Curriculum Overview: Temporary Credential Mechanisms in AWS
Configure mechanisms to issue temporary credentials (for example, AWS Security Token Service [AWS STS], Amazon S3 presigned URLs).
Curriculum Overview: Temporary Credential Mechanisms
This curriculum covers the design and implementation of temporary security credentials within AWS, focusing on AWS Security Token Service (STS) and Amazon S3 Presigned URLs. These mechanisms are critical for adhering to the principle of least privilege and reducing the blast radius of potential credential compromises.
Prerequisites
Before starting this module, students should have a firm grasp of the following:
- IAM Fundamentals: Understanding of IAM Users, Groups, and Roles.
- Resource-Based Policies: Basic knowledge of S3 Bucket Policies.
- AWS CLI: Ability to execute basic commands and configure local profiles.
- Identity Basics: Familiarity with the difference between authentication (who you are) and authorization (what you can do).
Module Breakdown
| Module | Focus Area | Difficulty |
|---|---|---|
| 1. STS Essentials | Components of temporary credentials (Access Key, Secret Key, Session Token). | Intermediate |
| 2. Cross-Account Access | Configuring trust policies and assuming roles across AWS accounts. | Intermediate |
| 3. S3 Presigned URLs | Generating time-limited URLs for object access via CLI and Console. | Beginner |
| 4. Identity Federation | Exchanging SAML 2.0 and OIDC tokens for AWS temporary credentials. | Advanced |
Learning Objectives per Module
Module 1: AWS STS Fundamentals
- Define the structure of temporary credentials and explain why a Session Token is required alongside the Access Key and Secret Key.
- Configure credential expiration intervals (ranging from 15 minutes to 12 hours).
Module 2: Cross-Account & Service Roles
- Create a Trust Policy that allows an external entity or service to perform the
sts:AssumeRoleaction. - Implement service roles for EC2 or Lambda to eliminate the need for long-term access keys.
Module 3: Amazon S3 Presigned URLs
- Generate a presigned URL using the AWS CLI:
aws s3 presign s3://bucket/key --expires-in <seconds>. - Differentiate between expiration limits: Up to 7 days via CLI/SDK vs. 12 hours via the AWS Management Console.
Module 4: Federation and Web Identity
- Explain the flow of exchanging external IdP (Active Directory, Okta, Google) tokens for STS credentials.
- Understand the role of Amazon Cognito in social identity federation for mobile/web applications.
Visual Overview
The STS Credential Request Flow
Expiration Limits Comparison
Success Metrics
To demonstrate mastery of this curriculum, the learner must:
- Generate and Validate: Successfully generate an S3 presigned URL and confirm it works for a user without AWS credentials.
- Cross-Account Configuration: Set up a role in Account B that can be assumed by a user in Account A, confirming successful credential exchange via
sts:AssumeRole. - Troubleshooting: Identify why an STS session might fail (e.g., maximum session duration exceeded or invalid trust policy).
- CLI Proficiency: Correctly use the
--expires-inparameter to set custom timeouts for temporary access.
Real-World Application
- Secure Content Delivery: Providing temporary access to a private video file in S3 to a premium subscriber without making the bucket public.
- Corporate SSO: Allowing employees to log into the AWS Management Console using their existing corporate Windows credentials (Active Directory).
- Mobile Apps: Enabling a mobile photo-sharing app to upload directly to S3 using Amazon Cognito to trade a Facebook or Google login for temporary AWS permissions.
[!IMPORTANT] Temporary credentials are not just a "best practice"—they are a requirement for passing the AWS Certified Security Specialty exam. Always favor IAM Roles over IAM Users with long-term keys.