Quick Answer
The answer is that the AWS Config managed rule for detecting public buckets only evaluates S3 bucket ACLs, not bucket policies. This is why a bucket policy granting s3:GetObject to Principal: * would not be flagged as non-compliant, because the rule specifically checks for public read access via ACLs rather than analyzing the resource-based policy attached to the bucket. On the AWS Certified Security Specialty SCS-C02 exam, this distinction between ACL-based and policy-based public access is a common trap—candidates often assume that the managed rule covers all forms of public access, but it does not. To detect public access granted through bucket policies, you must create a custom AWS Config rule using an AWS Lambda function that evaluates the bucket policy document. A helpful memory tip: ACLs are legacy and coarse, policies are modern and fine-grained—Config’s managed rules only watch the old gate, not the new one.
This SCS-C02 practice question tests your understanding of management and security governance. 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 company has an AWS account with multiple S3 buckets that contain sensitive data. The security team wants to ensure that no public access is granted to any bucket. The team has enabled AWS Config and set up a rule to detect public buckets. The rule reports that all buckets are compliant. However, during a security review, a team member finds that one bucket has a bucket policy that grants 's3:GetObject' to 'Principal': '*'. Why did the AWS Config rule not detect this?
AWS CloudTrail must be enabled for Config to evaluate policies.
Why wrong: Incorrect: CloudTrail is not required.
The AWS Config rule only checks ACLs, not bucket policies.
Correct: The managed rule checks ACLs only.
The bucket is in a different AWS account.
Why wrong: Incorrect: The rule works per account.
IAM Access Analyzer must be enabled first.
Why wrong: Incorrect: Access Analyzer is separate.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The AWS Config rule only checks ACLs, not bucket policies.
Option A is correct. The AWS Config managed rule 's3-bucket-public-read-prohibited' checks for public read access via ACLs, not bucket policies. To detect public access via bucket policies, a custom rule is needed. Option B is wrong because CloudTrail would log access, not detect compliance. Option C is wrong because SCPs are for Organizations. Option D is wrong because IAM Access Analyzer analyzes resource-based policies but does not enforce.
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
For each option: why learners choose it and why it is or isn't the right answer here.
AWS CloudTrail must be enabled for Config to evaluate policies.
Why it's wrong here
Incorrect: CloudTrail is not required.
The AWS Config rule only checks ACLs, not bucket policies.
Why this is correct
Correct: The managed rule checks ACLs only.
Related concept
Standard ACLs match source addresses.
The bucket is in a different AWS account.
Why it's wrong here
Incorrect: The rule works per account.
IAM Access Analyzer must be enabled first.
Why it's wrong here
Incorrect: Access Analyzer is separate.
Common exam traps
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
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.
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
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
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.
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FAQ
Management and Security Governance — This question tests Management and Security Governance — Standard ACLs match source addresses..
The correct answer is: The AWS Config rule only checks ACLs, not bucket policies. — Option A is correct. The AWS Config managed rule 's3-bucket-public-read-prohibited' checks for public read access via ACLs, not bucket policies. To detect public access via bucket policies, a custom rule is needed. Option B is wrong because CloudTrail would log access, not detect compliance. Option C is wrong because SCPs are for Organizations. Option D is wrong because IAM Access Analyzer analyzes resource-based policies but does not enforce.
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.
Standard ACLs match source addresses.
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Last reviewed: Jun 20, 2026
This SCS-C02 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-C02 exam.
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