SCS-C02 Infrastructure Security Practice Question
A company uses AWS Key Management Service (KMS) to encrypt data at rest. The security team needs to ensure that only specific IAM roles can use a particular KMS key to encrypt and decrypt data. What is the most secure way to achieve this?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a KMS key policy that grants access only to the specific IAM roles using the kms:CallerArn condition.
Using a key policy with a condition for the kms:CallerArn attribute restricts usage to the specified roles. Option A is wrong because IAM policies alone cannot restrict KMS key usage if the key policy allows all principals. Option C is wrong because key policy with Principal "*" grants access to all, even with a condition. Option D is wrong because a condition for the IAM role's ARN is not a standard KMS condition key.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create an IAM policy that allows kms:Encrypt and kms:Decrypt for the roles and attach it to the roles.
Why it's wrong here
The key policy must also allow the roles; otherwise, the default key policy denies all.
- ✓
Create a KMS key policy that grants access only to the specific IAM roles using the kms:CallerArn condition.
Why this is correct
This restricts key usage to the specified roles.
- ✗
Create a KMS key policy that grants access to the account and use IAM policies to restrict the roles.
Why it's wrong here
This does not prevent other roles in the account from using the key.
- ✗
Create a KMS key policy with Principal "*" and a condition that the request originates from the roles.
Why it's wrong here
Principal "*" allows all, and condition may not be evaluated correctly.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.