Amazon SCS-C03 Exam Questions

Comprehensive and Detailed 100to 150 words of Explanation From AWS Certified Security -- Specialty topics: AWSCompromisedKeyQuarantineV3 is applied by AWS when IAM user credentials are compromised or exposed, and AWS explicitly warns not to remove the policy until the support-case instructions are followed. The correct response is to first determine scope by reviewing CloudTrail activity for the compromised key, identify API calls and unauthorized resources, remove unauthorized resources, rotate or replace the compromised access keys, and only then remove the quarantine policy after remediation is complete. Deleting the user immediately can destroy useful attribution and may break legitimate dependencies. Removing the quarantine policy first is unsafe because it may restore attacker capability. CloudWatch logs alone do not provide the full account-wide API activity trail needed for scope determination.

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AWS Config requires permissions at two levels to deliver configuration data: the AWS Config service role and the S3 bucket policy. The AWS Certified Security -- Specialty Study Guide states that the S3 bucket policy must explicitly allow the config.amazonaws.com service principal to write objects. Additionally, the IAM role used by AWS Config must allow s3:GetBucketAcl and s3:PutObject.

If either permission is missing, AWS Config cannot deliver snapshots and will log delivery errors in CloudTrail. This dual-permission model ensures least privilege while maintaining secure delivery of compliance data.

Other options reference incorrect principals or irrelevant permissions.

Referenced AWS Specialty Documents:

AWS Certified Security -- Specialty Official Study Guide

AWS Config Prerequisites

When Amazon CloudFront is used in front of an Application Load Balancer, CloudFront becomes the immediate source of incoming requests to the ALB. As a result, AWS WAF logs record theCloudFront edge location IP addressesas the client IPs, not the original viewer IP addresses. This behavior is explicitly documented in the AWS Certified Security -- Specialty Study Guide and the AWS WAF and CloudFront integration documentation.

To preserve the original client IP address, CloudFront automatically adds theX-Forwarded-For HTTP header, which contains the IP address of the originating client followed by any proxy addresses involved in forwarding the request. AWS WAF logs include this header, making it the authoritative source for identifying true client IP addresses when CloudFront is used.

Option A is incorrect because VPC Flow Logs capture network-level metadata and will only show CloudFront IP addresses, not the original client IPs. Option C is incorrect because disabling connection reuse does not change how client IPs are logged in AWS WAF. Option D is unnecessary and unsupported as a requirement because CloudFront already provides the required information through standard headers.

AWS documentation consistently states thatX-Forwarded-Foris the correct and supported mechanism for tracing client IPs in CloudFront-protected applications.

AWS Certified Security -- Specialty Official Study Guide

AWS WAF Developer Guide -- Logging

Amazon CloudFront Developer Guide -- Request Headers

A credential stuffing attack at the ALB is aLayer 7problem and is best mitigated withAWS WAF. The attacker is distributed across many IPs, so blocking by IP in a security group (Option B) is ineffective and operationally heavy. A CloudWatch alarm (Option A) only alerts; it does not block or mitigate requests.

Because the malicious traffic uses a distinctive, knownUser-Agentstring associated with a mobile device emulator, AWS WAF can quickly reduce the attack by inspecting the User-Agent header and blocking matching requests. This approach is targeted: it blocks the identified automated attack pattern while allowing legitimate users who do not present that emulator User-Agent to continue logging in. The WAF rule can be deployed immediately on the existing ALB-associated web ACL and can be further refined (for example, applied only to /login paths, combined with rate-based rules, or integrated with Bot Control) to minimize false positives.

Option D is risky because ''allow only legitimate user agents'' is brittle: user agents are diverse and change frequently, and a strict allow-list can accidentally block real users. Therefore, a WAF custom block rule for the known malicious User-Agent string is the correct solution.

Amazon S3 Lifecycle rules are the native and most efficient way to enforce data retention policies. AWS Certified Security -- Specialty documentation recommends lifecycle rules over custom automation to reduce operational complexity and failure risk.

Lifecycle rules automatically and reliably delete objects after a specified age, ensuring compliance without additional compute services. Lambda-based solutions increase cost and management overhead. Intelligent-Tiering manages storage cost, not data deletion.

Referenced AWS Specialty Documents:

AWS Certified Security -- Specialty Official Study Guide

Amazon S3 Lifecycle Management