cis-oke-v150-5.4.4

DevOps & Security

Ensure Network Policy is Enabled and set as appropriate (Automated)

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5.4.4 Ensure Network Policy is Enabled and set as appropriate (Automated)

Profile Applicability

Level 1

Description

Use Network Policy to restrict pod to pod traffic within a cluster and segregate workloads.

Rationale

By default, all pod to pod traffic within a cluster is allowed. Network Policy creates a pod-level firewall that can be used to restrict traffic between sources. Pod traffic is restricted by having a Network Policy that selects it (through the use of labels). Once there is any Network Policy in a namespace selecting a particular pod, that pod will reject any connections that are not allowed by any Network Policy. Other pods in the namespace that are not selected by any Network Policy will continue to accept all traffic.

Network Policies are managed via the Kubernetes Network Policy API and enforced by a network plugin, simply creating the resource without a compatible network plugin to implement it will have no effect. OKE supports Network Policy enforcement through the use of Calico.

Impact

Network Policy requires the Network Policy add-on. This add-on is included automatically when a cluster with Network Policy is created, but for an existing cluster, needs to be added prior to enabling Network Policy.

Enabling/Disabling Network Policy causes a rolling update of all cluster nodes, similar to performing a cluster upgrade. This operation is long-running and will block other operations on the cluster (including delete) until it has run to completion.

If Network Policy is used, a cluster must have at least 2 nodes of type n1-standard-1 or higher. The recommended minimum size cluster to run Network Policy enforcement is 3 n1-standard-1 instances.

Enabling Network Policy enforcement consumes additional resources in nodes. Specifically, it increases the memory footprint of the kube-system process by approximately 128MB, and requires approximately 300 millicores of CPU.

Audit

Check for the following:

export OKE_CLUSTERID=<oke cluster id>
oci ce cluster get --cluster-id $OKE_CLUSTERID

Check settings for Network Policy is enabled set correctly for the cluster:

"kubernetesNetworkConfig": {
    "podsCidr": "10.244.0.0/16",
    "servicesCidr": "10.96.0.0/12",
    "networkPolicyConfig": {
        "isEnabled": true
    }
}

Remediation

Configure Network Policy for the Cluster.

Default Value

By default, Network Policy is disabled.

References

https://docs.cloud.oracle.com/en-us/iaas/Content/ContEng/Concepts/contengnetworkconfig.htm

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	4.4 Implement and Manage a Firewall on Servers - Implement and manage a firewall on servers, where supported. Example implementations include a virtual firewall, operating system firewall, or a third-party firewall agent.	x	x	x
v7	9.2 Ensure Only Approved Ports, Protocols and Services Are Running - Ensure that only network ports, protocols, and services listening on a system with validated business needs, are running on each system.		x	x
v7	9.4 Apply Host-based Firewalls or Port Filtering - Apply host-based firewalls or port filtering tools on end systems, with a default-deny rule that drops all traffic except those services and ports that are explicitly allowed.	x	x	x

MITRE ATT&CK Mappings

Techniques / Sub-techniques	Tactics	Mitigations
T1046	TA0007	M1030, M1042

Profile

Level 1 - OKE