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How to configure and scan an API

Configure Snyk API & Web to scan an API defined by an OpenAPI or Postman Collection

Tiago Mendo avatar
Written by Tiago Mendo
Updated yesterday

This article explains how to scan a standalone API target with Snyk API & Web.

How does the API scanning work?

To scan an API, we need its specification, the schema. You can define it with an URL pointing to the schema, or upload it to Snyk API & Web. The former has the advantage of us fetching the schema before every scan, ensuring we always get the most up-to-date version.

Snyk API & Web supports APIs with different authentication methods. You can set a fixed API key in a custom header or configure a login endpoint from which you obtain an authentication token.

You can also define custom parameter values that replace those found in the schema. This allows you to override example values or to ensure domain-specific values are properly filled.

How do I scan an API?

Scanning an API is a simple three-step process:

  1. Add an API target

  2. Configure the API target

  3. Start the scan

This article describes these steps in detail, covering multiple authentication scenarios.

Step 1: Adding an API target

To add a target, do the following:

  1. Go to the Snyk API & Web app.

  2. Access the Targets menu entry and click on Add.

  3. Fill out the Add target form. Make sure to:

    1. Type in a meaningful Name for the target.

    2. Set the URL field to the API base URL, i.e., the domain from which your API is actually serving clients.

    3. Select API and, in API Type, choose between an OpenAPI and a Postman Collection. Please note the following:

    4. Choose between entering your API schema URL or uploading it. We support both JSON and YAML schemas. However, setting the schema URL has the advantage of Snyk API & Web fetching it before a scan, so we always scan the API's latest version.

  4. Click on Add to create the new target.

    If the server defined in the schema is not within the scope of the target, a warning will appear. You can opt to ignore the server from the OpenAPI schema file and use the target URL instead.

Step 2: Configure an API target

After adding (and verifying, if needed) the API target, go to its settings where there are some differences when compared with a web target, namely:

  • The Target Authentication section is replaced with API Target Authentication, if available.

  • There's a new API Scanning Settings section, where the schema and custom values are set.

  • There's no Seeds List section, as we only crawl and scan endpoints defined in the schema.

  • There's no Extra Hosts section, as this only makes sense for web apps.

Configure the API Authentication

If the API requires authentication, the configuration depends on whether the API target was configured as OpenAPI or Postman Collection:

Configure the API Scanning Settings

In the API Scanning Settings section, you can override or set values for the endpoint parameters described in the schema.

Our scanning engine has a set of predetermined values for the most common parameters, such as email, address, and dates.

If we cannot infer the adequate value for a parameter, we use a default value. You can override that behavior by setting specific values, such as email and the product_id, as shown in the example below:

Step 3: Start the scan

Just press Scan button, and follow its progress on the scan page.

Afterward, you can download a coverage report in CSV format that lists the endpoints parsed from the schema and the respective HTTP response code. The coverage report is a great tool for determining whether there were failed endpoints. Learn more about it in What is the meaning of the .CSV coverage report?

See also these articles:

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