DEA-C01 Data Security and Governance Practice Question
A healthcare company uses AWS Glue to process patient data stored in Amazon S3. The data is encrypted at rest using SSE-KMS with a customer managed key. The Glue ETL job runs on a schedule and reads from an S3 bucket, transforms the data, and writes to another S3 bucket also encrypted with the same KMS key. Recently, the security team rotated the KMS key. After the rotation, the Glue job started failing with 'AccessDenied' errors when trying to read from the source bucket. The Glue job's IAM role has permissions to use the KMS key (kms:Decrypt, kms:GenerateDataKey). The S3 bucket policies allow the role to read/write. What is the MOST likely cause of the failure?
⚠ Common exam trap
Many exam-takers assume KMS key rotation is seamless and never breaks existing access, but they overlook that the IAM role or key policy must still grant kms:Decrypt on the key resource, and that the old backing key remains in use for previously encrypted data.
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
✓
The KMS key rotation created a new backing key, but the Glue job's IAM role does not have permission to decrypt with the old backing key.
When you rotate a customer managed KMS key, AWS KMS retains the old backing key to allow decryption of data encrypted before the rotation. However, the Glue job's IAM role must have permission to use the old backing key via the kms:Decrypt action. If the key policy or IAM policy does not explicitly allow decryption with the old backing key (or if the key policy was inadvertently updated to remove access to the old key material), the Glue job will fail with AccessDenied when reading SSE-KMS encrypted objects that were encrypted with the previous key version.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The KMS key rotation created a new backing key, but the Glue job's IAM role does not have permission to decrypt with the old backing key.
Why this is correct
If automatic rotation is enabled, old backing keys are retained, but if the key was manually rotated (new key created), the old key may be disabled. Also, the key policy may have been updated incorrectly.
- ✗
The Glue job's IAM role is missing the kms:Encrypt permission on the KMS key.
Why it's wrong here
kms:Encrypt is not needed for reading encrypted data.
- ✗
The Glue job is using the wrong encryption context when calling KMS.
Why it's wrong here
Encryption context mismatches can cause failures, but rotation does not change the encryption context.
- ✗
The S3 bucket policy has a condition that requires the request to use the latest version of the KMS key.
Why it's wrong here
S3 bucket policies do not have such conditions; they can use kms:EncryptionContext but not key version.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-C01 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 DEA-C01 exam.