SCS-C03 Incident Response Practice Question
Exhibit
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "s3:ListBucket",
"Resource": "arn:aws:s3:::production-data"
}
]
}Refer to the exhibit. An incident responder needs to access the production-data bucket to investigate a breach. They apply this policy to their IAM user, but get 'Access Denied' when running 'aws s3 ls s3://production-data'. Why?
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 is missing the 'kms:Decrypt' permission for encrypted objects.
The policy provided only grants the 's3:ListBucket' permission, which allows the user to see the objects within the bucket. However, the 'aws s3 ls' command often requires additional permissions, such as 's3:GetBucketLocation' or 's3:ListBucket'. More importantly, if the bucket is encrypted with a KMS key, the user must also have 'kms:Decrypt' permissions, which are absent here. This is a common stumbling block in granular IAM policy management.
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 user is missing the 's3:GetObject' permission.
Why it's wrong here
The 's3:ListBucket' permission is sufficient for listing the contents of a bucket. The 's3:GetObject' permission is only required if the user attempts to download or read the content of the files themselves, which is not required for the initial 'ls' command to execute successfully.
- ✓
The policy is missing the 'kms:Decrypt' permission for encrypted objects.
Why this is correct
If the bucket uses SSE-KMS, the user requires the 'kms:Decrypt' permission on the specific key used to encrypt the data. Without this permission, the S3 service cannot decrypt the bucket metadata required to list the objects, causing the command to fail with an Access Denied error.
- ✗
The resource ARN is incorrectly formatted for S3.
Why it's wrong here
The resource ARN 'arn:aws:s3:::production-data' is the correct format for referencing an S3 bucket in an IAM policy. The list action is bucket-level, and the resource scope is correctly defined for that action, so this does not contribute to the Access Denied error.
- ✗
The user needs the 's3:PutObject' permission to list files.
Why it's wrong here
The 's3:PutObject' permission is strictly for uploading data to a bucket. It is entirely unrelated to the ability to list objects within a bucket. Providing this permission would violate the principle of least privilege and would not resolve the issue preventing the list operation from working.
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 |
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This SCS-C03 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 SCS-C03 exam.