mediumMultiple ChoiceObjective-mapped
CAS-004 Practice Question: A cloud security engineer reviews the above S3…
Exhibit
Refer to the exhibit.
```
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::bucket123/*",
"Condition": {
"IpAddress": {
"aws:SourceIp": "203.0.113.0/24"
}
}
},
{
"Effect": "Allow",
"Action": "s3:PutObject",
"Resource": "arn:aws:s3:::bucket123/*",
"Principal": "*"
}
]
}
```A cloud security engineer reviews the above S3 bucket policy. Which of the following is the most significant security concern?
⚠ Common exam trap
CompTIA often tests the distinction between read and write permissions in S3 policies, and the trap here is that candidates focus on the IP restriction or the read permission being 'public' while overlooking that the write action (s3:PutObject) has no such restriction, making it the more dangerous vulnerability.
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 bucket policy allows any user to upload objects to the bucket.
The bucket policy statement includes a Principal of '*' and an Action of 's3:PutObject' without any condition restricting who can upload, meaning any unauthenticated user on the internet can write objects to the bucket. This creates a severe data integrity and malware-upload risk, as attackers can place arbitrary content into the bucket, potentially leading to data corruption, storage cost abuse, or serving malicious files.
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 bucket policy grants unnecessary permissions for s3:GetObject.
Why it's wrong here
The GetObject permission is appropriately restricted by IP; it's not unnecessary if the use case requires it.
- ✗
The IP address restriction uses an incorrect format for the condition key.
Why it's wrong here
The format is correct: "aws:SourceIp" with CIDR notation.
- ✗
The bucket policy allows public read access to all objects.
Why it's wrong here
Read access (s3:GetObject) is restricted to a specific IP range, not public.
- ✓
The bucket policy allows any user to upload objects to the bucket.
Why this is correct
The second statement grants s3:PutObject to Principal "*", meaning anyone can write to the bucket.
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
Related to this question
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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.