Security and Microservice Architecture on AWS

Appendix D. A Hands-On Example of Applying the Principle of Least Privilege

In this appendix, I will try to show you a hands-on example of how security professionals can apply the principle of least privilege (PoLP) to create Identity and Access Management (IAM) policies on AWS. Chapter 2 talked about PoLP at length, but as a reminder, the purpose of PoLP is to ensure that each principal (an AWS user or AWS role) within an organization gets only the bare minimum access privileges they need in order to perform their job and nothing more. Access is controlled on AWS using IAM policies. Each IAM policy in an account should serve a specific purpose and exist independently of the principal to which it is attached.

Let us consider a typical organization that has many departments. For the sake of this example, I want to allow employees of the finance department to gain access to objects in a certain Amazon Simple Storage Service (Amazon S3) bucket within the organization’s account. As a responsible security administrator, I want to make sure that I apply the PoLP while defining access policies for the principals (users or roles) within my organization.

Hence, in order to secure access, I will enforce the following conditions:

• The principal who this policy is attached to should have the AWS tag department set to finance. In other words, I want to make sure that the principal (the user or role who attempts to gain access to these objects) belongs to the finance department.

• Multifactor ...