Graphql Introspection in Chi

Graphql Introspection in Chi-based APIs typically manifests through default enabled introspection queries that expose the entire schema structure. When a Chi application uses graphql-go libraries or similar GraphQL middleware, the introspection system becomes accessible without authentication, allowing attackers to retrieve all available types, queries, mutations, and field definitions.

The most common attack pattern involves sending a POST request to the GraphQL endpoint with an introspection query like:

POST /graphql HTTP/1.1
Content-Type: application/json

{"query": "query { __schema { types { name fields { name args { name } } } } }"}

In Chi applications, this vulnerability often appears when developers use middleware like github.com/99designs/gqlgen or github.com/graphql-go/graphql without proper configuration. The middleware might be mounted at a route like:

router := chi.NewRouter()
router.Post("/graphql", graphqlHandler)
router.Handle("/playground", playground.Handler())

The playground endpoint itself can be a significant security risk, as it provides an interactive interface for crafting introspection queries and exploring the schema. Attackers can use the playground to map out the entire API surface, identifying sensitive queries, mutations, and input types that should not be publicly accessible.

Another manifestation occurs when Chi applications implement GraphQL subscriptions or real-time features. The subscription endpoint might expose additional introspection capabilities that reveal internal data structures, user types, or system metadata that could aid in further attacks.

Detecting GraphQL introspection vulnerabilities in Chi applications requires both manual testing and automated scanning. Using middleBrick's CLI tool, you can scan your Chi GraphQL endpoint with:

npx middlebrick scan https://your-api.com/graphql

middleBrick performs black-box scanning that tests for introspection endpoints by sending standard GraphQL introspection queries and analyzing the responses. The scanner specifically looks for Chi applications by identifying routing patterns and middleware signatures common in Go applications.

Manual detection involves sending introspection queries to your GraphQL endpoint and examining the response structure. A vulnerable Chi application will return a complete schema definition including:

• All object types and their fields
• Available queries and mutations
• Input object types and arguments
• Enum values and scalar types
• Interfaces and unions

You can also check for the presence of GraphQL playground at /playground or /graphiql endpoints, which are often enabled by default in Chi applications using common GraphQL libraries. The playground provides an interactive interface that makes introspection trivial for attackers.

middleBrick's LLM/AI Security checks are particularly relevant here, as they can detect if your GraphQL endpoint is also serving as an LLM inference endpoint, which would introduce additional attack surfaces through prompt injection vulnerabilities.

Remediating GraphQL introspection vulnerabilities in Chi applications requires a multi-layered approach. First, configure your GraphQL server to disable introspection in production environments. Using the github.com/graphql-go/graphql library with Chi, you can create a custom schema with introspection disabled:

package main

import (
	"github.com/graphql-go/graphql"
	"github.com/gorilla/mux"
	"github.com/pressly/chi/v5"
)

func createSchema() graphql.Schema {
	// Define your types and queries
	queryType := graphql.NewObject(graphql.ObjectConfig{
		Name: "Query",
		Fields: graphql.Fields{
			"hello": &graphql.Field{
				Type: graphql.String,
				Resolve: func(p graphql.ResolveParams) (interface{}, error) {
					return "Hello world", nil
				},
			},
		},
	})

	// Create schema without enabling introspection
	schema, _ := graphql.NewSchema(graphql.SchemaConfig{
		Query: queryType,
	})

	return schema
}

func main() {
	r := chi.NewRouter()
	
	r.Post("/graphql", func(w http.ResponseWriter, r *http.Request) {
		// Disable introspection by not including it in the schema
		// or by implementing custom query validation
	})
	
	http.ListenAndServe(":8080", r)
}

For production deployments, implement environment-based configuration to disable the GraphQL playground entirely:

func graphqlHandler() http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if os.Getenv("ENVIRONMENT") == "production" {
			// Disable playground in production
			w.Header().Set("X-GraphQL-Playground", "disabled")
		}
		// Handle GraphQL query
	}
}

Additionally, implement authentication and authorization middleware in your Chi application to ensure that even if introspection is technically available, it requires proper credentials. Use Chi's middleware chain to wrap your GraphQL handler:

router := chi.NewRouter()
router.Use(authMiddleware)
router.Post("/graphql", graphqlHandler)

For applications using github.com/99designs/gqlgen, configure the server to disable introspection in the generated server code or implement a custom directive that restricts introspection queries based on user roles.