Kubernetes Security Best Practices: How to Protect Your Containerized Applications in 2025
- Black Castle
- Aug 18
- 8 min read
Kubernetes is the standard for container orchestration, with the Cloud Native Computing Foundation reporting that 96% of organizations are using or evaluating Kubernetes¹. However, this widespread adoption has also made Kubernetes environments attractive targets for cyber criminals. According to Red Hat's State of Kubernetes Security Report 2024, 67% of organizations experienced a security incident in their Kubernetes environments in the past year².
The complexity of Kubernetes with multiple layers of components, networking, and access controls, securing a Kubernetes cluster requires a comprehensive approach that goes far beyond traditional security measures. A single misconfiguration can expose your entire infrastructure to attack.
At Black Castle, we've helped dozens of organizations implement robust Kubernetes security frameworks. Through our experience securing production Kubernetes environments, we've identified the critical practices that separate secure deployments from vulnerable ones.
This guide presents the essential Kubernetes security best practices, and strategies to protect your containerized applications against external threats.
Why Kubernetes Security is Critical in 2025
According to Palo Alto Networks' Unit 42 Cloud Threat Report, attacks on Kubernetes environments increased by 200% in 2024³. Attackers usually target misconfigurations, vulnerable container images, and weak access controls.
The shared responsibility model in Kubernetes adds another layer of complexity. While cloud providers like AWS and Google Cloud secure the underlying infrastructure, you're responsible for securing your applications, configurations, and data within the cluster.
Consider these statistics:
91% of Kubernetes deployments contain misconfigurations that could lead to security breaches⁴
The average time to detect a container security incident is 207 days⁵
Container escape vulnerabilities increased by 35% in 2024⁶
The good news is most Kubernetes security incidents are preventable with proper implementation of security best practices.
1. Secure Container Images from the Start
The first step begins before containers ever reach your Kubernetes cluster. Container images are the foundation of your applications, and vulnerable images can compromise your entire environment.
Container Image Security Best Practices:
Use Minimal Base Images: Choose minimal base images like Alpine Linux or Google's Distroless images to reduce attack surface. These images contain only essential components, eliminating unnecessary packages that could introduce vulnerabilities.
Implement Image Scanning:
AWS: Amazon ECR Image Scanning for vulnerability detection
Google Cloud: Artifact Registry Container Analysis API for security scanning
Third-party tools: Integrate Trivy, Snyk, or Grype for advanced scanning capabilities
Keep Images Updated: Regularly update base images and dependencies to patch known vulnerabilities. Implement automated image rebuilding when security updates are available.
When deploying never Use 'latest' Tags: Always use specific version tags for production deployments. The 'latest' tag can introduce unexpected changes and security vulnerabilities.
Image Security Implementation:
# Example: Secure image specification
apiVersion: apps/v1
kind: Deployment
metadata:
name: secure-app
spec:
template:
spec:
containers:
- name: app
image: myapp:v1.2.3 # Specific version, not 'latest'
securityContext:
runAsNonRoot: true
runAsUser: 1000
readOnlyRootFilesystem: true
Key Metrics to Track on container images:
Number of critical/high vulnerabilities in deployed images
Time between vulnerability disclosure and image updates
Percentage of images using specific version tags
2. Role-Based Access Control (RBAC)
Kubernetes RBAC is an important line of defense against unauthorized access to your Kubernetes cluster. According to the CNCF Security Audit, 78% of Kubernetes security incidents involve inadequate access controls⁷.
RBAC Implementation Strategy:
Principle of Least Privilege: Grant users and service accounts only the minimum permissions necessary to perform their functions. Start with restrictive permissions and expand as needed.
Namespace-Level Isolation: Use namespaces to create logical boundaries between applications and teams. Implement RBAC policies that restrict access to specific namespaces.
Service Account Management: Create dedicated service accounts for each application with specific, limited permissions. Avoid using the default service account for production workloads.
RBAC Configuration Example:
# Example: Restrictive RBAC policy
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
namespace: production
name: app-reader
rules:
- apiGroups: [""]
resources: ["pods", "services"]
verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: app-reader-binding
namespace: production
subjects:
- kind: ServiceAccount
name: app-service-account
namespace: production
roleRef:
kind: Role
name: app-reader
apiGroup: rbac.authorization.k8s.io
RBAC Best Practices:
Regularly audit RBAC permissions and remove unused access
Implement break-glass procedures for emergency access
Use tools like kubectl-who-can to analyze permissions
Monitor RBAC events for suspicious activity
3. Network Policies for micro-segmentation
Network segmentation is critical for limiting the blast radius of security incidents. Kubernetes Network Policies provide fine-grained control over pod-to-pod communication.
Network Policy Implementation:
Default Deny All: Start with a default deny-all network policy and explicitly allow only necessary traffic. This approach ensures that new pods have no network access by default.
Ingress and Egress Controls: Define both ingress (incoming) and egress (outgoing) rules for comprehensive traffic control. Many organizations focus only on ingress rules, leaving egress traffic uncontrolled.
Label-Based Policies: Use Kubernetes labels to create dynamic and maintainable network policies that automatically apply to pods based on their characteristics.
Network Policy Example:
# Example: Restrictive network policy
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: web-app-netpol
namespace: production
spec:
podSelector:
matchLabels:
app: web-app
policyTypes:
- Ingress
- Egress
ingress:
- from:
- podSelector:
matchLabels:
app: frontend
ports:
- protocol: TCP
port: 8080
egress:
- to:
- podSelector:
matchLabels:
app: database
ports:
- protocol: TCP
port: 5432
Network Policy Tools:
Calico: Advanced network policy engine with enterprise features
Cilium: eBPF-based networking with enhanced security capabilities
AWS VPC CNI: Native AWS networking with security group integration
4. Pod Security Standards
Pod Security Standards (PSS) replace the deprecated Pod Security Policies, providing a simplified approach to enforcing security constraints on pods.
Pod Security Standards Implementation:
Security Levels:
Privileged: Unrestricted policy for system-level workloads
Baseline: Minimally restrictive policy preventing known escalations
Restricted: Heavily restricted policy following current pod hardening best practices
Enforcement Modes:
Enforce: Policy violations cause pod creation to fail immediately
Audit: Policy violations are logged but pods are still created
Warn: Policy violations trigger user-facing warnings
Pod Security Configuration:
# Example: Namespace with Pod Security Standards
apiVersion: v1
kind: Namespace
metadata:
name: secure-apps
labels:
pod-security.kubernetes.io/enforce: restricted
pod-security.kubernetes.io/audit: restricted
pod-security.kubernetes.io/warn: restricted
Security Context Best Practices:
Run containers as non-root users
Use read-only root filesystems
Drop unnecessary Linux capabilities
Disable privilege escalation
Set resource limits and requests
5. Secure Secrets Management
Kubernetes Secrets provide a mechanism for storing sensitive information, but they require careful handling to maintain security.
Secrets Security Best Practices:
Encryption at Rest: Enable etcd encryption to protect secrets stored in the cluster database. Both AWS EKS and Google GKE support envelope encryption for enhanced security.
External Secrets Management: Consider using external secret management systems like:
AWS: AWS Secrets Manager with External Secrets Operator
Google Cloud: Secret Manager with CSI Secret Store driver
HashiCorp Vault: Enterprise-grade secret management
Least Privilege Access: Limit secret access to only the pods and service accounts that require them. Use RBAC to control secret access permissions.
External Secrets Implementation:
# Example: External Secrets Operator configuration
apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
name: aws-secrets-manager
namespace: production
spec:
provider:
aws:
service: SecretsManager
region: us-west-2
auth:
secretRef:
accessKeyID:
name: aws-creds
key: access-key-id
secretAccessKey:
name: aws-creds
key: secret-access-key
Secret Rotation: Implement automated secret rotation to limit the impact of compromised credentials. Both AWS and Google Cloud provide automated rotation capabilities for their secret management services.
6. Monitoring and Logging
Observability is key for detecting and responding to security incidents in Kubernetes environments. According to SANS Institute, organizations with comprehensive logging detect breaches 200 days faster than those without⁸.
Monitoring and Logging Strategy:
Audit Logging: Enable Kubernetes audit logging to track all API server requests. Configure appropriate audit policies to capture security-relevant events without overwhelming your logging infrastructure.
Container Runtime Security: Implement runtime security monitoring to detect anomalous behavior in running containers:
Falco: Open-source runtime security monitoring
AWS GuardDuty: Kubernetes protection for EKS clusters
Google Cloud Security Command Center: Comprehensive security monitoring
Metrics and Alerting: Monitor key security metrics and configure alerting for suspicious activities:
Failed authentication attempts
Privilege escalation attempts
Unusual network traffic patterns
Resource usage anomalies
Monitoring Configuration Example:
# Example: Falco rule for detecting suspicious activity
- rule: Terminal shell in container
desc: A shell was used as the entrypoint/exec point into a container
condition: >
spawned_process and container and
shell_procs and proc.tty != 0 and
container_entrypoint
output: >
A shell was spawned in a container with an attached terminal
(user=%user.name container_id=%container.id image=%container.image.repository)
priority: NOTICE
7. Supply Chain Security
Supply chain attacks have increased significantly, with the 2024 State of Software Supply Chain Report showing a 742% increase in malicious packages⁹. Securing your software supply chain is critical for Kubernetes security.
Supply Chain Security Measures:
Software Bill of Materials (SBOM): Generate and maintain SBOMs for all container images to track dependencies and identify vulnerable components.
Image Signing and Verification: Implement container image signing using tools like Cosign and enforce signature verification in your Kubernetes clusters.
Admission Controllers: Use admission controllers to enforce security policies and prevent deployment of non-compliant resources:
OPA Gatekeeper: Policy-based admission control
Kyverno: Kubernetes-native policy management
Falco Admission Controller: Runtime security policy enforcement
Admission Controller Example:
# Example: Gatekeeper constraint requiring image signatures
apiVersion: templates.gatekeeper.sh/v1beta1
kind: ConstraintTemplate
metadata:
name: requiredsignature
spec:
crd:
spec:
names:
kind: RequiredSignature
validation:
properties:
trustedKeys:
type: array
items:
type: string
targets:
- target: admission.k8s.gatekeeper.sh
rego: |
package requiredsignature
violation[{"msg": msg}] {
container := input.review.object.spec.containers[_]
not has_valid_signature(container.image)
msg := sprintf("Container image %v must be signed", [container.image])
}
8. Regular Security Assessments and Updates
Kubernetes security is not a one-time implementation but an ongoing process requiring regular assessment and updates.
Security Assessment Practices:
Regular Penetration Testing: Conduct regular penetration testing of your Kubernetes environments to identify vulnerabilities and misconfigurations.
Compliance Scanning: Use tools like kube-bench to assess your cluster against CIS Kubernetes Benchmark standards.
Vulnerability Management: Implement automated vulnerability scanning and patching processes for both cluster components and container images.
Security Training: Provide regular security training for development and operations teams to ensure they understand current threats and best practices.
Assessment Tools:
kube-bench: CIS Kubernetes Benchmark assessment
kube-hunter: Kubernetes cluster penetration testing
kubesec: Static analysis of Kubernetes manifests
Polaris: Configuration validation and best practices
Conclusion: Building a Secure Kubernetes Future
Kubernetes security requires a layered approach that addresses every aspect of your containerized environment. From secure container images to robust monitoring, each component plays a crucial role in your overall security posture.
The key to successful Kubernetes security is understanding that it's not a destination but a journey. Threats evolve, new vulnerabilities are discovered, and best practices continue to develop.
Organizations that treat security as an ongoing process, rather than a one-time implementation, will be best positioned to protect their containerized applications.
Remember these fundamental principles:
Security starts with container images - scan, update, and harden from the beginning
Implement defense in depth - use multiple security layers that work together
Principle of least privilege - grant minimal necessary permissions
Continuous monitoring - visibility is essential for threat detection
Regular assessment - test and validate your security controls
At Black Castle, we've seen how proper implementation of these practices transforms vulnerable Kubernetes environments into secure, resilient platforms that enable business growth. The investment in Kubernetes security pays dividends through reduced risk, improved compliance, and increased confidence in your containerized infrastructure.
Ready to Secure Your Kubernetes Environment?
Implementing strong Kubernetes security can seem overwhelming, but you don't have to navigate this complexity of the landscape alone. Black Castle's Kubernetes security experts specialize in designing and implementing robust security frameworks that protect your containerized applications while maintaining operational efficiency.
Our proven methodologies have helped organizations across Canada build secure, scalable Kubernetes environments that meet the highest security standards. From security assessments and implementation to ongoing monitoring and training, we provide the expertise you need to confidently run production Kubernetes workloads.
Contact us today for a Kubernetes security assessment and discover how we can help you build an impenetrable container security framework.
References:
Cloud Native Computing Foundation. (2024). CNCF Annual Survey 2024. Retrieved from https://www.cncf.io/reports/cncf-annual-survey-2024/
Red Hat. (2024). State of Kubernetes Security Report 2024. Retrieved from https://www.redhat.com/en/resources/kubernetes-security-practices-risks-report
Palo Alto Networks Unit 42. (2024). Cloud Threat Report. Retrieved from https://www.paloaltonetworks.com/resources/research/unit-42-cloud-threat-report
Accurics. (2024). State of DevSecOps Report. Retrieved from https://www.accurics.com/resources/research/state-of-devsecops/
IBM Security. (2024). Cost of a Data Breach Report 2024. Retrieved from https://www.ibm.com/reports/data-breach
Aqua Security. (2024). Cloud Native Security Report. Retrieved from https://www.aquasec.com/resources/cloud-native-security-report/
Cloud Native Computing Foundation. (2024). Kubernetes Security Audit Report. Retrieved from https://www.cncf.io/reports/kubernetes-security-audit/
SANS Institute. (2024). Incident Response Survey. Retrieved from https://www.sans.org/reading-room/whitepapers/incident/incident-response-survey-2024
Sonatype. (2024). State of the Software Supply Chain Report. Retrieved from https://www.sonatype.com/resources/state-of-the-software-supply-chain-report
About the Author: This guide was developed by the Kubernetes security experts at Black Castle, with years of experience securing production Kubernetes environments for organizations.
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