Enhancing edge security entails both protecting the application from direct attacks and efficiently managing traffic routes. Moving web servers to private subnets without public IP addresses increases security by only allowing access through the Application Load Balancer, thus reducing exposure to direct attacks. Configuring AWS WAF provides an additional layer of security by protecting against web-layer attacks, including DDoS and malicious bots, which helps secure the ALB and, consequently, the EC2 instances.
To restrict the usage of member root user accounts across an AWS organization, the most effective method is to use Service Control Policies (SCPs). SCPs can be applied at the organizational unit (OU) level and impose restrictions on what actions users and even the root user in member accounts can perform. Creating an OU and applying a specifically tailored SCP to it ensures control over the root user's actions across all member accounts within that OU. This is the most appropriate approach given the capabilities and features of AWS Organizations.
To configure outbound mail through Amazon Simple Email Service (SES) while ensuring compliance with current TLS standards, the mail application should use the SMTP protocol. The correct endpoint for SES SMTP is email-smtp.us-east-1.amazonaws.com, and port 587 is commonly used for SMTP with STARTTLS to upgrade the connection to TLS. Using port 587 allows for establishing a secure, encrypted connection as required for compliance with TLS standards.
To mitigate the threat of data exfiltration to an unauthorized S3 bucket, it is necessary to implement controls that restrict S3 access to only the intended and authorized S3 buckets. Using an S3 VPC endpoint and configuring its policy to whitelist specific S3 buckets within the authorized AWS account ensures that Server X can only interact with permitted S3 buckets, bypassing the proxy server. Additionally, blocking outbound access to public S3 endpoints at the proxy server will prevent any attempts by the rogue employee to bypass the VPC endpoint and upload data to unauthorized S3 buckets. This combination ensures legitimate access is maintained while preventing unauthorized data exfiltration.
The correct approach to meet the security requirements is to create a Customer Master Key (CMK) for each data classification type and enable the automatic rotation of these keys annually. For the 'Restricted' bucket, implementing a key policy that requires multi-factor authentication (MFA) is essential. AWS Key Management Service (KMS) provides envelope encryption, meaning that while each object is encrypted with a unique data encryption key (DEK), the DEK itself is encrypted with the CMK. This ensures each object is encrypted uniquely, as required. S3 SSE-KMS encryption meets all the outlined requirements, making this the optimal choice.