The correct answer is to use IAM policies to grant permissions to users and roles, combined with an S3 bucket policy to explicitly restrict access. This dual approach works because IAM policies are identity-based, controlling what actions a specific user or role can perform, while the S3 bucket policy is a resource-based policy that directly defines which principals can access the bucket and its objects, regardless of their IAM permissions. On the AWS Certified Security Specialty SCS-C02 exam, this tests your understanding of how to layer security for sensitive data, often appearing in scenarios where you must prevent unauthorized access even if an IAM user has broad permissions. A common trap is assuming IAM policies alone are sufficient, but the bucket policy provides a critical explicit deny or allow for specific principals like cross-account roles. Memory tip: think of IAM as the “who” and the bucket policy as the “where”—both must agree for access.
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.
Exhibit
Which TWO methods can be used to protect an S3 bucket from unauthorized access?
A security engineer needs to protect an S3 bucket that contains sensitive data. Which two methods should the engineer use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Apply an S3 bucket policy that restricts access to specific IAM users or roles.
Option C is correct because an S3 bucket policy is a resource-based policy that can explicitly restrict access to specific IAM users or roles, providing a direct mechanism to control who can access the bucket and its objects. This is essential for protecting sensitive data by ensuring only authorized principals can perform actions like s3:GetObject or s3:PutObject, regardless of other permissions.
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.
✗
Use Amazon CloudFront to serve the content.
Why it's wrong here
CloudFront is for content delivery, not access control.
✗
Enable VPC Flow Logs on the bucket.
Why it's wrong here
VPC Flow Logs capture network traffic, not access control.
✓
Apply an S3 bucket policy that restricts access to specific IAM users or roles.
Why this is correct
Bucket policies define who can access the bucket.
Related concept
Read the scenario before looking for a memorised answer.
✓
Use IAM policies to grant permissions to users and roles.
Why this is correct
IAM policies control access to AWS resources including S3.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable S3 object ACLs.
Why it's wrong here
ACLs are legacy and less secure; bucket policies and IAM are preferred.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse resource-based policies (bucket policies) with identity-based policies (IAM policies) and may think only one is sufficient, but the question asks for two methods, and both C and D are correct because they work together to enforce least-privilege access.
Detailed technical explanation
How to think about this question
S3 bucket policies are evaluated along with IAM policies; the effective permissions are the intersection of the IAM policy and the bucket policy (unless an explicit deny exists). For sensitive data, a common best practice is to use a bucket policy with a condition like 'aws:SourceIp' or 'aws:PrincipalArn' to restrict access to specific IP ranges or roles, and to block public access using the S3 Block Public Access settings. In real-world scenarios, combining bucket policies with IAM policies allows for fine-grained control, such as requiring MFA (aws:MultiFactorAuthPresent) for delete operations.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Infrastructure Security — This question tests Infrastructure Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Apply an S3 bucket policy that restricts access to specific IAM users or roles. — Option C is correct because an S3 bucket policy is a resource-based policy that can explicitly restrict access to specific IAM users or roles, providing a direct mechanism to control who can access the bucket and its objects. This is essential for protecting sensitive data by ensuring only authorized principals can perform actions like s3:GetObject or s3:PutObject, regardless of other permissions.
What should I do if I get this SCS-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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Question Discussion
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