How to find personally identifiable information (PII) and secrets exposed by your APIs

As companies grow in size, more and more APIs tend to be added. As these APIs are added, it becomes exponentially more difficult to track how sensitive information flows throughout the code base. Despite best intentions, it can be quite easy for PII or secrets to be accidentally exposed by an API.

Doing a text-based search for sensitive field names such as ssn or dateOfBirth might help you find where that data is – but you might also get a ton of irrelevant results, and you'd definitely miss out on cases where classes create or call out to other classes that have sensitive data.

Fortunately, Moderne offers a recipe that uses rich type information to detect how sensitive data flows throughout your code base. This recipe can detect all sorts of things that a text-based search would fail at. For instance, it can detect if an API returns a class that extends another class that has a method that returns sensitive data – or it can detect when an API returns a class that has a method that returns a different class that has a method that returns sensitive data. It can even recursively step through classes to find sensitive data flow through multiple levels of dependencies.

Let's walk through how to find and use this recipe so you can be more confident that your APIs are not unintentionally exposing sensitive data.

Using the find sensitive API endpoints recipe

  • After you've come up with the list of field names to search for, you can select whether or not you want the recipe to perform a transitive search. Setting this field to true (recommended) will recursively check through objects for sensitive data. For instance, if this field is true and an Owner object has a getPet method that returns a Pet object that contains PII or secrets (for example, birthDate from the options we chose), then the recipe would flag any methods that return an Owner because it could then return a Pet. If this field is set to false, then the recipe would only check the Owner class and any objects the Owner class extends (such as a Person class).

  • Once you've configured the recipe as you want, press the Dry run button and Moderne will begin searching for sensitive APIs. You'll be redirected to a page that looks like this:

  • You can click on any of the repositories to see what APIs return sensitive information:

  • Clicking on the text that is underlined will provide you with context about what sensitive data is exposed:

  • If you enabled a transitive search, you may find results that step through multiple classes such as in the Owner -> Pet example we discussed above:

If you want to find all outbound API calls that your application is making, you can do so with the find API calls recipe.

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