Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Account B has an IAM role that includes kms:Decrypt for a specific KMS key ARN in account A. However, when the role tries to read an S3 object encrypted with that CMK, the application fails with AccessDenied: not authorized to perform kms:Decrypt. CloudTrail shows the KMS API call is denied by key policy. What is the most secure and correct fix?
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 role in account B to include kms:Encrypt and kms:GenerateDataKey; then kms:Decrypt will start working automatically.
kms:Encrypt and kms:GenerateDataKey do not grant kms:Decrypt authorization. The error indicates that the KMS key policy is denying the decrypt call, so the fix must adjust KMS key policy (and/or grants), not add unrelated IAM KMS actions.
B
Best answer
Update the KMS key policy in account A to allow the account B role principal to use kms:Decrypt on the key.
Cross-account use of a CMK requires the KMS key policy (in the CMK’s account) to allow the external principal to perform kms:Decrypt. Since CloudTrail shows the denial is by key policy, updating the key policy to grant the account B role kms:Decrypt on the specific key is the correct and least-privilege solution.
C
Distractor review
Disable key policy for the CMK by switching to S3-managed encryption, because KMS key policies are always enforced regardless of grants.
Switching encryption types changes the encryption configuration and does not address the underlying requirement for authorization to use the specific CMK. Additionally, KMS key policy is not a concept that can be “disabled” for a CMK; the correct fix is to modify the CMK key policy (and/or create appropriate grants).
D
Distractor review
Create an SCP in account A that allows kms:Decrypt for all accounts, avoiding changes to the key policy.
Service Control Policies (SCPs) are organization-level guardrails. Even if an SCP allows kms:Decrypt, KMS can still deny the call if the CMK’s key policy does not allow it. SCPs also do not replace the CMK key policy requirement for cross-account authorization.
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 KMS key policy in account A to allow the account B role principal to use kms:Decrypt on the key. — KMS authorization is determined by evaluating the caller’s IAM permissions and the KMS key policy (and, depending on the scenario, grants). In cross-account cases, even if the IAM role in account B has kms:Decrypt, the CMK key policy in account A must also allow that role to perform kms:Decrypt. Because CloudTrail shows the denial is from key policy, the correct fix is to update the CMK key policy in account A to grant the account B role principal permission to decrypt for that specific key. Option A addresses the wrong authorization edge: adding encrypt-related permissions does not fix a decrypt denial. Option C avoids the problem by changing encryption rather than correcting the CMK key policy authorization for the existing CMK. Option D misunderstands SCPs: SCP allow does not override a CMK key policy denial, so the application would likely continue failing until the CMK policy allows kms:Decrypt.
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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