Cascading Scans

What is "Cascading Scans" Hook about?

The Cascading Scans Hook can be used to orchestrate security scanners based on defined rule sets. The so called CascadingRules consist of a matches section which contains one or multiple rules which are compared against findings. When a finding matches a rule the scanSpec section will then be used to create a new scan. To customize the scan to match the finding, the mustache templating language can be used to reference fields of the finding.

This Hook is based on the ADR https://www.securecodebox.io/docs/architecture/adr/adr_0003

More information about how to use cascading scans can be found here:

• Custom Resource Definition: https://www.securecodebox.io/docs/api/crds/cascading-rule/
• How-To Network Scanning: https://www.securecodebox.io/docs/how-tos/scanning-networks/

Deployment

The cascading-scans chart can be deployed via helm:

# Install HelmChart (use -n to configure another namespace)
helm upgrade --install cascading-scans secureCodeBox/cascading-scans

Requirements

Kubernetes: >=v1.11.0-0

Additional Chart Configurations

Installing the Cascading Scans hook will add a ReadOnly Hook to your namespace which looks for matching CascadingRules in the namespace and start the according scans.

Verification

kubectl get ScanCompletionHooks
NAME   TYPE       IMAGE
dssh   ReadOnly   docker.io/securecodebox/hook-cascading-scans:latest

CascadingScan Rules

The CascadingRules are included directly in each helm chart of the individual scanners. There is a configuration option cascadingRules.enabled for each scanner to prevent this inclusion.

# Check your CascadingRules
kubectl get CascadingRules
NAME             STARTS              INVASIVENESS   INTENSIVENESS
https-tls-scan   sslyze              non-invasive   light
imaps-tls-scan   sslyze              non-invasive   light
nikto-http       nikto               non-invasive   medium
nmap-smb         nmap                non-invasive   light
pop3s-tls-scan   sslyze              non-invasive   light
smtps-tls-scan   sslyze              non-invasive   light
ssh-scan         ssh-scan            non-invasive   light
zap-http         zap-baseline-scan   non-invasive   medium

Starting a cascading Scan

When you start a normal Scan, no CascadingRule will be applied. To use a CascadingRule the scan must be marked to allow cascading rules. This is implemented using kubernetes label selectors, meaning that scans mark the classes of scans which are allowed to be cascaded by the current one.

Example

cat <<EOF | kubectl apply -f -
apiVersion: "execution.securecodebox.io/v1"
kind: Scan
metadata:
  name: "example.com"
spec:
  scanType: nmap
  parameters:
    - -p22,80,443
    - example.com
  cascades:
    matchLabels:
      securecodebox.io/intensive: light
EOF

This Scan will use all CascadingRules which are labeled with a "light" intensity. You can lookup which CascadingRules this selects by running:

kubectl get CascadingRules -l "securecodebox.io/intensive=light"
NAME             STARTS     INVASIVENESS   INTENSIVENESS
https-tls-scan   sslyze     non-invasive   light
imaps-tls-scan   sslyze     non-invasive   light
nmap-smb         nmap       non-invasive   light
pop3s-tls-scan   sslyze     non-invasive   light
smtps-tls-scan   sslyze     non-invasive   light
ssh-scan         ssh-scan   non-invasive   light

The label selectors also allow the more powerful matchExpressions selectors:

cat <<EOF | kubectl apply -f -
apiVersion: "execution.securecodebox.io/v1"
kind: Scan
metadata:
  name: "example.com"
spec:
  scanType: nmap
  parameters:
    - -p22,80,443
    - example.com
  cascades:
    # Using matchExpressions instead of matchLabels
    matchExpressions:
    - key: "securecodebox.io/intensive"
      operator: In
      # This select both light and medium intensity rules
      values: [light, medium]
EOF

This selection can be replicated in kubectl using:

kubectl get CascadingRules -l "securecodebox.io/intensive in (light,medium)"
NAME             STARTS              INVASIVENESS   INTENSIVENESS
https-tls-scan   sslyze              non-invasive   light
imaps-tls-scan   sslyze              non-invasive   light
nikto-http       nikto               non-invasive   medium
nmap-smb         nmap                non-invasive   light
pop3s-tls-scan   sslyze              non-invasive   light
smtps-tls-scan   sslyze              non-invasive   light
ssh-scan         ssh-scan            non-invasive   light
zap-http         zap-baseline-scan   non-invasive   medium

Values

Key	Type	Default	Description
hook.affinity	object	{}	Optional affinity settings that control how the hook job is scheduled (see: https://kubernetes.io/docs/tasks/configure-pod-container/assign-pods-nodes-using-node-affinity/)
hook.image.repository	string	"docker.io/securecodebox/hook-cascading-scans"	Hook image repository
hook.image.tag	string	defaults to the charts version	The image Tag defaults to the charts version if not defined.
hook.labels	object	{}	Add Kubernetes Labels to the hook definition
hook.priority	int	0	Hook priority. Higher priority Hooks are guaranteed to execute before low priority Hooks.
hook.resources	object	{ requests: { cpu: "200m", memory: "100Mi" }, limits: { cpu: "400m", memory: "200Mi" } }	Optional resources lets you control resource limits and requests for the hook container. See https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/
hook.tolerations	list	[]	Optional tolerations settings that control how the hook job is scheduled (see: https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/)
hook.ttlSecondsAfterFinished	string	nil	Seconds after which the kubernetes job for the hook will be deleted. Requires the Kubernetes TTLAfterFinished controller: https://kubernetes.io/docs/concepts/workloads/controllers/ttlafterfinished/
imagePullSecrets	list	[]	Define imagePullSecrets when a private registry is used (see: https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/)

License

Code of secureCodeBox is licensed under the Apache License 2.0.