kubernetes security

Eamon Carroll

min read

What is Kubernetes security and why does it matter?

Kubernetes security is the set of controls and processes that protect a Kubernetes cluster, its workloads, and its supporting infrastructure from misconfiguration, abuse, and attack. Because Kubernetes centralizes deployment and networking for many applications, a single weak setting can expose multiple services.

Strong kubernetes security also supports compliance, reduces blast radius during incidents, and improves reliability by preventing unauthorized changes. It’s a core part of cloud-native security and container security, not a “nice to have,” especially when clusters are internet-accessible or shared by many teams.

What are the biggest Kubernetes security risks?

Common kubernetes security risks include misconfigurations and overly broad permissions that enable lateral movement. Other high-impact issues come from insecure defaults or gaps between teams managing apps versus infrastructure.

Key risks include:

Overly permissive RBAC and service accounts
Exposed dashboards, kubelets, or APIs
Weak secrets management (plain text env vars, shared keys)
Untrusted container images (supply chain security failures)
Missing network policies allowing unrestricted pod-to-pod traffic
Privileged pods, hostPath mounts, or unsafe capabilities

How do RBAC and least privilege work in Kubernetes?

RBAC (role-based access control) limits what users, groups, and service accounts can do in the Kubernetes API. Least privilege means granting only the minimum verbs (get/list/watch/create, etc.) on the minimum resources in the minimum namespaces.

Practical steps for kubernetes security:

Avoid using cluster-admin except for break-glass scenarios.
Prefer namespace-scoped Roles over ClusterRoles.
Separate human access from workload identities (service accounts).
Review bindings regularly and remove unused permissions.

Good Kubernetes cluster security usually starts with cleaning up RBAC sprawl.

How should you secure container images and registries?

Image security is a cornerstone of kubernetes security because compromised images become compromised pods. Treat your registry and build pipeline as part of your attack surface.

Recommended controls (container security + supply chain security):

Scan images for vulnerabilities and malware before deployment
Enforce signed images (e.g., Sigstore/cosign) and verify at admission
Pin images by digest, not mutable tags like latest
Use minimal base images and remove package managers where possible
Restrict who can push to production registries
Block running images from untrusted registries

What network controls improve Kubernetes security?

Kubernetes networking is permissive by default in many environments, so segmentation is crucial. Network policies can restrict pod-to-pod and pod-to-service traffic, limiting lateral movement after a breach.

Effective kubernetes security network controls include:

Default-deny network policies per namespace
Allow lists for critical services (databases, control-plane endpoints)
Ingress controls with TLS and WAF where appropriate
Service mesh mTLS for east-west encryption (when it fits)

This is a major part of cloud-native security: assume compromise and limit communication paths.

How do you manage secrets safely in Kubernetes?

Kubernetes Secrets are not automatically secure unless you configure them correctly. For kubernetes security, treat secrets as sensitive data requiring encryption, access control, and rotation.

Good secrets management practices:

Enable encryption at rest for secrets in etcd
Restrict secret access via RBAC and namespace boundaries
Prefer external secret stores (Vault, cloud KMS/secret managers)
Avoid embedding secrets in images, ConfigMaps, or logs
Rotate credentials and use short-lived tokens when possible

How do you harden nodes and the Kubernetes control plane?

Kubernetes hardening covers both worker nodes and Kubernetes control plane security (API server, etcd, controller manager, scheduler). A strong baseline reduces the chance that a single exploit becomes cluster-wide compromise.

Core hardening steps:

Patch OS, container runtime, and Kubernetes versions promptly
Restrict node SSH access; use MFA and just-in-time access
Limit privileged workloads; reduce Linux capabilities
Use Pod Security Standards to block risky pod specs
Lock down etcd access and enforce TLS everywhere

Consistent kubernetes security requires aligning runtime controls with configuration controls.

How do you monitor and audit a Kubernetes cluster?

Monitoring and auditing detect attacks and configuration drift that preventive controls miss. Kubernetes security is ongoing: new deployments and role changes can introduce new exposures.

Focus areas:

Enable and retain Kubernetes audit logs
Alert on anomalous API calls (new ClusterRoleBindings, exec into pods)
Collect runtime signals (process, network, file activity)
Track configuration changes via GitOps and policy checks
Continuously assess misconfigurations across namespaces and clusters

Strong Kubernetes cluster security combines prevention, detection, and rapid response.