1.2.2. 💡 First Principle: Principle of Least Privilege

First Principle: The Principle of Least Privilege (PoLP) dictates granting only the minimum permissions necessary for an IAM identity (human or machine) to perform its task, fundamentally reducing the attack surface and limiting the impact of a breach.

PoLP is a fundamental security best practice that is central to AWS Identity and Access Management (IAM). Instead of granting broad access, you grant only the specific permissions required for an IAM identity to perform its intended function.

Key Aspects of PoLP:

• Minimal Permissions: Grant only the actions needed for a specific task on specific resources.
• Reduced Attack Surface: Fewer ways for attackers to exploit privileges if an identity is compromised.
• Limited "Blast Radius": If a credential is compromised, the impact of unauthorized actions is contained to only the allowed resources and actions.
• Enhanced Auditability: Easier to audit and understand access patterns and resource interactions.

AWS Implementation:

• IAM Policies: Define granular permissions using JSON (e.g., s3:GetObject on a specific S3 bucket instead of s3:*).
• IAM Roles: Use roles for AWS services and applications to grant temporary permissions, avoiding long-lived credentials.
• Permissions Boundaries: Set the maximum permissions that an identity-based policy can grant to an IAM entity. For delegating permission management while enforcing guardrails.

Scenario: An application running on an EC2 instance needs to read data from a specific Amazon S3 bucket and nothing else. Granting it full S3 access would be a security risk.

Reflection Question: How does applying the Principle of Least Privilege (PoLP) by granting only the minimum necessary IAM permissions (e.g., s3:GetObject on a specific S3 bucket) fundamentally reduce the attack surface and limit the impact of a breach for your AWS resources?