The correct answer is the combination of a trust policy in Account A that allows Account B to assume the role, and an IAM policy in Account B that grants users the sts:AssumeRole permission. This works because cross-account IAM role setup relies on a two-way authorization: the trust policy acts as a gate on the target role, explicitly listing which external accounts are allowed to assume it, while the calling account’s users must have an IAM policy that permits the sts:AssumeRole API call to initiate the session. On the AWS Certified Security Specialty SCS-C02 exam, this question tests your understanding of the fundamental distinction between trust policies and identity-based policies, a common trap being that a resource-based policy on the role is not used—roles use trust policies, not resource policies. Another frequent pitfall is confusing permission boundaries or SCPs as required components, but they are optional or denial-based, not mandatory. Memory tip: think of the trust policy as the “door lock” on the target role, and the sts:AssumeRole permission as the “key” in the source account.
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.
A security engineer is designing a cross-account access solution. An IAM role in Account A needs to be assumed by users from Account B. Which two components are required?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Trust policy allowing Account B to assume the role, and IAM policy in Account B allowing sts:AssumeRole
Option D is correct because the trust policy in Account A allows Account B to assume the role, and users in Account B need permissions to call sts:AssumeRole. Option A is wrong because a resource-based policy on the role is not used. Option B is wrong because permission boundary is optional. Option C is wrong because an SCP in Account B might deny the action.
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.
✗
Permissions boundary on the role to limit permissions
Why it's wrong here
Permissions boundary is optional and limits the role's permissions.
✗
Service control policy in Account A allowing AssumeRole
Why it's wrong here
SCPs are in the organization, not needed for role trust.
✓
Trust policy allowing Account B to assume the role, and IAM policy in Account B allowing sts:AssumeRole
Why this is correct
This is the standard cross-account role setup.
Related concept
Standard ACLs match source addresses.
✗
Resource-based policy on the role allowing cross-account access
Why it's wrong here
Roles use trust policies, not resource-based policies.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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: Trust policy allowing Account B to assume the role, and IAM policy in Account B allowing sts:AssumeRole — Option D is correct because the trust policy in Account A allows Account B to assume the role, and users in Account B need permissions to call sts:AssumeRole. Option A is wrong because a resource-based policy on the role is not used. Option B is wrong because permission boundary is optional. Option C is wrong because an SCP in Account B might deny the action.
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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