hardMultiple ChoiceObjective-mapped
CCSP Practice Question: Refer to the exhibit
Exhibit
IAM Policy Document:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": ["s3:GetObject", "s3:ListBucket"],
"Resource": ["arn:aws:s3:::example-db-backup", "arn:aws:s3:::example-db-backup/*"]
},
{
"Effect": "Allow",
"Action": "kms:Decrypt",
"Resource": "*"
}
]
}Refer to the exhibit. An organization has attached this IAM policy to a role used by a backup application to access encrypted objects in an S3 bucket. The application is failing with an access denied error when trying to download objects. What is the most likely cause?
⚠ Common exam trap
ISC2 often tests the nuance that KMS resource ARNs must be explicit for decrypt operations, not wildcarded, even though wildcards are syntactically valid in IAM policies.
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 policy does not specify the SSE-KMS key ARN in the KMS action.
The policy grants kms:Decrypt using a wildcard resource ("arn:aws:kms:*:*:key/*") instead of specifying the exact KMS key ARN used to encrypt the S3 objects. When an S3 object is encrypted with SSE-KMS, the backup application must have explicit permission to use that specific KMS key. Without the correct key ARN in the KMS action's Resource element, KMS denies the decryption request, causing the access denied error.
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 policy uses wildcard resource for KMS, which is not allowed.
Why it's wrong here
Wildcard resources are allowed for KMS actions, although best practice is to specify the key ARN.
- ✓
The policy does not specify the SSE-KMS key ARN in the KMS action.
Why this is correct
Correct: To decrypt objects, the policy must include the specific key ARN or the key's policy must grant the role permission.
- ✗
The policy does not grant s3:GetObject on the bucket itself.
Why it's wrong here
The policy grants s3:GetObject on the objects (arn:aws:s3:::example-db-backup/*) and s3:ListBucket on the bucket.
- ✗
The policy omits kms:DescribeKey permission.
Why it's wrong here
kms:DescribeKey is not required for decrypt; kms:Decrypt is sufficient if the key policy allows it.
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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JA
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.