IAM best practices in AWS - Commands & Configuration

Introduction

IAM helps control who can do what in your cloud account. Using best practices keeps your account safe and organized.

When you want to give a new team member access to only the tools they need.

When you need to allow an application to access cloud resources securely.

When you want to avoid using the root account for daily tasks.

When you want to track who made changes in your cloud environment.

When you want to remove access quickly if someone leaves your team.

Commands

Create a new IAM user named example-user to give them access without using the root account.

Terminal

aws iam create-user --user-name example-user

Expected Output

{"User":{"Path":"/","UserName":"example-user","UserId":"AIDAEXAMPLEUSERID","Arn":"arn:aws:iam::123456789012:user/example-user","CreateDate":"2024-06-01T12:00:00Z"}}

→

--user-name - Specifies the name of the new IAM user.

Attach the ReadOnlyAccess policy to example-user to give them permission to view resources but not change them.

Terminal

aws iam attach-user-policy --user-name example-user --policy-arn arn:aws:iam::aws:policy/ReadOnlyAccess

Expected Output

No output (command runs silently)

→

--policy-arn - Specifies the ARN of the policy to attach.

→

--user-name - Specifies which user to attach the policy to.

Create access keys for example-user so they can use the AWS CLI or SDK securely.

Terminal

aws iam create-access-key --user-name example-user

Expected Output

{"AccessKey":{"UserName":"example-user","AccessKeyId":"AKIAEXAMPLEKEYID","Status":"Active","SecretAccessKey":"wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY","CreateDate":"2024-06-01T12:05:00Z"}}

→

--user-name - Specifies the user to create access keys for.

List all IAM users to verify example-user was created successfully.

Terminal

aws iam list-users

Expected Output

Users:

- UserName: example-user

  UserId: AIDAEXAMPLEUSERID

  Arn: arn:aws:iam::123456789012:user/example-user

  CreateDate: 2024-06-01T12:00:00Z

Key Concept

If you remember nothing else from this pattern, remember: always give the least permissions needed and avoid using the root account.

Common Mistakes

Using the root account for everyday tasks.

The root account has full access and can cause big problems if compromised.

Create individual IAM users with limited permissions for daily work.

Giving users more permissions than they need.

This increases security risks if a user or their credentials are compromised.

Attach only the policies that allow the exact actions the user needs.

Not rotating or deleting unused access keys.

Old keys can be stolen and used to access your account.

Regularly rotate keys and delete keys that are no longer needed.

Summary

Create IAM users to avoid using the root account.

Attach only necessary policies to users for least privilege.

Create and manage access keys securely for programmatic access.

Verify users and permissions with list commands.

Practice

1. What is the main reason to follow the principle of least privilege in AWS IAM?

easy

A. To create permanent access keys for all users

B. To allow users full access to all AWS services

C. To give users only the permissions they need to do their job

D. To disable multi-factor authentication (MFA) for easier access

Solution

1. Step 1: Understand least privilege concept

   Least privilege means giving users only the permissions they need, nothing more.

2. Step 2: Identify correct option

   To give users only the permissions they need to do their job matches this concept by limiting permissions to what is necessary.

3. Final Answer:

   To give users only the permissions they need to do their job -> Option C

4. Quick Check:

   Least privilege = minimal permissions [OK]

Hint: Least privilege means minimal needed permissions only [OK]

Common Mistakes:

• Giving users full access unnecessarily
• Using permanent keys instead of temporary credentials
• Ignoring MFA setup

2. Which of the following is the correct way to assign permissions to an AWS service using IAM?

easy

A. Create an IAM role and assign it to the AWS service

B. Generate permanent access keys and embed them in the service code

C. Create an IAM user and attach policies directly to the user

D. Use root account credentials for the service

Solution

1. Step 1: Understand IAM roles for services

   IAM roles allow AWS services to assume permissions temporarily without permanent keys.

2. Step 2: Identify best practice

   Assigning an IAM role to the service is the recommended way to grant permissions securely.

3. Final Answer:

   Create an IAM role and assign it to the AWS service -> Option A

4. Quick Check:

   Use roles for services, not permanent keys [OK]

Hint: Use roles for AWS services, not permanent keys [OK]

Common Mistakes:

• Attaching policies directly to users for services
• Embedding permanent keys in code
• Using root account credentials

3. Consider this IAM policy snippet attached to a user:

{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Action": ["s3:ListBucket"],
    "Resource": ["arn:aws:s3:::example-bucket"]
  }]
}

What can this user do?

medium

A. Upload files to example-bucket

B. List the contents of the example-bucket

C. Delete files from example-bucket

D. Access all S3 buckets

Solution

1. Step 1: Analyze the policy actions

   The policy allows only the "s3:ListBucket" action on the specific bucket resource.

2. Step 2: Determine allowed operations

   "s3:ListBucket" lets the user see the list of objects but not upload or delete.

3. Final Answer:

   List the contents of the example-bucket -> Option B

4. Quick Check:

   Action = s3:ListBucket means list only [OK]

Hint: Check the Action field to know allowed operations [OK]

Common Mistakes:

• Assuming upload or delete permissions from list permission
• Thinking the policy applies to all buckets
• Ignoring the specific resource ARN

4. You created an IAM user with full S3 access but forgot to enable MFA. What is the best way to fix this?

medium

A. Attach an MFA policy and require MFA for sensitive actions

B. Delete the user and create a new one with MFA enabled

C. Remove all permissions from the user

D. Share the root account credentials with the user

Solution

1. Step 1: Understand MFA enforcement

   MFA can be required by attaching policies that enforce MFA for sensitive actions.

2. Step 2: Apply best practice

   Attaching an MFA policy is better than deleting the user or removing permissions.

3. Final Answer:

   Attach an MFA policy and require MFA for sensitive actions -> Option A

4. Quick Check:

   Enable MFA via policy, don't delete users [OK]

Hint: Use policies to enforce MFA, not user deletion [OK]

Common Mistakes:

• Deleting users unnecessarily
• Removing all permissions without MFA
• Sharing root credentials

5. Your company wants to allow temporary access to AWS resources for contractors without creating permanent IAM users. Which approach follows best IAM practices?

hard

A. Give contractors permanent access keys with admin permissions

B. Create permanent IAM users with full access for contractors

C. Share your root account credentials with contractors

D. Create IAM roles with limited permissions and let contractors assume them

Solution

1. Step 1: Identify temporary access method

   IAM roles allow temporary credentials that contractors can assume without permanent users.

2. Step 2: Match best practice

   Creating roles with limited permissions follows least privilege and avoids permanent keys.

3. Final Answer:

   Create IAM roles with limited permissions and let contractors assume them -> Option D

4. Quick Check:

   Temporary roles for contractors = best practice [OK]

Hint: Use roles for temporary access, avoid permanent users [OK]

Common Mistakes:

• Creating permanent users for contractors
• Sharing root credentials
• Giving admin permissions unnecessarily