Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A microservice running in ECS retrieves a secret from AWS Secrets Manager. The secret is encrypted with a customer-managed CMK. An administrator re-keyed the secret to a new CMK (the key ARN changed), but kept the same KMS alias name. After re-keying, the service fails with an error from KMS: AccessDenied for kms:Decrypt. The ECS task role’s IAM policy still grants kms:Decrypt but only for the old CMK ARN. What is the best remediation to restore access while maintaining least privilege?
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
Distractor review
Update the IAM policy to allow kms:Decrypt for all CMKs in the account using a wildcard resource (for example, arn:aws:kms:region:account-id:key/*).
This is not least privilege because it broadens access beyond the specific CMK used by the secret.
B
Best answer
Update the ECS task role IAM policy to grant kms:Decrypt on the CMK alias ARN (arn:aws:kms:region:account-id:alias/<alias-name>) or to include the new CMK ARN, so decrypt authorization matches the re-keyed CMK.
Since the IAM policy references only the old CMK ARN, it no longer matches the CMK used after re-keying. Using the alias ARN maintains least privilege and continues to work because the alias now points to the new CMK.
C
Distractor review
Change the application to decrypt the secret itself using SSE-C keys so Secrets Manager no longer needs KMS.
Secrets Manager manages encryption at the service layer; the microservice still needs permission to allow Secrets Manager to decrypt using the CMK associated with the secret.
D
Distractor review
Enable KMS key rotation for the old CMK so the CMK ARN resolves to the new key.
Key rotation affects the key material and versioning behavior, but it does not cause the old key ARN to become the new key ARN. The IAM resource mismatch remains.
Common exam trap
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Technical deep dive
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
- Authentication checks who the user is.
- Authorization controls what the user is allowed to do after login.
- Privilege levels affect access to EXEC and configuration commands.
- AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
- Do not assume successful login means full administrative access.
- Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
- Separate login problems from permission problems before choosing the answer.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A team needs to distribute TCP traffic (not HTTP) across multiple services. The services must see the original client source IP for auditing. Which AWS load balancer is the best fit?
Question 2
A team wants to run containerized services with AWS-managed orchestration and autoscaling. They do NOT require Kubernetes compatibility. Which AWS service choice is most appropriate to meet these goals?
Question 3
A solutions architect is designing an S3 bucket for a IoT ingestion API. The objects must never be publicly accessible, even if a developer later adds an overly broad bucket policy. What should the architect configure? The design must avoid adding custom operational scripts.
Question 4
A solutions architect is designing an S3 bucket for a claims portal. The objects must never be publicly accessible, even if a developer later adds an overly broad bucket policy. What should the architect configure?
Question 5
A team wants to delegate IAM management to developers, but must ensure developers can never grant themselves permissions beyond a specific limit. Which AWS mechanism best matches this requirement?
Question 6
A solutions architect is designing an S3 bucket for a healthcare document service. The objects must never be publicly accessible, even if a developer later adds an overly broad bucket policy. What should the architect configure?
FAQ
Questions learners often ask
What does this SAA-C03 question test?
Authentication checks who the user is.
What is the correct answer to this question?
The correct answer is: Update the ECS task role IAM policy to grant kms:Decrypt on the CMK alias ARN (arn:aws:kms:region:account-id:alias/<alias-name>) or to include the new CMK ARN, so decrypt authorization matches the re-keyed CMK. — After re-keying, Secrets Manager uses the new CMK (different key ARN). IAM permissions that reference only the old CMK ARN no longer authorize kms:Decrypt, causing AccessDenied. The least-privilege fix is to update the ECS task role policy to authorize kms:Decrypt for the CMK alias ARN (preferred here because the alias name remains the same) or to include the new CMK ARN, so the policy matches the CMK currently backing the secret. Option A expands KMS access beyond the specific CMK/alias. Option C changes encryption strategy incorrectly; Secrets Manager still requires KMS decrypt authorization for its customer-managed CMK. Option D does not address the ARN mismatch introduced by re-keying.
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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