SCS-C02 Threat Detection and Incident Response Practice Question
A security engineer is setting up automated incident response for a compromised IAM user. The engineer wants to automatically revoke the user's access keys and attach a deny-all policy when a GuardDuty finding of type 'UnauthorizedAccess:IAMUser/InstanceCredentialExfiltration' is generated. Which services should be used to achieve this automation?
⚠ Common exam trap
Candidates often confuse CloudWatch Events with SNS or Config, not realizing that CloudWatch Events is the only service that natively integrates with GuardDuty as an event source for real-time, automated remediation workflows.
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 and AWS Lambda
Amazon CloudWatch Events (now part of Amazon EventBridge) can capture GuardDuty findings in real-time and trigger a Lambda function to revoke IAM user access keys and attach a deny-all policy. This is the native, event-driven pattern for automated incident response to GuardDuty findings, as CloudWatch Events directly supports GuardDuty as an event source.
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 Simple Notification Service (SNS) and AWS Lambda
Why it's wrong here
Amazon Simple Notification Service is a pub/sub notification channel, not an event source for GuardDuty; GuardDuty publishes findings only to EventBridge (or Security Hub), not directly to SNS. Without a publisher to push the finding to the SNS topic, a Lambda subscription would never be invoked by the GuardDuty finding itself. SNS can fan out to Lambda, but it cannot detect or route security findings, so this combination lacks the necessary event-driven trigger.
- ✗
AWS Config and AWS Lambda
Why it's wrong here
AWS Config records and evaluates resource configurations against compliance rules, but it does not consume GuardDuty findings — those are emitted as events in EventBridge, not as Config configuration changes. A Config rule can invoke Lambda for remediation, but nothing in Config would be triggered by a GuardDuty finding. This architecture would require a separate mechanism to translate the finding into a Config evaluation, making it an indirect, non-functional response path for IAM credential revocation.
- ✓
Amazon CloudWatch Events and AWS Lambda
Why this is correct
Amazon CloudWatch Events (now Amazon EventBridge) detects the GuardDuty finding via a rule filtering on the specific finding type, then invokes an AWS Lambda function. The Lambda function executes the IAM API calls to revoke access keys and attach a deny-all policy, satisfying the requirement for automated, event-driven remediation without manual intervention.
- ✗
AWS Systems Manager Automation and AWS Lambda
Why it's wrong here
AWS Systems Manager Automation runbooks are built for operational workflows, typically targeting EC2 instances and managed nodes, and they are not natively triggered by GuardDuty findings. Even though an Automation document could use aws:executeAwsApi to make IAM calls, you would still need an EventBridge rule or Lambda to start the runbook, adding an unnecessary hop. Lambda alone can directly revoke access keys and attach a deny-all policy, so Systems Manager Automation does not provide the required GuardDuty-to-IAM event connection.
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 |
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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.