Profile Applicability:
- Level 1
Description:
A VPC endpoint allows private connections between a VPC (Virtual Private Cloud) and supported AWS services or your VPC resources. These endpoints are crucial for securely accessing services without routing traffic over the public internet. Trust boundaries in VPC endpoint connections refer to the access control boundaries that determine which resources can communicate with each other. It is essential to assess trust boundaries to ensure that the access between VPCs, services, and endpoints aligns with security requirements, preventing unauthorized access to sensitive data.
Rationale:
Understanding and defining trust boundaries in VPC endpoint connections is crucial for network security. By ensuring that resources only have access to the services and data they need, organizations can prevent data leaks, unauthorized access, and cross-VPC security risks. Assessing and managing these boundaries provides better control over how traffic flows within the VPC and how external services and data are accessed.
Impact:
Pros:
Improved Security: Helps ensure that only trusted resources can access critical services.
Access Control: Enables better management of who can connect to which resources within your VPC, minimizing exposure.
Compliance: Helps meet security standards and access control requirements.
Cons:
Configuration Complexity: Mapping trust boundaries in a large-scale environment can be complex and requires ongoing monitoring.
Performance Overhead: Some additional management may be needed to ensure proper network segmentation and access controls.
Default Value:
By default, VPC endpoints are configured with certain trust boundaries based on IAM policies, security groups, and route tables. However, explicit configuration is required to ensure that trust boundaries are well-defined and traffic flows securely.
Pre-requisite:
AWS IAM Permissions:
ec2:DescribeVpcEndpoints
ec2:DescribeVpcEndpointServices
ec2:DescribeVpcPeeringConnections
AWS CLI installed and configured.
Basic understanding of VPC, VPC endpoints, IAM policies, and network segmentation.
Remediation:
Test Plan:
Using AWS Console:
Sign in to the AWS Management Console.
Navigate to VPC under Services.
In the VPC Dashboard, select Endpoints.
For each VPC endpoint, review the following:
Service: Identify whether the endpoint is connecting to an internal AWS service (e.g., S3, DynamoDB) or an external service (e.g., custom VPC).
VPC Peering Connections: Ensure that the endpoint is not inadvertently allowing traffic from untrusted VPCs or other external sources.
Security Groups: Check the security group rules that are associated with the endpoint. Ensure they restrict access based on the intended trust boundary.
Route Tables: Verify the route tables associated with the VPC endpoint to ensure that routing is properly defined, and no unintended routes exist.
Using AWS CLI:
To list all VPC endpoints and identify the associated services and trust boundaries, use:
aws ec2 describe-vpc-endpoints --query 'VpcEndpoints[*].{ID:VpcEndpointId,ServiceName:ServiceName,Type:VpcEndpointType}' --output tableTo check VPC endpoint services and their trust boundaries:
aws ec2 describe-vpc-endpoint-services --query 'ServiceDetails[*].{ServiceName:ServiceName,ServiceType:ServiceType}' --output tableTo inspect the route tables for endpoints, use:
aws ec2 describe-route-tables --query 'RouteTables[*].{ID:RouteTableId,Routes:Routes}'To check for VPC peering connections and whether endpoints are accessible across peered VPCs:
aws ec2 describe-vpc-peering-connections --query 'VpcPeeringConnections[*].{ID:VpcPeeringConnectionId,Status:Status}' --output tableImplementation Steps:
Using AWS Console:
Sign in to the AWS Management Console
Navigate to VPC.
Select Endpoints under Virtual Private Cloud in the sidebar.
Review the Service Name, VPC, Subnet, and Security Groups associated with each endpoint to verify trust boundaries.
Check if the VPC endpoint connects to any external services or other VPCs and ensure there are no unnecessary wide-open routes or insecure trust relationships.
Modify the configuration as necessary to align with security best practices by restricting access through security groups, routing, and VPC peering.
Using AWS CLI:
Run the following command to check VPC endpoints:
aws ec2 describe-vpc-endpoints --query 'VpcEndpoints[*].{ID:VpcEndpointId,ServiceName:ServiceName,Type:VpcEndpointType}'For peering connections, run:
aws ec2 describe-vpc-peering-connections --query 'VpcPeeringConnections[*].{ID:VpcPeeringConnectionId,Status:Status}'Inspect the route tables for associated endpoints:
aws ec2 describe-route-tables --query 'RouteTables[*].{ID:RouteTableId,Routes:Routes}'Based on the findings, reconfigure security groups, route tables, or VPC peering as necessary to restrict access to trusted endpoints.
Backout Plan:
If modifying VPC endpoint configurations or trust boundaries causes access issues:
Identify the changes that were made and the affected resources.
Revert the route tables, security groups, or VPC peering configurations to their previous states:
Modify the security groups to remove wide-open access.
Update route tables to restrict routing paths that were opened to unintended destinations.
Verify that the resources are still functioning as expected without violating trust boundaries.