Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Account A hosts a role named AppReadRole. Account B needs to access it using STS AssumeRole. Account A’s role trust policy includes this condition: - StringEquals: { "sts:ExternalId": "b-7f9a" } When Account B runs: aws sts assume-role --role-arn arn:aws:iam::111111111111:role/AppReadRole --role-session-name test the call fails with: "AccessDenied: ExternalId mismatch". What should Account B change?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
Provide the correct --external-id value (b-7f9a) in the AssumeRole call.
The trust policy requires sts:ExternalId to equal b-7f9a. If the caller does not supply the matching external ID, STS fails the trust-policy condition and denies AssumeRole. Supplying --external-id b-7f9a satisfies the condition.
B
Distractor review
Add kms:Decrypt permissions to Account B’s IAM user because trust policy failures are KMS related.
The error is about trust policy evaluation for AssumeRole (sts:ExternalId mismatch). KMS permissions are not involved in evaluating that trust condition.
C
Distractor review
Remove the ExternalId condition from the trust policy so any caller can assume the role.
This would weaken security by removing a deliberate external-party verification control. The scenario’s stated fix is to satisfy the existing trust condition rather than eliminate it.
D
Distractor review
Use AssumeRoleWithSAML instead of AssumeRole so ExternalId is not required.
AssumeRoleWithSAML still results in STS evaluating the same role trust policy conditions. If the trust policy requires sts:ExternalId, it must be satisfied regardless of the AssumeRole API used.
Common exam trap
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Technical deep dive
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
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FAQ
Questions learners often ask
What does this SAA-C03 question test?
Standard ACLs match source addresses.
What is the correct answer to this question?
The correct answer is: Provide the correct --external-id value (b-7f9a) in the AssumeRole call. — Account A’s trust policy explicitly requires sts:ExternalId to equal "b-7f9a". STS denies AssumeRole when the caller does not provide an external ID matching that condition. Account B should update the STS AssumeRole invocation to include --external-id b-7f9a. Adding unrelated permissions or changing the STS federation method does not bypass trust policy condition evaluation. B incorrectly attributes the issue to KMS. C removes a security control and does not address why STS is denying the request. D is incorrect because trust policy conditions are enforced for any method that attempts to assume the role.
What should I do if I get this SAA-C03 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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