Why you should not use GraphQL schema generators

It has been quite a while since GraphQL has been introduced by Facebook, lots of tools and frameworks has appeared and are being used in the wild now. In 2017 I made an overview of the technology from the security point of view in the post “Looting GraphQL for Fun and Profit” and some of the predictions turned out to be true. For instance, “resolvers may contain ACL-related flaws“. In this post I would like to show an example of such case in a popular GraphQL backend called graphcool.

Looting GraphQL Endpoints for Fun and Profit

In one of the previous posts about the state of modern web applications security I mentioned GraphQL – a new technology for building APIs developed by Facebook. GraphQL is rapidly gaining popularity, more and more services switch to this technology, both web and mobile applications. Some of the GraphQL users are: GitHub, Shopify, Pintereset, HackerOne and many more. You can find many posts about GraphQL benefits and advantages over classic REST API on the internet, however there is not so much information about GraphQL security considerations. In this post I would like to elaborate on GraphQL: how it works, what the weak points are, how an attacker can abuse them, and which tools can be used.