The answer is that no Amazon EventBridge rule is configured to send Security Hub findings to the Lambda function. Security Hub custom actions do not invoke Lambda directly; instead, they publish findings to the default EventBridge event bus, and a dedicated EventBridge rule must be created to match those findings and route them to the target Lambda function. Without that rule, the custom action completes but the event never reaches the function, even if the Lambda resource-based policy and execution role are correctly configured. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of the Security Hub and EventBridge integration pattern—a common trap is assuming Security Hub can invoke Lambda natively, like it does with AWS Config rules. Remember the key chain: custom action → EventBridge rule → Lambda target. A helpful memory tip is “No rule, no route”—the EventBridge rule is the essential bridge between the custom action and the function.
SCS-C02 Threat Detection and Incident Response Practice Question
This SCS-C02 practice question tests your understanding of threat detection and incident response. 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 GuardDuty and AWS Security Hub in a single AWS account. The security team has created a custom action in Security Hub to send findings to a custom Lambda function for automated response. The Lambda function is designed to take remediation actions based on the finding type. During testing, the team notices that the Lambda function is not being invoked when new findings are generated. The Lambda function's resource-based policy allows invocations from Security Hub, and the function's execution role has necessary permissions. What is the most likely reason for the failure?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
No Amazon EventBridge rule is configured to send Security Hub findings to the Lambda function.
Option C is correct because Security Hub custom actions require an EventBridge rule to route findings to the Lambda function. Without the rule, Security Hub cannot invoke Lambda directly. Option A is wrong because the function's execution role permissions are for accessing other AWS resources, not for being invoked. Option B is wrong because Security Hub findings are generated even if GuardDuty is enabled. Option D is wrong because the Lambda function's resource-based policy allows invocation from Security Hub, but Security Hub does not directly invoke Lambda; it uses EventBridge.
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.
✓
No Amazon EventBridge rule is configured to send Security Hub findings to the Lambda function.
Why this is correct
Custom actions in Security Hub rely on EventBridge rules to target Lambda.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
GuardDuty is not enabled for all required resource types.
Why it's wrong here
GuardDuty generates findings regardless, and Security Hub ingests them.
✗
The Lambda function's execution role does not have permission to access GuardDuty.
Why it's wrong here
The execution role is for the function's actions, not for invocation.
✗
The Lambda function's resource-based policy does not include Security Hub as a principal.
Why it's wrong here
The policy includes Security Hub, but Security Hub does not directly invoke Lambda.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 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.
Identify which SCS-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Threat Detection and Incident Response — This question tests Threat Detection and Incident Response — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: No Amazon EventBridge rule is configured to send Security Hub findings to the Lambda function. — Option C is correct because Security Hub custom actions require an EventBridge rule to route findings to the Lambda function. Without the rule, Security Hub cannot invoke Lambda directly. Option A is wrong because the function's execution role permissions are for accessing other AWS resources, not for being invoked. Option B is wrong because Security Hub findings are generated even if GuardDuty is enabled. Option D is wrong because the Lambda function's resource-based policy allows invocation from Security Hub, but Security Hub does not directly invoke Lambda; it uses EventBridge.
What should I do if I get this SCS-C02 question wrong?
Identify which SCS-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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