├── Dockerfile.capsh ├── Dockerfile.naughty ├── Dockerfile.user ├── LICENSE ├── README.md ├── Vagrantfile ├── default.conf ├── mount-root.yaml ├── naughty.yaml ├── non-root-user.yaml ├── non-root.yaml ├── pod.yaml └── priv.yaml /Dockerfile.capsh: -------------------------------------------------------------------------------- 1 | FROM nginx 2 | RUN apt-get update && apt-get install -y libcap2-bin 3 | -------------------------------------------------------------------------------- /Dockerfile.naughty: -------------------------------------------------------------------------------- 1 | FROM alpine 2 | RUN echo 'while :; do echo "I could be mining crypto-currency"; sleep 3; done'> mine.sh 3 | RUN cat mine.sh 4 | CMD ["/bin/sh", "mine.sh"] 5 | -------------------------------------------------------------------------------- /Dockerfile.user: -------------------------------------------------------------------------------- 1 | FROM nginx:capsh 2 | 3 | # Serve from port 8080 since you can't bind to port 80 as non-root 4 | COPY ./default.conf /etc/nginx/conf.d/default.conf 5 | 6 | RUN touch /var/run/nginx.pid && \ 7 | chown -R 1001:1001 /var/run/nginx.pid && \ 8 | chown -R 1001:1001 /var/cache/nginx 9 | 10 | USER 1001 -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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See some ways this can easily be abused! 3 | 4 | ## Kubernetes cluster 5 | I used a single-node Kubernetes cluster running in a VM on my laptop, that I set up using Vagrant. The Vagrantfile is included in this repo, and it's based on the set-up [described here](https://medium.com/@lizrice/kubernetes-in-vagrant-with-kubeadm-21979ded6c63). 6 | 7 | You could use any Kubernetes cluster where you can get access to host machine / VM, but note that if you have multiple nodes in your cluster, you'll only be able to see containerized processes on the same node where the pod is actually running. 8 | 9 | ## Docker images 10 | This demo uses a few Docker images. For the sake of ease and to avoid any network dependencies during the live demo I built and tagged them on the VM as follows: 11 | 12 | ``` 13 | # nginx image with cash utility installed 14 | $ docker build -f Dockerfile.capsh -t nginx:capsh . 15 | 16 | # non-root version of the nginx image 17 | $ docker build -f Dockerfile.user -t nginx:user . 18 | 19 | # a very naughty container! 20 | $ docker build -f Dockerfile.naughty -t lizrice:naughty:0.1 . 21 | ``` 22 | 23 | The tags I've used for nginx are for convenience, and are not good practice for anything other than local demos. I haven't pushed these images to Docker Hub. 24 | 25 | ## Terminal setup 26 | When I gave the talk, I split my terminal window into three panes, all of which were ssh'd into the VM. 27 | 28 | I used the top one to run and exec into pods, and the middle one to run commands on the host while pod(s) were running, to see what's happening from the host's perspective. The third pane is constantly watching for running pods: 29 | 30 | ``` 31 | $ watch kubectl get pods 32 | ``` 33 | 34 | ## Pod YAML 35 | I edited the YAML live, but in this repo you'll find files for each of the different scenarios: 36 | 37 | * `pod.yaml` - running the nginx image as root 38 | * `priv.yaml` - add the privileged securityContext 39 | * `non-root.yaml` - try to run the nginx image with runAsNonRoot securityContext 40 | * `non-root-user.yaml` - run the non-root nginx image 41 | * `mount-root.yaml` - run nginx as root, with the host's root filesystem mounted as /host inside the container 42 | * `naughty.yaml` - run the naughty container 43 | 44 | Run a pod with `kubectl apply -f pod.yaml`. Stop them with `kubectl delete pod nginx`. Exec into a shell inside the container with `kubectl exec -it nginx /bin/bash`. I aliased `k` for `kubectl` to save some keypresses. 45 | 46 | Aside from `naughty.yaml` these YAML files all use the same name for the nginx pod, so you won't be able to run them simultaneously. 47 | 48 | ## Observing processes from the host's perspective 49 | I often run a `sleep` command inside a container, and then find any sleep processes from the host's perspective. You might find these useful: 50 | ``` 51 | # Find process ID's for any sleep processes 52 | pidof sleep 53 | 54 | # Print out user name & ID for any sleep processes 55 | ps -C sleep -o user,uid 56 | ``` 57 | 58 | [![Running with Scissors](https://img.youtube.com/vi/ltrV-Qmh3oY/0.jpg)](https://youtu.be/ltrV-Qmh3oY) 59 | 60 | 61 | -------------------------------------------------------------------------------- /Vagrantfile: -------------------------------------------------------------------------------- 1 | # -*- mode: ruby -*- 2 | # vi: set ft=ruby : 3 | 4 | # After loading this 5 | # Install a pod network 6 | # $ kubectl apply -f https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n') 7 | 8 | # Allow pods to run on the master node 9 | # $ kubectl taint nodes --all node-role.kubernetes.io/master- 10 | 11 | $script = <<-SCRIPT 12 | 13 | # Install kubernetes 14 | apt-get update && apt-get install -y apt-transport-https 15 | curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add - 16 | cat </etc/apt/sources.list.d/kubernetes.list 17 | deb http://apt.kubernetes.io/ kubernetes-xenial main 18 | EOF 19 | apt-get update 20 | apt-get install -y kubelet kubeadm kubectl 21 | 22 | # kubelet requires swap off 23 | swapoff -a 24 | 25 | # This adds the line twice, but the second time doesn't matter 26 | sed '/ExecStart=/a Environment="KUBELET_EXTRA_ARGS=--cgroup-driver=cgroupfs"' /etc/systemd/system/kubelet.service.d/10-kubeadm.conf 27 | 28 | # Get the IP address that VirtualBox has given this VM 29 | IPADDR=`ifconfig enp0s8 | grep Mask | awk '{print $2}'| cut -f2 -d:` 30 | echo This VM has IP address $IPADDR 31 | 32 | # Set up Kubernetes 33 | kubeadm init --apiserver-cert-extra-sans=$IPADDR --node-name vagrant 34 | 35 | # Set up admin creds for the vagrant user 36 | echo Copying credentials to /home/vagrant... 37 | sudo --user=vagrant mkdir -p /home/vagrant/.kube 38 | cp -i /etc/kubernetes/admin.conf /home/vagrant/.kube/config 39 | chown $(id -u vagrant):$(id -g vagrant) /home/vagrant/.kube/config 40 | 41 | # User will need to complete the setup: 42 | echo "" 43 | echo As well as adding pod networking you will probably want to allow pods to run on this master node: 44 | echo "" 45 | echo kubectl taint nodes --all node-role.kubernetes.io/master- 46 | echo "" 47 | SCRIPT 48 | 49 | Vagrant.configure("2") do |config| 50 | config.vm.box = "bento/ubuntu-16.04" 51 | config.vm.network "private_network", type: "dhcp" 52 | config.vm.synced_folder ".", "/kubecon" 53 | config.vm.provision "docker" 54 | config.vm.provision "shell", inline: $script 55 | end 56 | -------------------------------------------------------------------------------- /default.conf: -------------------------------------------------------------------------------- 1 | server { 2 | listen 8080; 3 | server_name localhost; 4 | location / { 5 | root /var/www/htdocs; 6 | index index.html index.htm; 7 | } 8 | } -------------------------------------------------------------------------------- /mount-root.yaml: -------------------------------------------------------------------------------- 1 | apiVersion: v1 2 | kind: Pod 3 | metadata: 4 | name: nginx 5 | labels: 6 | app: nginx 7 | spec: 8 | containers: 9 | - name: nginx 10 | image: nginx:capsh 11 | volumeMounts: 12 | - name: host 13 | mountPath: /host 14 | volumes: 15 | - name: host 16 | hostPath: 17 | path: "/" 18 | -------------------------------------------------------------------------------- /naughty.yaml: -------------------------------------------------------------------------------- 1 | apiVersion: v1 2 | kind: Pod 3 | metadata: 4 | name: naughty 5 | labels: 6 | app: naughty 7 | spec: 8 | containers: 9 | - name: naughty 10 | image: lizrice/naughty:0.1 11 | -------------------------------------------------------------------------------- /non-root-user.yaml: -------------------------------------------------------------------------------- 1 | apiVersion: v1 2 | kind: Pod 3 | metadata: 4 | name: nginx 5 | labels: 6 | app: nginx 7 | spec: 8 | containers: 9 | - name: nginx 10 | image: nginx:user 11 | securityContext: 12 | runAsNonRoot: true 13 | # This pod succeeds because the image is built to run as a non-root user 14 | -------------------------------------------------------------------------------- /non-root.yaml: -------------------------------------------------------------------------------- 1 | apiVersion: v1 2 | kind: Pod 3 | metadata: 4 | name: nginx 5 | labels: 6 | app: nginx 7 | spec: 8 | containers: 9 | - name: nginx 10 | image: nginx:capsh 11 | securityContext: 12 | runAsNonRoot: true 13 | # This pod fails because runAsNonRoot is incompatible with the image, which is built to run as root 14 | -------------------------------------------------------------------------------- /pod.yaml: -------------------------------------------------------------------------------- 1 | apiVersion: v1 2 | kind: Pod 3 | metadata: 4 | name: nginx 5 | labels: 6 | app: nginx 7 | spec: 8 | containers: 9 | - name: nginx 10 | image: nginx:capsh 11 | -------------------------------------------------------------------------------- /priv.yaml: -------------------------------------------------------------------------------- 1 | apiVersion: v1 2 | kind: Pod 3 | metadata: 4 | name: nginx 5 | labels: 6 | app: nginx 7 | spec: 8 | containers: 9 | - name: nginx 10 | image: nginx:capsh 11 | securityContext: 12 | privileged: true 13 | # Run the capsh command inside this container to see the additional privileges that this 14 | # security context grants --------------------------------------------------------------------------------