Quick Answer
The answer is AWS Systems Manager Automation, which is the correct choice because it provides a pre-built runbook, AWS-DetachAndIsolateEC2Instance, that can be triggered by Amazon EventBridge when a high-severity GuardDuty finding is generated. This runbook automatically modifies the instance’s security group to deny all traffic, enabling automated EC2 isolation with Systems Manager Automation from GuardDuty findings without requiring custom code or manual intervention. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of incident response orchestration—specifically, that Systems Manager Automation is designed for operational workflows with built-in error handling and approval steps, unlike AWS Lambda, which would require custom scripting. A common trap is choosing Lambda because it can also react to events, but the exam emphasizes that Systems Manager Automation is the managed, no-code solution for this exact use case. Memory tip: think “Automation for isolation, Lambda for custom logic”—if the task is a standard runbook action, Automation is your answer.
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 is designing an automated incident response workflow. When a high-severity GuardDuty finding is generated, the security team wants to automatically isolate the affected EC2 instance by modifying its security group to deny all traffic. Which service should orchestrate this response?
AWS Lambda
Why wrong: Lambda can be used but Systems Manager Automation is more appropriate for runbook-style responses.
AWS Config
Why wrong: Config is for compliance, not automated response.
AWS Step Functions
Why wrong: Step Functions can orchestrate but is less specialized than Automation.
AWS Systems Manager Automation
Automation provides predefined runbooks for incident response, including security group modification.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
AWS Systems Manager Automation
AWS Systems Manager Automation is the correct choice because it provides a pre-built runbook (AWS-DetachAndIsolateEC2Instance) that can be triggered by Amazon EventBridge when a GuardDuty finding is generated. This runbook automatically modifies the EC2 instance's security group to deny all traffic, effectively isolating the instance without requiring custom code. Systems Manager Automation is designed for such operational workflows, offering built-in error handling and approval steps.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
AWS Lambda
Why it's wrong here
Lambda can be used but Systems Manager Automation is more appropriate for runbook-style responses.
AWS Config
Why it's wrong here
Config is for compliance, not automated response.
AWS Step Functions
Why it's wrong here
Step Functions can orchestrate but is less specialized than Automation.
AWS Systems Manager Automation
Why this is correct
Automation provides predefined runbooks for incident response, including security group modification.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often choose AWS Lambda because they think they need custom code to modify security groups, overlooking that AWS Systems Manager Automation provides a purpose-built, no-code runbook for EC2 isolation that integrates directly with GuardDuty findings via EventBridge.
Detailed technical explanation
The AWS-DetachAndIsolateEC2Instance runbook uses the aws:executeScript action to call the EC2 ModifySecurityGroupRules API, removing all inbound and outbound rules and adding a deny-all rule. Under the hood, Systems Manager Automation leverages the AWS Systems Manager Agent (SSM Agent) on the instance to execute steps, but for security group changes, it uses API calls directly. In a real-world scenario, you might combine this with an approval step in the runbook to require a security analyst to confirm isolation before the change takes effect, preventing accidental isolation of critical instances.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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Threat Detection and Incident Response — study guide chapter
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FAQ
Threat Detection and Incident Response — This question tests Threat Detection and Incident Response — Read the scenario before looking for a memorised answer..
The correct answer is: AWS Systems Manager Automation — AWS Systems Manager Automation is the correct choice because it provides a pre-built runbook (AWS-DetachAndIsolateEC2Instance) that can be triggered by Amazon EventBridge when a GuardDuty finding is generated. This runbook automatically modifies the EC2 instance's security group to deny all traffic, effectively isolating the instance without requiring custom code. Systems Manager Automation is designed for such operational workflows, offering built-in error handling and approval steps.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 →
Same concept, more angles
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 automate the response to a specific GuardDuty finding. When GuardDuty detects a finding of type `UnauthorizedAccess:EC2/SSHBruteForce`, they want to automatically block the offending IP address using a network ACL. Which AWS service can they use to orchestrate this response?
easyWhy B: AWS Systems Manager Automation can be used to run predefined runbooks that modify network ACLs. AWS Config is for compliance, not automation. AWS CloudFormation is for infrastructure as code. AWS Lambda can be used but requires custom code; Systems Manager Automation provides a managed solution.
Variation 2. A security engineer is configuring automated response to a GuardDuty finding of type 'UnauthorizedAccess:EC2/SSHBruteForce'. The engineer needs to isolate the compromised instance by modifying the security group to deny all inbound traffic. Which AWS service should be used to orchestrate this response?
mediumWhy D: Option A is correct because AWS Systems Manager Automation can run a runbook to modify security group rules in response to a GuardDuty finding via EventBridge. Option B is wrong because Lambda can be used but is not the orchestration service; it is a compute service. Option C is wrong because Config is for compliance, not response. Option D is wrong because CloudFormation is for infrastructure provisioning, not real-time response.
Last reviewed: Jun 24, 2026
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.
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