← SCS-C02·Amazon Web Services

Question 133 of 1,748

Threat Detection and Incident Response →easyMultiple ChoiceObjective-mapped

Automated EC2 Isolation with GuardDuty

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 wants to automatically isolate an EC2 instance that is suspected to be compromised. What is the MOST effective AWS-native approach?

A
Terminate the instance immediately
Why wrong: Termination destroys evidence and is not a best practice.
B
Use Amazon GuardDuty to detect the compromise and automatically modify the instance's security group to deny all traffic
GuardDuty can trigger a Lambda to modify security group, isolating the instance.
C
Use AWS Config to change the instance's IAM role
Why wrong: Changing IAM role does not isolate the instance from network traffic.
D
Use AWS Systems Manager to run a script that stops the instance
Why wrong: Systems Manager may not be available if agent is compromised.

Full breakdown with real-world context →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Use Amazon GuardDuty to detect the compromise and automatically modify the instance's security group to deny all traffic

Amazon GuardDuty can detect suspicious activity on an EC2 instance (e.g., cryptocurrency mining, unusual outbound traffic) and, when integrated with Amazon EventBridge and AWS Lambda, automatically modify the instance's security group to deny all traffic. This approach isolates the instance without terminating it, preserving forensic evidence and allowing further investigation. It is the most effective AWS-native approach because it combines threat detection with automated, least-privilege response actions.

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.

✗
Terminate the instance immediately
Why it's wrong here
Termination destroys evidence and is not a best practice.
✓
Use Amazon GuardDuty to detect the compromise and automatically modify the instance's security group to deny all traffic
Why this is correct
GuardDuty can trigger a Lambda to modify security group, isolating the instance.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use AWS Config to change the instance's IAM role
Why it's wrong here
Changing IAM role does not isolate the instance from network traffic.
✗
Use AWS Systems Manager to run a script that stops the instance
Why it's wrong here
Systems Manager may not be available if agent is compromised.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often choose termination (Option A) thinking it is the fastest way to stop the threat, but the exam emphasizes preserving forensic evidence and using automated, reversible isolation mechanisms like security group modification.

Detailed technical explanation

How to think about this question

Under the hood, GuardDuty generates findings that can be sent to Amazon EventBridge as events. A Lambda function subscribed to those events can call the EC2 ModifySecurityGroupRules API to revoke all inbound and outbound rules on the instance's security group, effectively dropping all traffic at the hypervisor level. This approach works even if the instance's guest OS is compromised because security groups operate at the VPC network layer, not within the instance itself.

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 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.

Quick reference

Cloud Service Model Comparison

Model	You Manage	Provider Manages	Examples
IaaS	OS, runtime, apps, data	Hardware, hypervisor, networking	EC2, Azure VMs, GCP Compute Engine
PaaS	Apps and data	OS, runtime, middleware, hardware	Elastic Beanstalk, Azure App Service
SaaS	Data and settings only	Everything else	Microsoft 365, Salesforce, Workday
FaaS / Serverless	Function code only	Infra, scaling, runtime	Lambda, Azure Functions, Cloud Run
CaaS	Containers and apps	Kubernetes, OS, hardware	EKS, AKS, GKE

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.

Related SCS-C02 practice-question pages

Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

Threat Detection and Incident Response practice questions

Practise SCS-C02 questions linked to Threat Detection and Incident Response.

Security Logging and Monitoring practice questions

Practise SCS-C02 questions linked to Security Logging and Monitoring.

Identity and Access Management practice questions

Practise SCS-C02 questions linked to Identity and Access Management.

Management and Security Governance practice questions

Practise SCS-C02 questions linked to Management and Security Governance.

Infrastructure Security practice questions

Practise SCS-C02 questions linked to Infrastructure Security.

Data Protection practice questions

Practise SCS-C02 questions linked to Data Protection.

SCS-C02 fundamentals practice questions

Practise SCS-C02 questions linked to SCS-C02 fundamentals.

SCS-C02 scenario practice questions

Practise SCS-C02 questions linked to SCS-C02 scenario.

SCS-C02 troubleshooting practice questions

Practise SCS-C02 questions linked to SCS-C02 troubleshooting.

Practice this exam

Start a free SCS-C02 practice session

Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.

10 questions 20 questions 30 questions 50 questions Timed 30

SCS-C02 practice-test guide →Study guide →Browse all practice tests

FAQ

Questions learners often ask

What does this SCS-C02 question test?

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: Use Amazon GuardDuty to detect the compromise and automatically modify the instance's security group to deny all traffic — Amazon GuardDuty can detect suspicious activity on an EC2 instance (e.g., cryptocurrency mining, unusual outbound traffic) and, when integrated with Amazon EventBridge and AWS Lambda, automatically modify the instance's security group to deny all traffic. This approach isolates the instance without terminating it, preserving forensic evidence and allowing further investigation. It is the most effective AWS-native approach because it combines threat detection with automated, least-privilege response actions.

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.

About these practice questions

Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →

How Courseiva writes practice questions · Editorial policy

Same concept, more angles

2 more ways this is tested on SCS-C02

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. A security team is setting up incident response automation. Which TWO steps should be taken to ensure that a compromised EC2 instance is isolated while preserving forensic data? (Choose TWO.)

medium

A.Assign a new security group that denies all inbound and outbound traffic.
B.Shut down the instance from the OS.
✓ C.Remove the instance from any Auto Scaling group or load balancer target group.
✓ D.Create an EBS snapshot of the instance's root volume.
E.Terminate the instance.

Why C: Option C is correct because removing the instance from Auto Scaling groups or load balancer target groups stops new traffic from being routed to it, effectively isolating it from application traffic without destroying the instance. Option D is correct because creating an EBS snapshot preserves the root volume's data for forensic analysis before any changes occur. Together, these steps ensure the instance is isolated for investigation while retaining evidence.

Variation 2. A security engineer is investigating a GuardDuty finding of type 'Backdoor:EC2/C&CActivity.B!DNS'. Which TWO actions should the engineer take as part of the initial response? (Choose two.)

hard

A.Enable Amazon GuardDuty in the account if not already enabled.
✓ B.Isolate the EC2 instance by modifying its security group to deny all traffic.
C.Immediately terminate the EC2 instance to stop the activity.
✓ D.Take a snapshot of the instance's EBS volume for forensic analysis.
E.Disable termination protection on the instance to allow future termination.

Why B: Option B is correct because isolating the EC2 instance by modifying its security group to deny all traffic is a critical containment step in incident response. This immediately stops the C2 (command and control) communication detected by GuardDuty's 'Backdoor:EC2/C&CActivity.B!DNS' finding, preventing further data exfiltration or lateral movement while preserving the instance for forensic analysis.

Keep practising

Question Discussion

Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.

Loading comments…

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.