Vulnerability Discussion

The container platform must be capable of validating that container images are signed and that the digital signature is from a recognized and source approved by the organization. Allowing any container image to be introduced into the registry and instantiated into a container can allow for services to be introduced that are not trusted and may contain malicious code, which introduces unwanted services. These unwanted services can cause harm and security risks to the hosting server, the container platform, other services running within the container platform, and the overall organization.

Check

Determine if a policy has been put in place by running the following command:

for node in $(oc get node -oname); do oc debug $node -- chroot /host /bin/bash -c 'echo -n "$HOSTNAME "; cat /etc/containers/policy.json' 2>/dev/null; done

If the policy is not set to "reject" by default, or the signature keys are not configure appropriately on the registries, this is a finding.

The following is an example of how this will look on a system using Red Hat's public registries:

    {
  "default": [{"type": "reject"}],
  "transports": {
    "docker": {
      "registry.access.redhat.com": [
        {
          "type": "signedBy",
          "keyType": "GPGKeys",
          "keyPath": "/etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release"
        }
      ],
      "registry.redhat.io": [
        {
          "type": "signedBy",
          "keyType": "GPGKeys",
          "keyPath": "/etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release"
        }
      ],

      ...
    }
     

Fix

Configure the OpenShift Container policy to validate that image signatures are verified and enforced by executing the following:
Note: This can be configured manually or through the use of the MachineConfig Operator published by Red Hat.

for mcpool in $(oc get mcp -oname | sed "s:.*/::" ); do
echo "apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
labels:
machineconfiguration.openshift.io/role: $mcpool
name: 51-rh-registry-trust-$mcpool
spec:
config:
ignition:
version: 3.2.0
storage:
files:
- contents:
source: data:text/plain;charset=utf-8;base64,LS0tCmRvY2tlcjoKICByZWdpc3RyeS5hY2Nlc3MucmVkaGF0LmNvbToKICAgIHNpZ3N0b3JlOiBodHRwczovL2FjY2Vzcy5yZWRoYXQuY29tL3dlYmFzc2V0cy9kb2NrZXIvY29udGVudC9zaWdzdG9yZQo=
verification: {}
filesystem: root
mode: 420
path: /etc/containers/registries.d/registry.access.redhat.com.yaml
- contents:
source: data:text/plain;charset=utf-8;base64,LS0tCmRvY2tlcjoKICByZWdpc3RyeS5yZWRoYXQuaW86CiAgICBzaWdzdG9yZTogaHR0cHM6Ly9yZWdpc3RyeS5yZWRoYXQuaW8vY29udGFpbmVycy9zaWdzdG9yZQo=
verification: {}
filesystem: root
mode: 420
path: /etc/containers/registries.d/registry.redhat.io.yaml
- contents:
source: data:text/plain;charset=utf-8;base64,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
verification: {}
filesystem: root
mode: 420
path: /etc/containers/policy.json
" | oc apply -f -
done