In the AWS Shared Responsibility Model, AWS is responsible for the security of the cloud, while customers are responsible for security in the cloud. This means customers are accountable for securing the AWS services they use, such as Amazon EC2, Amazon S3, Amazon VPC, Amazon DynamoDB, Amazon RDS, Amazon IAM, and more.
In this article, we’ll focus on Cloud Security with AWS Identity and Access Management (IAM)—a powerful tool for controlling access to AWS resources.
What is AWS IAM?
AWS Identity and Access Management (IAM) is a web service that allows you to securely manage access to AWS resources. With IAM, you define who can access what and under what conditions. It provides the infrastructure necessary to manage authentication (who can sign in) and authorization (what they can do) across your AWS account.
Identities in IAM
When you first create an AWS account, you start with a root user—the identity that has full access to all AWS services and resources. This root user is tied to the email address used during account creation.
Security Best Practice: Avoid using the root user for day-to-day tasks. Instead, create an IAM user with administrative privileges and use that for regular operations.
Access Management
Once a user is created in IAM, they can authenticate using their credentials. IAM evaluates whether the user has permission to access specific AWS resources. This is determined by the policies attached to the user or their group or role.
For instance, when a user selects a service in the AWS Console, a request is sent to check:
- Is the user authorized?
- What policies are in place?
- Are there any additional restrictions?
IAM ensures only authorized principals (users, roles, or federated identities) can access resources.
With IAM, you can:
- Create users and user groups
- Assign fine-grained permissions
- Enforce security controls like MFA and password policies
- Define who can do what across your AWS account
Tags are key-value pairs used to label AWS resources. They help with identification, organization, and cost tracking.
For example, if you have two EC2 instances, you might tag one as "Environment: Development" and the other as "Environment: Production"—making management and filtering easier.
Key Components of IAM
IAM Users
These represent individuals who need access to your AWS resources—like you or your teammates.
IAM Groups
User groups (e.g., "Admins", "Developers") allow you to manage permissions collectively. Policies attached to a group apply to all its users.
IAM Roles
Roles provide temporary access to AWS resources. They're ideal for:
- Applications running on EC2
- Users from another AWS account
- Federated users from corporate directories
IAM Policies
Policies are JSON or Visual Editor documents that define permissions. A policy specifies:
- Effect:
Allow or Deny
- Action: What the principal can do (e.g.,
ec2:StartInstances)
- Resource: What the action applies to
Example policy:
- Allows all actions on a development EC2 instance
- Denies tag creation and deletion
Account Alias
An account alias is a friendly name you can assign to your AWS account, making sign-in URLs more memorable than using your 12-digit AWS account ID.
Instead of:
https://88885770278076.signin.aws.amazon.com/console
You can use:
https://your-company.signin.aws.amazon.com/console
IAM Security Best Practices
- Avoid using the root account for regular tasks
- ✅ Enable Multi-Factor Authentication (MFA) for all users
- Follow the principle of least privilege—grant only the permissions necessary
- Rotate access keys and passwords regularly
- Use AWS CloudTrail to log and monitor activity
- Use IAM roles for applications instead of hardcoding credentials
Common IAM Use Cases
- Grant an EC2 instance access to read/write data in S3
- Allow developers to deploy to Lambda but not modify billing settings
- Share access between AWS accounts using cross-account roles
- Integrate with corporate identity providers using SAML or Active Directory
Conclusion
IAM is at the heart of AWS security. By effectively managing identities and access, you can maintain strong security postures, minimize risks, and ensure only the right people (or systems) have access to the right resources at the right time.
Security in the cloud starts with smart IAM practices.
