12 AWS IAM Security Best Practices

Managing access to AWS resources through AWS Identity and Access Management (IAM) is a powerful toolset, but it can be challenging to configure and manage. However, by adhering to best practices, you can guarantee that your AWS environment is well-managed and secure.

AWS IAM security best practices include:

1. Avoid using root user credentials for daily tasks
2. Attach permissions to groups instead of individual users
3. Aim for least privilege permissions
4. Focus on separation of duties
5. Enforce multi-factor authentication for IAM Users
6. Leverage the natural security boundaries of AWS accounts via a multi-account environment and AWS Organizations
7. Make use of AWS Identity Center and Federation
8. Utilize roles as much as possible
9. Avoid inline policies
10. Regularly review permissions
11. Avoid common IAM mistakes
12. Extend your AWS fundamentals beyond IAM

AWS Identity and Access Management (IAM) is a service that enables AWS customers to manage access to AWS resources in a secure and scalable manner. IAM allows users to create and manage AWS users and groups and provides granular permissions to users and groups to access specific AWS resources.

AWS IAM focuses on Role Based Access Control (RBAC) which allows administrators to assign permissions to roles rather than individual users, making it easier to manage access control at scale.

Additionally, IAM offers temporary security credentials which can be used to grant access to AWS resources for a limited time, reducing the risk of unauthorized access. This approach increases the security of AWS resources and ensures that only authorized users have access to them.

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It is not good practice to use the root user of an AWS account because it has unrestricted access to all AWS resources in the account. This means that if the root user’s credentials are compromised, an attacker would have complete control over the account and all of its resources. 

Using the root user also makes it difficult to manage access control and monitor activity within the account. Instead, it is recommended to create individual IAM users with limited permissions and to use multi-factor authentication (MFA – more on that later) to secure access to the account. Lock away your root user after assigning MFA and creating your first IAM user.

By using IAM users with appropriate permissions, you can limit access to specific resources and activities within the account, reducing the risk of unauthorized access or accidental modifications. Additionally, IAM users can be easily added or removed as needed, allowing for more efficient management of access control.

IAM Groups are a way to manage permissions for multiple users at once. Rather than attaching policies directly to individual users, policies can be attached to groups, which can then be assigned to users.

This approach simplifies the management of permissions by allowing policies to be updated for a group of users all at once. It also reduces the risk of errors and inconsistencies that can arise when policies are applied to individual users.

Read more about AWS IAM policies.

Adhering to the principle of least privilege is essential for ensuring the security and proper management of your AWS resources. If users or roles are granted too many permissions, it can result in them accessing AWS resources they shouldn’t have access to, which can lead to data breaches or other security incidents. 

By granting only the permissions that are necessary for users and services to fulfill their tasks, you can help minimize the risk of unauthorized access and prevent accidental modifications to your resources. This can also help you comply with regulatory requirements and industry best practices for security and data protection.

It’s important to regularly review and update permissions to ensure that they remain appropriate and necessary. This can involve removing permissions that are no longer needed, as well as adding new permissions as necessary. By following the principle of least privilege and regularly reviewing permissions, you can help ensure the proper management and security of your AWS resources.

Creating customized roles that grant permissions for specific or limited tasks is an essential aspect of IAM best practices. By avoiding broad permissions or roles that are applied to multiple tasks and grant excessive access, you can help minimize the risk of unauthorized access and prevent accidental modifications to your resources.

It’s important to clearly separate roles by their duties and assign permissions based on the specific tasks that users or services need to perform. This can involve creating roles for specific applications, tasks, or teams, and assigning permissions accordingly. By doing so, you can ensure that users have only the permissions they need to perform their specific tasks, and can help prevent unauthorized access to your AWS resources.

Rather than creating a single role that encompasses all possible permissions for every function, it’s recommended to create a dedicated role for each function. This role should include only the required permissions needed to fulfill its specific task, and no more.

There are multiple guides that explain the fundamentals of IAM in-depth, including AWS IAM Users, Roles, and Policies. These guides provide a comprehensive overview of IAM and its key components and can help you develop a solid understanding of how to manage access to your AWS resources.

Enabling multi-factor authentication (MFA) for your root user or any other IAM user is a simple yet crucial step in securing your AWS account. MFA adds an extra layer of protection to your account by requiring a second factor, such as a code generated by an authenticator app or a physical token, in addition to the user’s password.

To enable MFA for an IAM user, you can navigate to the IAM console and follow the prompts to set up MFA. It’s also possible to mandate the use of MFA across your entire AWS account or organization by creating a dedicated policy.

By requiring MFA for all users, you can significantly reduce the risk of unauthorized access and protect your AWS resources from potential threats. It’s important to note that MFA should be used in conjunction with other security best practices, such as regularly reviewing and rotating access keys and implementing strong password policies.

There’s a dedicated guide you can find in the AWS documentation on how to create the policy so that users are able to manage their own credentials but nothing else until they successfully set up MFA.

Using a multi-account strategy with AWS Organizations can provide several benefits for managing your AWS resources, including increased security and improved organization and management.

Each AWS account comes with natural security boundaries, meaning that resources within one account are isolated from those in another account. By using separate accounts for different teams, applications, or environments, you can reduce the risk of unauthorized access or accidental modifications, as well as limit the potential impact of security incidents or failures.

Additionally, using multiple accounts can make it easier to manage and organize your AWS resources. You can assign separate budgets and billing information to each account, allowing for more granular control over spending. You can also use separate accounts to isolate development and testing environments from production environments, reducing the risk of disruptions or conflicts.

AWS Organizations provides a centralized management console for managing multiple accounts, making it easier to set up and manage policies, permissions, and resources across your organization. By using a multi-account strategy with AWS Organizations, you can improve the security, organization, and management of your AWS resources.

If you’re new to working with AWS Organizations, you may be interested in having a look at this in-depth introduction guide that will take you step-by-step through the process of creating your first organization and Service Control Policy, with hands-on examples to help you get started.

To simplify the process of managing identities and access to AWS resources, it’s no longer recommended to set up users directly on AWS IAM. Instead, AWS advises using a specialized identity provider (IdP) and relying on roles to assign access to those identities.

An IdP is a service that focuses solely on managing identities, which can be used across your AWS organization via federation. While the AWS Identity Center can serve as an IdP, it may be more beneficial to choose a third-party service that specializes in identity management, especially for larger-scale environments.

By using an IdP, you can streamline the process of managing user access and reduce the risk of unauthorized access. Additionally, AWS Identity Center can facilitate Single-Sign-On (SSO), making it easier for users to access multiple applications, services, and AWS accounts without having to enter separate credentials.

If you’re working on a small project and want to use IAM users without a dedicated external identity provider, it’s important to use the AWS Identity Center to create your users. This will ensure that you can easily switch to a multi-account strategy in the future if needed, and provide your users with single sign-on capability and easy multi-account user management.

While using IAM users without an external identity provider may be appropriate for small projects, it’s essential to consider the potential risks and limitations. Using an external identity provider can provide additional security and management capabilities, and may be necessary for larger or more complex projects. It’s essential to regularly review and update your IAM policies and configurations to ensure that they remain appropriate and effective for your needs.

IAM Roles are a powerful and flexible concept in IAM, similar to IAM users but with the crucial difference that multiple entities can assume a role simultaneously. This allows for more temporary access grants without long-lived access credentials, providing a secure mechanism for granting permissions.

By granting permission as a Principal via a role’s trust policy, an identity like an IAM user can assume that role, enabling secure access patterns such as keeping IAM users in an account with minimal permissions and allowing them to assume roles for work in a separate account.

Inline policies are policies integrated directly with an IAM identity, useful to ensure that only that identity will have a specific policy.

However, the widespread use of inline policies can be difficult to manage and prevent enforcing homogenous policy configuration and usage for a larger number of identities. Managed policies attached to an identity are more effective for centralizing change management and administration in complex, distributed systems.

Regularly reviewing permissions for IAM roles and groups is crucial for maintaining the security of an organization’s resources. Over time, the access needs of users may change, and new resources may be added or removed.

If permissions are not regularly reviewed and updated, users may accumulate unnecessary permissions, which can increase the risk of data breaches or other security incidents. Additionally, regular reviews can help to identify any misconfigured permissions, such as overly permissive policies or roles that grant more access than is necessary.

By performing regular reviews of IAM roles and groups, organizations can ensure that users have the appropriate level of access to perform their job duties, while also minimizing the risk of security incidents.

Along with the detailed recommendations mentioned previously, there are several other common IAM mistakes that are frequently encountered in both small and large projects. Among them are:

• Failing to use IAM roles: When using AWS services for your workloads, it’s crucial to utilize roles with customized permissions. This ensures that users have only the permissions they need to perform their specific tasks, and AWS will handle the issuance of temporary credentials to prevent concerns about database password leaks.
• Not regularly rotating access keys: If you require long-term access keys, it’s important to rotate them regularly to minimize the risk of accidental leakage. This can help prevent unauthorized access to your AWS resources.
• Using your root user for daily tasks: While it may be tempting to use your AWS root user for daily tasks, it’s best to avoid doing so. The root user has broad permissions that can be risky to use on a regular basis. Instead, use individual IAM users with appropriate permissions.
• Failing to use SCPs: If you’re working with multiple accounts within an organization, it’s important to establish guardrails across your organization via service control policies (SCPs). SCPs can help ensure that users have only the permissions they need to perform their specific tasks, and can help prevent unauthorized access to your AWS resources.
• Not using permission boundaries: Another advanced feature of IAM is permission boundary policies, which can be applied to roles. These boundaries do not grant permissions on their own, but restrict the maximum permissions that can be delegated via a role. This can help ensure that users have only the permissions they need to perform their specific tasks, and can help prevent unauthorized access to your AWS resources.

While this list is not exhaustive, it serves as a valuable starting point for implementing best practices in IAM.

To become a successful DevOps engineer, it’s crucial to first understand the fundamentals of AWS IAM. This critical component of the AWS ecosystem serves as a central control point for managing access to AWS resources. However, it’s also important to continue learning about other core services such as Lambda, DynamoDB, and ECS. These services form the backbone of many successful organizations and projects, and mastering them will help you excel in your role as a DevOps engineer.

If you’re looking to get more comfortable with AWS core services and learn how to build applications for the real world, you may want to consider joining the bi-weekly newsletter that Sandro Volpicella and I are running.

Mastering AWS IAM is a critical component of managing and securing AWS resources. By adhering to best practices, you can help ensure that your AWS environment is well-managed and secure. 

• Avoid using root user credentials for daily tasks, as the root user has unrestricted access to all AWS resources in the account. Instead, create individual IAM users with limited permissions and use multi-factor authentication to secure access to the account.
• Aim for least privilege permissions by granting only the permissions that are necessary for users and services to fulfill their tasks. This can help minimize the risk of unauthorized access and prevent accidental modifications to your resources.
• Focus on the separation of duties by creating customized roles that grant permissions for specific or limited tasks. By avoiding broad permissions or roles that are applied to multiple tasks, you can help minimize the risk of unauthorized access and prevent accidental modifications to your resources.
• Leverage the natural security boundaries of AWS accounts via a multi-account environment and AWS Organizations. By using separate accounts for different teams, applications, or environments, you can reduce the risk of unauthorized access or accidental modifications, as well as limit the potential impact of security incidents or failures.
• Enforce multi-factor authentication for IAM users to add an extra layer of protection to your account. This can significantly reduce the risk of unauthorized access and protect your AWS resources from potential threats.
• Utilize roles as much as possible to enable secure access patterns such as keeping IAM users in an account with minimal permissions and allowing them to assume roles for work in a separate account.
• Avoid using inline policies as they can be difficult to manage and prevent enforcing homogenous policy configuration and usage for a larger number of identities. Managed policies attached to an identity are more effective for centralizing change management and administration in complex, distributed systems. 

By following these best practices, you can help minimize the risk of unauthorized access and prevent accidental modifications to your resources, ensuring the proper management and security of your AWS resources. Investing time in mastering AWS IAM is essential as it serves as the core of every application.