OWASP Global AppSec US 2021

With the usage of Kubernetes in large companies ever increasing, it is important to get security right early on in the adoption process. As with any new technology best practices are still emerging, so there is no “one true way” to secure a cluster.

When it comes to clusters big and small, many mistakes are still made during and these mistakes often come with increased risk at very little cost of putting them right.

The goal of this talk is to be a practical, defence-oriented look at two main areas of Kubernetes security. This is usable defensive measures you can implement now (well, once you’ve seen my talk)

The information used is based on the real-world cluster reviews that I’ve done in previous roles, knowledge of Kubernetes security built up via participation in the project and initiatives like the CIS benchmarks and also the intelligence on attack patterns coming from our security research team.

First we’ll look at common mis-configurations that are seen in newly deployed clusters. As Kubernetes is a relatively complex product, typically companies will deploy default configurations which are not always secure.

There are some, sometimes surprising, defaults chosen by providers, and we’ll discuss those. For one example, the use of a generic cluster admin credential, which can only be revoked by changing the keys for an entire certificate authority.

In addition to default security the talk will look at approaches to Kubernetes cluster security that can work and scale up well. There’s a lot of variety on how companies deploy the product, in terms of cluster size and whether developers have direct access to the main Kubernetes API and they have consequences for security, so we can recommend approaches that will work for different threat models.

Whilst having shared clusters amongst groups of developers may be appropriate for internal clusters, where companies are using Kubernetes in a multi-tenant configuration with Internet facing applications, it is difficult to properly segregate permissions to enable this to operate securely, and the talk will delve into some specifics around that.