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Approve Base Image

In many organizations, security teams vet and approve specific base images for developers to use. Even if these images contain known vulnerabilities, they are considered acceptable. STO's Base Image Approval feature helps you implement this process and enforce policies on it. This document details about:

note

This feature is behind the feature flag STO_BASE_IMAGE_DETECTION. Contact Harness Support to enable this flag.

What is Base Image Approval?​

Base Image Approval is a manual process where you explicitly approve one or more tags of a base image target in STO. This action signals that the selected base image tags are trusted for use in your pipelines. When you scan an application image built on an approved base image tag, you will find the scan results with the following indicators:

  • UI Indicator: Vulnerabilities originating from the approved base image are marked with a green base image label in the Vulnerabilities tab. Vulnerabilities from unapproved base images are marked in blue.
  • Step Output Variable: The BASE_IMAGE_APPROVED output variable in the scanner step is set to true. This variable allows you to create policies to ignore vulnerabilities from approved base images.

How to Approve a Base Image​

Before approving a base image, make sure you’ve reviewed What is Base Image Approval? and understood the process. To approve a base image, you must have the Approve / Reject permission for Test Targets in the project where you want to approve the base image. Or you must have the Security Testing AppSec role assigned. Refer to the RBAC documentation for more information.

warning

Approving a base image in a project is applied across the entire account. Once approved, the base image is considered trusted throughout the account, including all organizations and projects even those you may not have direct access to. Be aware that the approval will be applied at the account level.

A base image can only be approved in the project where it was last scanned. If you try to approve it elsewhere, the approval will not take effect.

Identify the Correct Project to Approve

To identify the correct project:

  1. Go to your pipeline execution window.
  2. Switch to Vulnerabilities tab.
  3. Open the issue details of a vulnerability labeled with Base.
  4. Check the Base Origin field. This field displays the project name where the base image was last scanned.

For example, the Base Origin might appear as: Base_Image_testing_2/baseimagescan/openjdk This aligns with the format OrgName/ProjectName/TargetName. So you can approve the base image in Base_Image_testing_2 project.

To approve a base image, follow the steps:

  1. Go to Test Targets page from left navigation.
  2. Find your base image(target) in the list. (for example, library/debian).
  3. Click the ellipsis menu on the right and select Approve Base Image.
  4. In the dialog, select one or more tags of the base image to approve (for example, bookworm-slim).
  5. Click Submit.

To unapprove a base image, you can follow the same steps and deselect the tags you want to unapprove and click Confirm. The approval or unapproval takes effect from the next pipeline execution.

How to view Vulnerabilities from Approved Base Image​

To view the vulnerabilities associated with the approved base image, follow these steps:

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Before proceeding, make sure that:

  1. Go to Security Testing Orchestration module.
  2. Go to Execution page from the left navigation.
  3. Find the pipeline execution with your container image scanning and open it.
  4. Go to Vulnerabilities tab.
  5. You will see the vulnerabilities from approved base image marked with a green Base Image label.

Policies for Vulnerabilities from Application and Base Images​

You can enforce policies on vulnerabilities from both application layers and base images by using the step output variables of your scanner step. Refer to Step Output Variables for App and Base Image Vulnerabilities for details.

Depending on your use case, you can apply the following sample policies: