Creating a Custom Benchmark Version for Running a Cluster Scan

Each Benchmark Version defines a set of test configuration files that define the Compliance tests to be run by the kube-bench tool. The rancher-compliance application installs a few default Benchmark Versions which are listed under Compliance application menu.

But in the following cases, a custom configuration or remediation may be required:

• Non-standard file locations: When Kubernetes binaries, configuration or certificate paths deviate from upstream benchmark defaults. Example: Unlike traditional Kubernetes, K3s bundles control plane components into a single binary. Therefore, --anonymous-auth flag presence and configuration should be verified in K3s' logs (journalctl), not via kube-apiserver process checks (ps).

• Alternative risk mitigations: If a setup doesn't meet a check but has an equally effective compensating control with justification. Or simply is not concerned by the check requirement because of its design. Example: By default, K3s embeds the api server within the k3s process. There is no API server pod specification file, so verifying the latter's file permissions is not required.

1. Prepare the Custom Benchmark Version ConfigMap

To create a custom benchmark version, first you need to create a ConfigMap containing the benchmark version's config files and upload it to your Kubernetes cluster where you want to run the scan.

To prepare a custom benchmark version ConfigMap, suppose we want to add a custom Benchmark Version named foo.

1. Create a directory named foo and inside this directory, place all the config YAML files that the kube-bench tool looks for. For example, here are the config YAML files for a Generic CIS 1.5 Benchmark Version https://github.com/aquasecurity/kube-bench/tree/master/cfg/cis-1.5

2. Place the complete config.yaml file, which includes all the components that should be tested.

3. Add the Benchmark version name to the target_mapping section of the config.yaml:

   target_mapping:
     "foo":
       - "master"
       - "node"
       - "controlplane"
       - "etcd"
       - "policies"

4. Upload this directory to your Kubernetes Cluster by creating a ConfigMap:

   kubectl create configmap -n <namespace> foo --from-file=<path to directory foo>

2. Add a Custom Benchmark Version to a Cluster

1. In the upper left corner, click ☰ > Cluster Management.
2. On the Clusters page, go to the cluster where you want to add a custom benchmark and click Explore.
3. In the left navigation bar, click Compliance > Benchmark Version.
4. Click Create.
5. Enter the Name and a description for your custom benchmark version.
6. Choose the cluster provider that your benchmark version applies to.
7. Choose the ConfigMap you have uploaded from the dropdown.
8. Add the minimum and maximum Kubernetes version limits applicable, if any.
9. Click Create.

3. Create a New Profile for the Custom Benchmark Version

To run a scan using your custom benchmark version, you need to add a new Profile pointing to this benchmark version.

1. In the upper left corner, click ☰ > Cluster Management.
2. On the Clusters page, go to the cluster where you want to add a custom benchmark and click Explore.
3. In the left navigation bar, click Compliance > Profile.
4. Click Create.
5. Provide a Name and description. In this example, we name it foo-profile.
6. Choose the Benchmark Version from the dropdown.
7. Click Create.

4. Run a Scan Using the Custom Benchmark Version

Once the Profile pointing to your custom benchmark version foo has been created, you can create a new Scan to run the custom test configs in the Benchmark Version.

To run a scan,

1. In the upper left corner, click ☰ > Cluster Management.
2. On the Clusters page, go to the cluster where you want to add a custom benchmark and click Explore.
3. In the left navigation bar, click Compliance > Scan.
4. Click Create.
5. Choose the new cluster scan profile.
6. Click Create.

Result: A report is generated with the scan results. To see the results, click the name of the scan that appears.