SCS-C02 Threat Detection and Incident Response Practice Question
This SCS-C02 practice question tests your understanding of threat detection and incident response. 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 company uses Amazon GuardDuty and AWS Security Hub. The security team wants to automatically remediate high-severity GuardDuty findings that indicate an EC2 instance is communicating with a known command and control (C&C) server. The remediation should isolate the instance by modifying the security group to deny all inbound and outbound traffic. Which solution is the most efficient?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Send Security Hub findings to Amazon EventBridge, which triggers a Lambda function to modify the security group.
Option B is correct because it leverages Security Hub as a central aggregation point for GuardDuty findings, then uses EventBridge to trigger a Lambda function that modifies the security group. This is the most efficient architecture as Security Hub normalizes findings from multiple sources, and EventBridge provides reliable, low-latency event routing to Lambda for custom remediation logic without requiring direct GuardDuty-to-security-group integration.
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 CloudWatch Events to directly modify the security group when a GuardDuty finding is published.
Why it's wrong here
CloudWatch Events cannot directly modify security groups; it needs a target like Lambda.
✓
Send Security Hub findings to Amazon EventBridge, which triggers a Lambda function to modify the security group.
Why this is correct
EventBridge can route findings to Lambda for custom remediation actions.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure GuardDuty to automatically update the security group when a finding is generated.
Why it's wrong here
GuardDuty does not have built-in remediation actions; it only generates findings.
✗
Create an AWS Config rule that triggers a Lambda function when a security group change is detected.
Why it's wrong here
This would react to changes, not to GuardDuty findings.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume GuardDuty can directly modify security groups (Option C) or that CloudWatch Events can directly perform API actions (Option A), when in reality both require a Lambda function as an intermediary to execute the remediation logic.
Detailed technical explanation
How to think about this question
Under the hood, Security Hub consolidates findings using the AWS Security Finding Format (ASFF), which includes standardized fields like 'Severity' and 'Types'. EventBridge can filter on these fields with event patterns (e.g., 'source': ['aws.securityhub'], 'detail-type': ['Security Hub Findings - Imported']), allowing precise triggering. The Lambda function then uses the AWS SDK to call ec2:RevokeSecurityGroupIngress and ec2:RevokeSecurityGroupEgress, then adds a deny-all rule (e.g., 0.0.0.0/0 for IPv4) to effectively isolate the instance. A real-world scenario might involve a compromised EC2 instance beaconing to a C&C server; this automated isolation stops data exfiltration within seconds of detection.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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.
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: Send Security Hub findings to Amazon EventBridge, which triggers a Lambda function to modify the security group. — Option B is correct because it leverages Security Hub as a central aggregation point for GuardDuty findings, then uses EventBridge to trigger a Lambda function that modifies the security group. This is the most efficient architecture as Security Hub normalizes findings from multiple sources, and EventBridge provides reliable, low-latency event routing to Lambda for custom remediation logic without requiring direct GuardDuty-to-security-group integration.
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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