Cis Ocp V190 4.2.6

CIS Red Hat OpenShift Container Platform Benchmark v1.9.0 - Control 4.2.6

Profile Applicability

• Level: 1

Description

Do not disable timeouts on streaming connections.

Rationale

Setting idle timeouts ensures that you are protected against Denial-of-Service attacks, inactive connections and running out of ephemeral ports.

Note: By default, --streaming-connection-idle-timeout is set to 4 hours which might be too high for your environment. Setting this as appropriate would additionally ensure that such streaming connections are timed out after serving legitimate use cases.

Impact

Long-lived connections could be interrupted.

Audit Procedure

OpenShift uses the kubernetes default of 4 hours for the streaming-connection-idle-timeout argument. Unless the cluster administrator has added the value to the node configuration, the default will be used. The value is a timeout for HTTP streaming sessions going through a kubelet, like the port-forward, exec, or attach pod operations. The streaming-connection-idle-timeout should not be disabled by setting it to zero, but it can be lowered. Note that if the value is set too low, then users using those features may experience a service interruption due to the timeout.

The kubelet configuration is currently serialized as an ignition configuration, so it can be directly edited. However, there is also a new kubelet-config-controller added to the Machine Config Controller (MCC). This allows you to create a KubeletConfig custom resource (CR) to edit the kubelet parameters.

Run the following command to view the streaming connection timeout for each node:

for node in $(oc get nodes -ojsonpath='{.items[*].metadata.name}'); do
oc get --raw /api/v1/nodes/$node/proxy/configz | jq '.kubeletconfig.streamingConnectionIdleTimeout'
done

Verify the values returned for each node are not 0.

Remediation

Follow the instructions in the documentation to create a kubeletconfig CRD and set the streamingConnectionIdleTimeout to the desired value. Do not set the value to 0.

Default Value

By default, streamingConnectionIdleTimeout is set to 4 hours.

References

1. https://docs.openshift.com/container-platform/latest/architecture/control-plane.html#understanding-machine-config-operator_control-plane
2. https://docs.openshift.com/container-platform/latest/post_installation_configuration/machine-configuration-tasks.html#create-a-kubeletconfig-crd-to-edit-kubelet-parameters_post-install-machine-configuration-tasks
3. https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet/
4. https://github.com/kubernetes/kubernetes/pull/18552

CIS Controls

MITRE ATT&CK Mappings

Profile

Level 1 (Automated)