Use cases for IAM users
IAM users are mostly suitable in the following situations:
- Human users: These are individuals such as developers, system administrators, or any other personnel who interact with AWS services via the console or the CLI. They typically require credentials to access services and resources.
- Non-human users: These are applications, scripts, or tools that make programmatic calls to AWS services. Examples include a SaaS application that needs to read a file from your S3 bucket or a script running on-premises that periodically starts and stops certain instances.
Best practices for IAM users
Here are some guidelines to ensure secure and efficient management of IAM users:
- Distinguish between human and non-human users: Recognize that applications or scripts might not need the same level of access as human users. Tailor permissions accordingly, and do not use the same IAM user for both types of access. A common mistake is developers using their own IAM users (human access) to grant access keys to an application (non-human access). This situation leads to too broad permissions granted to the application, and it may cause the application to stop working when the developer leaves the organization, and their user account is deleted.
- Prefer IAM roles for non-human identities: When dealing with non-human identities, especially those running within the AWS environment such as EC2 instances, Lambda functions, or ECS tasks, it is best to use IAM roles instead of IAM users to access other AWS resources. Roles automatically provide temporary credentials, eliminating the risks associated with managing long-term credentials.
- Avoid using the root user: It is strongly recommended to avoid using the root user for everyday tasks.
- Enable MFA: For an added layer of security, enable MFA for all IAM users, especially for users with extensive permissions or access to sensitive data.
- Restrict IP addresses: Further, enhance security by limiting access based on network location using conditions such as SourceIP or SourceVPC within the IAM policies associated with IAM users. This ensures they can only access AWS resources from trusted and specified network ranges or VPCs, effectively whitelisting corporate network ranges or specific VPCs.
- Regularly rotate credentials: Regularly rotate security credentials for IAM users. If an access key is compromised, the potential impact is reduced if the keys are changed regularly. Therefore, it is recommended to rotate access keys at least every 90 days to 365 days, depending on your security requirements.
- Utilize tags for efficient management: When dealing with a large number of IAM users, using tags can be invaluable. Tags allow for categorization based on department, role, project, or any other criteria, making it easier to manage, audit, and control access.
- Regularly review and audit: Periodically review IAM user access, permissions, and activity. Remove or modify any outdated permissions and delete users who no longer need access.