The correct answer is D.

To design a solution that will proactively monitor for suspicious behavior across all the accounts that contain production workloads, the security engineer needs to use a service that can aggregate and analyze security findings from multiple sources. AWS Security Hub is a service that provides a comprehensive view of your security posture across your AWS accounts and enables you to check your environment against security standards and best practices. Security Hub also integrates with other AWS services, such as Amazon GuardDuty, AWS Config, and AWS Systems Manager, to collect and correlate security findings.

To automate remediation of incidents across the production accounts, the security engineer needs to use a service that can trigger actions based on events. Amazon EventBridge is a serverless event bus service that allows you to connect your applications with data from a variety of sources. EventBridge can use rules to match events and route them to targets for processing. You can use EventBridge to invoke a custom AWS Lambda function from the Security Hub findings. Lambda is a serverless compute service that lets you run code without provisioning or managing servers.

To publish a notification to an Amazon SNS topic when a critical security finding is detected, the security engineer needs to use a service that can send messages to subscribers. Amazon SNS is a fully managed messaging service that enables you to decouple and scale microservices, distributed systems, and serverless applications. SNS can deliver messages to a variety of endpoints, such as email, SMS, or HTTP. You can configure the Lambda function to also publish notifications to the SNS topic.

To send all security incident logs to a dedicated account, the security engineer needs to use a service that can aggregate and store log data from multiple sources. AWS Security Hub allows you to aggregate security findings from multiple accounts into a single account using the delegated administrator feature. This feature enables you to designate an AWS account as the administrator for Security Hub in an organization. The administrator account can then view and manage Security Hub findings from all member accounts.

Therefore, option D is correct because it meets all the requirements of the solution. Option A is incorrect because GuardDuty does not provide a comprehensive view of your security posture across your AWS accounts. GuardDuty is primarily a threat detection service that monitors for malicious or unauthorized behavior. Option B is incorrect because Config and Systems Manager are not designed to automate remediation of incidents based on Security Hub findings. Config is a service that enables you to assess, audit, and evaluate the configurations of your AWS resources, while Systems Manager is a service that allows you to manage your infrastructure on AWS at scale. Option C is incorrect because GuardDuty does not provide a comprehensive view of your security posture across your AWS accounts.

To meet the requirements of securing access management and implementing a centralized logging solution, the most secure solution would be to:

Install a bastion host in the management account.

Reconfigure all SSH and RDP to allow access only from the bastion host.

Install AWS Systems Manager Agent (SSM Agent) on the bastion host.

Attach the AmazonSSMManagedlnstanceCore role to the bastion host.

Configure session data streaming to Amazon CloudWatch Logs in a separate logging account to audit log data

This solution provides the following security benefits:

It uses AWS Systems Manager Session Manager instead of traditional SSH and RDP protocols, which provides a secure method for accessing EC2 instances without requiring inbound firewall rules or open ports.

It provides audit trails by configuring Session Manager logging to Amazon CloudWatch Logs and creating a separate logging account to audit the log data.

It uses the AWS Systems Manager Agent to automate common administrative tasks and improve the security posture of the instances.

The separate logging account with cross-account permissions provides better data separation and improves security posture.

https://aws.amazon.com/solutions/implementations/centralized-logging/

The correct answer is D.

To implement short-term credentials for third-party AWS accounts, you can use IAM roles and trust policies. A trust policy is a policy document that defines who can assume the role. You can specify the AWS account ID of the third-party account as a principal in the trust policy, and use the sts:ExternalId condition key to enhance the security of the role. The sts:ExternalId condition key is a unique identifier that is agreed upon by both parties and included in the AssumeRole request. This way, you can prevent the “confused deputy” problem, where an unauthorized party can use the same role as a legitimate party.

Option A is incorrect because bearer token authentication with OAuth or SAML is not suitable for granting access to AWS accounts and resources. Amazon Cognito and API Gateway are used for building web and mobile applications that require user authentication and authorization.

Option B is incorrect because AWS IAM Identity Center (AWS Single Sign-On) is a service that simplifies the management of access to multiple AWS accounts and cloud applications for your workforce users. It does not support granting access to third-party AWS accounts.

Option C is incorrect because using AWS Secrets Manager to create a random external key is not necessary and adds operational complexity. You can use the sts:ExternalId condition key instead to provide a unique identifier for each external account.

Establishing a VPC peering connection between the VPCs in Account A and Account B and updating route tables, network ACLs, and security groups to permit the necessary traffic ensures private connectivity for the application to write to the S3 bucket without traversing the public internet. This solution is efficient and maintains network security and integrity.

https://awscli.amazonaws.com/v2/documentation/api/latest/reference/kms/import-key-material.html

aws kms import-key-material \

--key-id 1234abcd-12ab-34cd-56ef-1234567890ab \

--encrypted-key-material fileb://EncryptedKeyMaterial.bin \

--import-token fileb://ImportToken.bin \

--expiration-model KEY_MATERIAL_EXPIRES \

--valid-to 2021-09-21T19:00:00Z

The correct answer is A. A customer managed CMK that uses customer provided key material.

A customer managed CMK is a KMS key that you create, own, and manage in your AWS account. You have full control over the key configuration, permissions, rotation, and deletion.You can use a customer managed CMK to encrypt and decrypt data in AWS services that are integrated with AWS KMS, such as Amazon EBS1.

A customer managed CMK can use either AWS provided key material or customer provided key material. AWS provided key material is generated by AWS KMS and never leaves the service unencrypted. Customer provided key material is generated outside of AWS KMS and imported into a customer managed CMK.You can specify an expiration date for the imported key material, after which the CMK becomes unusable until you reimport new key material2.

To meet the criteria of automatically expiring the key material in 90 days, you need to use customer provided key material and set the expiration date accordingly. This way, you can ensure that the data encrypted with the CMK will not be accessible after 90 days unless you reimport new key material and re-encrypt the data.

The other options are incorrect for the following reasons:

B. A customer managed CMK that uses AWS provided key material does not expire automatically. You can enable automatic rotation of the key material every year, but this does not prevent access to the data encrypted with the previous key material.You would need to manually delete the CMK and its backing key material to make the data inaccessible3.

C. An AWS managed CMK is a KMS key that is created, owned, and managed by an AWS service on your behalf. You have limited control over the key configuration, permissions, rotation, and deletion. You cannot use an AWS managed CMK to encrypt data in other AWS services or applications.You also cannot set an expiration date for the key material of an AWS managed CMK4.

D. Operation system-native encryption that uses GnuPG is not a solution that uses AWS KMS. GnuPG is a command line tool that implements the OpenPGP standard for encrypting and signing data. It does not integrate with Amazon EBS or other AWS services.It also does not provide a way toautomatically expire the key material used for encryption5.

To prevent developers from configuring unauthenticated Lambda function URLs, the most effective approach is to use Service Control Policies (SCPs) at the organizational level. By explicitly denying actions such as lambda:CreateFunctionUrlConfig and lambda:UpdateFunctionUrlConfig when the lambda:FunctionUrlAuthType is set to NONE, the organization ensures that only authenticated function URLs are deployed in production.

This method imposes no additional workload on developers and leverages AWS Organizations' SCPs to enforce centralized security policy — a recommended practice in the Identity and Access Management domain.

To address the issue of an Amazon EC2 instance receiving suspicious requests over an open TCP port, the most effective solution is to update the Network Access Control List (NACL) associated with the subnet where the EC2 instance resides. By adding a deny rule for the specific TCP port and source IP addresses involved in the suspicious activity, the security team can effectively block unwanted traffic at the subnet level. NACLs act as a stateless firewall for controlling traffic in and out of subnets, allowing for broad-based traffic filtering. This measure ensures that only legitimate traffic can reach the EC2 instance, thereby enhancing security without affecting the application's availability to other users. It's a more granular and immediate way to block specific traffic compared to modifying security group rules, which are stateful and apply at the instance level.

To ensure that application content is accessible only through CloudFront and not directly, the security engineer should do the following:

Add an origin custom header. This is a header that CloudFront adds to the requests that it sends to the origin, but viewers cannot see or modify.

Set the viewer protocol policy to redirect HTTP to HTTPS. This ensures that the viewers always use HTTPS when they access the website through CloudFront.

Set the origin protocol policy to HTTPS only. This ensures that CloudFront always uses HTTPS when it connects to the origin.

Update the application to validate the CloudFront custom header. This means that the application checks if the request has the custom header and only responds if it does. Otherwise, it denies or ignores the request. This prevents users from bypassing CloudFront and accessing the content directly on the origin.