Authorization methods (role-based, policy-based, tag-based, and attributebased)

Role-based access control (RBAC) is one of the most common and straightforward authorization methods. RBAC assigns permissions based on predefined roles within an organization, grouping several permissions together that are necessary for a particular job function.

Example:
Imagine an AWS environment where there are different teams like Developers, Testers, and Ops. You can create IAM roles such as DeveloperRole, TesterRole, and OpsRole. Each role would have corresponding policies attached to it that allow the necessary permissions for tasks that each team undertakes.

Developers might need access to Amazon S3 to read and write to development buckets but should not have access to delete production databases in Amazon RDS. Similarly, an operations team member might need access to manage EC2 instances but not to modify IAM roles.

Policy-Based Access Control (PBAC):

Policy-based access control (PBAC) is more granular and flexible than RBAC. Instead of using roles, PBAC uses detailed policies to define permissions. Policies are JSON documents that specify what actions are allowed or denied.

Example:
A policy can permit a user to access specific S3 buckets between 8 AM and 5 PM on weekdays. It would look something like:

{
“Version”: “2012-10-17”,
“Statement”: [
{
“Effect”: “Allow”,
“Action”: “s3:*”,
“Resource”: “arn:aws:s3:::example_bucket/*”,
“Condition”: {
“DateGreaterThan”: {
“aws:CurrentTime”: “2023-03-18T08:00:00Z”
},
“DateLessThan”: {
“aws:CurrentTime”: “2023-03-18T17:00:00Z”
},
“Bool”: {
“aws:ViaAWSService”: “false”
}
}
}
]
}

Tag-Based Access Control (TBAC):

Tag-based access control (TBAC) uses tags attached to AWS resources to manage access. Tags are key-value pairs associated with resources, and policies can leverage these tags to grant or restrict permissions.

Example:
Suppose you have tagged different resources with a tag key Environment and values Dev, Test, or Prod. You can create a policy that allows access only to resources tagged with Environment:Dev for developers. Such a policy would enforce that only development resources are accessible, like so:

{
“Version”: “2012-10-17”,
“Statement”: [
{
“Effect”: “Allow”,
“Action”: “s3:*”,
“Resource”: “*”,
“Condition”: {
“StringEquals”: {
“s3:ResourceTag/Environment”: “Dev”
}
}
}
]
}

Attribute-Based Access Control (ABAC):

Attribute-based access control (ABAC) leverages user, resource, and environment attributes to create more dynamic and granular policies. ABAC can use a variety of attributes such as department, job function, or sensitivity of data to make access decisions.

Example:
In an ABAC model, you can create policies that grant access based on the user’s department. If a user with an attribute "department":"finance" attempts to access data, the policy would evaluate the user’s attributes and the requested resource’s attributes before granting access.

Best Practices:

• Least Privilege: Always follow the principle of least privilege, granting only the permissions necessary to perform a task.
• Regular Audits: Regularly review and audit your policies and roles to ensure they are still relevant and secure.
• Combine Methods: Consider combining these authorization methods for more sophisticated and layered access control strategies. For example, you could use RBAC for general access control, supplemented by ABAC for fine-grained permissions.

Each of these authorization methods has its unique strengths and trade-offs, and choosing the right one depends on the specific needs of the AWS Certified Data Engineer. Understanding the intricacies and appropriate application of these methods is crucial for designing a secure and efficient cloud infrastructure on AWS.