Joshua Jebaraj
May 9, 2023

Understanding Kubernetes Service Accounts: Authentication and Security

Table of Contents:

  1. Introduction
  2. What are Kubernetes Service Accounts?
  3. Why are Kubernetes Service Accounts Important?
  4. How do Service Accounts Work in Kubernetes?
  5. How to Authenticate Kubernetes Service Accounts?
  6. Conclusion

Introduction

Today, most IT companies globally use Kubernetes. Its popularity has surpassed expectations, and it is estimated that between 2022-2030, K8s will grow at a CAGR of 23.40% and reach USD 7.8 billion at the end of this decade.  

Kubernetes is a fascinating container orchestration system that helps automate containerized applications' deployment, scaling, and management. However, to ensure the security and integrity of your Kubernetes cluster, you need to have a robust authentication and authorization system in place. This is where service accounts come in handy.

In this blog post, we'll dive deep into the topic of Kubernetes service accounts and cover all the essential aspects of this topic. We'll discuss service accounts, how they work, and how they're authenticated in Kubernetes. We'll also cover best practices for securing your service accounts and the different options available for customizing your service accounts. 

So, buckle up and get ready to explore the world of Kubernetes service accounts! And if you are looking for expert assistance with securing your Kubernetes containers, then get in touch with consultants at we45.

What are Kubernetes Service Accounts?

In Kubernetes, service accounts enable applications to authenticate with the Kubernetes API server and perform various actions in the cluster. These actions can include creating or deleting pods, secrets, or jobs, among other things.

Service accounts act as machine users that allow applications to interact with the Kubernetes API server on behalf of a user or a group of users. While users are typically managed outside the cluster, service accounts are managed by the cluster itself.

When a pod is deployed in a namespace, a service account token is mounted on the pod in the path: run/secrets/kubernetes.io/serviceaccount. 

This token is used to authenticate the pod with Kubernetes, enabling the pod to perform actions in the cluster.

The service account token is a JSON web token (JWT) with a public-private key pair. The private key is used to sign the token, and the public key is used to verify it. This token is generated when the service account is created and is stored securely in the cluster.

To avoid attacks, Kubernetes provides several security measures for securing service accounts, such as Role-Based Access Control (RBAC), pod security, and network policies. 

You can also disable the automounting of service account tokens on pods that don't require them, reducing the attack surface of your Kubernetes deployment.

Why are Kubernetes Service Accounts Important?

Kubernetes service accounts play a critical role in securing a Kubernetes cluster by providing a way to authenticate and authorize applications running on the cluster. 

Here are some reasons why service accounts are essential.

  • Security: Service accounts provide a mechanism for authenticating applications to the Kubernetes API server, which helps prevent unauthorized access and potential security breaches.
  • Access Control: By creating and managing service accounts, administrators can enforce access control policies to limit applications' permissions on the cluster.
  • Automation: Service accounts allow for the automation of tasks by providing a way for applications to authenticate themselves with the Kubernetes API server and perform actions like deploying a pod, creating a secret, or running a job in the cluster.
  • Integration: You can use service accounts to integrate Kubernetes with other systems, like CI/CD pipelines or external authentication providers, to provide a more comprehensive security and access control strategy.

All in all, Kubernetes service accounts are a crucial component of a secure and well-managed Kubernetes cluster. By adequately managing service accounts and their associated tokens, administrators can ensure that applications are authorized to perform only the necessary actions and that the cluster remains secure from potential threats.

How do Service Accounts Work in Kubernetes?

When a pod is deployed in a namespace, a service account token is mounted on the pod in the path run/secrets/kubernetes.io/serviceaccount. This token is used to authenticate the service account with the Kubernetes API server to perform actions in the cluster.

By default, a service account token has no access to Kubernetes resources. However, the token mounted on the pod can have access to a lot of privileges. If an attacker gains access to the pod, they can steal the token and escalate their privileges in the cluster.

To avoid this, you can set the automountServiceAccountToken property to false in the pod specification if the pod doesn't need to access other Kubernetes objects or services.

How to Authenticate Kubernetes Service Accounts?

A service account token is a JSON web token (JWT) that uses a public-private key pair. The private key is typically used to sign the token, and the public key is used to verify it. The Kubernetes API server verifies the token's signature to authenticate the service account.

If a Kubernetes cluster needs to pull a container image from a private registry, it must have access to a Docker registry token. You can add an imagePullSecrets parameter to your service account to authenticate your Kubernetes cluster with the private registry.

Conclusion

Kubernetes service accounts are machine users that enable applications to interact with the Kubernetes API to perform actions in the cluster. The cluster manages service accounts, and their tokens can authenticate the service accounts with Kubernetes. Securing the tokens and limiting their privileges are essential when using service accounts to prevent security breaches.

If you are struggling to secure your Kubernetes applications, we are here to help! Kubernetes security can be challenging, and automated tests aren't always beneficial. At We45, we customize a Kubernetes security solution that meets your business's exact needs

Get in touch with us to know more!