Cis K8S V1120 5.2.2

5.2.2 Minimize the admission of privileged containers (Manual)

Profile Applicability

• Level 1 - Master Node

Description

Do not generally permit containers to be run with the securityContext.privileged flag set to true.

Rationale

Privileged containers have access to all Linux Kernel capabilities and devices. A container running with full privileges can do almost everything that the host can do. This flag exists to allow special use-cases, like manipulating the network stack and accessing devices.

There should be at least one admission control policy defined which does not permit privileged containers.

If you need to run privileged containers, 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 spec.containers[].securityContext.privileged: true, spec.initContainers[].securityContext.privileged: true and spec.ephemeralContainers[].securityContext.privileged: true will not be permitted.

Audit Procedure

Run the following command:

kubectl get pods -A -o=jsonpath=$'{range .items[*]}{@.metadata.name}: {@..securityContext}\n{end}'

It will produce an inventory of all the privileged use on the cluster, if any. Further grepping can be done to automate each specific violation detection.

Remediation

Add policies to each namespace in the cluster which has user workloads to restrict the admission of privileged containers.

Default Value

By default, there are no restrictions on the creation of privileged containers.

References

1. https://kubernetes.io/docs/concepts/security/pod-security-standards/

CIS Controls