C-0218 - Minimize the admission of root containers
Framework
cis-aks-t1.2.0, cis-eks-t1.2.0
Severity
Medium
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
PodSecurityPolicy
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.
Remediation
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.
Example
No example
Updated 3 days ago