Ensure AppArmor is Active and Configured

Description

Verify that the Apparmor tool is configured to control whitelisted applications and user home directory access control.

The apparmor service can be enabled with the following manifest:

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: master
  name: 75-master-apparmor-enable
spec:
  config:
    ignition:
      version: 3.1.0
    systemd:
      units:
      - name: apparmor.service
        enabled: true

This will enable the apparmor service in all the nodes labeled with the "master" role.

Note that this needs to be done for each MachineConfigPool

For more information on how to configure nodes with the Machine Config Operator see the relevant documentation.

Rationale

Using a whitelist provides a configuration management method for allowing the execution of only authorized software. Using only authorized software decreases risk by limiting the number of potential vulnerabilities.

The organization must identify authorized software programs and permit execution of authorized software by adding each authorized program to the "pam_apparmor" exception policy. The process used to identify software programs that are authorized to execute on organizational information systems is commonly referred to as whitelisting.

Verification of whitelisted software occurs prior to execution or at system startup.

Users' home directories/folders may contain information of a sensitive nature. Nonprivileged users should coordinate any sharing of information with a System Administrator (SA) through shared resources.

Apparmor can confine users to their home directory, not allowing them to make any changes outside of their own home directories. Confining users to their home directory will minimize the risk of sharing information.