Container Scanning

Your application’s Docker image may itself be based on Docker images that contain known vulnerabilities. By including an extra job in your pipeline that scans for those vulnerabilities and displays them in a merge request, you can use GitLab to audit your Docker-based apps.

GitLab provides integration with open-source tools for vulnerability static analysis in containers:

To integrate GitLab with security scanners other than those listed here, see Security scanner integration.

You can enable container scanning by doing one of the following:

GitLab compares the found vulnerabilities between the source and target branches, and shows the information directly in the merge request.

Container Scanning Widget

Requirements

To enable container scanning in your pipeline, you need the following:

  • GitLab Runner with the docker or kubernetes executor.
  • Docker 18.09.03 or higher installed on the same computer as the runner. If you’re using the shared runners on GitLab.com, then this is already the case.
  • An image matching the supported distributions.
  • Build and push the Docker image to your project’s container registry. If using a third-party container registry, you might need to provide authentication credentials using the DOCKER_USER and DOCKER_PASSWORD configuration variables.
  • The name of the Docker image to scan, in the DOCKER_IMAGE configuration variable.

Configuration

To enable container scanning, add the Container-Scanning.gitlab-ci.yml template to your .gitlab-ci.yml file:

include:
  - template: Security/Container-Scanning.gitlab-ci.yml

The included template:

  • Creates a container_scanning job in your CI/CD pipeline.
  • Pulls the built Docker image from your project’s container registry (see requirements) and scans it for possible vulnerabilities.

GitLab saves the results as a Container Scanning report artifact that you can download and analyze later. When downloading, you always receive the most-recent artifact.

The following is a sample .gitlab-ci.yml that builds your Docker image, pushes it to the container registry, and scans the image:

build:
  image: docker:latest
  stage: build
  services:
    - docker:dind
  variables:
    IMAGE: $CI_REGISTRY_IMAGE/$CI_COMMIT_REF_SLUG:$CI_COMMIT_SHA
  script:
    - docker info
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
    - docker build -t $IMAGE .
    - docker push $IMAGE

include:
  - template: Security/Container-Scanning.gitlab-ci.yml

Customizing the container scanning settings

There may be cases where you want to customize how GitLab scans your containers. For example, you may want to enable more verbose output, access a Docker registry that requires authentication, and more. To change such settings, use the variables parameter in your .gitlab-ci.yml to set CI/CD variables. The variables you set in your .gitlab-ci.yml overwrite those in Container-Scanning.gitlab-ci.yml.

This example includes the container scanning template and enables verbose output for the analyzer:

include:
  - template: Security/Container-Scanning.gitlab-ci.yml

variables:
    SECURE_LOG_LEVEL: 'debug'

Available CI/CD variables

You can configure analyzers by using the following CI/CD variables:

CI/CD Variable Default Description Scanner
ADDITIONAL_CA_CERT_BUNDLE "" Bundle of CA certs that you want to trust. See Using a custom SSL CA certificate authority for more details. All
CI_APPLICATION_REPOSITORY $CI_REGISTRY_IMAGE/$CI_COMMIT_REF_SLUG Docker repository URL for the image to be scanned. All
CI_APPLICATION_TAG $CI_COMMIT_SHA Docker repository tag for the image to be scanned. All
CS_ANALYZER_IMAGE registry.gitlab.com/security-products/container-scanning:4 Docker image of the analyzer. All
CS_DOCKER_INSECURE "false" Allow access to secure Docker registries using HTTPS without validating the certificates. All
CS_REGISTRY_INSECURE "false" Allow access to insecure registries (HTTP only). Should only be set to true when testing the image locally. Works with all scanners, but the registry must listen on port 80/tcp for Trivy to work. All
CS_SEVERITY_THRESHOLD UNKNOWN Severity level threshold. The scanner outputs vulnerabilities with severity level higher than or equal to this threshold. Supported levels are Unknown, Low, Medium, High, and Critical. Trivy
DOCKER_IMAGE $CI_APPLICATION_REPOSITORY:$CI_APPLICATION_TAG The Docker image to be scanned. If set, this variable overrides the $CI_APPLICATION_REPOSITORY and $CI_APPLICATION_TAG variables. All
DOCKER_PASSWORD $CI_REGISTRY_PASSWORD Password for accessing a Docker registry requiring authentication. The default is only set if $DOCKER_IMAGE resides at $CI_REGISTRY. All
DOCKER_USER $CI_REGISTRY_USER Username for accessing a Docker registry requiring authentication. The default is only set if $DOCKER_IMAGE resides at $CI_REGISTRY. All
DOCKERFILE_PATH Dockerfile The path to the Dockerfile to use for generating remediations. By default, the scanner looks for a file named Dockerfile in the root directory of the project. You should configure this variable only if your Dockerfile is in a non-standard location, such as a subdirectory. See Solutions for vulnerabilities for more details. All
SECURE_LOG_LEVEL info Set the minimum logging level. Messages of this logging level or higher are output. From highest to lowest severity, the logging levels are: fatal, error, warn, info, debug. Introduced in GitLab 13.1. All

Supported distributions

Support depends on the scanner:

UBI-based images

GitLab also offers Red Hat UBI versions of the container-scanning images. You can therefore replace standard images with UBI-based images. To configure the images, set the CS_ANALYZER_IMAGE variable to the standard tag plus the -ubi extension.

Scanner name CS_ANALYZER_IMAGE
Default (Trivy) registry.gitlab.com/security-products/container-scanning:4-ubi
Grype registry.gitlab.com/security-products/container-scanning/grype:4-ubi
Trivy registry.gitlab.com/security-products/container-scanning/trivy:4-ubi

Overriding the container scanning template

If you want to override the job definition (for example, to change properties like variables), you must declare and override a job after the template inclusion, and then specify any additional keys.

This example sets GIT_STRATEGY to fetch:

include:
  - template: Security/Container-Scanning.gitlab-ci.yml

container_scanning:
  variables:
    GIT_STRATEGY: fetch

Change scanners

The container-scanning analyzer can use different scanners, depending on the value of the CS_ANALYZER_IMAGE configuration variable.

The following options are available:

Scanner name CS_ANALYZER_IMAGE
Default (Trivy) registry.gitlab.com/security-products/container-scanning:4
Grype registry.gitlab.com/security-products/container-scanning/grype:4
Trivy registry.gitlab.com/security-products/container-scanning/trivy:4

If you’re migrating from a GitLab 13.x release to a GitLab 14.x release and have customized the container_scanning job or its CI variables, you might need to perform these migration steps in your CI file:

  1. Remove these variables:

    • CS_MAJOR_VERSION
    • CS_PROJECT
    • SECURE_ANALYZERS_PREFIX
  2. Review the CS_ANALYZER_IMAGE variable. It no longer depends on the variables above and its new default value is registry.gitlab.com/security-products/container-scanning:4. If you have an offline environment, see Running container scanning in an offline environment.

  3. If present, remove the .cs_common and container_scanning_new configuration sections.

  4. If the container_scanning section is present, it’s safer to create one from scratch based on the new version of the Container-Scanning.gitlab-ci.yml template. Once finished, it should not have any variables that are only applicable to Klar or Clair. For a complete list of supported variables, see available variables.

  5. Make any necessary customizations to the chosen scanner. We recommend that you minimize such customizations, as they might require changes in future GitLab major releases.

  6. Trigger a new run of a pipeline that includes the container_scanning job. Inspect the job output and ensure that the log messages do not mention Clair.

note
Prior to the GitLab 14.0 release, any variable defined under the scope container_scanning is not considered for scanners other than Clair. In GitLab 14.0 and later, all variables can be defined either as a global variable or under container_scanning.

Using a custom SSL CA certificate authority

You can use the ADDITIONAL_CA_CERT_BUNDLE CI/CD variable to configure a custom SSL CA certificate authority, which is used to verify the peer when fetching Docker images from a registry which uses HTTPS. The ADDITIONAL_CA_CERT_BUNDLE value should contain the text representation of the X.509 PEM public-key certificate. For example, to configure this value in the .gitlab-ci.yml file, use the following:

container_scanning:
  variables:
    ADDITIONAL_CA_CERT_BUNDLE: |
        -----BEGIN CERTIFICATE-----
        MIIGqTCCBJGgAwIBAgIQI7AVxxVwg2kch4d56XNdDjANBgkqhkiG9w0BAQsFADCB
        ...
        jWgmPqF3vUbZE0EyScetPJquRFRKIesyJuBFMAs=
        -----END CERTIFICATE-----

The ADDITIONAL_CA_CERT_BUNDLE value can also be configured as a custom variable in the UI, either as a file, which requires the path to the certificate, or as a variable, which requires the text representation of the certificate.

Vulnerability allowlisting

To allowlist specific vulnerabilities, follow these steps:

  1. Set GIT_STRATEGY: fetch in your .gitlab-ci.yml file by following the instructions in overriding the container scanning template.
  2. Define the allowlisted vulnerabilities in a YAML file named vulnerability-allowlist.yml. This must use the format described in vulnerability-allowlist.yml data format.
  3. Add the vulnerability-allowlist.yml file to the root folder of your project’s Git repository.

vulnerability-allowlist.yml data format

The vulnerability-allowlist.yml file is a YAML file that specifies a list of CVE IDs of vulnerabilities that are allowed to exist, because they’re false positives, or they’re not applicable.

If a matching entry is found in the vulnerability-allowlist.yml file, the following happens:

  • The vulnerability is not included when the analyzer generates the gl-container-scanning-report.json file.
  • The Security tab of the pipeline does not show the vulnerability. It is not included in the JSON file, which is the source of truth for the Security tab.

Example vulnerability-allowlist.yml file:

generalallowlist:
  CVE-2019-8696:
  CVE-2014-8166: cups
  CVE-2017-18248:
images:
  registry.gitlab.com/gitlab-org/security-products/dast/webgoat-8.0@sha256:
    CVE-2018-4180:
  your.private.registry:5000/centos:
    CVE-2015-1419: libxml2
    CVE-2015-1447:

This example excludes from gl-container-scanning-report.json:

  1. All vulnerabilities with CVE IDs: CVE-2019-8696, CVE-2014-8166, CVE-2017-18248.
  2. All vulnerabilities found in the registry.gitlab.com/gitlab-org/security-products/dast/webgoat-8.0@sha256 container image with CVE ID CVE-2018-4180.
  3. All vulnerabilities found in your.private.registry:5000/centos container with CVE IDs CVE-2015-1419, CVE-2015-1447.
File format
  • generalallowlist block allows you to specify CVE IDs globally. All vulnerabilities with matching CVE IDs are excluded from the scan report.

  • images block allows you to specify CVE IDs for each container image independently. All vulnerabilities from the given image with matching CVE IDs are excluded from the scan report. The image name is retrieved from one of the environment variables used to specify the Docker image to be scanned, such as $CI_APPLICATION_REPOSITORY:$CI_APPLICATION_TAG or DOCKER_IMAGE. The image provided in this block must match this value and must not include the tag value. For example, if you specify the image to be scanned using DOCKER_IMAGE=alpine:3.7, then you would use alpine in the images block, but you cannot use alpine:3.7.

    You can specify container image in multiple ways:

    • as image name only (such as centos).
    • as full image name with registry hostname (such as your.private.registry:5000/centos).
    • as full image name with registry hostname and sha256 label (such as registry.gitlab.com/gitlab-org/security-products/dast/webgoat-8.0@sha256).
note
The string after CVE ID (cups and libxml2 in the previous example) is an optional comment format. It has no impact on the handling of vulnerabilities. You can include comments to describe the vulnerability.
Container scanning job log format

You can verify the results of your scan and the correctness of your vulnerability-allowlist.yml file by looking at the logs that are produced by the container scanning analyzer in container_scanning job details.

The log contains a list of found vulnerabilities as a table, for example:

+------------+-------------------------+------------------------+-----------------------+------------------------------------------------------------------------+
|   STATUS   |      CVE SEVERITY       |      PACKAGE NAME      |    PACKAGE VERSION    |                            CVE DESCRIPTION                             |
+------------+-------------------------+------------------------+-----------------------+------------------------------------------------------------------------+
|  Approved  |   High CVE-2019-3462    |          apt           |         1.4.8         | Incorrect sanitation of the 302 redirect field in HTTP transport metho |
|            |                         |                        |                       | d of apt versions 1.4.8 and earlier can lead to content injection by a |
|            |                         |                        |                       |  MITM attacker, potentially leading to remote code execution on the ta |
|            |                         |                        |                       |                             rget machine.                              |
+------------+-------------------------+------------------------+-----------------------+------------------------------------------------------------------------+
| Unapproved |  Medium CVE-2020-27350  |          apt           |         1.4.8         | APT had several integer overflows and underflows while parsing .deb pa |
|            |                         |                        |                       | ckages, aka GHSL-2020-168 GHSL-2020-169, in files apt-pkg/contrib/extr |
|            |                         |                        |                       | acttar.cc, apt-pkg/deb/debfile.cc, and apt-pkg/contrib/arfile.cc. This |
|            |                         |                        |                       |  issue affects: apt 1.2.32ubuntu0 versions prior to 1.2.32ubuntu0.2; 1 |
|            |                         |                        |                       | .6.12ubuntu0 versions prior to 1.6.12ubuntu0.2; 2.0.2ubuntu0 versions  |
|            |                         |                        |                       | prior to 2.0.2ubuntu0.2; 2.1.10ubuntu0 versions prior to 2.1.10ubuntu0 |
|            |                         |                        |                       |                                  .1;                                   |
+------------+-------------------------+------------------------+-----------------------+------------------------------------------------------------------------+
| Unapproved |  Medium CVE-2020-3810   |          apt           |         1.4.8         | Missing input validation in the ar/tar implementations of APT before v |
|            |                         |                        |                       | ersion 2.1.2 could result in denial of service when processing special |
|            |                         |                        |                       |                         ly crafted deb files.                          |
+------------+-------------------------+------------------------+-----------------------+------------------------------------------------------------------------+

Vulnerabilities in the log are marked as Approved when the corresponding CVE ID is added to the vulnerability-allowlist.yml file.

Running container scanning in an offline environment

For self-managed GitLab instances in an environment with limited, restricted, or intermittent access to external resources through the internet, some adjustments are required for the container scanning job to successfully run. For more information, see Offline environments.

Requirements for offline container Scanning

To use container scanning in an offline environment, you need:

  • GitLab Runner with the docker or kubernetes executor.
  • To configure a local Docker container registry with copies of the container scanning images. You can find these images in their respective registries:
GitLab Analyzer Container Registry
Container-Scanning Container-Scanning container registry

Note that GitLab Runner has a default pull policy of always, meaning the runner tries to pull Docker images from the GitLab container registry even if a local copy is available. The GitLab Runner pull_policy can be set to if-not-present in an offline environment if you prefer using only locally available Docker images. However, we recommend keeping the pull policy setting to always if not in an offline environment, as this enables the use of updated scanners in your CI/CD pipelines.

Support for Custom Certificate Authorities

Support for custom certificate authorities was introduced in the following versions:

Scanner Version
Trivy 4.0.0
Grype 4.3.0

Make GitLab container scanning analyzer images available inside your Docker registry

For container scanning, import the following images from registry.gitlab.com into your local Docker container registry:

registry.gitlab.com/security-products/container-scanning:4
registry.gitlab.com/security-products/container-scanning/grype:4
registry.gitlab.com/security-products/container-scanning/trivy:4

The process for importing Docker images into a local offline Docker registry depends on your network security policy. Please consult your IT staff to find an accepted and approved process by which you can import or temporarily access external resources. These scanners are periodically updated, and you may be able to make occasional updates on your own.

For more information, see the specific steps on how to update an image with a pipeline.

For details on saving and transporting Docker images as a file, see Docker’s documentation on docker save, docker load, docker export, and docker import.

Set container scanning CI/CD variables to use local container scanner analyzers

  1. Override the container scanning template in your .gitlab-ci.yml file to refer to the Docker images hosted on your local Docker container registry:

    include:
      - template: Security/Container-Scanning.gitlab-ci.yml
    
    container_scanning:
      image: $CI_REGISTRY/namespace/gitlab-container-scanning
    
  2. If your local Docker container registry is running securely over HTTPS, but you’re using a self-signed certificate, then you must set CS_DOCKER_INSECURE: "true" in the above container_scanning section of your .gitlab-ci.yml.

Automating container scanning vulnerability database updates with a pipeline

We recommend that you set up a scheduled pipeline to fetch the latest vulnerabilities database on a preset schedule. Automating this with a pipeline means you do not have to do it manually each time. You can use the following .gitlab-ci.yml example as a template.

variables:
  SOURCE_IMAGE: registry.gitlab.com/security-products/container-scanning:4
  TARGET_IMAGE: $CI_REGISTRY/namespace/gitlab-container-scanning

image: docker:stable

update-scanner-image:
  services:
    - docker:dind
  script:
    - docker pull $SOURCE_IMAGE
    - docker tag $SOURCE_IMAGE $TARGET_IMAGE
    - echo "$CI_REGISTRY_PASSWORD" | docker login $CI_REGISTRY --username $CI_REGISTRY_USER --password-stdin
    - docker push $TARGET_IMAGE

The above template works for a GitLab Docker registry running on a local installation. However, if you’re using a non-GitLab Docker registry, you must change the $CI_REGISTRY value and the docker login credentials to match your local registry’s details.

Scan images in external private registries

To scan an image in an external private registry, you must configure access credentials so the container scanning analyzer can authenticate itself before attempting to access the image to scan.

If you use the GitLab Container Registry, the DOCKER_USER and DOCKER_PASSWORD configuration variables are set automatically and you can skip this configuration.

This example shows the configuration needed to scan images in a private Google Container Registry:

include:
  - template: Security/Container-Scanning.gitlab-ci.yml

container_scanning:
  variables:
    DOCKER_USER: _json_key
    DOCKER_PASSWORD: "$GCP_CREDENTIALS"
    DOCKER_IMAGE: "gcr.io/path-to-you-registry/image:tag"

Before you commit this configuration, add a CI/CD variable for GCP_CREDENTIALS containing the JSON key, as described in the Google Cloud Platform Container Registry documentation. Also:

  • The value of the variable may not fit the masking requirements for the Mask variable option, so the value could be exposed in the job logs.
  • Scans may not run in unprotected feature branches if you select the Protect variable option.
  • Consider creating credentials with read-only permissions and rotating them regularly if the options aren’t selected.

Running the standalone container scanning tool

It’s possible to run the GitLab container scanning tool against a Docker container without needing to run it within the context of a CI job. To scan an image directly, follow these steps:

  1. Run Docker Desktop or Docker Machine.

  2. Run the analyzer’s Docker image, passing the image and tag you want to analyze in the CI_APPLICATION_REPOSITORY and CI_APPLICATION_TAG variables:

    docker run \
      --interactive --rm \
      --volume "$PWD":/tmp/app \
      -e CI_PROJECT_DIR=/tmp/app \
      -e CI_APPLICATION_REPOSITORY=registry.gitlab.com/gitlab-org/security-products/dast/webgoat-8.0@sha256 \
      -e CI_APPLICATION_TAG=bc09fe2e0721dfaeee79364115aeedf2174cce0947b9ae5fe7c33312ee019a4e \
      registry.gitlab.com/security-products/container-scanning
    

The results are stored in gl-container-scanning-report.json.

Reports JSON format

The container scanning tool emits a JSON report file. For more information, see the schema for this report.

Here’s an example container scanning report:

{
  "version": "3.0.0",
  "vulnerabilities": [
    {
      "id": "df52bc8ce9a2ae56bbcb0c4ecda62123fbd6f69b",
      "category": "container_scanning",
      "message": "CVE-2019-3462 in apt-1.4.8",
      "description": "Incorrect sanitation of the 302 redirect field in HTTP transport method of apt versions 1.4.8 and earlier can lead to content injection by a MITM attacker, potentially leading to remote code execution on the target machine.",
      "severity": "High",
      "confidence": "Unknown",
      "solution": "Upgrade apt from 1.4.8 to 1.4.9",
      "scanner": {
        "id": "trivy",
        "name": "trivy"
      },
      "location": {
        "dependency": {
          "package": {
            "name": "apt"
          },
          "version": "1.4.8"
        },
        "operating_system": "debian:9.4",
        "image": "registry.gitlab.com/gitlab-org/security-products/dast/webgoat-8.0@sha256:bc09fe2e0721dfaeee79364115aeedf2174cce0947b9ae5fe7c33312ee019a4e"
      },
      "identifiers": [
        {
          "type": "cve",
          "name": "CVE-2019-3462",
          "value": "CVE-2019-3462",
          "url": "http://www.securityfocus.com/bid/106690"
        }
      ],
      "links": [
        {
          "url": "http://www.securityfocus.com/bid/106690"
        },
        {
          "url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-3462"
        },
        {
          "url": "https://lists.apache.org/thread.html/8338a0f605bdbb3a6098bb76f666a95fc2b2f53f37fa1ecc89f1146f@%3Cdevnull.infra.apache.org%3E"
        },
        {
          "url": "https://lists.debian.org/debian-lts-announce/2019/01/msg00013.html"
        },
        {
          "url": "https://lists.debian.org/debian-lts-announce/2019/01/msg00014.html"
        },
        {
          "url": "https://security.netapp.com/advisory/ntap-20190125-0002/"
        },
        {
          "url": "https://usn.ubuntu.com/3863-1/"
        },
        {
          "url": "https://usn.ubuntu.com/3863-2/"
        },
        {
          "url": "https://usn.ubuntu.com/usn/usn-3863-1"
        },
        {
          "url": "https://usn.ubuntu.com/usn/usn-3863-2"
        },
        {
          "url": "https://www.debian.org/security/2019/dsa-4371"
        }
      ]
    }
  ],
  "remediations": []
  "scan": {
    "scanner": {
      "id": "trivy",
      "name": "Trivy",
      "url": "https://github.com/aquasecurity/trivy/",
      "vendor": {
        "name": "GitLab"
      },
      "version": "0.16.0"
    },
    "type": "container_scanning",
    "start_time": "2021-04-14T19:45:58",
    "end_time": "2021-04-14T19:46:18",
    "status": "success"
  }
}

Security Dashboard

The Security Dashboard shows you an overview of all the security vulnerabilities in your groups, projects and pipelines.

Vulnerabilities database update

If you use container scanning and want more information about the vulnerabilities database update, see the maintenance table.

Interacting with the vulnerabilities

After a vulnerability is found, you can address it.

Solutions for vulnerabilities (auto-remediation)

Some vulnerabilities can be fixed by applying the solution that GitLab automatically generates.

To enable remediation support, the scanning tool must have access to the Dockerfile specified by the DOCKERFILE_PATH CI/CD variable. To ensure that the scanning tool has access to this file, it’s necessary to set GIT_STRATEGY: fetch in your .gitlab-ci.yml file by following the instructions described in this document’s overriding the container scanning template section.

Read more about the solutions for vulnerabilities.

Troubleshooting

docker: Error response from daemon: failed to copy xattrs

When the runner uses the docker executor and NFS is used (for example, /var/lib/docker is on an NFS mount), container scanning might fail with an error like the following:

docker: Error response from daemon: failed to copy xattrs: failed to set xattr "security.selinux" on /path/to/file: operation not supported.

This is a result of a bug in Docker which is now fixed. To prevent the error, ensure the Docker version that the runner is using is 18.09.03 or higher. For more information, see issue #10241.

Getting warning message gl-container-scanning-report.json: no matching files

For information on this, see the general Application Security troubleshooting section.

Changes

  • GitLab 13.6 introduced better support for FIPS by upgrading the CS_MAJOR_VERSION from 2 to 3. Version 3 of the container_scanning Docker image uses centos:centos8 as the new base. It also removes the use of the start.sh script and instead executes the analyzer by default. Any customizations made to the container_scanning job’s before_script and after_script blocks may not work with the new version. To roll back to the previous alpine:3.11.3-based Docker image, you can specify the major version through the CS_MAJOR_VERSION variable.
  • GitLab 13.9 introduced integration with Trivy by upgrading CS_MAJOR_VERSION from 3 to 4.
  • GitLab 13.9 deprecated the integration with Clair.
  • GitLab 14.0 introduced an integration with Trivy as the default for container scanning, and also introduced an integration with Grype as an alternative scanner.

Other changes to the container scanning analyzer can be found in the project’s changelog.