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CCSP Practice Question: A healthcare organization uses a cloud-based…
A healthcare organization uses a cloud-based electronic health record system. Patient data is encrypted at rest using server-side encryption with AWS KMS keys. The security team notices that during a recent security incident, an attacker used compromised credentials to decrypt and exfiltrate a large number of patient records. The attacker performed decryption operations using the KMS API, which was logged in CloudTrail. The organization wants to implement additional controls to prevent such bulk decryption in the future while still allowing authorized access. Which of the following is the BEST course of action?
⚠ Common exam trap
ISC2 often tests the misconception that network-layer controls (like IP restrictions) or key rotation are sufficient to prevent unauthorized decryption, when in fact they do not address the core issue of compromised credentials being used to make legitimate API calls.
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
✓
Implement a key vault with an access broker that requires multi-factor authentication for each decryption request.
A is correct because implementing a key vault with an access broker that requires multi-factor authentication for each decryption request directly addresses the root cause: compromised credentials. By requiring MFA per decryption operation, even if an attacker steals credentials, they cannot perform bulk decryption without also bypassing the MFA challenge for each API call. This control operates at the application layer, independent of the KMS key policy, and provides granular, per-request authorization.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Implement a key vault with an access broker that requires multi-factor authentication for each decryption request.
Why this is correct
MFA adds strong authentication for each decryption, preventing bulk decryption even with compromised credentials.
- ✗
Change the encryption to client-side encryption using keys stored on-premises.
Why it's wrong here
Significant architectural change; may reduce availability and performance.
- ✗
Create a KMS key policy that requires a condition for a specific IP range or VPC endpoint.
Why it's wrong here
Attacker could use a compromised machine within the allowed IP range.
- ✗
Enable automatic key rotation on the KMS key.
Why it's wrong here
Does not stop decryption with the existing key.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CCSP practice question is part of Courseiva's free ISC2 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 CCSP exam.