Kubernetes Security - A Complete Guide to Securing Your Containers

Learn about Kubernetes Security, the 4Cs of Kubernetes, and nodes. Fully manage and operate Kubernetes with the help of Weave Works

Kubernetes Security - An Overview

When it comes to Kubernetes security, the devil is in the details. Its system, aimed at simplifying infrastructure management, is so complex and intricate that you can’t secure Kubernetes with basic security checks. Kubernetes security needs a deeper understanding of the ecosystem and strategies to secure it at different levels, like nodes, pods, and data. Additionally, you need purpose-built tools that can adapt to the complexity of Kubernetes and secure the system end-to-end.

Red Hat reports that 94% of DevOps engineers faced at least one Kubernetes security issue in 2022. Further, security concerns have delayed application deployment in over 67% of the cases. Another significant consequence of weak security is loss of revenue and customers as they lose trust in the organizations to provide a secure experience.

With Kubernetes clusters attracting significant interest from hostile actors in addition to its security loopholes, any development team must be increasingly cautious.

For that, we first need to understand what Kubernetes security is.

What is Kubernetes Security?

Kubernetes security can be defined as a set of processes, methods, and tools used to ensure clusters and pods within a Kubernetes ecosystem are formidable against security risk. You can keep your Kubernetes deployments safe from attacks by securing containers and infrastructure, avoiding misconfigurations, and implementing Kubernetes network security.

Why is Kubernetes Security important?

Kubernetes is layered like an onion; it comes with its challenges when securing your environment. Although Kubernetes offers many native security features, tackling every potential vulnerability across its infrastructure layers calls for an automated and scalable security strategy.

A study by Cyble found that about 900,000 Kubernetes instances are exposed on the internet. In addition to the fact that 96% of the companies are inclined towards using Kubernetes for their applications. This statistic should tell you that if Kubernetes security is left unaddressed, it can have detrimental consequences.

Kubernetes and containerization are widely accepted deployment methods. It enables a microservices architecture to introduce portability and speed within your development lifecycle. As you scale your application by adding more containers, it increases the attack surface area and reduces your capacity to monitor every container. The distributed ecosystem of Kubernetes can create multiple security blindspots, making it hard to detect risks and misconfigurations.

What are the threats affecting Kubernetes?

According to a RedHat report, most organizations were forced to delay their application delivery due to unresolved security issues. The report states that a shocking 93% of respondents witnessed at least one security incident in their Kubernetes ecosystem. What’s clear is that security concerns grow in complexity when it comes to Kubernetes and container technologies. Due to this, there is a greater need to protect the entire application lifecycle. We’ve listed below some of the potential threats affecting Kubernetes.

Malicious actors

Once a threat actor intrudes into your Kubernetes ecosystem, it becomes easy for them to spread the malicious actors across the cluster. This is possible because containers and pods interact with each other, and a corrupted container could cause the collapse of the entire application.

Malware running inside containers

In 2018, Tesla’s cloud infrastructure was breached, and crypto-mining malware was placed deep within the environment. The investigation revealed that a particular Kubernetes administrative portal wasn't password protected. Attackers exploited this misconfiguration to place malware inside a container.

Broken container images

Another intrusion method criminals employ is slipping in or leveraging vulnerabilities in container images and image registries. Regular image scanning, strict image creation policies, and using trusted registries are ways to secure Kubernetes from broken container images.

Compromised or rogue users

Attackers are constantly looking for exposed containers or portals with either no authentication system or a poor one. Such containers often fall into blindspots; way too often, the organizations will not even realize the exploitation or the breach.

While security is an issue in Kubernetes, it comes with native tools to help you cover the basics of cloud-native application security.

4Cs of Kubernetes Security

Kubernetes security for cloud-native applications is designed to have a layered approach derived from the Defense in Depth (DiD) model. The 4Cs model demands enforcement of security best practices at all four cloud layers, clusters, containers, and code.

Let’s understand these 4Cs in detail:

Cloud

The cloud or corporate data center is the outermost layer and first line of defense against cyberattacks. Moreover, this layer forms the base for all your components. With Kubernetes being a distributed system, the complexity of securing the cloud layer will only increase when containerized applications are spread across different cloud environments.

Administrators must thoroughly evaluate any access to a Kubernetes cluster. Therefore securing your cloud environment must be a priority. Although third-party cloud providers like AWS, Azure, Google, or Oracle recommend their security measures and best practices, you must ensure the implementation of practices like identity and access management (IAM) and zero trust policy.

Clusters

The second C after Cloud represents the Cluster level. At this stage, you must secure both cluster components like API calls, node access, etcd access, and applications or workloads running on the cluster. The internal Kubernetes components follow security practices like encrypted communication and TLS certificate authorization. However, one of the key elements at this level is the kube-API-server or Kubernetes API. It acts as an interface between external requests and Kubernetes clusters. Therefore, you must enforce the API authentication mechanism and TLS usage to harden cluster security.

Kubernetes offers several measures to secure cluster layers like pod networks, pod security policies, namespaces, and network policies.

Container

Container security involves restricting access to network ports. Any malicious actor that breaches the container layer can move within the environment, easily communicating with other containers and pods. In its default mode, Kubernetes offers minimal security guardrails to ensure faster software deployment. But you need to harden the security at this level by introducing robust governance policies to ensure container images are created and stored in trusted image registries.

You can secure the container layer by

• Scanning containers for known vulnerabilities and dependencies
• Signing trusted images to deploy containers with confidence
• Offering the least privilege for users inside containers

Code

The innermost layer is the Code, where developers must assume accountability to shift left for the application's overall security. It is the most targeted attack surface for any Kubernetes environment. There are many measures that you must take to safeguard your code. Policies like TCP encryption, static code analysis, security scanning, limiting communication ports, and automated testing against well-known service attacks should secure your code.

Securing Kubernetes the cloud-native way

As discussed, Kubernetes offers basic security features like equipping each pod with a unique IP address to block illegal requests. However, these simple measures won’t be enough given the seriousness of the security threat looming around Kubernetes applications. You must rely on security solutions and tools to monitor, track and mitigate threats and ensure compliance effectively.

Given the constant changes in the Kubernetes environment, with containers constantly added and removed, you need a cloud-native approach to security to keep up with the changing security policies and demands. Kubernetes security tools will empower you with a protective layer beyond a firewall for your application. They help you with 24/7 visibility, vulnerability detection, sanitizing network traffic, and secure container host.

While a gamut of tools available in the market can easily confuse any development team, we want to discuss the key areas that will undoubtedly need tools for protection.

Areas of Kubernetes that need added security

Workload security

Kubernetes workloads are simply the applications or programs that containers carry. Kubernetes workloads are vulnerable to many threats through corrupted nodes, pods, or containers. A compromised workload could wreak havoc within your environment giving access to secrets and confidential data directly or through other containers.

Using a software tool for workload security can help you automate security checks like identifying vulnerable container images and workload misconfigurations.

Workload configuration

Security issues through misconfigurations constitute a significant challenge in Kubernetes. If your workload configuration is not secure, attackers can exploit the same to change access rules or run illicit tasks. Further, they can change the configuration of applications that are already running. You can mitigate such risks through strong security steps and tools to implement least privilege and access policies.

Cluster configuration

Like workload configuration, cluster configuration is critical for avoiding unwanted incidents. But cluster configurations are not secure by default. You need to implement best practices to avoid misconfigurations. Using third-party tools, you can scan clusters against compliance benchmarks like CIS Benchmark, set up RBAC (Role-Based Access Control), and implement multi-factor security and TLS policies.

Kubernetes networking

There are many parts of a Kubernetes system that needs to be secured. There is the frontend and backend of applications hosted in Kubernetes, databases where data is stored and analyzed, and the pods and containers themselves.

Securing Kubernetes networking begins with a list of best practices, like installing a firewall to block unwanted requests from overloading hosts. You must use third-party tools to completely secure your network, like service mesh monitoring traffic and identifying breaches. Through Kubernetes networking, you can dictate how pods communicate with each other. You can also use tools to enforce strong network policies to manage traffic within the cluster, isolate pods, and riddle network architecture with security checkpoints.

Enterprise security controls

Investing time, effort, and money in enterprise security controls like enabling TLS encryption for workloads will pay rich dividends when securing Kubernetes. With compliance being one of the significant aspects of enterprise security, ensure industry standards and regulatory demands are met by automating compliance report generation for PCI, HIPAA, GDPR, etc.

Network security controls

By including security details within your Kubernetes workloads, you can ensure they follow specific network security controls when traversing on-prem or cloud environments. You can use a Kubernetes-native network policy tool like Kube-router or Kubernetes-native proxy to enforce network security policy at network layers.

Pod security policy

Pods form an essential unit within Kubernetes, comprising one or a set of containerized applications. Kubernetes Pod Security Policy imposes rules that pods must meet before running in the cluster. The other native tools that Kubernetes offers are measures like RBAC policies and admission controllers.

Kubernetes Nodes Security

A Kubernetes Node is a powerful concept within the Kubernetes ecosystem that enables the orchestration platform to simplify the containerization of applications. Simply put, Kubernetes nodes are the smallest computing unit that executes workloads. It could be your bare metal data center or virtual machine hosted on a cloud. A node contains IT resources to run pods in a Kubernetes cluster.

When a pod is to be executed, it is matched to a node that contains the required resources or services to create the runtime environment for the specific workload.

There are two types of nodes in Kubernetes:

• Control plane node: Also known as Master Node, it controls the entire cluster. Its key components are the Kubernetes API server to enable communication between nodes and cluster components, etcd to hold cluster data, node controller, Kube Scheduler, and Kubernetes agent.

• Worker node: It is the node that runs containerized workloads. Its two components are the Kubernetes agent and Kube proxy to enforce network rules on nodes.

Securing Kubernetes nodes

Given the critical role of nodes in Kubernetes, it is essential to approach node security carefully. Nodes are servers and must have similar security measures. For example, Kubernetes nodes shouldn’t be exposed to public networks and must be isolated. Some of the security strategies to secure nodes include:

• Reduce vulnerability by eliminating irrelevant OS components like libraries and applications.
• Tracking and monitoring logs to be proactive in detecting possible attacks.
• Remove unwanted user access and workloads from running on nodes.

Automate Kubernetes Security with Weave GitOps

Kubernetes is a mainstream approach and a very popular one. It facilitates faster runtime and simplified application management, empowering businesses to run cloud applications at scale and speed. It is safe to say that Kubernetes is here to stay, but so are the cyberattacks. Therefore Kubernetes security should be a priority for companies if it isn’t already. In this article, we discussed the significant loopholes that Kubernetes possess and the 4C security system that the orchestration tool offers for cloud-native security.

One widely accepted approach to simplifying container security is GitOps. With GitOps, you isolate policy enforcement from software development to ensure consistent security across the pipeline. GitOps is designed with security in mind.

Weave GitOps Enterprise is a full-stack GitOps platform that enables automatic continuous delivery of cloud-native applications. Weave GitOps automates policy management and remediation, introducing better security by design that starts from Git and goes all the way to production clusters.

While policy-driven deployment automation is critical to ensure Kubernetes security, it compromises developer flexibility. Weaveworks allows you to include policy as code to your workflows so that you can automate enforcing security and compliance by ensuring coding standards from source to production.

Contact Us for a demo and learn how we can help you secure your Kubernetes environment.