Cross Account Assume Role without External ID and MFA Table

Introduction

In AWS, the AssumeRole operation allows you to request temporary security credentials to access resources in another AWS account (often called a resource account). However, not using an External ID or Multi-Factor Authentication (MFA) can pose significant security risks.

Importance for IT and Security Engineers

Understanding the mechanics of the AssumeRole operation without External ID and MFA is crucial for IT and Security Engineers. This knowledge helps in evaluating the security posture of cross-account access setups and enforcing appropriate policies to mitigate potential risks.

Security Considerations

• Risk of Unauthorized Access: Without the use of External IDs, the AssumeRole can potentially be misused if the role's trust policy is overly permissive, allowing unauthorized accounts to assume the role.

• Lack of Multi-Layer Security: MFA adds an additional layer of security. Its absence means relying solely on permissions, increasing the risk if credentials are compromised.

Best Practices

1. Implement Strong Role Policies: Define clear and restricted policies for roles to minimize permissions and limit the scope of access.

2. Use Conditionals for Sensitive Roles: Even without External ID and MFA, conditions in role policies can restrict access based on IP range, VPC, or user attributes.

3. Regular Audits: Conduct periodic reviews and audits of IAM roles and policies to ensure they comply with the organization's security standards and practices.

Conclusion

For IT and Security Engineers, ensuring the security of cross-account role assumptions without External ID and MFA requires careful planning, robust policy enforcement, and continuous monitoring. While not ideal, understanding and mitigating the associated risks is paramount.