AWS Glue Fails: Missing kms:Decrypt Permission for SSE-KMS
A data engineer is troubleshooting an issue where an IAM role used by AWS Glue cannot read data from an S3 bucket encrypted with SSE-KMS. The bucket policy allows the role to perform s3:GetObject. What additional permission is needed?
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
✓
kms:Decrypt on the KMS key
For SSE-KMS, the IAM role needs kms:Decrypt permission on the KMS key to read encrypted objects. Option A (s3:GetObjectVersion) is not required because the bucket policy already allows s3:GetObject; versioning is not relevant here. Option C (s3:GetObjectAcl) is for access control lists, not encryption. Option D (kms:GenerateDataKey) is used for encrypting new objects, not reading existing ones. Therefore, the correct answer is B.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
s3:GetObjectVersion
Why it's wrong here
s3:GetObjectVersion permits reading a specific object version, which is irrelevant when the failure is KMS decryption. It is tempting because it is a genuine S3 read permission, and would be correct when a bucket has versioning enabled and the role must retrieve a non-current version.
- ✓
kms:Decrypt on the KMS key
Why this is correct
SSE-KMS encrypts objects with a KMS key, so s3:GetObject alone is insufficient: S3 must call KMS to unwrap the data key on the caller's behalf. The role therefore needs kms:Decrypt on that key, satisfying the stem's requirement to read the SSE-KMS-encrypted objects.
- ✗
s3:GetObjectAcl
Why it's wrong here
s3:GetObjectAcl governs reading an object's access control list, which is unrelated to decrypting SSE-KMS objects. It is tempting because ACL permissions sound access-related, but the correct choice is kms:Decrypt, which unwraps the data key so Glue can read the object.
- ✗
kms:GenerateDataKey on the KMS key
Why it's wrong here
kms:GenerateDataKey is required when writing encrypted objects, not reading them; decryption needs kms:Decrypt on the key. It is tempting because it is a genuine KMS permission tied to SSE-KMS, and would be correct for a role uploading data to the bucket.
Visual reference
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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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.