Permission management delegation by using IAM permissions boundaries

What is an IAM Permission Boundary in the context of AWS IAM?

IAM Permission Boundary is an advanced feature in AWS IAM that allows for the setting of the maximum permissions that an identity-based policy can grant to an IAM user or role. In essence, a permissions boundary is a policy that acts as a safeguard to prevent users and roles from gaining access to resources beyond what’s intended. It sets the outermost limits and is often used in conjunction with other policies for more granular permission control.

How do Permission Boundaries help with the Principle of Least Privilege in AWS?

Permission Boundaries help enforce the Principle of Least Privilege by ensuring that IAM users and roles can only access the resources and perform the actions that are absolutely necessary for their work. They prevent the escalation of privileges by defining the maximum permissions an entity can have, regardless of the permissions granted through other policies.

Can you explain how one might delegate administration tasks without giving away full administrative privileges using Permission Boundaries?

To delegate administration tasks without giving away full administrative privileges, an administrator can set a Permission Boundary for a user or role that outlines the specific scope of permissions they can use. This way, when administrators delegate tasks, they can attach a policy that grants the necessary permissions within the constraints set by the Permission Boundary, thus controlling the extent to which privileges can be elevated.

How would you use IAM Permission Boundaries to segregate duties in a large organization?

In a large organization, IAM Permission Boundaries can be used to segregate duties by creating different boundaries for distinct roles or departments. For instance, a boundary for the networking team might limit access to VPC-related actions, while a boundary for the development team might restrict permissions to certain EC2 instances and S3 buckets. This ensures that each team has only the access they need to perform their specific tasks and cannot interfere with other teams’ resources.

How do IAM Permission Boundaries interact with other IAM policies attached to a user or role?

IAM Permission Boundaries act as a filter on top of other IAM policies attached to a user or role. The effective permissions are the intersection of the entity’s IAM policies and the Permission Boundary; an entity can only perform an action if it’s allowed by both the entity’s policies and the boundary policy.

Give an example of a situation where you might use IAM Permission Boundaries instead of managed policies?

IAM Permission Boundaries are best used in situations where you want to delegate permission management to other users without giving them unrestricted control. For example, allowing a team lead to manage permissions of their team members without being able to grant full administrative access. This cannot be as effectively achieved using managed policies alone, as managed policies do not inherently limit the scope of permissions they can grant.

Can you deny a permission using a Permission Boundary?

No, a Permission Boundary does not explicitly deny permissions. Instead, it sets the maximum allowed permissions. If an action is not allowed by the Permission Boundary, it’s implicitly denied, even if it’s allowed by the user’s or role’s other policies.

What would happen if you don’t define a Permission Boundary for an IAM user or role?

If you don’t define a Permission Boundary for an IAM user or role, there will be no additional restrictions on what permissions can be granted through their assigned policies. The user or role can potentially be granted permissions as wide as the account’s resource and action space, subject to other existing IAM policy limits.

Is it possible to use Permission Boundaries to delegate permissions across different AWS accounts in an organization?

Yes, Permission Boundaries can be used in conjunction with AWS Organizations and Service Control Policies (SCPs) to delegate permissions across different AWS accounts in a multi-account setup. Permission Boundaries apply to individual IAM users and roles within an account, while SCPs apply to all IAM entities in member accounts.

How do you create or manage a Permission Boundary for an IAM role using the AWS Management Console?

To create or manage a Permission Boundary for an IAM role using the AWS Management Console, you navigate to the IAM role, go to the “Permissions” tab, and then click “Add Permission Boundary.” Choose the policy you want to set as the boundary, which limits the permissions for the role. This procedure sets or updates the existing Permission Boundary for that role.

What is the effect of removing a Permission Boundary from an IAM user or role?

Removing a Permission Boundary from an IAM user or role removes the restriction on the maximum permissions they can have. Consequently, their effective permissions may increase because they’re now dictated solely by the user or role’s actual identity-based IAM policies without the overarching limits set by the Permission Boundary.

How might you audit the use of IAM Permission Boundaries within an AWS environment?

To audit the use of IAM Permission Boundaries within an AWS environment, you can use AWS CloudTrail logs to track API calls that create, modify, or delete Permission Boundaries. Additionally, you can use the IAM console or CLI commands to list all IAM users or roles with attached Permission Boundaries. AWS Config can also help to track changes and compliance of IAM entities with company policies regarding Permission Boundaries.