C-0218 - Minimize the admission of root containers


cis-eks-t1.2.0, cis-aks-t1.2.0



Description of the the issue

Containers may run as any Linux user. Containers which run as the root user, whilst constrained by Container Runtime security features still have a escalated likelihood of container breakout.

Ideally, all containers should run as a defined non-UID 0 user.

There should be at least one PodSecurityPolicy (PSP) defined which does not permit root users in a container.

If you need to run root containers, this should be defined in a separate PSP and you should carefully check RBAC controls to ensure that only limited service accounts and users are given permission to access that PSP.

Related resources


What does this control test

Do not generally permit containers to be run as the root user.

How to check it manually

Get the set of PSPs with the following command:

kubectl get psp

For each PSP, check whether running containers as root is enabled:

kubectl get psp <name> -o=jsonpath='{.spec.runAsUser.rule}'

Verify that there is at least one PSP which returns MustRunAsNonRoot or MustRunAs with the range of UIDs not including 0.


Create a PSP as described in the Kubernetes documentation, ensuring that the .spec.runAsUser.rule is set to either MustRunAsNonRoot or MustRunAs with the range of UIDs not including 0.

Impact Statement

Pods with containers which run as the root user will not be permitted.

Default Value

By default, PodSecurityPolicies are not defined.


No example