Intermediate

AWS IAM and Policies Deep Dive

Build and validate IAM policies from scratch using the CLI and Policy Simulator: identity-based, resource-based, and permission boundaries, plus a Service Control Policy to see how AWS evaluates layered permission logic.

~3.5h

0 / 7 steps

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Intro

What you're building

Prerequisites: An AWS account, AWS CLI v2 installed and configured (aws configure), basic understanding of AWS services.

IAM is the single most important security surface in an AWS account. Every API call is authorized against IAM — and it's the most common source of access-related misconfigurations. In this project you'll write and test real policies by hand, see how the evaluation logic works, and use two of AWS's own debugging tools (IAM Access Analyzer and the Policy Simulator) to confirm the behavior before attaching anything to a real principal.

The key concept to internalize before starting: an explicit Deny always wins over an Allow. An Allow must come from both the identity side and (for cross-account) the resource side. Anything not explicitly allowed is implicitly denied. Every step below exercises one layer of that model.

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Write and create your first identity-based policy

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Create a role, attach the policy, and test with the Policy Simulator

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Add a Condition to restrict by resource tag and validate with Access Analyzer

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Write a resource-based policy (S3 bucket policy) and see cross-account evaluation

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Secret Mission

Secret Mission: Permission boundary

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Wrap Up

Before You Go

Pro

Test what you just learned

Self-testing is one of the best ways to retain new skills. Unlock project quizzes to check your understanding.

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