The correct step is to delete the public bucket policy and attach a new policy that allows access only through a VPC Endpoint. This works because the existing policy grants universal public read access via `"Principal": "*"`, so simply adding a condition without removing that broad permission would leave the bucket exposed. By replacing the policy with one that includes a `aws:SourceVpce` condition, you restrict `s3:GetObject` to traffic originating from your specific VPC Endpoint, effectively locking out the public internet while preserving access for authorized users inside your VPC. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of how bucket policies interact with VPC Endpoints to enforce network-level controls—a common trap is assuming an IAM role alone suffices, but roles do not override a permissive bucket policy. Another pitfall is enabling "Block all public access" without a VPC Endpoint policy, which would block even legitimate VPC traffic. Memory tip: think "Policy first, then condition"—remove the wildcard principal before adding the VPC Endpoint restriction.
SCS-C02 Infrastructure Security Practice Question
This SCS-C02 practice question tests your understanding of infrastructure security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A security team notices that an S3 bucket containing sensitive data is publicly accessible. The bucket policy is as follows:
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Delete the public bucket policy and attach a new policy that allows access only through a VPC Endpoint.
Option B is correct because removing the public access and using a VPC Endpoint with a bucket policy that restricts access to the endpoint ensures only authorized users within the VPC can access the bucket. Option A is wrong because an IAM role alone does not prevent public access. Option C is wrong because the bucket policy already allows public access. Option D is wrong because blocking all public access prevents even authorized users if they are not in the VPC.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use AWS Config to automatically block all public access.
Why it's wrong here
Blocking all public access would also block authorized external users.
✗
Create an IAM role with S3 access and assign it to the bucket.
Why it's wrong here
Bucket policies and IAM policies work together; this does not remove public access.
✗
Add a Deny statement for any IP address outside the corporate network.
Why it's wrong here
The Allow to Principal * still allows public access.
✓
Delete the public bucket policy and attach a new policy that allows access only through a VPC Endpoint.
Why this is correct
Restricts access to the VPC endpoint.
Related concept
Standard ACLs match source addresses.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SCS-C02 ACL questions on filtering logic and placement.
Infrastructure Security — This question tests Infrastructure Security — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Delete the public bucket policy and attach a new policy that allows access only through a VPC Endpoint. — Option B is correct because removing the public access and using a VPC Endpoint with a bucket policy that restricts access to the endpoint ensures only authorized users within the VPC can access the bucket. Option A is wrong because an IAM role alone does not prevent public access. Option C is wrong because the bucket policy already allows public access. Option D is wrong because blocking all public access prevents even authorized users if they are not in the VPC.
What should I do if I get this SCS-C02 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SCS-C02 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Question Discussion
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