API Security 101: Securing GraphQL and REST Endpoints Like a Pro

GraphQL vs. REST Security: Understanding the Risks and Hardening API Endpoints

A Comparison of GraphQL vs. REST Security: The popularity of GraphQL over REST APIs is due to several reasons including flexibility, efficiency and the ability to get all needed data in one request. But, as a result of its dynamic behaviour, some special security risks such as over fetching, injection attacks and unauthorized data exposure are possible. Let’s compare the security risks of GraphQL and REST and outline the best practices for securing API endpoints in distributed architectures.

Why Organizations are Moving from REST to GraphQL ?

The trend of web and mobile applications rely on APIs for functionality is increasing and REST remains the conventional network protocol for data communication. The use of REST APIs produces both over-fetching and under-fetching problems that create more API calls and performance issues.

GraphQL provides a solution to these limitations because it lets clients define exactly the data requirements within one request. The same API flexibility creates additional security problems that organizations need to address:

• The single endpoint of GraphQL causes an increased attack surface.
• Absent rate limiting makes the API vulnerable to Denial of Service (DoS) attacks.
• Complex queries create data scraping problems while simultaneously causing over-fetching issues.
• The insecure introspection feature reveals the detailed structure of API endpoints.

Knowledge of GraphQL security differences from REST becomes essential for developing both API strategies and security protocols.

Here are the Security Risks:

1. Over-fetching & Excessive Data Exposure

• GraphQL enables clients to request multiple resources within one query, this leads to data exposure the client may not intend.
• As GraphQL allows clients to query multiple resources at once, this leads to data exposure the client may not intend.

Solution: set query depth and only return selected fields to avoid data exposure.

2. Injection Attacks (SQLi, NoSQLi, XSS)

• GraphQL queries can be exploited for malicious code injection just as much as SQL injection (SQLi) and NoSQL injection (NoSQLi).
• Both systems face risks, but since REST APIs are typically more structured in input, they are less likely to be exploited.

Solution: Use technologies such as query sanitization, validation and prepared statements to counter these risks.

3. Broken Authorization & Access Control

• GraphQL requires custom authorization logic because it does not include built-in default role-based access control (RBAC).
• Endpoint-based access control is built into REST APIs, it provides simpler ways to manage permission enforcement.

Solution: This vulnerability can be mitigated by developing specific authorization rules and implementing attribute-based access control (ABAC).

4. Unrestricted API Introspection

• Attackers can exploit GraphQL introspection because it reveals all available queries and mutations to developers.
• REST does not expose an equivalent level of API schema information, there is less exposure.

Solution: Production API introspection should be disabled unless access is authenticated and during development enable limited access.

5. Rate Limiting & Denial-of-Service (DoS) Risks

• GraphQL APIs process complex nested queries which can overload their servers if adequate limitations are absent.
• They enforce rate limits per endpoint which makes them more manageable against abuse.

Solution: Query cost analysis should be performed and both query depth and number of requests per second should be limited.

Let’s move to the best Practices for Securing GraphQL & REST APIs

Secure Login Credentials & Protect Endpoints for Authentication & Authorization:

• Use OAuth 2.0, OpenID Connect (OIDC), and JWT for token-based authentication.
• Implement role-based access control (RBAC) and attribute-based access control (ABAC).
• Make certain all queries and mutations check permission validation.

Restrict Data Exposure & Query Depth

• Set query depth limits to stop queries from loading too many results.
• Enforce field restrictions through allowlisting to limit accessed data.
• Enforce security rules via APIs like GraphQL Shield.

Injection Attacks Prevention

• Clean GraphQL input with the help of GraphQL-Parser libraries.
• Use parameterized queries to prevent SQL and NoSQL injection.
• Set Content Security Policy (CSP) headers to stop XSS attacks.

Disable Introspection in Production

• Disable GraphQL introspection or limit it to only authenticated developers.
• Set up API schema validation to enforce strict request structures.

Last but not least, Apply Rate Limiting & Throttling

• Implement query complexity scoring to prevent resource exhaustion.
• Enforce rate limiting on API requests using GraphQL middleware or API gateways.
• Watch query patterns to see unexpected traffic behaviour.

Let’s dive in to a case Study: Securing a FinTech GraphQL API

Scenario: Graphql FinTech uses banking APIs to fetch transactions alongside account details within one request but attackers exploited these vulnerabilities to steal sensitive financial information through over-fetching and BOLA (Broken Object Level Authorization).

How could we addressed this situation ?

The service enforced query depth limiting to stop nested queries occurring.

• Field-based access control limited queryable fields depending on user roles.
• Production API introspection was disabled to stop attackers from revealing API schema details.
• Request throttling & anomaly detection were implemented to stop API abuse attempts.

Outcome: The company removed excessive data exposure and tightened API access controls without sacrificing GraphQL efficiency.

It’s time for conclusion: Choosing the Right API Security Strategy

Both GraphQL and REST are powerful API solutions, but they require different security approaches.

• Choose REST APIs when access control and rate limiting are top priority.
• Use GraphQL for complex data queries but with strict security controls.
• Disable introspection, enforce authentication, and set query depth limits.
• Continuously monitor API traffic for anomalies and abuse patterns.

Organizations can secure their API endpoints against threats by applying strong security practices while still benefiting from GraphQL and REST capabilities (Valente, 2020).
Reference:
Valente, M. T. (2020). REST vs GraphQL: A controlled experiment. ResearchGate. https://www.researchgate.net/publication/339413273