This SCS-C02 practice question tests your understanding of data protection. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Refer to the exhibit. A security engineer is troubleshooting a decryption failure. The command uses the AWS CLI to decrypt a file. The decryption fails with an 'AccessDeniedException' error. The IAM user has the following policy attached:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "kms:Decrypt",
"Resource": "*"
}
]
}What is the most likely cause of the failure?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
The KMS key policy does not grant the IAM user decrypt permission
Key policies can restrict access even if IAM allows.
The IAM user does not have permission to call kms:Decrypt on the specific key
Why wrong: The IAM policy allows Decrypt on all keys.
The ciphertext blob is not valid
Why wrong: An invalid ciphertext would produce a different error.
The IAM user is not authorized to use the AWS CLI
Why wrong: The error is AccessDenied, not authorization to use CLI.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The KMS key policy does not grant the IAM user decrypt permission
The IAM policy grants kms:Decrypt on all resources ('*'), but KMS requires both an IAM policy and a key policy to allow access. The key policy is the resource-based policy on the KMS key itself. If the key policy does not explicitly grant the IAM user (or the user's account) decrypt permission, the request is denied with AccessDeniedException. Option A is correct because the key policy is missing the necessary permission. Option B is incorrect because the IAM policy does allow kms:Decrypt on all keys. Option C is incorrect because an invalid ciphertext would cause a different error (e.g., InvalidCiphertextException), not AccessDeniedException. Option D is incorrect because the user is authorized to use the CLI; the failure is at the KMS level.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The KMS key policy does not grant the IAM user decrypt permission
Why this is correct
Key policies can restrict access even if IAM allows.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
The IAM user does not have permission to call kms:Decrypt on the specific key
Why it's wrong here
The IAM policy allows Decrypt on all keys.
The ciphertext blob is not valid
Why it's wrong here
An invalid ciphertext would produce a different error.
The IAM user is not authorized to use the AWS CLI
Why it's wrong here
The error is AccessDenied, not authorization to use CLI.
Common exam traps
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Identify which SCS-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Data Protection — This question tests Data Protection — Read the scenario before looking for a memorised answer..
The correct answer is: The KMS key policy does not grant the IAM user decrypt permission — The IAM policy grants kms:Decrypt on all resources ('*'), but KMS requires both an IAM policy and a key policy to allow access. The key policy is the resource-based policy on the KMS key itself. If the key policy does not explicitly grant the IAM user (or the user's account) decrypt permission, the request is denied with AccessDeniedException. Option A is correct because the key policy is missing the necessary permission. Option B is incorrect because the IAM policy does allow kms:Decrypt on all keys. Option C is incorrect because an invalid ciphertext would cause a different error (e.g., InvalidCiphertextException), not AccessDeniedException. Option D is incorrect because the user is authorized to use the CLI; the failure is at the KMS level.
Identify which SCS-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Refer to the exhibit. A security engineer runs the AWS CLI command shown and receives an AccessDenied error. The IAM user Alice has a policy that grants kms:Decrypt on all resources. What is the most likely cause of the error?
hardWhy A: The AccessDenied error is caused by the KMS key policy, which explicitly restricts which principals can decrypt using the key. Even though Alice's IAM policy allows kms:Decrypt on all resources, the key policy must also grant her access. If the key policy does not list Alice (or her role) as a principal allowed to decrypt, the request fails. Option A correctly identifies this as the most likely cause.
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Last reviewed: Jun 20, 2026
This SCS-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SCS-C02 exam.
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