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CAS-004 Practice Question: Is reviewing the configuration of an AWS S3…
A security engineer is reviewing the configuration of an AWS S3 bucket that stores customer data. Which of the following settings is most likely to cause a data breach?
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
✓
Bucket policy that allows public read access
A bucket policy allowing public read access exposes data to anyone. Option A (versioning) is a feature, not a risk. Option C (encryption) is secure. Option D (MFA delete) is a security control.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Versioning enabled on the bucket
Why it's wrong here
Versioning enables preservation of object versions but does not inherently expose data.
- ✓
Bucket policy that allows public read access
Why this is correct
A bucket policy allowing public read access exposes all objects in the bucket to anyone, leading to potential data breach.
- ✗
Server-side encryption with AWS KMS
Why it's wrong here
Server-side encryption with AWS KMS protects data at rest and is a security control.
- ✗
MFA delete enabled on the bucket
Why it's wrong here
MFA delete adds an extra authentication requirement for delete operations, enhancing security.
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 CAS-005 practice question is part of Courseiva's free CompTIA 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 CAS-005 exam.