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Kubernetes Security Best Practices and Tools

Gursimran Singh | 02 November 2023

Kubernetes Security Tools and Best Practices

Kubernetes Security for Cloud-Native Environments

Kubernetes Security secures the cloud-native systems, which develop with the help of containers. Implement services in cloud-native systems using small clouds of boxes. Google open-sourced Kubernetes in 2014 to control and manage the containers. One of the best choices for Kubernetes deployment can be the Go language. Go has many features that make it a good fit for Kubernetes deployments. Some of the features include static typing, a powerful library, utilities, minimalism, fast compilation, and fantastic performance.

Many companies use Kubernetes to manage some of their container workloads and services, making it a significant and fast-growing ecosystem.

This means security solutions, support, and services are widely available. Still, Kubernetes container environments pose significant security threats, such as

  1. Runtime Security Incidents
  2. Misconfigurations,
  3. Supply Chain Vulnerabilities

The security concerns associated with Kubernetes correspond to container lifecycle stages.

Security is the number one challenge for users adopting Kubernetes, cited by 46% of users (which rises to 55% in larger enterprises). Source, The State of the Kubernetes Ecosystem

What is Kubernetes Security?

It is built on the four Cs of cloud-native security: cloud, cluster, container, and code.

1. Cloud

Security is based on the underlying physical infrastructure.
Basic cloud provider (or physical security) best practices must be followed whether the cluster is constructed on one's own data center or a cloud provider.

2. Cluster

Securing a Kubernetes cluster includes configurable components like the Kubernetes API and the security of all the cluster's apps.

Because most cloud-native apps are built on microservices and APIs, they're only as safe as the weakest link in the chain of services that make up the whole thing.

3. Container

Examples of container design best practices are starting with the most straightforward code base feasible (excluding superfluous libraries or functions), avoiding granting excessive access to users in the container, and ensuring that containers are inspected for vulnerabilities at build time.

4. Code

For any Kubernetes setup, code is a large attack surface.

Simple measures like encrypting TCP with TLS handshakes, not exposing unused ports, scanning, and testing on a regular basis can help prevent security vulnerabilities in a production setting.

Why is Kubernetes Security Important?

Due to the distributed and dynamic nature of a Kubernetes cluster, security is critical throughout the container lifetime. For each of the three phases of an application's lifecycle: build, deploy, and runtime, different security measures are necessary. Kubernetes has built-in security features.

Application containers, for example, are rarely patched or updated; instead, container images are entirely replaced with new versions. This allows for strict version control and quick rollbacks if a vulnerability in new code is discovered.

However, because individual pods are temporary and ephemeral, IT security experts may face issues in the ever-changing runtime environment, as applications and API linkages to other applications and services are continually changing.

Kubernetes Security Advantages

Cloud Orchestration Security provides various key Advantages

1. Enhanced Resource Utilization

The amount of resources required by a container or pod in a production Kubernetes environment is referred to as Kubernetes resource utilization.

Ops teams are responsible for keeping track of the resource utilization of containers and pods.

Kubernetes resources are abstractions on the underlying computational infrastructure (AWS, Azure, bare-metal). Therefore utilization equals cost.

Cost allocation attempts need monitoring of Kubernetes resource utilization for containers and pods.

2. Improved Security

By tapping into Kubernetes' declarative data to discover vulnerabilities in Kubernetes and containers, Kubernetes-native security gives more significant insights.

3. Boost Operational Efficiency

The Kubernetes learning curve is lowered using the same architecture for infrastructure management and security, and the Kubernetes context enables faster threat detection and prioritized risk assessments.

4. Reduced Operational Risk

Kubernetes-native security aids in the reduction of operational issues caused by inconsistencies in configuration, a lack of coordination, and user errors.

Given the steep learning curve most users face with Kubernetes, it's easy to make mistakes like granting elevated privileges via Kubernetes Role-based Access Controls (RBAC), such as giving a user or service account entire cluster administrative permissions, or exposing Kubernetes secrets unnecessarily by allowing deployments to pull secrets even when they aren't needed.

The risk of having separate control software in the event of a failure would either fail to open and allow all traffic with no security enabled or fail to close and break all application traffic is also eliminated by embedding security controls directly in Kubernetes.

As the complexity of Kubernetes deployments grows, traditional monitoring tools often fall short in providing comprehensive visibility and proactive insights. AIOps solutions leverage ML algorithms and advanced analytics to automate and enhance the monitoring process, allowing organizations to detect and respond to potential issues in real-time. Read the Article, AIOps Solutions for Monitoring at Scale

What are the most common Vulnerabilities in Kubernetes?

Kubernetes is Complex, and it's easy to make a mistake while configuring it. If the vulnerabilities are left unpatched, it might lead to severe exposures.

1. Kubernetes Node Vulnerability

A security flaw has been discovered in Kube-proxy, a network component that operates on Kubernetes nodes. It exposes Kubernetes node internal services, allowing them to be accessed from afar without requiring authentication.

The local host service of a node is vulnerable to hosts on the local network and pods operating on the node. Because they anticipate only local trusted processes to engage with them, services bound to the local host may often handle unauthenticated requests. This vulnerability affects nodes that run the localhost service without requiring authentication.

2. Man-in-the-Middle Vulnerability

An attacker can take advantage of this flaw by initiating a man-in-the-middle (MITM) attack, which allows them to listen in on conversations.

The flaw is present in all versions of Kubernetes and poses a severe threat to multitenant clusters.

The MITM vulnerability has a significant risk component because it allows people with minimal rights to wreak damage.

Even users with the ability to establish or alter services and pods can take advantage of this flaw and intercept traffic from other pods in the same cluster.

Users can define a cluster IP address and expose services using external IP addresses while creating a service.

The cluster's traffic destined for the external IP address can then be directed to the service. The user can intercept it after it reaches the service.

3. Kubernetes API Server Vulnerability

In 2019, a vulnerability in the Kubernetes API server was uncovered. A fix was published to solve the problem immediately after it was discovered. The patch, however, corrects the problem in versions 1.13, 1.14, and 1.15. Kubernetes versions prior to this one were not fixed. The Kubernetes API is used to exploit this flaw.

It gives users access to the cluster's custom resources, allowing them to read, modify, and delete them. Role-based access control (RBAC) permissions, which only apply to namespace resources, are useless in this situation.

Kubernetes Security Risks

Kubernetes uses a flat network model that allows each pod to communicate with others in the cluster by default. This creates significant security concerns as it allows attackers to compromise pods and communicate with other resources in the cluster freely.

1. Numerous Containers

Containers provide increased speed, portability, and the possibility to use microservices architectures, but they can also introduce security vulnerabilities and increase your attack surface.

Maintaining proper insight into your cloud-native infrastructure components becomes more difficult as more containers are deployed.

2. Image Registries pose Security Risks

Organizations require strict governance procedures for creating and storing pictures in trusted image registries.

Container images must be produced using secure and approved base images scanned regularly. Only images from image registries on allow lists should be used to launch containers in your Kubernetes system.

3. Container Endpoints

To perform successfully, containers and pods will need to communicate with one other within deployments and with other internal and external endpoints.

The ability of a malicious actor to move laterally within the environment if a container is breached is directly tied to how widely that container can connect with other containers and pods.

What are the Best Practices for Kubernetes Security Deployment?

Let us explore the best security practices for Kubernetes Deployment Strategy. While working on the Kubernetes cluster, there are some security practices that we should keep in mind to ensure the security of the deployment process. Some of these security best practices are below:
Protect your entire clusters with runtime protection of kubernetes workloads by automating security configuration and compliance. Click to explore, Azure Kubernetes Services

1. Set Security context for Pods and Containers

While designing pods and containers, we need to keep in mind applying security context to your pods and containers. It is a property defined in the deployment YAML. The security context controls the security parameters for the pod or container. For example, we can security context as: SecurityContext->runAsNonRoot. Also, 'DenyEscalatingExec' admission control can be used to deny exec and attach commands to pods if you run pods with escalated privileges.

2. Use Authorized Images in the Environment

A process to check and ensure that only the images that adhere to the organization's area's policy are used and are allowed to run in your environment. Without this process, there is a significant risk of running malicious or vulnerable containers. It can be dangerous for the organization. The approved images should be stored in private registries. Make sure that these private registries only store approved models and not untrusted images.

Before pushing the image to the individual record, a built image must be scanned for vulnerabilities. Only pictures, which have no issues or weaknesses, sell only to the registry. Made CI pipeline to integrate security assessment. With this CI pipeline being part of the build process, we can approve code use for production. Suppose an error occurs in the security assessment. In that case, it should fail the pipeline process so that the images that are vulnerable and not approved after the evaluation are not pushed to the image registry.

Container Design Patterns for Kubernetes are essential for optimizing and improving the efficiency of your Kubernetes deployments. In this article, we will explore various design patterns that can help you make the most out of your containerized applications in a Kubernetes environment. Read the Article, Container Design Patterns for Kubernetes

3. Moving Deployments to Production

Organizations must check for vulnerabilities before moving the deployments to production. Otherwise, the migration of deployments to production increases the vulnerable workloads. Also, a healthy  DevOps/DevSecOps culture must be maintained in the organization to prevent these issues.

4. Secure CI/CD Pipelines on Kubernetes

Make sure to have a CI/CD pipeline running on the built environment, which develops, tests, and deploys the workloads before using them in the Kubernetes cluster. Also, configuring CI/CD must report potential vulnerabilities to the developers quickly. Otherwise, if these potentially vulnerable images are pushed to the Kubernetes production cluster, attackers can exploit these vulnerabilities and gain access to the groups. Check code regularly, to avoid this problem, for code deployment configurations.

5. Using Authorization Policies

The complexity arises when multiple devices and interconnected microservices are multiple users; this is a nightmare. Kubernetes offer several authorization methods. We should use Role-Based Access Control(commonly referred to as RBAC) or Attribute-Based Access control (ABAC), ensuring that no user has more permission than they need to accomplish their task.

6. Create Network Segmentation between Containers

If we run different applications on one Kubernetes cluster, there is a considerable risk that if one of the forms is compromised, the other becomes an easy target. Network segmentation can be the solution to this problem, as it ensures secure communication between containers. But the task of creating network segmentation between containers is not an easy task because of the 'dynamic' nature of the container IPs. Use Network firewalls to prevent cross-cluster communication if necessary.

Implement Spinnaker with Kubernetes to streamline and automate the deployment process. By leveraging Spinnaker's capabilities, organizations can achieve faster and more reliable deployments in their Kubernetes clusters.

Kubernetes Security Tools

Kubernetes automates various tasks required to deploy containerized apps. But one crucial thing that it doesn't take care of is SecuritySecurity. It does have a few features that can surely help to secure the containerized apps. But that is not much.   When properly configured, it can enforce role-based access control policies, for example, and it can restrict the ability of a container to access resources on the host server.

Beyond these security measures, however, Kubernetes offer nothing in the securing of applications. It doesn't review the contents of a container for security flaws or detect anomalous behavior within a containerized app that could signal a breach. It doesn't secure nodes or harden networks against attack. In short, Kubernetes is a container orchestration tool. It's not a security tool. But Thankfully, we have third-party tools that can help us with security. 

1. Project Calico

Project Calico is an open-source tool that connects and secures containers and the services it runs. Integrate all the major cloud platforms with Calico, be it Kubernetes or OpenStack. 

2. Kube-Bench

The Center for Internet Security (CIS) offers guidance and evaluation checks to insure the application is safe.  Kube-Bench is an open-source Kubernetes testing application that verifies that the Kubernetes implementation follows CIS standards. It supports benchmark testing of several Kubernetes versions. Kube-Bench is an application from Go. 

3. Twistlock

Twistlock is a provider of full-lifecycle container and cloud-native security solutions. It helps you to perform over 200 built-in checks for the Kubernetes CIS Benchmarks. Twistlock defends software through the product life cycle with actionable risk detection mechanisms and dynamically configured firewalls.

4. Falco

Falco is a targeted Kubernetes tool for SecuritySecurity that detects unusual activity in your containers. Derive it from the Sysdig Project and has become a commercial product. Falco monitors containers with a greater focus on kernel system calls. 

5. Aqua Security 

Until deployment Aqua Security scans the container images, this feature lets you make images read-only. Immutable images are less vulnerable to threat. Additionally, it allows quick detection of anomalies.
Next-gen cyber security encircles a holistic approach—right from detection to protection, prevention, and remediation. Kubernetes Security Consulting Services

Kubernetes Security and the Future 

The emergence of Kubernetes and containers hasn't modified the security goals. The aim is still to make it impossible, for cyberattackers to hack into the software and the networks and find and avoid them as soon as possible should they succeed. However, XenonStack being a Kubernetes Certified Service Provider can tailor the methods and methodologies to fit the requirements of DevOps operations and cloud-native concepts.