Checklists 🇮🇳 Indian Mandate Aligned 13 min read

Kubernetes & Container Attack Surface Hardening: CIS Benchmark & Production Security Manual

The definitive enterprise hardening checklist for production Kubernetes clusters (EKS, GKE, AKS, and self-hosted OpenShift). Aligned with the CIS Kubernetes Benchmark v1.8, NSA/CISA Kubernetes Hardening Guidance, and MeitY cloud standards. Covers API server protection, Pod Security Standards (PSS), eBPF-based runtime observability, immutable root filesystems, and network policy microsegmentation.

By BlueCiphr Threat Research Desk • Lead CEH & PenTest+ Auditors

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[Control Plane Security] Disable anonymous authentication on kube-apiserver (--anonymous-auth=false).

Mandate: CIS Benchmark 1.2.1

[Control Plane Security] Encrypt Kubernetes secrets at rest in etcd using AWS KMS / Azure Key Vault envelope encryption provider.

Mandate: CIS Benchmark 1.2.31

[Control Plane Security] Restrict API server access to corporate egress IP CIDRs; disable public internet endpoint access.

Mandate: RBI Perimeter Control

[Workload Hardening] Enforce Pod Security Standard 'Restricted' profile on all application namespaces via admission controllers.

Mandate: NSA/CISA Hardening

[Workload Hardening] Configure readOnlyRootFilesystem=true and runAsNonRoot=true on all container securityContext definitions.

Mandate: Container Immutability

[Workload Hardening] Drop all Linux capabilities (capabilities.drop: ['ALL']) and explicitly add back only required capabilities.

Mandate: Least Privilege

[Network Microsegmentation] Deploy default-deny NetworkPolicy in every namespace blocking unauthorized ingress and egress.

Mandate: Zero Trust Architecture

[Network Microsegmentation] Block access from application pods to Cloud Instance Metadata Service (169.254.169.254) via NetworkPolicy.

Mandate: Metadata Service Defense

[Runtime Observability] Deploy eBPF runtime security agent (Falco / Tetragon) to detect process spawning, privilege escalations, and kernel exploits.

Mandate: CERT-In Threat Detection

[Supply Chain & Images] Scan all container images with Trivy or Grype in CI/CD; fail build on any Critical/High CVE with available patch.

Mandate: Vulnerability Management

[Supply Chain & Images] Enforce container image signature verification at admission time via Kyverno or Gatekeeper using Cosign.

Mandate: Supply Chain Integrity

[RBAC & Service Accounts] Audit ClusterRoleBindings; eliminate excessive cluster-admin grants; set automountServiceAccountToken=false by default.

Mandate: RBAC Hardening

☸️ Production K8s Hardening: Zero Trust Container Defense Aligned with CIS Benchmark

Default Kubernetes configurations prioritize developer ease-of-use over security. Containers run with elevated capabilities, shared host namespaces, and unrestricted network egress. This hardening manual enforces cryptographic boundaries across cluster control planes and container runtimes.

1. Hardened Production Pod Security Context

Every production pod deployment manifest must declare an explicit securityContext enforcing immutable root filesystems and dropping dangerous Linux capabilities:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hardened-api-service
spec:
  template:
    spec:
      automountServiceAccountToken: false  # Prevent service account token theft
      securityContext:
        runAsNonRoot: true
        runAsUser: 10001
        runAsGroup: 10001
        fsGroup: 10001
        seccompProfile:
          type: RuntimeDefault
      containers:
      - name: api
        image: enterprise-registry.in/api:v2.4@sha256:abc123...
        securityContext:
          allowPrivilegeEscalation: false
          readOnlyRootFilesystem: true     # Prevents malware persistence
          capabilities:
            drop:
            - ALL                         # Drop all 38+ Linux capabilities
        resources:
          limits:
            cpu: "500m"
            memory: "512Mi"

2. Metadata Service (IMDSv2) Protection via NetworkPolicy

A common SSRF exploit path enables compromised pods to query the AWS/Azure instance metadata service (169.254.169.254) to steal node IAM credentials. The following NetworkPolicy blocks this egress path:

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: block-instance-metadata
  namespace: default
spec:
  podSelector: {}
  policyTypes:
  - Egress
  egress:
  - to:
    - ipBlock:
        cidr: 0.0.0.0/0
        except:
        - 169.254.169.254/32  # Denies traffic to AWS/Azure/GCP metadata service

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Kubernetes & Container Attack Surface Hardening: CIS Benchmark & Production Security Manual

Interactive Technical Checklist (12 Verification Checkpoints)

1. Hardened Production Pod Security Context

2. Metadata Service (IMDSv2) Protection via NetworkPolicy

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