SCS-C02 Threat Detection and Incident Response Practice Question
A security engineer is setting up automated incident response for a compromised EC2 instance. The engineer wants to isolate the instance immediately upon detection of a GuardDuty finding. Which AWS service can be used to automatically trigger a Lambda function that modifies the instance's security group?
⚠ Common exam trap
Many exam-takers confuse Amazon Inspector (a vulnerability scanner) with GuardDuty (a threat detection service), or assume AWS Config's compliance rules can react to security findings, when in fact only CloudWatch Events/EventBridge provides the direct event-driven trigger for GuardDuty findings.
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
✓
Amazon CloudWatch Events
Amazon CloudWatch Events (now part of Amazon EventBridge) can be configured with a rule that matches specific GuardDuty finding events. When a finding is detected, the rule triggers a Lambda function that can modify the EC2 instance's security group to isolate it, for example by removing all inbound rules or replacing the group with a restrictive one. This provides the automated, event-driven response required.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS Step Functions
Why it's wrong here
AWS Step Functions is a workflow orchestration service, not an event source. While you could design a state machine to coordinate incident response steps, Step Functions cannot natively subscribe to or match GuardDuty findings. You would need a CloudWatch Events/EventBridge rule as the trigger to start a Step Functions execution, which makes CloudWatch Events the primary and native integration point for GuardDuty.
- ✗
Amazon Inspector
Why it's wrong here
Amazon Inspector is a vulnerability management service that scans EC2 instances and container workloads for software vulnerabilities and unintended network exposure. It produces its own findings in Inspector, not GuardDuty. Inspector does not consume GuardDuty findings and cannot invoke a Lambda function based on a GuardDuty alert. It may integrate with EventBridge for its own findings, but it is not a mechanism for responding to GuardDuty.
- ✓
Amazon CloudWatch Events
Why this is correct
Amazon CloudWatch Events (also known as Amazon EventBridge) is the native service that GuardDuty uses to emit findings as events. You create an event rule with a pattern that matches fields like the finding type or severity, and set a Lambda function as the target. This rule can invoke Lambda in near real time whenever a qualifying GuardDuty finding is generated, making it the correct foundational service for automated incident response.
- ✗
AWS Config
Why it's wrong here
AWS Config is a service that records and evaluates resource configurations for compliance against rules. It can trigger custom Lambda evaluations when configuration changes occur, but it does not ingest event data from GuardDuty findings. GuardDuty findings are not configuration items, and Config's evaluation engine is not designed to react to threat detection alerts in real time, so it would not be an appropriate trigger for automated incident response.
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 |
Go deeper
Related to this question
About these practice questions
One of 1,205 original SCS-C02 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.