The answer is to review both bucket policies and S3 Block Public Access settings. Bucket policies are resource-based policies that explicitly define who can access the bucket, and a public grant is typically identified by a statement using `"Principal": "*"` or `"Effect": "Allow"` combined with a wide action scope. S3 Block Public Access settings act as an overarching security override that can prevent even a permissive bucket policy from taking effect, so a misconfigured or absent block is often the root cause of unintended public readability. On the AWS Certified Cloud Practitioner CLF-C02 exam, this question tests your understanding of the layered security model for S3—specifically that IAM policies alone do not control bucket-level access, and that public access is a result of both a permissive resource policy and the absence of a block. A common trap is assuming IAM user policies are the culprit, but they only apply to identities, not to anonymous requests. Memory tip: think of the bucket policy as the “key” that opens the door, and Block Public Access as the “deadbolt” that keeps it locked—you must check both to know if the door is actually open.
CLF-C02 Security and Compliance Practice Question
This CLF-C02 practice question tests your understanding of security and compliance. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 audit found that an S3 bucket is publicly readable. Which IAM/S3 mechanism should be reviewed to identify what grants the public access?
IAM identity-based policies attached to the root user
Why wrong: IAM identity-based policies control what IAM identities can do to S3 — they don't grant anonymous public access to S3 objects.
B
Bucket policies and S3 Block Public Access settings
Public S3 access is granted through bucket policies with Principal '*' and/or bucket/object ACLs. Block Public Access settings can override these to prevent public exposure.
C
AWS Organizations Service Control Policies
Why wrong: SCPs restrict what member accounts can do — they can't grant public S3 access (only IAM/bucket policies and ACLs can).
D
Amazon Macie classification rules
Why wrong: Macie discovers sensitive data in S3 — it doesn't control access permissions on buckets.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Bucket policies and S3 Block Public Access settings
Bucket policies are resource-based policies that explicitly define who has access to an S3 bucket, including public access grants like `"Principal": "*"`. S3 Block Public Access settings act as an overarching security control that can override bucket policies to prevent public access. Reviewing both mechanisms together identifies exactly how public readability was granted and whether any block was misconfigured or absent.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
IAM identity-based policies attached to the root user
Why it's wrong here
IAM identity-based policies control what IAM identities can do to S3 — they don't grant anonymous public access to S3 objects.
✓
Bucket policies and S3 Block Public Access settings
Why this is correct
Public S3 access is granted through bucket policies with Principal '*' and/or bucket/object ACLs. Block Public Access settings can override these to prevent public exposure.
Related concept
Read the scenario before looking for a memorised answer.
✗
AWS Organizations Service Control Policies
Why it's wrong here
SCPs restrict what member accounts can do — they can't grant public S3 access (only IAM/bucket policies and ACLs can).
✗
Amazon Macie classification rules
Why it's wrong here
Macie discovers sensitive data in S3 — it doesn't control access permissions on buckets.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse IAM identity-based policies (which control user permissions) with resource-based policies (like bucket policies) that directly grant public access, leading them to incorrectly select Option A.
Detailed technical explanation
How to think about this question
Under the hood, S3 evaluates access by combining bucket policies, user policies, and Block Public Access settings; a bucket policy with `"Effect": "Allow"` and `"Principal": "*"` on `s3:GetObject` makes the bucket publicly readable unless Block Public Access is enabled. A real-world scenario is when a developer sets a bucket policy for a static website but forgets to enable Block Public Access, leaving the bucket open to the internet. The S3 Block Public Access settings can block all public access at the account or bucket level, overriding even explicit allow statements in bucket policies.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CLF-C02 question in full detail.
Security and Compliance — This question tests Security and Compliance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Bucket policies and S3 Block Public Access settings — Bucket policies are resource-based policies that explicitly define who has access to an S3 bucket, including public access grants like `"Principal": "*"`. S3 Block Public Access settings act as an overarching security control that can override bucket policies to prevent public access. Reviewing both mechanisms together identifies exactly how public readability was granted and whether any block was misconfigured or absent.
What should I do if I get this CLF-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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