The answer is AWS CloudTrail logs and OS-level logs, as these two sources provide the most direct evidence for investigating the initial attack vector using logs. CloudTrail records all API calls made to the AWS environment, allowing you to trace exactly who launched the compromised EC2 instance, what security groups were applied, and what IAM roles or keys were used—critical for identifying the entry point. OS-level logs from the instance itself reveal login attempts, process executions, and file modifications, which can pinpoint how the attacker gained access at the operating system level. On the AWS Certified Security Specialty SCS-C02 exam, this tests your ability to differentiate between log types: VPC Flow Logs show network-level traffic but lack application details, while CloudWatch Metrics are aggregated and Config records configuration changes, neither of which reveal the initial compromise vector. A common trap is assuming VPC Flow Logs are sufficient, but they miss the authentication and process-level events that CloudTrail and OS logs capture. Memory tip: think “API + OS” for the attack vector—CloudTrail shows the door opened, OS logs show who walked through.
SCS-C02 Threat Detection and Incident Response Practice Question
This SCS-C02 practice question tests your understanding of threat detection and incident response. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 investigating a potential incident where an EC2 instance was compromised. The engineer has access to the following logs: CloudTrail, VPC Flow Logs, and OS-level logs from the instance. Which TWO log sources would be MOST useful to determine the initial attack vector? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
OS-level authentication and system logs
Option A is correct because CloudTrail logs API calls, which can show who launched the instance and what security groups were used. Option D is correct because OS-level logs show login attempts, processes, and file changes. Option B is wrong because VPC Flow Logs show network traffic but not application-level details. Option C is wrong because CloudWatch Metrics are aggregated and do not provide detailed logs. Option E is wrong because Config records configuration changes, not attack vectors.
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.
✗
Amazon CloudWatch Metrics for the instance
Why it's wrong here
Metrics are aggregated and do not provide detailed logs for incident investigation.
✓
OS-level authentication and system logs
Why this is correct
OS logs (e.g., /var/log/auth.log) show login attempts, sudo commands, and other activities that can pinpoint the attack vector.
Related concept
Read the scenario before looking for a memorised answer.
✓
AWS CloudTrail logs
Why this is correct
CloudTrail logs API calls to EC2, such as RunInstances, which can reveal the user and IP that launched the instance.
Related concept
Read the scenario before looking for a memorised answer.
✗
AWS Config configuration history
Why it's wrong here
Config tracks resource configuration changes, not the initial attack vector.
✗
VPC Flow Logs
Why it's wrong here
Flow logs show network traffic but do not indicate whether traffic was malicious.
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.
Trap categories for this question
Command / output trap
Flow logs show network traffic but do not indicate whether traffic was malicious.
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: OS-level authentication and system logs — Option A is correct because CloudTrail logs API calls, which can show who launched the instance and what security groups were used. Option D is correct because OS-level logs show login attempts, processes, and file changes. Option B is wrong because VPC Flow Logs show network traffic but not application-level details. Option C is wrong because CloudWatch Metrics are aggregated and do not provide detailed logs. Option E is wrong because Config records configuration changes, not attack vectors.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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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