A company has a set of Instances hosting an application.
These Instances are located in a private subnet in a VPC.
The application now needs to make use of the KMS service.
How can you achieve this in the MOST secure way possible?
Click on the arrows to vote for the correct answer
A. B. C. D.Answer - C.
The AWS Documentation mentions the following.
You can connect directly to AWS KMS through a private endpoint in your VPC instead of connecting over the internet.
When you use a VPC endpoint, communication between your VPC and AWS KMS is conducted entirely within the AWS network.
AWS KMS supports Amazon Virtual Private Cloud (Amazon VPC) interface endpoints powered by AWS PrivateLink.
Each VPC endpoint is represented by one or more Elastic Network Interfaces (ENIs) with private IP addresses in your VPC subnets.
Options A and D are incorrect since we should not route traffic via the Internet in this situation.
Option B is incorrect since the gateway is only used for the DynamoDB and S3 services.
For more information on KMS VPC Endpoints, please visit the below URL.
https://docs.aws.amazon.com/kms/latest/developerguide/kms-vpc-endpoint.htmlThe MOST secure way to allow an application in a private subnet of a VPC to use the KMS service is by creating a VPC Endpoint Interface and making the application use the VPC Endpoint. The answer is option C.
Here's a more detailed explanation of each answer:
A. Attach an Internet gateway to the VPC and convert the subnet to a public subnet. This option is not secure because it requires the private subnet to be converted into a public subnet by attaching an internet gateway to the VPC. This exposes the Instances to the internet and increases the attack surface, which can lead to security vulnerabilities.
B. Create a VPC Endpoint gateway and make the application use the VPC gateway. This option is not the MOST secure because a VPC Endpoint gateway only supports S3 and DynamoDB services. It does not support KMS. Therefore, it is not possible to use a VPC Endpoint gateway to provide access to the KMS service.
C. Create a VPC Endpoint Interface and make the application use the VPC Endpoint. This is the MOST secure option because it allows the application to access the KMS service privately without exposing the Instances to the internet. A VPC Endpoint Interface is a virtual device that is horizontally scaled, highly available, and redundant. It allows private connectivity to AWS services from within a VPC, which is achieved by creating an elastic network interface with a private IP address within the VPC. The traffic is routed through the VPC Endpoint Interface and does not leave the Amazon network.
D. Attach a NAT gateway to the VPC and convert the subnet to a public subnet. This option is not as secure as Option C because it requires a NAT gateway to be attached to the VPC, which adds an additional attack surface. Additionally, this option requires the subnet to be converted into a public subnet, which exposes the Instances to the internet. It is also more costly because NAT gateways have an hourly charge as well as a data processing charge.
In conclusion, the MOST secure option to allow an application in a private subnet of a VPC to use the KMS service is to create a VPC Endpoint Interface and make the application use the VPC Endpoint. This option provides private connectivity to the KMS service without exposing the Instances to the internet.