AWS WAF logs contain detailed request-level information, including source IP addresses, requested URIs, and rule matches. According to AWS Certified Security – Specialty guidance, enabling AWS WAF logging provides the most reliable and tamper-resistant method to investigate web-based attacks, especially when instance-level logs are unavailable.

By streaming WAF logs through Amazon Kinesis Data Firehose to Amazon S3, the company ensures durable, centralized log storage that is independent of EC2 lifecycle events. Amazon Athena can then query the logs efficiently to identify repeated requests to the new-user-creation.php endpoint and extract attacker IP addresses.

VPC Flow Logs do not capture HTTP-level details. ALB access logs alone may not capture blocked requests. WAF logs provide the best forensic visibility for future detection.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS WAF Logging and Monitoring

Amazon Athena Log Analysis

AWS Config provides managed rules that continuously evaluate resource configurations against compliance requirements. The AWS Certified Security – Specialty documentation highlights AWS Config managed rules as the preferred mechanism for enforcing configuration compliance at scale. The managed rule for encrypted RDS storage automatically detects DB instances and clusters that are created without encryption enabled.

By configuring automatic remediation, AWS Config can immediately invoke corrective actions without manual intervention. Integrating remediation with an Amazon SNS topic enables automated email notifications, while an AWS Lambda function can terminate the noncompliant resource. This creates a fully automated detect-alert-remediate workflow.

Option B requires manual remediation, which increases operational effort and delays enforcement. Options C and D rely on Amazon EventBridge, which evaluates events rather than configuration state and does not provide continuous compliance monitoring. AWS Config is explicitly designed for configuration compliance and governance use cases.

This solution aligns with AWS governance best practices by combining continuous monitoring, automated remediation, and centralized alerting with minimal operational overhead.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS Config Managed Rules

AWS Config Automatic Remediation

The most secure and AWS-recommended pattern for cross-account access is to create anIAM role in the target account (production)and allow trusted principals from the source account (developer) toassume the roleby using AWS STS. This avoids long-term credentials in the production account, supports short-lived session credentials, and enables strong controls such as MFA requirements, session duration limits, and precise least-privilege permissions attached to the role. It also centralizes ownership of production permissions in the production account, which is important for separation of duties and governance.

Option A is insecure because it requires password sharing and uses a long-lived IAM user credential, which is against AWS best practices. Option C is also poor because it relies on a long-lived IAM user in the production account and encourages credential sharing/duplication. Option B places the role in the developer account; while you can attach permissions there, access to production resources is governed by the production account. The standard approach is a production-account role with a trust policy that names the developer account principals (or a role) as allowed to assume it. Therefore, Option D is the most secure solution.