

To set up AWS Organizations, you need an AWS account that will serve as the management account. The management account has special permissions to create and manage the organization.

Create an Organization

1. Log in to the AWS Management Console using your management account.
2. Navigate to the AWS Organizations service.
3. Click on Create organization. This action will automatically create the first organizational unit (OU) called the root.

Invite Existing Accounts (Optional)

If you have existing AWS accounts you want to include in your organization, you can invite them:

1. In the AWS Organizations console, select Accounts.
2. Click on Invite account.
3. Enter the email address associated with the account you want to invite and specify an optional note.
4. The invited account will receive an email to accept the invitation.

Create Organizational Units

You can create OUs to better manage your accounts:

1. In the AWS Organizations console, select Organizational units.
2. Click on Create organizational unit.
3. Name the OU and specify the parent OU if necessary.
4. You can then move accounts into this OU for more granular management.

Understanding Service Control Policies (SCPs)

Service Control Policies (SCPs) are JSON policies that specify the maximum permissions for accounts within your organization. SCPs are not resource-based policies; they do not grant permissions directly but instead act as a filter for the permissions that users and roles can obtain from IAM policies.

Key Features of SCPs

1. Centralized Permission Management: Manage permissions across accounts from a single location.
2. Allow or Deny Permissions: Use SCPs to explicitly allow or deny actions on AWS services.
3. Hierarchy Based Policy Application: SCPs can be applied at the organization root, OUs, or individual accounts, allowing for different permission sets at each level.

Structure of SCPs

An SCP has the following key components:

• Version: Specifies the policy language version (current version is 2012-10-17).
• Statement: An array of policy statements, each containing:
  • Effect: Indicates whether the statement allows or denies access.
  • Action: Specifies the actions allowed or denied (e.g., ec2:StartInstances).
  • Resource: Defines the resources to which the actions apply (wildcards are allowed).
  • Condition (optional): Specifies conditions for when the policy is effective.

Creating and Managing SCPs

Creating and managing SCPs involves several steps, from defining your policies to attaching them to the appropriate accounts or OUs.

 Access the SCPs Section

1. Log in to the AWS Management Console using your management account.
2. Navigate to the AWS Organizations service.
3. Click on the Policies tab to view existing SCPs or create new ones.

 Create an SCP

1. Click on Create policy.
2. Select Custom policy and enter a name and description for the SCP.
3. Use the JSON editor to define the policy.
4. Click on Create policy to save it.

 Attach the SCP

After creating an SCP, you can attach it to the organization root, an OU, or an individual account:

1. Navigate to the Policies section.
2. Select the SCP you want to attach.
3. Click on Attach.
4. Choose the organizational unit or account to which you want to apply the SCP.
5. Confirm the attachment.

 Modify or Delete SCPs

To modify or delete an existing SCP:

1. Navigate to the Policies section in AWS Organizations.
2. Select the SCP you wish to modify or delete.
3. For modification, click on Edit policy to update the JSON.
4. For deletion, click on Delete policy and confirm the action.

Best Practices for AWS Organizations and SCPs

Implement the Principle of Least Privilege

Always adhere to the principle of least privilege when designing your organizational structure and SCPs. Only grant permissions necessary for users and services to perform their tasks.

 Use Service Control Policies Wisely

• Use Deny Statements: It’s often better to use explicit deny statements to prevent specific actions rather than relying solely on allow statements. This ensures unwanted actions are blocked even if IAM policies allow them.
• Test SCPs: Use AWS Organizations to test the impact of SCPs before deploying them to production environments. This practice can prevent unintended access restrictions.

 Regularly Review SCPs

Establish a routine for reviewing and updating SCPs. Regular audits can help identify unnecessary permissions and ensure compliance with organizational security policies.

Monitor and Log Activities

Enable AWS CloudTrail to monitor API calls made across your organization. This capability allows you to track changes in account access and permissions, providing visibility into your organization’s security posture.

 Document Policies and Procedures

Maintain clear documentation of your SCPs and organizational structure. This practice aids in compliance audits and assists new team members in understanding the access model.

Common Pitfalls to Avoid

1. Overly Broad SCPs: Creating SCPs that are too permissive can expose your accounts to security risks. Be specific in your allow and deny statements.

2. Neglecting Hierarchical Structures: Failing to utilize the hierarchical nature of AWS Organizations can lead to complications in managing permissions. Organize accounts into logical OUs and apply SCPs appropriately.

3. Not Testing Policies: Always test your SCPs in a safe environment before applying them broadly. This approach helps prevent operational disruptions.

4. Ignoring Costs: AWS Organizations can simplify billing, but neglecting to monitor costs across accounts can lead to unexpected expenses. Regularly review billing reports and cost allocation tags.

5. Failing to Communicate Changes: If you modify SCPs, communicate those changes to relevant stakeholders. Unexpected changes can disrupt workflows and access patterns.

AWS Organizations and Service Control Policies provide powerful tools for managing access and permissions across multiple AWS accounts. By leveraging these features, organizations can establish a robust governance framework that ensures security, compliance, and cost management.

By following best practices, regularly reviewing policies, and utilizing the hierarchical nature of AWS Organizations, businesses can effectively manage their AWS environments while minimizing risks. This knowledge base serves as a comprehensive guide to understanding and implementing AWS Organizations and SCPs, laying the groundwork for effective cloud governance.