Graphql Introspection in Fiber with Dynamodb

GraphQL introspection in a Fiber application that uses DynamoDB as a backend can expose schema details and operational patterns that increase the risk of information disclosure and unintended data access. When introspection is enabled in production, an attacker can query the GraphQL schema to discover types, queries, and mutations, including field names and argument structures. This becomes more sensitive when the underlying resolver logic interacts directly with DynamoDB, because naming patterns and response shapes may reveal how data is organized in tables and indexes.

In a typical Fiber setup, GraphQL handlers are registered without restricting introspection, and resolvers may construct DynamoDB API calls based on incoming arguments, such as using GetItem with a partition key derived from an ID argument. If introspection responses include field descriptions or argument names that map to DynamoDB attribute names, an attacker gains insight into how data is stored and accessed. For example, a field named userID that maps to a DynamoDB partition key PK suggests how records are identified. Additionally, if the GraphQL schema exposes nested types that correspond to DynamoDB item attributes, an attacker can infer relationships and data sensitivity without making authenticated requests.

Crucially, this risk is not about GraphQL exposing DynamoDB internals directly, but about how schema design and naming choices, combined with introspection, create an indirect information channel. When combined with other checks such as Authentication and Property Authorization in middleBrick scans, such patterns are flagged as potential BOLA/IDOR risks if object-level permissions are not enforced. Introspection thus becomes one piece of the puzzle that an attacker can use to plan enumeration or privilege escalation attempts against the DynamoDB-backed API.

To reduce exposure, disable GraphQL introspection in production environments and ensure that resolver logic does not leak DynamoDB-specific details through error messages or response structures. Below are concrete Fiber code examples that demonstrate secure handling of GraphQL operations with DynamoDB integration.

Disable introspection in production

Configure the GraphQL server to disable introspection when deploying to production. In Fiber, this can be done by setting the appropriate option when initializing the GraphQL handler.

// main.go
package main

import (
    "github.com/gofiber/fiber/v2"
    "github.com/hasura/graphql-go/graphql"
)

func main() {
    app := fiber.New()

    schema, _ := graphql.NewSchema(graphql.SchemaConfig{
        Query:    graphql.NewObject(graphql.ObjectConfig{Name: "Query", Fields: graphql.Fields{}}),
        DisableIntrospection: true, // Disable introspection in production
    })

    app.All("/graphql", func(c *fiber.Ctx) error {
        gqlHandler := graphql.GraphQL(schema, graphql.Params{Context: c.Context()})
        result := gqlHandler(c)
        return c.SendString(result)
    })

    app.Listen(":3000")
}

Use parameterized DynamoDB calls in resolvers

Ensure that resolvers construct DynamoDB API calls using strongly-typed inputs and avoid concatenating user input into request parameters. This prevents injection-style issues and keeps the interaction predictable.

// resolvers.go
package resolvers

import (
    "context"
    "github.com/aws/aws-sdk-go-v2/aws"
    "github.com/aws/aws-sdk-go-v2/service/dynamodb"
    "github.com/aws/aws-sdk-go-v2/service/dynamodb/types"
)

func GetUserProfile(ctx context.Context, userID string, client *dynamodb.Client) (map[string]types.AttributeValue, error) {
    output, err := client.GetItem(ctx, &dynamodb.GetItemInput{
        TableName: aws.String("UserProfiles"),
        Key: map[string]types.AttributeValue{
            "PK": &types.AttributeValueMemberS{Value: userID},
        },
    })
    if err != nil {
        return nil, err
    }
    return output.Item, nil
}

Apply field-level authorization before DynamoDB access

Even when introspection is disabled, enforce authorization at the resolver level to prevent horizontal privilege escalation. Validate the requesting user’s permissions before constructing DynamoDB requests.

// auth_resolvers.go
package resolvers

import (
    "context"
    "errors"
)

func AuthorizedGetUserProfile(ctx context.Context, userID string, requesterID string, client *dynamodb.Client) (map[string]interface{}, error) {
    if userID != requesterID {
        return nil, errors.New("access denied: cannot access other user profiles")
    }
    // proceed with safe DynamoDB call
    item, err := GetUserProfile(ctx, userID, client)
    if err != nil {
        return nil, err
    }
    return convertToInterfaceMap(item), nil
}

Mask sensitive errors and avoid schema leaks

Ensure that error messages returned by GraphQL do not include DynamoDB internal details. Use generic error responses and log detailed issues server-side only.

// error_handling.go
package main

import (
    "github.com/gofiber/fiber/v2"
    "github.com/hasura/graphql-go/graphql"
)

func safeErrorHandler(err error) string {
    // Do not expose DynamoDB error codes or table names
    return "An error occurred while processing your request"
}

func graphqlHandler(schema graphql.Schema) fiber.Handler {
    return func(c *fiber.Ctx) error {
        gqlParams := graphql.Params{
            RequestString: c.Query("query"),
            Context:       c.Context(),
        }
        result := graphql.Do(gqlParams)
        if result.Errors != nil {
            return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{
                "errors": []string{safeErrorHandler(result.Errors[0])},
            })
        }
        return c.JSON(result.Data)
    }
}