Advanced IAM Policies - AWS Security

Identity and Access Management (IAM) is a fundamental component of AWS security, allowing you to control who can access your resources and what actions they can perform. Advanced IAM policies enable fine-grained control over permissions, leveraging JSON syntax to define conditions, principals, and resources.

2.1 Policies

Policies are documents that define permissions and are written in JSON format. They specify what actions are allowed or denied on specific resources.

2.2 Roles

Roles are IAM entities that define a set of permissions for making AWS service requests. They can be assumed by users, applications, or services.

2.3 Permissions

Permissions dictate the allowed actions on AWS resources. They can be granted through policies attached to users, groups, or roles.

An IAM policy consists of one or more statements. Each statement can include the following elements:

• Effect: Specifies whether the statement allows or denies access.
• Action: Lists the actions that are allowed or denied (e.g., s3:PutObject).
• Resource: Specifies the resources to which the actions apply (e.g., an S3 bucket).
• Condition: Optional; specifies conditions for when the policy is in effect.

Example of a basic IAM policy:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": "s3:GetObject",
            "Resource": "arn:aws:s3:::example-bucket/*"
        }
    ]
}

4.1 Allowing Access Based on Conditions

Policies can define conditions under which permissions are granted or denied:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": "s3:PutObject",
            "Resource": "arn:aws:s3:::example-bucket/*",
            "Condition": {
                "StringEquals": {
                    "aws:SourceIp": "203.0.113.0/24"
                }
            }
        }
    ]
}

4.2 Denying Access

You can also create policies that explicitly deny certain actions:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Deny",
            "Action": "s3:DeleteObject",
            "Resource": "arn:aws:s3:::example-bucket/*"
        }
    ]
}

• Use the principle of least privilege, granting only the permissions necessary for users to perform their tasks.
• Regularly review and audit IAM policies and permissions assigned to users and roles.
• Utilize IAM roles for applications running on AWS services to avoid embedding credentials in code.
• Implement multi-factor authentication (MFA) for sensitive accounts and actions.
• Use AWS CloudTrail to monitor and log API calls made to IAM.