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Zorluk: ZorMulti-Account Identity and Access Management Federation

An enterprise uses AWS Organizations with a delegated administrator account for AWS IAM Identity Center. The organization federates with an external SAML 2.0 Identity Provider (IdP) to manage employee access. The security team must enforce a central security control: users accessing any member accounts in the 'Production' Organizational Unit (OU) must have authenticated using Multi-Factor Authentication (MFA) at the IdP. The IdP includes a SAML attribute named MFA_Verified with a value of true for sessions where MFA was completed. The security team wants to enforce this policy centrally across the Production OU without modifying individual permission sets.

Which combination of steps should a solutions architect implement to meet these requirements?

  1. Enable Attributes for Access Control (ABAC) in AWS IAM Identity Center, and map the SAML attribute MFA_Verified to the IAM session tag MFA_Status. Apply a Service Control Policy (SCP) to the Production OU that denies all actions when the principal is an IAM Identity Center role under the path /aws-reserved/sso.amazonaws.com/ and the condition aws:PrincipalTag/MFA_Status is not equal to true.Cevap
  2. B
    Configure a SAML 2.0 Identity Provider (IdP) in each member account in the Production OU. Update the trust policy of all IAM Identity Center provisioned roles to allow sts:AssumeRole from the corporate IdP, adding a condition that checks saml:MFA_Verified is equal to true.
  3. C
    Apply a Service Control Policy (SCP) to the Production OU that explicitly allows access only to federated users presenting the SAML attribute MFA_Verified set to true, relying on the SCP to dynamically inject the SAML assertion attribute as a principal session tag in the member accounts.
  4. D
    Configure custom trust policies on the IAM Identity Center permission sets in the delegated administrator account. In the trust policies, allow sts:AssumeRoleWithWebIdentity from the external SAML IdP, and add a condition restricting access based on the saml:MFA_Verified attribute.

Cevap

Enable Attributes for Access Control (ABAC) in AWS IAM Identity Center to map the SAML attribute to the IAM session tag, and apply an SCP to the Production OU denying access to the IAM Identity Center roles if the session tag is not set to true.
The correct solution leverages Attribute-Based Access Control (ABAC) in AWS IAM Identity Center. By mapping the SAML attribute MFA_Verified to an IAM session tag (such as MFA_Status), the tag is automatically passed as a principal tag (aws:PrincipalTag/MFA_Status) when a user federates into a member account. Applying a Service Control Policy (SCP) to the Production OU that denies access to IAM Identity Center federated roles (which reside under the /aws-reserved/sso.amazonaws.com/ path) if the tag is not set to true ensures centralized, non-circumventable enforcement without having to modify the permissions of individual permission sets.

Adım Adım Çözüm

1
Enable Attributes for Access Control (ABAC) in the AWS IAM Identity Center console.
This allows SAML assertion attributes from the external Identity Provider (IdP) to be mapped to transient IAM session tags.
SAML attributes must be converted into IAM session tags before they can be evaluated by IAM policies or SCPs in target member accounts.
2
Map the SAML attribute 'MFA_Verified' to the IAM session tag 'MFA_Status' within the IAM Identity Center configuration.
Every federated session assumed via IAM Identity Center will automatically carry the 'aws:PrincipalTag/MFA_Status' tag with the value ('true' or 'false') passed from the IdP.
This establishes the PrincipalTag context key necessary for conditional evaluations.
3
Create a Service Control Policy (SCP) that denies all actions ('Action': '*') for IAM Identity Center roles if 'aws:PrincipalTag/MFA_Status' is not equal to 'true', and apply it to the Production Organizational Unit (OU).
Any federated user attempting to perform actions in production member accounts will be blocked unless their session tag verifies that MFA was completed at the IdP.
Applying the guardrail via an SCP ensures centralized enforcement across the Production OU without modifying individual permission sets.

Anahtar Kavram

Attribute-Based Access Control (ABAC) in IAM Identity Center combined with Service Control Policies (SCPs) for central policy enforcement.
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