5.2.7 Minimize the admission of containers with the NET_RAW capability

Information

Do not generally permit containers with the potentially dangerous NET_RAW capability.

Rationale:

Containers run with a default set of capabilities as assigned by the Container Runtime. By default this can include potentially dangerous capabilities. With Docker as the container runtime the NET_RAW capability is enabled which may be misused by malicious containers.

Ideally, all containers should drop this capability.

There should be at least one Security Context Constraint (SCC) defined which prevents containers with the NET_RAW capability from launching.

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

Impact:

Pods with containers which run with the NET_RAW capability will not be permitted.

Solution

Create a SCC as described in the OpenShift documentation, ensuring that the Required Drop Capabilities is set to include either NET_RAW or ALL.

Default Value:

By default, OpenShift 4 clusters include the following SCCs:

anyuid Required Drop Capabilities: MKNOD

hostaccess Required Drop Capabilities: KILL,MKNOD,SETUID,SETGID

hostmount-anyuid Required Drop Capabilities: MKNOD

hostnetwork Required Drop Capabilities: KILL,MKNOD,SETUID,SETGID

node-exporter Required Drop Capabilities: <none>

non-root Required Drop Capabilities: KILL,MKNOD,SETUID,SETGID

privileged Required Drop Capabilities: <none>

restricted Required Drop Capabilities: KILL,MKNOD,SETUID,SETGID

See Also

https://workbench.cisecurity.org/files/4260