trbngr / road-to-secure-kubernetes

Hardening a sketchy containerized application one step at a time

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Road to Secure Kubernetes

Hardening a containerized application one step at a time

This repository hosts a tutorial on security hardening a containerized workload in Kubernetes. Its a self-guided, hands on guide from the "default" settings we see in Kubernetes to a relatively well configured workload. The mitigations described are by no means exhaustive but show a lot of low hanging fruit anyone can take advantage of to harden a workload.

Prerequistes

To run through the tutorial you'll need

  • Docker
  • kind to run a Kubernetes cluster on your laptop with Docker
  • kubectl the Kubernetes CLI to interact with the cluster
  • helm to install Cilium in our cluster

Before you begin, install the kind cluster as follows:

$ cd cluster

# Install kind cluster
$ kind create cluster --config config.yaml

# Install Cilium into kind cluster
$ helm repo add cilium https://helm.cilium.io/
$ helm install cilium cilium/cilium --version 1.9.10 \
   --namespace kube-system \
   --set nodeinit.enabled=true \
   --set kubeProxyReplacement=partial \
   --set hostServices.enabled=false \
   --set externalIPs.enabled=true \
   --set nodePort.enabled=true \
   --set hostPort.enabled=true \
   --set bpf.masquerade=false \
   --set image.pullPolicy=IfNotPresent \
   --set ipam.mode=kubernetes

# Wait to be installed
$ kubectl wait --for=condition=available deployment.apps/cilium-operator -n kube-system

# Install Nginx Ingress controller
$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/main/deploy/static/provider/kind/deploy.yaml
$ kubectl wait --for=condition=available deployment.apps/ingress-nginx-controller -n ingress-nginx

Once you can run curl http://localhost and get back a 404 like this one from Nginx, you're ready to start

<html>
<head><title>404 Not Found</title></head>
<body>
<center><h1>404 Not Found</h1></center>
<hr><center>nginx</center>
</body>
</html>

How-to

The tutorial shows the step by step progression of an application configuration. Each configuration or step has a corresponding git tag from 1 to 10. Start at 1 and move from tag to tag. For every change there is a detailed explaination of whats been changed and what the change mitigates.

  • Step 1 is our starting point. If I was to hazard a guess, about 95% of Kubernetes application are deployed in this state. Its a functioning application with some vulnerabilities as you'll see.
  • Step 2 uses a non-root user in the container
  • Step 3 leverages read-only filesystems
  • Step 4 adds network policies
  • Step 5 uses a scratch container
  • Step 6 adds resource requests and limits
  • Step 7 drops linux capabilities
  • Step 8 disables privilege escalation
  • Step 9 adds seccomp profile
  • Step 10 removes service account credentials

Navigate to each tag to learn more!

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Hardening a sketchy containerized application one step at a time


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