DEA-C01 Data Security and Governance Practice Question
A healthcare company stores patient records in an S3 bucket encrypted with SSE-S3. The data engineering team uses AWS Glue ETL jobs to process this data and load it into an Amazon Redshift cluster for analytics. Recently, the security team mandated that all sensitive data must be encrypted at rest using customer-managed keys (CMK) in AWS KMS, and that the keys must be rotated automatically every year. The team updated the S3 bucket to use SSE-KMS with a CMK and enabled automatic key rotation. However, after the change, the Glue ETL jobs that read from the S3 bucket started failing with 'Access Denied' errors. The Glue job uses an IAM role named 'GlueETLRole' that has the following permissions: s3:GetObject on the bucket, kms:Decrypt and kms:GenerateDataKey on the CMK, and all necessary Glue permissions. The Redshift cluster is also encrypted with a different CMK, and the Glue role has kms:Decrypt on that key as well. What is the most likely cause of the failure?
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 policy for the CMK used for S3 encryption does not grant 'GlueETLRole' permission to use the key.
The issue is that while the IAM role 'GlueETLRole' has the necessary KMS permissions (kms:Decrypt and kms:GenerateDataKey) via IAM policies, the key policy for the CMK used for S3 encryption must also explicitly grant the role (or the principal) permission to use the key. Without this key policy grant, the role's IAM permissions are insufficient, resulting in 'Access Denied' errors. Option A correctly identifies this as the most likely cause.
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 policy for the CMK used for S3 encryption does not grant 'GlueETLRole' permission to use the key.
Why this is correct
The key policy must allow the IAM role to use the key.
- ✗
The IAM role 'GlueETLRole' does not have kms:Decrypt permission on the CMK used for S3 encryption.
Why it's wrong here
The role does have kms:Decrypt permission as stated.
- ✗
The Glue job requires kms:Encrypt permission to read encrypted data from S3.
Why it's wrong here
Reading requires kms:Decrypt, not Encrypt.
- ✗
The S3 VPC endpoint policy does not allow the Glue job to access the KMS key.
Why it's wrong here
VPC endpoint policy could be a factor, but the key policy is more direct.
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 |
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Same concept, more angles
1 more way this is tested on DEA-C01
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. A company is using AWS Glue to process data stored in an S3 bucket that is encrypted with SSE-KMS. The Glue job fails with an 'Access Denied' error when trying to read the data. The IAM role used by the Glue job has permissions to read from the S3 bucket and to use the KMS key. What is the most likely cause of the failure?
hard- A.The S3 bucket is using SSE-S3 instead of SSE-KMS
- ✓ B.The S3 bucket policy denies access to the Glue job
- C.The KMS key is in a different AWS account
- D.The IAM role is missing the kms:Decrypt permission
Why B: Although the IAM role has permissions to read from the S3 bucket and to use the KMS key, the S3 bucket policy might explicitly deny access to the Glue job. Bucket policies can override IAM permissions. The 'Access Denied' error often occurs when a bucket policy denies access even if the IAM role is authorized. Option A is incorrect because the bucket uses SSE-KMS as stated. Option C is possible but not necessarily the most likely without cross-account context. Option D is incorrect because the premise states the role has permissions to use the KMS key, which includes kms:Decrypt.
JA
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.