When I started learning AWS, IAM was one of those services I knew I needed to understand, but I didn't immediately appreciate how important it was. IAM stands for Identity and Access Management. It controls who can access AWS resources and what they can do with them.

As I learned more about AWS, I realized that getting IAM wrong can expose resources, create security problems, or make infrastructure hard to manage.

Here are some IAM mistakes worth avoiding as a beginner.

1. Using the Root Account for Everything

The AWS root account has unrestricted access to the account. It is created when you first sign up for AWS.

One mistake beginners can make is using this account for everyday activities.

Instead, secure the root account, enable MFA, and avoid using it for routine administration. Use IAM identities with appropriate permissions for your regular work.

2. Giving Everyone AdministratorAccess

Sometimes, when something doesn't work, the easiest solution seems to be granting AdministratorAccess. It may solve the immediate permission problem, but it also gives the identity far more access than it needs.

A better approach is to grant only the permissions required for a particular task.

This is called the principle of least privilege.

For example, if an application only needs to read files from an S3 bucket, it shouldn't have permission to delete buckets or modify IAM users.

3. Hardcoding AWS Access Keys

Another mistake is putting AWS access keys directly inside application code.

AWS_ACCESS_KEY_ID = "your-access-key" AWS_SECRET_ACCESS_KEY = "your-secret-key"

If this code gets pushed to a public repository, someone else could use those credentials to access your AWS resources. Instead, use IAM roles and temporary credentials where possible.

For applications running on EC2, an IAM role attached through an instance profile allows the application to obtain temporary credentials without storing long-term access keys in the code.

4. Confusing IAM Users, Groups, Roles, and Policies

These concepts are related, but they serve different purposes.

  • IAM users: Identities that can represent individual people or applications, though roles are generally preferred for workloads.
  • IAM groups: Collections of IAM users that can share permissions.
  • IAM roles: Identities that provide permissions to trusted users, services, or other accounts when assumed.
  • IAM policies: Documents that define what actions are allowed or denied on which resources.

Understanding these differences makes it easier to design access properly.

5. Forgetting MFA

A password alone may not be enough to protect an account. Multi-factor authentication (MFA) adds another layer of security by requiring an additional verification method.

Enable MFA for the root account and human users, especially those with privileged access.

6. Not Understanding IAM Roles in AWS Services

AWS services often need permission to interact with other AWS services.

For example:

  • EC2 may need permission to read files from S3.
  • Lambda may need permission to write logs to CloudWatch.
  • ECS tasks may need permission to retrieve secrets.

Instead of creating access keys for these services, assign appropriate IAM roles.

This keeps credentials out of application code and makes access easier to manage.

7. Ignoring IAM Policy Scope

An IAM policy can allow an action on a specific resource or on a much broader set of resources.

For example:

{ "Effect": "Allow", "Action": "s3:GetObject", "Resource": "arn:aws:s3:::my-app-bucket/*" }

This allows reading objects inside the specified bucket.

Compare that with granting access to every S3 object in the account.

The difference matters. Restrict permissions to the resources the identity actually needs.

What I Learned

IAM is not just another AWS service to configure. It is part of the security foundation of your infrastructure.

As a beginner, it is tempting to focus on getting services running first. But understanding IAM early makes working with EC2, S3, Lambda, RDS, and other AWS services much easier.

The goal isn't simply to make something work. It is to make it work with the right permissions.

That is one of the habits worth building early as a Cloud or DevOps engineer.