The correct answer is to enable S3 Block Public Access at the account level and use AWS Config rules to detect public ACLs and bucket policies. This combination works because S3 Block Public Access acts as a preventative guardrail that overrides any permissions that would make objects publicly accessible, while AWS Config continuously evaluates your bucket policies and ACLs against rules like s3-bucket-public-read-prohibited, providing detective coverage with minimal false positives. On the AWS Certified Security Specialty SCS-C02 exam, this question tests your understanding that detection alone is insufficient—you need both prevention and monitoring to comprehensively detect publicly accessible S3 objects. A common trap is choosing Amazon Macie, which focuses on sensitive data discovery rather than public access detection, or CloudTrail, which only logs API calls after the fact. Remember the memory tip: “Block first, Config second” to reinforce that prevention must precede detection for a complete security posture.
SCS-C02 Security Logging and Monitoring Practice Question
This SCS-C02 practice question tests your understanding of security logging and monitoring. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 uses Amazon S3 to store sensitive data. The security team wants to detect when objects are made publicly accessible. Which combination of services provides the MOST comprehensive detection with minimal false positives?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable S3 Block Public Access at the account level and use AWS Config rules to detect public ACLs and bucket policies.
Option D is correct because S3 Block Public Access prevents public access at the account level, and AWS Config rules can detect public ACLs and policies. Option A is wrong because CloudTrail alone cannot detect public access, only API calls. Option B is wrong because GuardDuty does not detect public S3 objects by default. Option C is wrong because Macie is for sensitive data discovery, not public access detection.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Enable S3 Block Public Access at the account level and use AWS Config rules to detect public ACLs and bucket policies.
Why this is correct
Block Public Access prevents accidental public access, and Config rules detect violations.
Related concept
Static NAT maps one inside address to one outside address.
✗
Use Amazon Macie to scan S3 buckets for publicly accessible objects.
Why it's wrong here
Macie focuses on sensitive data, not public access.
✗
Enable CloudTrail data events for S3 and create a CloudWatch Events rule for PutBucketAcl calls.
Why it's wrong here
This would generate many false positives for legitimate ACL changes.
✗
Enable Amazon GuardDuty and review the S3 findings for public access.
Why it's wrong here
GuardDuty does not have a specific finding for public S3 objects.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SCS-C02 NAT questions on configuration and troubleshooting.
Security Logging and Monitoring — This question tests Security Logging and Monitoring — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Enable S3 Block Public Access at the account level and use AWS Config rules to detect public ACLs and bucket policies. — Option D is correct because S3 Block Public Access prevents public access at the account level, and AWS Config rules can detect public ACLs and policies. Option A is wrong because CloudTrail alone cannot detect public access, only API calls. Option B is wrong because GuardDuty does not detect public S3 objects by default. Option C is wrong because Macie is for sensitive data discovery, not public access detection.
What should I do if I get this SCS-C02 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SCS-C02 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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