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kube-bench is a Go application that checks whether Kubernetes is deployed securely by running the checks documented in the [CIS Kubernetes Benchmark](https://www.cisecurity.org/benchmark/kubernetes/).
1. kube-bench implements the [CIS Kubernetes Benchmark](https://www.cisecurity.org/benchmark/kubernetes/) as closely as possible. Please raise issues here if kube-bench is not correctly implementing the test as described in the Benchmark. To report issues in the Benchmark itself (for example, tests that you believe are inappropriate), please join the [CIS community](https://cisecurity.org).
1. There is not a one-to-one mapping between releases of Kubernetes and releases of the CIS benchmark. See [CIS Kubernetes Benchmark support](#cis-kubernetes-benchmark-support) to see which releases of Kubernetes are covered by different releases of the benchmark.
1. It is impossible to inspect the master nodes of managed clusters, e.g. GKE, EKS and AKS, using kube-bench as one does not have access to such nodes, although it is still possible to use kube-bench to check worker node configuration in these environments.
By default, kube-bench will determine the test set to run based on the Kubernetes version running on the machine, but please note that kube-bench does not automatically detect OpenShift and GKE - see the section below on [Running kube-bench](https://github.com/aquasecurity/kube-bench#running-kube-bench).
* Run kube-bench from inside a container (sharing PID namespace with the host). See [Running inside a container](#running-inside-a-container) for additional details.
* Run a container that installs kube-bench on the host, and then run kube-bench directly on the host. See [Installing from a container](#installing-from-a-container) for additional details.
* install the latest binaries from the [Releases page](https://github.com/aquasecurity/kube-bench/releases), though please note that you also need to download the config and test files from the `cfg` directory. See [Download and Install binaries](#download-and-install-binaries) for details.
* Compile it from source. See [Installing from sources](#installing-from-sources) for details.
By default kube-bench attempts to auto-detect the running version of Kubernetes, and map this to the corresponding CIS Benchmark version. For example, Kubernetes version 1.15 is mapped to CIS Benchmark version `cis-1.15` which is the benchmark version valid for Kubernetes 1.15.
kube-bench also attempts to identify the components running on the node, and uses this to determine which tests to run (for example, only running the master node tests if the node is running an API server).
kube-bench uses the Kubernetes API, or access to the `kubectl` or `kubelet` executables to try to determine the Kubernetes version, and hence which benchmark to run. If you wish to override this, or if none of these methods are available, you can specify either the Kubernetes version or CIS Benchmark as a command line parameter.
You can specify a particular version of Kubernetes by setting the `--version` flag or with the `KUBE_BENCH_VERSION` environment variable. The value of `--version` takes precedence over the value of `KUBE_BENCH_VERSION`.
Check the contents of the benchmark directory under `cfg` to see which targets are available for that benchmark. Each file except `config.yaml` represents a target (also known as a `control` in other parts of this documentation).
If no targets are specified, `kube-bench` will determine the appropriate targets based on the CIS Benchmark version and the components detected on the node. The detection is done by verifying which components are running, as defined in the config files (see [Configuration](#configuration).
You can avoid installing kube-bench on the host by running it inside a container using the host PID namespace and mounting the `/etc` and `/var` directories where the configuration and other files are located on the host so that kube-bench can check their existence and permissions.
> Note: the tests require either the kubelet or kubectl binary in the path in order to auto-detect the Kubernetes version. You can pass `-v $(which kubectl):/usr/local/mount-from-host/bin/kubectl` to resolve this. You will also need to pass in kubeconfig credentials. For example:
You can run kube-bench inside a pod, but it will need access to the host's PID namespace in order to check the running processes, as well as access to some directories on the host where config files and other files are stored.
The default labels applied to master nodes has changed since Kubernetes 1.11, so if you are using an older version you may need to modify the nodeSelector and tolerations to run the job on the master node.
There is a `job-eks.yaml` file for running the kube-bench node checks on an EKS cluster. The significant difference on EKS is that it's not possible to schedule jobs onto the master node, so master checks can't be performed
1. To create an EKS Cluster refer to [Getting Started with Amazon EKS](https://docs.aws.amazon.com/eks/latest/userguide/getting-started.html) in the *Amazon EKS User Guide*
- Information on configuring `eksctl`, `kubectl` and the AWS CLI is within
2. Create an [Amazon Elastic Container Registry (ECR)](https://docs.aws.amazon.com/AmazonECR/latest/userguide/what-is-ecr.html) repository to host the kube-bench container image
#### Report kube-bench findings to AWS Security Hub
You can configure kube-bench with the `--asff` option to send findings to AWS Security Hub for any benchmark tests that fail or that generate a warning. See [this page][kube-bench-aws-security-hub] for more information on how to enable the kube-bench integration with AWS Security Hub.
kube-bench includes a set of test files for Red Hat's OpenShift hardening guide for OCP 3.10 and 3.11. To run this you will need to specify `--benchmark rh-07`, or `--version ocp-3.10` or `--version ocp-3.11`
when you run the `kube-bench` command (either directly or through YAML).
There is work in progress on a [CIS Red Hat OpenShift Container Platform Benchmark](https://workbench.cisecurity.org/benchmarks/5248) which we believe should cover OCP 4.* and we intend to add support in kube-bench when it's published.
It is possible to manually install and run kube-bench release binaries. In order to do that, you must have access to your Kubernetes cluster nodes. Note that if you're using one of the managed Kubernetes services (e.g. EKS, AKS, GKE), you will not have access to the master nodes of your cluster and you can’t perform any tests on the master nodes.
First, log into one of the nodes using SSH.
Install kube-bench binary for your platform using the commands below. Note that there may be newer releases available. See [releases page](https://github.com/aquasecurity/kube-bench/releases).
If you manually downloaded the kube-bench binary (using curl command above), you have to specify the location of configuration directory and file. For example:
If Go is installed on the target machines, you can simply clone this repository and run as follows (assuming your [`GOPATH` is set](https://github.com/golang/go/wiki/GOPATH)):
- [FAIL] indicates that the test was run successfully, and failed. The remediation output describes how to correct the configuration, or includes an error message describing why the test could not be run.
- [WARN] means this test needs further attention, for example it is a test that needs to be run manually. Check the remediation output for further information.
- If the test is Manual, this always generates WARN (because the user has to run it manually)
- If the test is Scored, and kube-bench was unable to run the test, this generates FAIL (because the test has not been passed, and as a Scored test, if it doesn't pass then it must be considered a failure).
- If the test is Not Scored, and kube-bench was unable to run the test, this generates WARN.
- If the test is Scored, type is empty, and there are no `test_items` present, it generates a WARN. This is to highlight tests that appear to be incompletely defined.
Kubernetes configuration and binary file locations and names can vary from installation to installation, so these are configurable in the `cfg/config.yaml` file.
If you are using one of the example `job*.yaml` files, you will need to edit the `command` field, for example `["kube-bench", "-v", "3"]`. Once the job has run, the logs can be retrieved using `kubectl logs` on the job's pod.
The tests (or "controls") are represented as YAML documents (installed by default into `./cfg`). There are different versions of these test YAML files reflecting different versions of the CIS Kubernetes Benchmark. You will find more information about the test file YAML definitions in our [documentation](docs/README.md).
If you decide that a recommendation is not appropriate for your environment, you can choose to omit it by editing the test YAML file to give it the check type `skip` as in this example:
Going forward we plan to release updates to kube-bench to add support for new releases of the CIS Benchmark. Note that these are not released as frequently as Kubernetes releases.
Our makefile contains targets to test your current version of kube-bench inside a [Kind](https://kind.sigs.k8s.io/) cluster. This can be very handy if you don't want to run a real Kubernetes cluster for development purposes.
First, you'll need to create the cluster using `make kind-test-cluster` this will create a new cluster if it cannot be found on your machine. By default, the cluster is named `kube-bench` but you can change the name by using the environment variable `KIND_PROFILE`.
Next, you'll have to build the kube-bench docker image using `make build-docker`, then we will be able to push the docker image to the cluster using `make kind-push`.
Finally, we can use the `make kind-run` target to run the current version of kube-bench in the cluster and follow the logs of pods created. (Ctrl+C to exit)
Every time you want to test a change, you'll need to rebuild the docker image and push it to cluster before running it again. ( `make build-docker kind-push kind-run` )
- Please include a comment with the results before and after your change.
- Your PR is more likely to be accepted if it includes tests. (We have not historically been very strict about tests, but we would like to improve this!).
- You're welcome to submit a draft PR if you would like early feedback on an idea or an approach.
