Title

MKE must enable kernel protection. (Cat II impact)

Discussion

System kernel is responsible for memory, disk, and task management. The kernel provides a gateway between the system hardware and software. Kubernetes requires kernel access to allocate resources to the Control Plane. Threat actors that penetrate the system kernel can inject malicious code or hijack the Kubernetes architecture. It is vital to implement protections through Kubernetes components to reduce the attack surface.

Check Content

Verify kernel protection. When using Kubernetes orchestration, change to the /etc/sysconfig/ directory on the Kubernetes Control Plane using the command: grep -i protect-kernel-defaults kubelet If the setting "protect-kernel-defaults" is set to false or not set in the Kubernetes Kubelet, this is a finding. When using Swarm orchestration: Linux: Execute the following command as a trusted user on the host operating system: docker ps --quiet --all | xargs docker inspect --format '{{ .Name }}: CapAdd={{ .HostConfig.CapAdd }} CapDrop={{ .HostConfig.CapDrop }}' The command will output all Linux Kernel Capabilities. If Linux Kernel Capabilities exceed what is defined in the System Security Plan (SSP), this is a finding.

Fix Text

When using Kubernetes orchestration, edit the Kubernetes Kubelet file in the /etc/sysconfig directory on the Kubernetes Control Plane. Set the argument "--protect-kernel-defaults" to "true". Reset Kubelet service using the following command: service kubelet restart When using Swarm orchestration, review and remove nonsystem containers previously created by these users that allowed capabilities to be added or must be removed using: docker container rm [container]

Additional Identifiers

Rule ID: SV-260933r966156_rule

Vulnerability ID: V-260933

Group Title: SRG-APP-000233-CTR-000585

Expert Comments

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