5.2.6 Minimize the admission of containers with allowPrivilegeEscalation

Information

Do not generally permit containers to be run with the allowPrivilegeEscalation flag set to true. Allowing this right can lead to a process running a container getting more rights than it started with.

It's important to note that these rights are still constrained by the overall container sandbox, and this setting does not relate to the use of privileged containers.

Rationale:

A container running with the allowPrivilegeEscalation flag set to true may have processes that can gain more privileges than their parent.

There should be at least one admission control policy defined which does not permit containers to allow privilege escalation. The option exists (and is defaulted to true) to permit setuid binaries to run.

If you have need to run containers which use setuid binaries or require privilege escalation, 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.allowPrivilegeEscalation: true will not be permitted unless they are run under a specific policy.

Solution

Add policies to each namespace in the cluster which has user workloads to restrict the admission of containers with .spec.allowPrivilegeEscalationset to true.

Default Value:

By default, there are no restrictions on contained process ability to escalate privileges, within the context of the container.

See Also

https://workbench.cisecurity.org/files/3892