AWS Multiple Accounts Security Strategies


To design security strategies for multiple AWS accounts, it’s essential to focus on gaining visibility, enforcing security standards, and setting up alerts and automation. Below is a detailed guide covering these aspects:

Use AWS Control Tower for Centralized Governance

AWS Control Tower provides an easy way to set up and govern a secure, multi-account AWS environment based on AWS best practices. It automates the setup of a multi-account environment and provides governance and best-practices recommendations for accounts.

1. Setting Up AWS Control Tower

Enable AWS Control Tower

  • Landing Zone: Set up a landing zone using AWS Control Tower, which includes a multi-account structure with built-in governance.
  • Guardrails: Implement guardrails to enforce governance and security policies automatically across accounts.

1. Designing Security Strategies for Multiple AWS Accounts

Use AWS Organizations

  • Centralized Management: Use AWS Organizations to manage multiple AWS accounts centrally.
  • Service Control Policies (SCPs): Implement SCPs to enforce compliance and security policies across all accounts.

Account Structure

  • Organizational Units (OUs): Group accounts into OUs based on their purpose (e.g., development, testing, production).
  • Least Privilege Principle: Apply the principle of least privilege across all accounts and resources.

2. Gaining Visibility

AWS CloudTrail

  • Logging: Enable AWS CloudTrail in all accounts to log all API calls and activities.
  • Centralized Logging: Aggregate CloudTrail logs to a central S3 bucket for analysis.

AWS Config

  • Resource Monitoring: Use AWS Config to monitor the configuration of AWS resources.
  • Compliance Audits: Continuously assess compliance with internal policies and external regulations.

Amazon GuardDuty

  • Threat Detection: Enable GuardDuty to detect threats and monitor for malicious activity.
  • Automated Responses: Set up automated responses for certain GuardDuty findings using AWS Lambda or AWS Step Functions.

3. Enforcing Security Standards

Identity and Access Management (IAM)

  • IAM Policies: Define and apply IAM policies to control access to resources.
  • IAM Roles: Use roles to delegate access across accounts securely.

AWS Shield and AWS WAF

  • DDoS Protection: Enable AWS Shield for DDoS protection.
  • Web Application Firewall (WAF): Use AWS WAF to protect web applications from common web exploits.


  • Data Encryption: Use AWS Key Management Service (KMS) to encrypt data at rest and in transit.
  • Managed Keys: Enforce the use of AWS-managed or customer-managed keys.

4. Alerting and Automating Based on Data

Amazon CloudWatch

  • Monitoring and Alerts: Use CloudWatch to monitor resource metrics and set up alerts.
  • Event Rules: Create CloudWatch Events rules to automate responses to specific events.

AWS Security Hub

  • Centralized View: Enable AWS Security Hub to get a comprehensive view of security alerts and compliance status.
  • Automated Checks: Use Security Hub to run automated security checks and aggregate findings from other services like GuardDuty, Inspector, and Macie.

AWS Lambda and Step Functions

  • Automation: Use AWS Lambda and Step Functions to automate incident response and remediation workflows.
  • Custom Scripts: Develop custom scripts to handle specific security incidents or compliance violations.

Example Workflow

  1. Set Up AWS Organizations: Create an organization and define OUs for different environments (e.g., development, production).
  2. Enable Logging and Monitoring:
    • Enable CloudTrail and aggregate logs centrally.
    • Set up AWS Config to monitor resource configurations.
    • Enable GuardDuty for threat detection.
  3. Enforce Security Standards:
    • Implement SCPs for baseline security policies.
    • Apply IAM policies and roles to control access.
    • Enable Shield and WAF for application protection.
    • Use KMS for data encryption.
  4. Alerting and Automation:
    • Use CloudWatch to monitor metrics and create alarms.
    • Set up Security Hub for centralized security management.
    • Implement automated responses with Lambda and Step Functions.

By following these steps, you can design a robust security strategy for managing multiple AWS accounts, ensuring visibility, compliance, and automated responses to security incidents.

AWS Security Token Service (STS) Within and Across Accounts

AWS Security Token Service (STS) enables you to request temporary, limited-privilege credentials for AWS Identity and Access Management (IAM) users or federated users. These temporary credentials can be used to access AWS resources within your own AWS account or across different AWS accounts. Here’s how you can use STS within and across accounts:

Use Cases for AWS STS

  1. Within a Single AWS Account:

    • Use Case: Grant temporary access to users or applications that need to perform specific tasks without creating long-term credentials.
    • Example: A mobile application that requests temporary access to read data from an S3 bucket.
  2. Across Multiple AWS Accounts:

    • Use Case: Allow users or services in one AWS account to access resources in another AWS account securely and temporarily.
    • Example: An IAM role in the central management account that can assume roles in other AWS accounts to perform centralized logging or monitoring.

Key Components of AWS STS

  1. Temporary Security Credentials:

    • Components: Access key ID, secret access key, and session token.
    • Expiration: Credentials expire after a specified duration (from a few minutes up to 36 hours).
  2. API Operations:

    • AssumeRole: Assume an IAM role to obtain temporary security credentials.
    • AssumeRoleWithSAML: Assume an IAM role based on SAML assertions.
    • AssumeRoleWithWebIdentity: Assume an IAM role based on web identity tokens.
    • GetSessionToken: Obtain temporary security credentials for IAM users or federated users.
    • GetFederationToken: Obtain temporary security credentials for a federated user.

Steps to Use AWS STS Within an Account

  1. Create an IAM Role:

    • Define an IAM role with the necessary permissions.
    • Specify a trust policy to allow the trusted entity to assume the role.
  2. Assume the IAM Role:

    • Use the AssumeRole API to obtain temporary security credentials.
    • Example AWS CLI command:

      aws sts assume-role --role-arn arn:aws:iam::123456789012:role/RoleName --role-session-name SessionName
  3. Use Temporary Credentials:

    • Use the obtained temporary credentials to access AWS resources.

Steps to Use AWS STS Across Accounts

  1. Create an IAM Role in the Target Account:

    • Define an IAM role with the necessary permissions in the target account.
    • Specify a trust policy to allow the source account or user to assume the role.
  2. Create a Trust Relationship:

    • Edit the trust relationship of the role in the target account to include the source account or user.
    • Example trust policy:

      "Version": "2012-10-17",
      "Statement": [
      "Effect": "Allow",
      "Principal": {
      "AWS": "arn:aws:iam::source-account-id:user/SourceUserName"
      "Action": "sts:AssumeRole"
  3. Assume the Role from the Source Account:

    • Use the AssumeRole API from the source account to obtain temporary security credentials.
    • Example AWS CLI command:

      aws sts assume-role --role-arn arn:aws:iam::target-account-id:role/RoleName --role-session-name SessionName
  4. Use Temporary Credentials:

    • Use the obtained temporary credentials to access AWS resources in the target account.

Example Scenarios

Within a Single Account

Scenario: A developer needs temporary access to an S3 bucket for a specific task.

  1. Create IAM Role: S3AccessRole with S3 read permissions.
  2. Assume Role: Developer uses AWS CLI to assume the role and get temporary credentials.
  3. Access Resources: Developer uses the temporary credentials to access the S3 bucket.

Across Multiple Accounts

Scenario: A central logging service in Account A needs access to CloudWatch logs in Account B.

  1. Create IAM Role in Account B: CentralLoggingRole with permissions to read CloudWatch logs.
  2. Trust Relationship: Allow Account A to assume CentralLoggingRole.
  3. Assume Role from Account A: Logging service in Account A assumes the role and gets temporary credentials.
  4. Access Resources in Account B: Logging service uses the temporary credentials to read CloudWatch logs in Account B.

Security Considerations

  1. Least Privilege:

    • Ensure roles and policies grant the minimum necessary permissions.
  2. Role Session Duration:

    • Set appropriate session durations for temporary credentials.
  3. Monitoring and Logging:

    • Use AWS CloudTrail to monitor STS API calls and track role assumptions.
  4. MFA:

    • Require multi-factor authentication (MFA) for assuming sensitive roles.


AWS STS provides a secure and flexible way to grant temporary access to AWS resources within and across accounts. By using temporary security credentials, you can reduce the risks associated with long-term credentials and implement robust security practices.