AWS Identity and Access Management (IAM), you can specify who or what can access services and resources in AWS, centrally manage fine-grained permissions, and analyze access to refine permissions across AWS.
Authentication and authorization
When you configure access to any account, two terms come up frequently: authentication and authorization. Although these terms might seem basic, you must fully understand them to properly configure access management on AWS.
Authentication
When you create your AWS account, you use the combination of an email address and a password to verify your identity. If a user types in the correct email address and password, the system assumes the user is allowed to enter and grants them access. This is the process of authentication.
Authentication ensures that the user is who they say they are. User names and passwords are the most common types of authentication. But you might also work with other forms, such as token-based authentication or biometric data, like a fingerprint.
Authorization
After you’re authenticated and in your AWS account, you might be curious about what actions you can take. This is where authorization comes in. Authorization is the process of giving users permission to access AWS resources and services. Authorization determines whether a user can perform certain actions, such as read, edit, delete, or create resources.
What is IAM?
AWS Identity and Access Management (IAM) is an AWS service that helps you manage access to your AWS account and resources. It also provides a centralized view of who and what are allowed inside your AWS account (authentication), and who and what have permissions to use and work with your AWS resources (authorization). with IAM, you can share access to an AWS account and resources without sharing your set of access keys or password. You can also provide granular access to those working in your account, so people and services only have permissions to the resources that they need. For example, to provide a user of your AWS account with read-only access to a particular AWS service, you can granularly select which actions and which resources in that service that they can access.
IAM features
IAM is global and not specific to any one Region. You can see and use your IAM configurations from any Region in the AWS Management Console.
IAM is integrated with many AWS services by default.
You can grant other identities permission to administer and use resources in your AWS account without having to share your password and key.
IAM supports MFA. You can add MFA to your account and to individual users for extra security.
IAM supports identity federation, which allows users with passwords elsewhere—like your corporate network or internet identity provider—to get temporary access to your AWS account.
Any AWS customer can use IAM; the service is offered at no additional charge.
IAM user
An IAM user represents a person or service that interacts with AWS. You define the user in your AWS account. Any activity done by that user is billed to your account. When you create a user, that user can sign in to gain access to the AWS resources inside your account.
IAM user credentials
An IAM user consists of a name and a set of credentials. When you create a user, you can provide them with the following types of access:
Access to the AWS Management Console
Programmatic access to the AWS CLI and AWS API
To access the console, provide the user with a user name and password. For programmatic access, AWS generates a set of access keys that can be used with the AWS CLI and AWS API. IAM user credentials are considered permanent, which means that they stay with the user until there’s a forced rotation by admins.
IAM groups
An IAM group is a collection of users. All users in the group inherit the permissions assigned to the group. This makes it possible to give permissions to multiple users at once. It’s a more convenient and scalable way of managing permissions for users in your AWS account. This is why using IAM groups is a best practice.
This provides a way to see who has what permissions in your organization. It also helps you scale when new people join, leave, and change roles in your organization.
Consider the following examples:
A new developer joins your AWS account to help with your application. You create a new user and add them to the developer group, without thinking about which permissions they need.
A developer changes jobs and becomes a security engineer. Instead of editing the user’s permissions directly, you remove them from the old group and add them to the new group that already has the correct level of access.
Keep in mind the following features of groups:
1. Groups can have many users.
2. Users can belong to many groups.
3. Groups cannot belong to groups.
The root user can perform all actions on all resources inside an AWS account by default. This is in contrast to creating new IAM users, new groups, or new roles. To allow an IAM identity to perform specific actions in AWS, such as implement resources, you must grant the IAM user the necessary permissions.
The way you grant permissions in IAM is by using IAM policies.
IAM policies
To manage access and provide permissions to AWS services and resources, you create IAM policies and attach them to an IAM identity. Whenever an IAM identity makes a request, AWS evaluates the policies associated with them. For example, if you have a developer inside the developers group who makes a request to an AWS service, AWS evaluates any policies attached to the developers group and any policies attached to the developer user to determine if the request should be allowed or denied.
IAM policy examples
Most policies are stored in AWS as JSON documents with several policy elements. The following example provides admin access through an IAM identity-based policy.
{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Action": "*",
"Resource": "*"
}]
}
This policy has four major JSON elements: Version, Effect, Action, and Resource.
The Version element defines the version of the policy language. It specifies the language syntax rules that are needed by AWS to process a policy. To use all the available policy features, include "Version": "2012-10-17" before the "Statement" element in your policies.
The Effect element specifies whether the policy will allow or deny access. In this policy, the Effect is "Allow", which means you’re providing access to a particular resource.
The Action element describes the type of action that should be allowed or denied. In the example policy, the action is "*". This is called a wildcard, and it is used to symbolize every action inside your AWS account.
The Resource element specifies the object or objects that the policy statement covers. In the policy example, the resource is the wildcard "*". This represents all resources inside your AWS console.
Putting this information together, you have a policy that allows you to perform all actions on all resources in your AWS account. This is what we refer to as an administrator policy.
IAM roles
IAM roles are identities in AWS that like an IAM user also have associated AWS credentials used to sign requests. However, IAM users have usernames and passwords as well as static credentials whereas IAM roles do not have any login credentials like a username and password and the credentials used to sign requests are programmatically acquired, temporary in nature, and automatically rotated.
IAM best practices
IAM best practices. This section summarizes some of the most important IAM best practices that you must be familiar with before building solutions in AWS.
Lock down the AWS root user
The root user is an all-powerful and all-knowing identity in your AWS account. If a malicious user were to gain control of root-user credentials, they would be able to access every resource in your account, including personal and billing information. To lock down the root user, you can do the following:
- Don’t share the credentials associated with the root user.
- Consider deleting the root user access keys.
- Activate MFA on the root account.
Follow the principle of least privilege
Least privilege is a standard security principle that advises you to grant only the necessary permissions to do a particular job and nothing more. To implement least privilege for access control, start with the minimum set of permissions in an IAM policy and then grant additional permissions as necessary for a user, group, or role.
Use IAM appropriately
IAM is used to secure access to your AWS account and resources. It provides a way to create and manage users, groups, and roles to access resources in a single AWS account. IAM is not used for website authentication and authorization, such as providing users of a website with sign-in and sign-up functionality. IAM also does not support security controls for protecting operating systems and networks.
Use IAM roles when possible
Maintaining roles is more efficient than maintaining users. When you assume a role, IAM dynamically provides temporary credentials that expire after a defined period of time, between 15 minutes and 36 hours. Users, on the other hand, have long-term credentials in the form of user name and password combinations or a set of access keys.
User access keys only expire when you or the account admin rotates the keys. User login credentials expire if you applied a password policy to your account that forces users to rotate their passwords.
Consider using an identity provider
If you decide to make your cat photo application into a business and begin to have more than a handful of people working on it, consider managing employee identity information through an identity provider (IdP). Using an IdP, whether it's with an AWS service such as AWS IAM Identity Center (successor to AWS Single Sign-On) or a third-party identity provider, provides a single source of truth for all identities in your organization.
Regularly review and remove unused users, roles, and other credentials
You might have IAM users, roles, permissions, policies, or credentials that you are no longer using in your account. IAM provides last accessed information to help you identify irrelevant credentials that you no longer need so that you can remove them. This helps you reduce the number of users, roles, permissions, policies, and credentials that you have to monitor.
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