The correct steps are to create an EBS snapshot of the instance’s root volume and to remove the instance from Auto Scaling groups or load balancer target groups. These two actions work together to isolate a compromised EC2 instance while preserving forensic data: removing the instance from traffic sources stops new application traffic from reaching it, preventing further damage or data exfiltration, while the EBS snapshot captures a point-in-time copy of the root volume for later forensic analysis before any changes occur. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of incident response automation and the principle of “preserve before you touch”—a common trap is to terminate the instance immediately, which destroys evidence. Remember the mnemonic “Snap and Separate”: snapshot the volume first, then separate the instance from traffic.
SCS-C02 Threat Detection and Incident Response Practice Question
This SCS-C02 practice question tests your understanding of threat detection and incident response. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 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.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Remove the instance from any Auto Scaling group or load balancer target group.
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.
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.
✗
Assign a new security group that denies all inbound and outbound traffic.
Why it's wrong here
Does not stop already established connections; better to remove from target group.
✗
Shut down the instance from the OS.
Why it's wrong here
May lose volatile data.
✓
Remove the instance from any Auto Scaling group or load balancer target group.
Why this is correct
Stops new traffic.
Related concept
Read the scenario before looking for a memorised answer.
✓
Create an EBS snapshot of the instance's root volume.
Why this is correct
Preserves disk data.
Related concept
Read the scenario before looking for a memorised answer.
✗
Terminate the instance.
Why it's wrong here
Destroys evidence.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose Option A (assigning a deny-all security group) thinking it isolates the instance, but they overlook that existing connections remain active and that Auto Scaling may immediately launch a replacement, losing the forensic opportunity.
Detailed technical explanation
How to think about this question
When an EC2 instance is compromised, isolating it from network traffic is critical to prevent lateral movement, but simply modifying security groups may not stop existing TCP connections (which rely on connection state tracking). Removing the instance from target groups ensures the load balancer stops sending new requests, and deregistering from Auto Scaling prevents automatic replacement. EBS snapshots are point-in-time copies stored in Amazon S3, and they capture the root volume's state, including memory swap files and logs, which are essential for forensic analysis; snapshots can be used to launch a separate investigation instance without affecting the original.
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: Remove the instance from any Auto Scaling group or load balancer target group. — 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.
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 →
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 company wants to automatically isolate an EC2 instance that is suspected to be compromised. What is the MOST effective AWS-native approach?
easy
A.Terminate the instance immediately
✓ B.Use Amazon GuardDuty to detect the compromise and automatically modify the instance's security group to deny all traffic
C.Use AWS Config to change the instance's IAM role
D.Use AWS Systems Manager to run a script that stops the instance
Why B: 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.
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.
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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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