The answer is sts:AssumeRoleWithWebIdentity. This is the correct choice because it is the only STS API action designed to grant temporary security credentials to users authenticated through an OIDC identity provider, such as Google, Amazon Cognito, or any OpenID Connect-compliant IdP, without requiring long-term AWS access keys. On the SAA-C03 exam, this question tests your understanding of how to federate external identities into AWS, often appearing in scenarios where you must choose between sts:AssumeRole (for cross-account access) and sts:AssumeRoleWithWebIdentity (for OIDC federation). A common trap is confusing it with sts:AssumeRoleWithSAML, which is for SAML 2.0 providers, not OIDC. Remember the memory tip: “WebIdentity = OIDC, SAML = SAML” — the action name explicitly includes “WebIdentity” to signal its use with web-based identity providers.
SAA-C03 Design Secure Architectures Practice Question
This SAA-C03 practice question tests your understanding of design secure architectures. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Your company uses an OIDC identity provider to let users assume an IAM role without long-term AWS credentials. In the IAM role trust policy, which STS action must be allowed to support this type of federation?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
sts:AssumeRoleWithWebIdentity
Option A is correct because sts:AssumeRoleWithWebIdentity is the STS API action specifically designed for federated users authenticated by an OIDC or SAML identity provider. This action returns temporary security credentials without requiring long-term AWS access keys, enabling the OIDC-based federation described in the question.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
sts:AssumeRoleWithWebIdentity
Why this is correct
OIDC/web identity federation uses sts:AssumeRoleWithWebIdentity in the trust policy.
Related concept
Read the scenario before looking for a memorised answer.
✗
sts:AssumeRole
Why it's wrong here
sts:AssumeRole is typically for trusted AWS principals, not OIDC web identity tokens.
✗
sts:GetCallerIdentity
Why it's wrong here
GetCallerIdentity is an API to retrieve identity information and is not used to assume roles.
✗
sts:TagSession
Why it's wrong here
TagSession can be used with AssumeRole flows, but it is not the core action required to trust web identity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse sts:AssumeRoleWithWebIdentity with sts:AssumeRole, not realizing that the former is required for OIDC/SAML federation while the latter is for IAM users or AWS services.
Detailed technical explanation
How to think about this question
Under the hood, sts:AssumeRoleWithWebIdentity validates the JWT token from the OIDC provider against the provider's JWKS endpoint and the configured audience (aud claim). The trust policy must include a Condition block checking the token's iss, aud, and sub claims to restrict which identities can assume the role. A real-world scenario is using Amazon Cognito as an OIDC provider for a mobile app, where the trust policy must allow only tokens from the specific user pool app client.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Design Secure Architectures — This question tests Design Secure Architectures — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: sts:AssumeRoleWithWebIdentity — Option A is correct because sts:AssumeRoleWithWebIdentity is the STS API action specifically designed for federated users authenticated by an OIDC or SAML identity provider. This action returns temporary security credentials without requiring long-term AWS access keys, enabling the OIDC-based federation described in the question.
What should I do if I get this SAA-C03 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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