When deploying Kubernetes on AWS, leaving the Amazon EKS control plane API endpoint publicly accessible exposes your cluster administration interface to the open internet. In this post, we explain how to detect this threat and restrict reachability in under 60 seconds.
The Danger of Public EKS Endpoints
By default, EKS cluster endpoints are created with public access enabled (`endpointPublicAccess = true`). While the Kubernetes API server relies on token-based RBAC authentication, exposing the endpoint allows zero-day scanning, credentials brute-forcing, and vulnerability probes directly from anonymous sources.
Smarth Path Routing with PosturaNet
To close the exposure boundary, we formally verify network paths using Z3 reachability checks. The solution is to disable public access or restrict allowed CIDRs directly in the cluster network config.
Locking the Boundary in 60 Seconds
PosturaNet detects public endpoint exposures and deploys a Terraform change to set `endpoint_public_access = false` while maintaining secure private node reachability via AWS VPC PrivateLink endpoints. The whole process runs autonomously, securing your infrastructure before external scans complete.