The answer is to add a condition in the bucket policy that checks `aws:MultiFactorAuthPresent` is true, or to use pre-signed URLs generated with MFA credentials. These two actions enforce MFA for S3 bucket operations by requiring a valid MFA session token at the point of access. The bucket policy condition works at the resource level, denying any request where the `aws:MultiFactorAuthPresent` key is false, while MFA-protected pre-signed URLs embed the authentication requirement directly into the temporary URL for specific object access. On the AWS Certified Security Specialty SCS-C02 exam, this tests your understanding of S3 policy conditions versus IAM policies—a common trap is thinking an IAM policy alone can enforce MFA at the bucket level, but only a bucket policy can restrict the S3 service itself. Remember, ACLs lack condition support and CloudTrail is audit-only, so focus on the policy condition and pre-signed URL method. Memory tip: think “MFA at the door, not the keychain”—the bucket policy guards the bucket, while pre-signed URLs guard individual objects.
SCS-C02 Identity and Access Management Practice Question
This SCS-C02 practice question tests your understanding of identity and access management. 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.
Which TWO actions can be used to restrict access to an S3 bucket to only users who authenticate using multi-factor authentication (MFA)? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use pre-signed URLs with MFA credentials
The correct answers are A and D. A bucket policy with a condition for aws:MultiFactorAuthPresent is the standard way to enforce MFA for S3 operations. Using pre-signed URLs with MFA can also enforce MFA for specific objects. Option B is wrong because IAM policies can enforce MFA but not at the bucket level. Option C is wrong because CloudTrail does not enforce MFA. Option E is wrong because S3 ACLs do not support conditions.
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 CloudTrail to log requests and deny those without MFA
Why it's wrong here
CloudTrail logs events, it does not enforce policies.
✓
Use pre-signed URLs with MFA credentials
Why this is correct
Pre-signed URLs can be generated with MFA, requiring MFA for access.
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.
Identity and Access Management — This question tests Identity and Access Management — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Use pre-signed URLs with MFA credentials — The correct answers are A and D. A bucket policy with a condition for aws:MultiFactorAuthPresent is the standard way to enforce MFA for S3 operations. Using pre-signed URLs with MFA can also enforce MFA for specific objects. Option B is wrong because IAM policies can enforce MFA but not at the bucket level. Option C is wrong because CloudTrail does not enforce MFA. Option E is wrong because S3 ACLs do not support conditions.
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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