Use vulnerability scanning in offline and air-gapped environments

For air-gapped (offline) environments, VMware recommends using Aqua Security’s Trivy scanner with Scan 2.0. Trivy scanner with Scan 2.0 greatly simplifies the installation and maintenance experiences over Anchore Grype and Scan 1.0. For a comparison of Scan 1.0 and Scan 2.0, see Overview of Supply Chain Security Tools - Scan.

Using Trivy with SCST - Scan 2.0

The Aqua Trivy vulnerability scanner uses two databases to perform vulnerability scans:

  1. Vulnerability Database: This database contains the vulnerability information used to scan artifacts. This database is built every six hours on GitHub and is distributed using GitHub Container registry (GHCR).

  2. Java Index Database: This database enables Trivy to identify the groupId, artifactId, and version of JAR files. It is built once a day on GitHub and distributed using GitHub Container registry (GHCR).

In an online installation of Tanzu Application Platform, these databases are automatically downloaded from GHCR (Github Container Registry) with each scan execution. To enable scanning in an offline environment, these two databases must be relocated to your private container image registry, and Trivy must be configured to use your private location instead of downloading from GHCR.

For more information about the Trivy vulnerability databases, see the Trivy documentation.

Relocate Trivy Images

The databases are stored in an OCI-compliant registry as OCI artifacts. To copy these to your private registry, Trivy recommends using the ORAS CLI.

To make the Trivy databases available in your private registry:

  1. Create a repository within your private registry. This example uses aquasecurity to remain consistent with the GHCR repository.

  2. Copy the vulnerability database from GHCR to your private registry:

    oras cp ghcr.io/aquasecurity/trivy-db:2 CONTAINER-REGISTRY/aquasecurity/trivy-db:2
    Note

    The Trivy scanner is hardcoded to use the 2 tag for the vulnerability database.

    Where CONTAINER-REGISTRY is the URL for your registry. For example, harbor.example.com

  3. Copy the Java index database from GHCR to your private registry:

    oras cp ghcr.io/aquasecurity/trivy-java-db:1 harbor.CONTAINER-REGISTRY/aquasecurity/trivy-java-db:1

    Where CONTAINER-REGISTRY is the URL for your registry. For example, harbor.example.com

    Note

    The Trivy scanner is hardcoded to use the 1 tag for the Java index database.

The databases are now available locally in your air-gapped environment. The next step is to configure the supply chain to use the air-gapped location for Trivy. For more information about using Trivy in an air-gapped environment, see the Trivy documentation.

Configure Trivy in the Supply Chain

Now that you have relocated the images, you must configure the scanning step of the supply chain to use Trivy with the SCST - Scan 2.0, and provide the location of the database artifacts in the private registry.

  1. To enable SCST - Scan 2.0 with Trivy with private registries, update your tap-values.yaml file to specify the Trivy ClusterImageTemplate. For example:

    ootb_supply_chain_testing_scanning:
  image_scanner_template_name: image-vulnerability-scan-trivy
  scanning:
    steps:
      env_vars:
      - name: TRIVY_DB_REPOSITORY
        value: CONTAINER-REGISTRY/aquasecurity/trivy-db
      - name: TRIVY_JAVA_DB_REPOSITORY
        value: CONTAINER-REGISTRY/aquasecurity/trivy-java-db
      - name: TRIVY_OFFLINE_SCAN
        value: "true"

    Where CONTAINER-REGISTRY is the URL for your registry. For example, harbor.example.com

  2. Update your Tanzu Application Platform installation by running:

    tanzu package installed update tap -p tap.tanzu.vmware.com -v TAP-VERSION  --values-file tap-values.yaml -n tap-install

    Where TAP-VERSION is the version of Tanzu Application Platform installed.

Trivy is now configured to use resources in your air-gapped environment when executed with the supply chain. For more information about using Trivy in an air-gapped environment, see the Trivy documentation.

Using Grype with Scan 1.0

VMware recommends using Aqua Trivy with SCST - Scan 2.0 for offline or air-gapped environments due to the simplified setup and maintenance. However, if you require policy enablement based on vulnerability scanning, use the following steps to enable Grype scanning with SCST - Scan 1.0.

The Grype CLI attempts to perform two over-the-Internet calls:

  • One to verify for later versions of the CLI.
  • One to update the vulnerability database before scanning.

For the Grype CLI to function in an offline or air-gapped environment, the vulnerability database must be hosted in the environment. You must configure the Grype CLI with the internal URL.

The Grype CLI accepts environment variables to satisfy these needs.

Host the Grype vulnerability database

To host the Grype vulnerability database in an air-gapped environment:

  1. Retrieve the Grype listing file from its public endpoint: https://toolbox-data.anchore.io/grype/databases/listing.json.

  2. Create your own listing.json file.

    Note Different Grype versions require specific database schema versions. To avoid compatibility issues between different versions, include a database schema for each version. For example:

        {
      "available": {
        "1": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 1,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v1_2023-06-16T01:33:30Z_1621f4169ffd15bea9e5.tar.gz",
            "checksum": "sha256:3f2c1b432945cca9a69b2e604f6fb231fec450fdd27f4946fc5608692b63a9d1"
          }
        ],
        "2": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 2,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v2_2023-06-16T01:33:30Z_d6eee5e78d9b78285e1a.tar.gz",
            "checksum": "sha256:7b7e3a2a7712c72b8c5cc777733c4d8d140d8cfee65e4f04540abbdfe3ef1f65"
          }
        ],
        "3": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 3,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v3_2023-06-16T01:33:30Z_f96ae38a7b05987c3ece.tar.gz",
            "checksum": "sha256:8ea9fae3fda3bf3bf35bd5e5eb656fc127b59cd3c42db4c36795556aab8a9cf0"
          }
        ],
        "4": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 4,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v4_2023-06-16T01:33:30Z_13bba2fa8ff62b7f8b26.tar.gz",
            "checksum": "sha256:3b53d20241b88e5aa45feb817b325c53d6efbe9fa1fc5a67eeddaecafa7687e0"
          }
        ],
        "5": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 5,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v5_2023-06-16T01:33:30Z_e07da3853f6db6eb1104.tar.gz",
            "checksum": "sha256:93d4d9d2f9e39f86570f832cf85b7149a949ca6f1613581b10c12393509d884f"
          }
        ]
      }
    }

    Where url points to a tarball containing Grype’s vulnerability.db and metadata.json files.

  3. Download and host the tarballs in your internal file server.

    Note

    Some storage solutions for internal file servers change the name of TAR files automatically because of their limits. Notice these modified names and reflect the changes in the url. Ensure that the timestamp in the name is correctly formatted because Grype parses the name of TAR artifact to get the timestamp.

  4. Update the download url to point at your internal endpoint.

    For information about setting up an offline vulnerability database, see the Anchore Grype README in GitHub.

To enable Grype in offline air-gapped environments

  1. Add the following to your tap-values.yaml file:

    grype:
  db:
    dbUpdateUrl: INTERNAL-VULN-DB-URL

    Where INTERNAL-VULN-DB-URL is the URL that points to the internal file server.

  2. Update Tanzu Application Platform:

    tanzu package installed update tap -f tap-values.yaml -n tap-install

Configure Grype environmental variables

  1. Create a secret that contains the ytt overlay to add the Grype environment variable to the ScanTemplates.

    apiVersion: v1
kind: Secret
metadata:
  name: grype-airgap-environmental-variables
  namespace: tap-install
stringData:
  patch.yaml: |
    #@ load("@ytt:overlay", "overlay")

    #@overlay/match by=overlay.subset({"kind":"ScanTemplate"}),expects="1+"
    ---
    spec:
      template:
        initContainers:
          #@overlay/match by=overlay.subset({"name": "scan-plugin"}), expects="1+"
          - name: scan-plugin
            #@overlay/match missing_ok=True
            env:
              #@overlay/append
              - name: GRYPE_CHECK_FOR_APP_UPDATE
                value: "false"

Where spec.template.initContainers[] specifies setting one or more environment variables in the scan-plugin initContainer.

Note

If you are using the Namespace Provisioner to provision a new developer namespace and want to apply a package overlay for Grype, you must import the overlay Secret. See Import overlay secrets.

Troubleshooting

ERROR failed to fetch latest cli version

Symptom

Error message:

ERROR failed to fetch latest version: Get "https://toolbox-data.anchore.io/grype/releases/latest/VERSION": dial tcp: lookup toolbox-data.anchore.io on [::1]:53: read udp [::1]:65010->[::1]:53: read: connection refused
Cause

The Grype CLI checks for later versions of the CLI by contacting the anchore endpoint over-the-Internet.

Solution

This message is a warning and the Grype scan still runs.

To deactivate this check, set the environment variable GRYPE_CHECK_FOR_APP_UPDATE to false by using a package overlay:

  1. Create a secret that contains the ytt overlay to add the Grype environment variable to the ScanTemplates.

    apiVersion: v1
kind: Secret
metadata:
  name: grype-airgap-deactivate-cli-check-overlay
  namespace: tap-install #! namespace where tap is installed
stringData:
  patch.yaml: |
    #@ load("@ytt:overlay", "overlay")

    #@overlay/match by=overlay.subset({"kind":"ScanTemplate"}),expects="1+"
    ---
    spec:
      template:
        initContainers:
          #@overlay/match by=overlay.subset({"name": "scan-plugin"}), expects="1+"
          - name: scan-plugin
            #@overlay/match missing_ok=True
            env:
              #@overlay/append
              - name: GRYPE_CHECK_FOR_APP_UPDATE
                value: "false"

  2. Configure tap-values.yaml to use package_overlays. Add the following to your tap-values.yaml file:

    package_overlays:
  - name: "grype"
    secrets:
        - name: "grype-airgap-deactivate-cli-check-overlay"

  3. Update Tanzu Application Platform:

    tanzu package installed update tap -f tap-values.yaml -n tap-install

Database is too old

Symptom

Error message:

1 error occurred:
  * db could not be loaded: the vulnerability database was built N days/weeks ago (max allowed age is 5 days)
Cause

Grype needs up-to-date vulnerability information to provide accurate matches. By default, it fails to run if the local database was not built in the last 5 days.

Solution

There are two options to resolve this:

  1. Stale databases weaken your security posture. VMware recommends updating the database daily.

  2. If you cannot update the database daily, configure the data staleness check using the environment variable GRYPE_DB_MAX_ALLOWED_BUILT_AGE and apply a package overlay:

    1. Create a secret that contains the ytt overlay to add the Grype environment variable to the ScanTemplates.

      apiVersion: v1
kind: Secret
metadata:
  name: grype-airgap-override-stale-db-overlay
  namespace: tap-install #! namespace where tap is installed
stringData:
  patch.yaml: |
    #@ load("@ytt:overlay", "overlay")

    #@overlay/match by=overlay.subset({"kind":"ScanTemplate"}),expects="1+"
    ---
    spec:
      template:
        initContainers:
          #@overlay/match by=overlay.subset({"name": "scan-plugin"}), expects="1+"
          - name: scan-plugin
            #@overlay/match missing_ok=True
            env:
              #@overlay/append
              - name: GRYPE_DB_MAX_ALLOWED_BUILT_AGE #! see note on best practices
                value: "120h"
      Note

      The default maximum allowed built age of Grype’s vulnerability database is 5 days. This means that scanning with a 6 day old database causes the scan to fail. You can use the GRYPE_DB_MAX_ALLOWED_BUILT_AGE parameter to override the default in accordance with your security posture.

    2. Configure tap-values.yaml to use package_overlays. Add the following to your tap-values.yaml file:

      package_overlays:
  - name: "grype"
    secrets:
        - name: "grype-airgap-override-stale-db-overlay"

    3. Update Tanzu Application Platform:

      tanzu package installed update tap -f tap-values.yaml -n tap-install

Vulnerability database is invalid

Symptom

Error message:

scan-pod[scan-plugin]  1 error occurred:
scan-pod[scan-plugin]  * failed to load vulnerability db: vulnerability database is invalid (run db update to correct): database metadata not found: /.cache/grype/db/5
Solution

Examine the listing.json file you created. This matches the format of the listing file. The listing file is located at Anchore Grype’s public endpoint. See the Grype README.md in GitHub.

An example listing.json:

{
  "available": {
    "5": [
      {
        "built": "2023-03-28T01:29:38Z",
        "version": 5,
        "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v5_2023-03-28T01:29:38Z_e49d318c32a6113eed07.tar.gz",
        "checksum": "sha256:408ce2932f04dee929a5df524e92494f2d635c6b19e30ff9f0a50425b1fc29a1"
      },
      .....
    ]
  }
}

Where:

  • 5 refers to the Grype vulnerability database schema.
  • built is the build timestamp in the format yyyy-MM-ddTHH:mm:ssZ.
  • url is the download URL for the tarball containing the database. This points at your internal endpoint. The tarball contains the following files:
    • vulnerability.db is an SQLite file that is Grype’s vulnerability database. Each time the data shape of the vulnerability database changes, a new schema is created. Different Grype versions require specific database schema versions. For example, Grype v0.54.0 requires database schema version v5.
    • metadata.json file
  • checksum is the SHA used to verify the database’s integrity.

Verify these possible reasons why the vulnerability database is not valid:

  1. The database schema is invalid. Confirm that the required database schema for the installed Grype version is used. Confirm that the top level version key matches the nested version. For example, the top level version 1 in the following snippet does not match the nested version: 5.

    {
  "available": {
    "1": [{
           "built": "2023-02-08T08_17_20Z",
           "version": 5,
           "url": "https://INTERNAL-ENDPOINT/PATH-TO-TARBALL/vulnerability-db_v5_2023-02-08T08_17_20Z_6ef73016d160043c630f.tar.gz",
           "checksum": "sha256:aab8d369933c845878ef1b53bb5c26ee49b91ddc5cd87c9eb57ffb203a88a72f"
    }]
  }
}

    Where PATH-TO-TARBALL is the path to the tarball containing the vulnerability database.

    As stale databases weaken your security posture, VMware recommends using the newest entry of the relevant schema version in the listing.json file. See Anchore’s grype-db in GitHub.

  2. The built parameters in the listing.json file are incorrectly formatted. The proper format is yyyy-MM-ddTHH:mm:ssZ.

  3. The url that you modified to point at an internal endpoint is not reachable from the cluster. For information about verifying connectivity, see Debug Grype database in a cluster.

  4. Verify if there are syntax errors in the listing.json:

    grype db check

  5. Validate the configured listing.json:

    grype db list -o raw
Debug Grype database in a cluster

  1. Describe the failed source scan or image scan to verify the name of the ScanTemplate being used.

    • For sourcescan, run:

      kubectl describe sourcescan SCAN-NAME -n DEV-NAMESPACE

    • For imagescan, run:

      kubectl describe imagescan SCAN-NAME -n DEV-NAMESPACE

    Where SCAN-NAME is the name of the source or image scan that failed.

  2. Pause reconciliation of the grype.scanning.apps.tanzu.vmware.com package:

    kctrl package installed pause -i <PACKAGE-INSTALL-NAME> -n tap-install

    Where PACKAGE-INSTALL-NAME is the name of the grype.scanning.apps.tanzu.vmware.com package, for example, grype

  3. Edit the ScanTemplate’s scan-plugin container to include a “sleep” entrypoint which allows you to troubleshoot inside the container:

    - name: scan-plugin
  volumeMounts:
    ...
  image: #@ data.values.scanner.image
  imagePullPolicy: IfNotPresent
  env:
    ...
  command: ["/bin/bash"]
  args:
  - "sleep 1800" # insert 30 min sleep here

  4. Re-run the scan.

  5. Get the name of the scan-plugin pod.

    kubectl get pods -n DEV-NAMESPACE

  6. Get a shell to the container.

    kubectl exec --stdin --tty SCAN-PLUGIN-POD -c step-scan-plugin -- /bin/bash

    Where SCAN-PLUGIN-POD is the name of the scan-plugin pod. For more information, see the Kubernetes documentation.

  7. Inside the container, run Grype CLI commands to report database status and verify connectivity from the cluster to the mirror. See the Grype documentation in GitHub.

    • Report current status of Grype’s database, such as location, build date, and checksum:

      grype db status

  8. Ensure that the built parameters in the listing.json have timestamps in this proper format yyyy-MM-ddTHH:mm:ssZ.

  9. After you complete troubleshooting, to trigger reconciliation, run:

    kctrl package installed kick -i <PACKAGE-INSTALL-NAME> -n tap-install

    Where PACKAGE-INSTALL-NAME is the name of the grype.scanning.apps.tanzu.vmware.com package, such as Grype.

Grype package overlays are not applied to scantemplates created by Namespace Provisioner

If you used the Namespace Provisioner to provision a new developer namespace and want to apply a package overlay for Grype, see Import overlay secrets.

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