SCS-C03 Exam Dumps : AWS Certified Security – Specialty

AWS KMS key policies can restrict how and when a key is used by applyingconditions such as kms:ViaService, which limits usage to requests that originate from a specific AWS service. According to the AWS Certified Security – Specialty Official Study Guide and AWS KMS documentation, the kms:ViaService condition is evaluated against the service that calls KMS on behalf of the principal.

Using StringEquals with kms:ViaService restricts usage toexactly one service endpoint. However, AWS services can invoke KMS throughservice variants, internal endpoints, or additional service integrations. When StringEquals is used, these variations can unintentionally bypass the condition, allowing the key to be used by other services through different internal service paths.

Changing the condition operator from StringEquals to StringLike ensures thatonly EC2-related service callsthat match the intended service pattern are allowed, while still preventing use by unrelated AWS services. This aligns with AWS guidance to use StringLike when service invocation patterns may vary.

Option B is incorrect because the root principal statement is required to retain administrative control over the key. Option C is invalid because changing Regions does not address unauthorized service usage. Option D does not restrict key usage and does not mitigate the issue.

AWS documentation explicitly recommendstightening condition operatorsin KMS key policies to prevent unintended service access while maintaining required functionality.

AWS Certified Security – Specialty Official Study Guide

AWS Key Management Service Developer Guide

AWS KMS Key Policy Best Practices

AWS incident response best practices emphasizerapid containment with minimal blast radius. According to the AWS Certified Security – Specialty Official Study Guide, isolating a compromised resource while allowing the application to continue running is the preferred initial response.

By using Amazon EventBridge to detect GuardDuty findings related to anomalous traffic and invoking a Lambda function, the security engineer can automatically remove the affected EC2 instance from the Auto Scaling group and attach arestricted security group. This immediately isolates the instance while allowing Auto Scaling to launch a replacement instance, ensuring application availability.

Option A is invalid because EC2 instance profiles do not use long-term access keys. Option C affects the entire subnet and could disrupt unrelated workloads. Option D provides notification only and does not meet the requirement for automated response.

AWS documentation explicitly recommendsinstance-level isolation using security groupsas a best practice for initial incident containment.

AWS Certified Security – Specialty Official Study Guide

Amazon GuardDuty User Guide

AWS Incident Response Best Practices

AWS WAF rate-based rules are designed specifically to track the number of requests from a single IP address over a configurable time window. According to AWS Certified Security – Specialty guidance, rate-based rules integrate natively with CloudFront and emit CloudWatch metrics that can trigger alarms.

CloudFront logs and VPC Flow Logs are not real-time detection tools. ASN match rules do not count request rates.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS WAF Rate-Based Rules

CloudFront and AWS WAF Integration