The answer is bucket policies, IAM roles, and S3 access points. These three methods are valid because each provides a distinct authorization mechanism: a bucket policy attached to the source bucket can grant access to a principal in another AWS account using the root user ARN, an IAM role in the target account allows users to assume cross-account permissions via AWS Security Token Service, and an S3 access point with its own policy enables granular, network-aware access control without altering the bucket’s base policy. On the AWS Certified Security Specialty SCS-C02 exam, this question tests your understanding of the principle of least privilege and the difference between resource-based policies (bucket policy, access point policy) and identity-based policies (IAM roles). A common trap is confusing a simple ACL that only grants list permissions with full access, or assuming that cross-account access requires a single policy type. Remember the mnemonic “BIR” – Bucket policy, IAM role, and access points – to recall the three valid cross-account S3 access methods.
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 THREE are valid ways to grant cross-account access to an S3 bucket? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create an IAM role in the target account and allow the source account to assume it.
Options A, B, and C are correct. A bucket policy with the target account's root user ARN (A), an IAM role in the target account that can be assumed (B), and an S3 access point with a policy (C) all allow cross-account access. Option D allows list but not full access. Option E is not a valid method.
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 an IAM user in the source account with access keys.
Why it's wrong here
This is not a cross-account method; it's direct access.
✓
Create an IAM role in the target account and allow the source account to assume it.
Why this is correct
Cross-account role assumption is a common pattern.
Related concept
Standard ACLs match source addresses.
✓
Use an S3 access point with a policy that allows cross-account access.
Why this is correct
Access points can be used for cross-account access.
Related concept
Standard ACLs match source addresses.
✓
Create a bucket policy that grants access to the other account's root user.
Why this is correct
Bucket policies can grant cross-account access.
Related concept
Standard ACLs match source addresses.
✗
Set the bucket ACL to grant full control to the other account.
Why it's wrong here
ACLs are legacy and not recommended for cross-account access.
Common exam traps
Common exam trap: ACLs stop at the first match
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: Create an IAM role in the target account and allow the source account to assume it. — Options A, B, and C are correct. A bucket policy with the target account's root user ARN (A), an IAM role in the target account that can be assumed (B), and an S3 access point with a policy (C) all allow cross-account access. Option D allows list but not full access. Option E is not a valid method.
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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which TWO actions are valid ways to grant an IAM user access to an S3 bucket owned by another AWS account? (Choose TWO.)
medium
✓ A.Have the user assume an IAM role in the bucket-owning account with appropriate permissions.
✓ B.Create a bucket policy that grants access to the user's AWS account.
C.Attach an IAM policy to the user in their own account allowing access to the bucket.
D.Add the user's ARN to the bucket's ACL.
E.Use an S3 access point with a policy that allows the user.
Why A: Correct answers are B and C. Bucket policies allow cross-account access when the bucket policy grants access to the user's account, and the user must have explicit permission. ACLs are legacy but can grant cross-account access. Role assumption is also valid.
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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.
Question Discussion
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