Getting Started with Kubernetes Security - Tools and Best Practices

Introduction

Kubernetes Security 

The cloud-native systems were built with the help of containers. Services are implemented 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 Go language. Go has many features that make it a good fit for kubernetes deployments. Some of the features include static typing, powerful library, utilities, minimalism, very-fast compilation and fantastic performance. The below survey results stress how important is Kubernetes Security and how organizations are concerned. 

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

About Kubernetes

Kubernetes can be described as a portable open-source platform which helps in managing containerized services and workloads. It is overgrowing, and its tools and services are widely available. It was open-sourced by Google in 2014 and has become very popular over the years.

Before kubernetes, organizations ran their applications on physical servers. But due to lack of resource boundaries, they had to face resource allocation issues. Even if they used different physical server, not all problems were solved as they had to face a new challenge, which was ‘underutilization’ of resources.

To solve these problems with physical servers, virtualization was introduced. Now, we could run multiple Virtual Machines on one physical system. It helped with resource utilization and security problems. Virtual Machine is itself a full machine with components of this own.

Then after successfully working and deployment using Virtual Machines, Containers came into light. Containers are similar to the Virtual Machines, but the are considered comparatively lightweight. A box like VM also has its filesystem, memory and CPU etc.

Security Best Practices for Kubernetes Deployment

Let us explore the best security practices for Kubernetes Deployment Strategy. While working on 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 described below:

Practise 1. Configure the security context for your pods and containers

While designing pods and containers, one thing that we need to keep in mind is to apply security context to your pods and containers. It is a property defined in the deployment yaml. The security parameters for the pod or container are controlled by the security context. 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 are running pods with escalated privileges.

Practise 2. Make sure only authorized images are used in the environment

A process to check and ensure that only the images which adhere to the policy of organization area used and are allowed to run in your environment. Without this process, there is a significant risk of running malicious or vulnerable containers. Do not run images which are downloaded from unknown or untrusted sources. 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, should be sold to the registry. A CI pipeline should be made to integrate security assessment. With this CI pipeline being the part of the build process, we can ensure that only the code that is approved for production is used for the operation of building images.

If an error occurs in the security assessment, it should fail the process of the pipeline, so that the images which are vulnerable and not approved after the evaluation are not pushed to the image registry.

Practise 3. Moving Deployments to production

Organizations must check for the vulnerabilities before moving the deployments to production, otherwise with 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.

Practise 4. Make sure to 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 to the kubernetes cluster. Also, CI/CD must be configured to 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. To avoid this problem, the code for deployment configurations should be checked at regular intervals.

Container software supports simplified images from the same container to create, check and deploy safely.

Read the Article, Understanding the Role of Containers in DevOps

Practise 5. Using Authorization Policies

The complexity arises when there are multiple devices and interconnected microservices many various users; this is a nightmare.

There are several authorization methods offered by kubernetes. We should use Role-Based Access Control(commonly referred to as RBAC) or Attribute-Based Access control(ABAC) which will make sure that no user has more permission than they need to accomplish their task.

Practise 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 one also becomes an easy target. Network segmentation can be the solution to this problem, as it ensures secure communication between containers. Containers can only communicate with the ones they are supposed to. But the task of creating network segmentation between containers is not an easy task, because of the ‘dynamic’ nature of the container IPs. Network firewalls can be used to prevent cross-cluster communication if necessary.

Kubernetes Security Tools 

Kubernetes automates various tasks required to deploy containerized apps. But one crucial thing that it doesn’t take care of is Security. 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 behaviour within a containerized app that could signal a breach. It doesn’t secure nodes or hardens 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

Project Calico

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

Kube-Bench

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

Twistlock

Twistlock is a provider of full-lifecycle container and cloud-native security solution. 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

Falco

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

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 anomalies to be quickly detected.

Kubernetes Security and future 

The emergence of Kubernetes and containers hasn’t modified the security goals. The aim is still to make it impossible for cyberattacker to hack into the software and the networks – and to find and avoid them as soon as possible should they succeed. However, the methods and methodologies must be tailored to fit the requirements of DevOps operations and cloud-native concepts.


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