KubernetesOverview
Do not generally permit containers which require the use of HostPorts.
Rationale
Host ports connect containers directly to the host's network. This can bypass controls such as network policy.
There should be at least one admission control policy defined which does not permit containers which require the use of HostPorts.
If you need to run containers which require HostPorts, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
Impact
Pods defined with hostPort settings in either the container, initContainer or
ephemeralContainer sections will not be permitted unless they are run under a specific
policy.
Audit
List the policies in use for each namespace in the cluster, ensure that each policy
disallows the admission of containers which have hostPort sections.
Remediation guidance
Add policies to each namespace in the cluster which has user workloads to restrict the
admission of containers which use hostPort sections.
Default Value
By default, there are no restrictions on the use of HostPorts.
References
Service-wide remediation
Recommended when many resources are affected: fix the platform baseline first so new resources inherit the secure setting, then remediate the existing flagged resources in batches.
Kubernetes
Use admission policies, baseline cluster configuration, GitOps templates, and namespace or workload guardrails so new deployments follow the control by default.
Operational rollout
- Fix the baseline first at the account, subscription, project, cluster, or tenant scope that owns this control.
- Remediate the currently affected resources in batches, starting with internet-exposed and production assets.
- Re-scan and track approved exceptions with an owner and expiry date.
Query logic
These are the stored checks tied to this control.
Minimize the admission of containers which use HostPorts (Pod)
Connectors
Covered asset types
Expected check: eq []
{
pods(where: { containers_SOME: { ports_SOME: { hostPort_GT: 0 } NOT: { namespace: "kube-system" } } }) {
...AssetFragment
}
}
