Securing Kubernetes

Author: Sonika BS, Associate Engineer – CloudDevOps

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Kubernetes is an open-source platform used to manage containerized workloads and services. It provides a way to deploy, scale, and manage containerized applications. With its popularity and increase usage Kubernetes has become a target for security threats, and therefore, security is a crucial aspect of Kubernetes deployment.

Kubernetes security is important throughout the container lifecycle due to the distributed, dynamic nature of a Kubernetes cluster. Kubernetes security includes securing the containerized applications and the Kubernetes infrastructure itself.

A Red Hat survey of Kubernetes adoption and security showed that:

• 67% of companies have delayed or slowed down deployment due to a security issue.
• 37% of respondents identified revenue/customer loss as a result of a container and Kubernetes security incident.
• 50% of respondents are worried about misconfigurations and vulnerabilities, owing to the fact that containers and Kubernetes are highly customizable.

Considering all this security becomes crucial factor when deploying applications to Kubernetes. In this series of blog, we will discuss some of the key security practices and considerations for Kubernetes and how to implement those best practices in Kubernetes Cluster.

Why is Kubernetes Security important?

Kubernetes security is important for several reasons, including:

Protecting sensitive data

Kubernetes is often used to manage sensitive data, such as personal information or financial data. Protecting this data is crucial to prevent data breaches and maintain the trust of your customers.

Compliance

Many industries have strict regulations regarding data privacy and security, such as HIPAA in healthcare or PCI DSS in finance. Failure to comply with these regulations can result in severe penalties and damage to your reputation.

Protecting against attacks

Kubernetes clusters are vulnerable to various types of attacks, such as DDoS attacks, malware attacks, and data theft. Proper security measures can help prevent these attacks and minimize the damage if they do occur.

Ensuring Availability

Kubernetes is used to manage critical applications, and any disruption or downtime can have severe consequences. Ensuring the security of the cluster is key to maintaining availability and preventing downtime.

Common Kubernetes Security Risks

Here are some of the common Kubernetes security risks that organizations face:

Unauthorized access

Attackers may gain unauthorized access to the Kubernetes cluster, giving them access to sensitive data and the ability to launch attacks on other systems.

Container escapes

Containers can sometimes be used to break out of their container and access the host system, potentially leading to a full-scale breach of the cluster.

Malware

Attackers may use malware to compromise the Kubernetes cluster, allowing them to steal data or launch further attacks.

Data breaches

Sensitive data stored on the Kubernetes cluster may be vulnerable to theft or other types of data breaches.

Configuration errors

Misconfigured Kubernetes resources, such as Kubernetes services or network policies, can create security vulnerabilities that attackers can exploit.

Securing Kubernetes Cluster

You can think about security of Kubernetes Cluster in layers. The 3C’s of Kubernetes security are Clusters, Containers, and Code. Below are critical best practices you must implement to secure your Kubernetes clusters

Securing the Kubernetes Control Plane

The Kubernetes control plane is the central brain of the cluster that manages the overall state and configuration of the cluster. It includes components such as the API server, etcd, and kube-controller-manager. Securing the control plane is critical for securing the entire Kubernetes infrastructure. The first step in securing the control plane is to ensure that only authorized users can access the API server. This can be achieved by setting up RBAC (Role-Based Access Control) and authentication mechanisms like certificates or tokens.

Another important consideration is to keep the Kubernetes control plane up-to-date with the latest security patches and updates.

Securing Kubernetes Nodes

Kubernetes nodes are the worker machines that run the containerized applications. These nodes can be compromised if not secured properly. The following practices can help secure Kubernetes nodes:

• Keep the operating system up-to-date with the latest security patches and updates.
• Ensure that only necessary ports are open on the nodes.
• Use firewalls to restrict inbound and outbound traffic.
• Restrict access to the Kubernetes nodes to only authorized users.
• Disable unused services and daemons on the nodes.

Securing Kubernetes Pods

Kubernetes pods are the smallest deployable units in Kubernetes, and they run one or more containers. Pods are ephemeral and can be created and destroyed frequently. Securing Kubernetes pods is essential for securing containerized applications running in the cluster.

• One of the most important aspects of securing Kubernetes pods is to use container images from trusted sources. Container images can contain vulnerabilities, so it’s crucial to use images that have been scanned for security issues.
• Another important consideration is to ensure that only necessary ports are open in the container. Pods should be configured to listen only on necessary ports and protocols.

Accessing Service Accounts

A service account is a Kubernetes object that provides an identity for processes that run in a Pod. A service account can be used to access cluster resources, such as secrets and persistent volumes.

When you create a cluster, Kubernetes automatically creates a default service account for each namespace. You can create additional service accounts as needed.

To use a service account, you need to specify the service account name in the Pod spec. You can also specify the service account name in the container spec.

Network Security

Network security is crucial for securing Kubernetes deployments. Kubernetes supports a range of network security features such as network policies and service mesh.

• Network policies can be used to control the network traffic between pods in a Kubernetes cluster. With network policies, you can specify which pods can communicate with each other and which ports and protocols they can use.
• Service mesh is a layer of infrastructure that handles service-to-service communication within a Kubernetes cluster. Service mesh provides features such as traffic control, load balancing, and encryption, which can help improve the security of Kubernetes applications.

Monitoring and Logging

Monitoring and logging are essential for detecting and responding to security threats in a Kubernetes environment. Kubernetes provides various built-in monitoring and logging mechanisms that can be used to monitor the cluster.

• Kubernetes provides a built-in monitoring tool called Prometheus, which can be used to collect and store metrics from the Kubernetes cluster. Prometheus can be used to monitor the performance and health of Kubernetes applications and infrastructure.
• Kubernetes also provides a built-in logging mechanism called Fluentd, which can be used to collect and store logs from the Kubernetes cluster. Fluentd can be configured to send logs to various destinations, including Elasticsearch and Splunk.

Kubernetes API server Bypass risks:

The Kubernetes API server is a critical component of any Kubernetes cluster. It provides a RESTful interface for users and applications to interact with the cluster. However, the API server is also a potential target for attackers. There are several ways that an attacker could bypass the API server’s security and gain unauthorized access to the cluster. There are a few steps that can be taken to mitigate the risks of API server bypass attacks. These steps include:

• Keeping Kubernetes up to date with the latest security patches.
• Configuring Kubernetes clusters securely.
• Educating users about social engineering attacks.
• Using a security scanner to identify misconfigurations and vulnerabilities.

General Security Guidelines

Here are some other security considerations / best practices that one should follow:-

• Using strong passwords and rotating them regularly.
• Enable two-factor authentication for all user accounts.
• Restricting access to the Kubernetes API server to only necessary users.
• Regularly backing up the Kubernetes etcd database.
• Regularly testing the Kubernetes security measures and updating

Wrapping up

Now you understand why Kubernetes security is important and what all best practices we can implement to secure all the three layers in Kubernetes i.e. Cluster, Nodes and Pods. In the next part of this blog post, I will be explaining how we can actually implement all these practices with some live examples to secure Kubernetes clusters.