5 API Security Features You Need to Know About

An application programming interface, or API, is the format through which one application interacts with another. The connective tissue of modern computing, APIs handle customer data, passwords, and patent-protected work.

But this interconnectivity introduces risk. As APIs shuttle an application’s data from secure servers to unknown clients, they bring it out of the secure confines of an application’s own database. API security focuses on keeping this data secure, while granting visibility back into the API data handling process.

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The Role of APIs, and Why API Security is So Important

When a customer opens the bank’s mobile app to view their balance, they aren’t directly connecting to the bank’s core database. Instead, the app communicates through a Banking API Gateway, which manages and secures all data exchanges between clients and backend systems. Essentially, APIs act as bridges, letting different software components exchange information securely and predictably, without revealing their internal workings. Modern enterprises manage thousands of APIs as part of their digital landscape – the F5 2024 API report discovered that large corporations with over $10 billion in annual revenue manage more than 1,400 APIs on average; some manage over 10,000.

There are generally 3 different types of API in use within organizations:

Public APIs: Public APIs, also known as open or external APIs, are accessible to any external developer or organization. They are popular with companies with an open-source business model.
Partner APIs: Partner APIs are those granted to approved external developers or business partners. Set up via a license, they support a more controlled approach to data exchange. For instance, a company may use a CRM vendor’s APIs to share customer information with a separate analytics tool. These API requests remain customer-specific, and are blocked from public access.
Private APIs: Private or internal APIs are designed for use solely within a single organization. They’re often used to connect internal systems to one another, like linking HR software to an in-house payroll application. Since they don’t face the public internet, internal APIs often have lighter security measures.

Note that all of these ‘types’ refer to the way in which access is granted to the API provider’s servers; access is one of the most foundational components to API security.

Foundational API Security Features

API security began to take shape in 1998: CVE-1999-0270 is one of the earliest examples of an API vulnerability, and it describes an exploit in the Performer API Search Tool that allowed attackers to gain access to random files. While this vulnerability wouldn’t garner much attention in the short-term, it marked the beginning of secure API features.

This would come to fruition in 2000, when Roy Fielding’s ‘Architectural Styles and the Design of Network-based Software Architectures’ was published. This defined REST as the API protocol of choice, and paved the way for standardized communication between API providers and clients. RESTful APIs offer GET, POST, PUT, and DELETE operations on application resources, a major step toward efficient standardization.

#1. API Keys

While REST allowed for highly scalable and efficient API calls, it didn’t inherently grant API providers visibility into the clients that are making requests. And in security, visibility is everything.

As web services and APIs became common in the early- to mid-2000s, there was a need for a lightweight way to check. Enter API keys – these are simple identifiers that each client includes in its API requests. The third-party application includes this key in its requests, in order to identify the application in question. The app usually generates its API key using cryptographically secure random number generators or hashing algorithms – the result is then included in the HTTP header within the API call.

While API keys are a simple way to identify itself to the server, they only authenticate the application – not the user. Furthermore, they don’t expire automatically, and can be easily exposed if embedded in hard code. The limitations of API keys became clear when Kubernetes entered the scene in the mid-2010s: since Kubernetes saw a widespread shift toward highly-distributed microservices, each implementing its own API. As a result, a new challenge arose in the form of securing large numbers of APIs at once. Alongside the REST protocol, further foundational security protocols would need to be implemented. This is roughly when OAuth 1.0 was developed.

#2. OAuth

OAuth 1.0 was an early authorization framework, which was designed to add a user-focused layer to API security. The OAuth protocol implemented a signed exchange to take place between the application, the user, and the API provider’s authorization server whenever an API call was made – a shift that added a whole new dimension to securing API calls. This reliance on digital signatures made OAuth secure – but also relatively complex to implement.

Its modern counterpart, OAuth 2.0, focuses on easier implementation. Let’s break it down into its core mechanisms:

Client Request: The client requests permission to access data on the application’s resource server. The request is forwarded to the service’s authorization server.
Authorization Request: The authorization server asks the client for permission to access their details. Once the user consents, the authorization server issues an authorization code to the client. This is where a client may see a login page.
Token Exchange: The client sends its own login credentials, alongside the authorization code, back to the authorization server. If successful, it then issues an access token.
API Access: The client is redirected back to the resource server, with the access token. The token proves the request is authorized, and the client can complete the API call.
Refresh (optional): When the access token expires, the client can use a refresh token to obtain a new one without user reapproval – if the client was issued with one.

OAuth’s token system allows API providers to separate authentication (who you are) from authorization (what you’re allowed to do). Its role-based and short-lived access allows the resource server to be tightly controlled.

Advanced API Security Features

While foundational API security measures can be built into API call mechanisms, they focus primarily on granting visibility for the API provider. For organizations that rely on microservices, it remains just as difficult to oversee how those different APIs are being used across the organization. This is the philosophy behind API posture management. Advanced API security features are built to improve observability for real-time threat detection and response across large numbers of APIs.

#3. API Gateways

In early API designs, services often communicated directly; clients sent requests to backend servers, which handled authentication, rate limiting, and logging independently. As APIs scaled, this point-to-point model became cumbersome. API gateways are middleware that enable one API call to access all necessary services and data, and return a single unified response.

Architecturally, an API gateway sits as a reverse proxy between clients and backend services. When a client sends a request, the gateway intercepts it first. It validates the request’s OAuth credentials, checks the gateway’s underlying policies, and determines where to route it. It can transform payloads, enforce API encryption, and aggregate responses from multiple microservices before returning data to the client. Instead of exposing multiple service endpoints to the public, the gateway presents a unified entry point — a controlled perimeter for all API traffic.

The security benefits of API gateways include:

A central control point: API gateways allow policy enforcement across all global APIs. For example, an API gateway can first determine whether the API request has been authorized, and validate the API’s schema. This allows it to identify and prevent injection attacks.
DDoS Protection: A gateway allows for fine control over the rate of API calls, and functions as a circuit breaker if requests flood in. Since APIs are an avenue for DDoS attacks, a central gateway can prevent a brute-force attack without impacting genuine users.

#4. Zero Trust API Security

Zero trust refers to a guiding principle within cybersecurity: never trust, always verify. In traditional API setups, trust was often implicit, particularly within API requests between internal applications. It’s this assumed trust that allows attackers to move laterally after an initial breach occurs.

Zero trust API security redefines this, and demands four key protocols to be followed when building or accessing APIs:

Each API request must be individually authenticated: API keys no longer work, as they are regularly leaked in bulk on public code repositories. Time-sensitive codes can help, but authenticated API connections (such as OAuth) are better.
Role-Based Access Control: API permissions should be restricted only to what is strictly required for the task, by that specific user.
Contextual Awareness: Authorization decisions are guided by dynamic policies that take wider device or API behavior into account.
Continuous Validation: Verification mechanisms aren’t a one-and-done thing, but persist continuously for the duration of a session.

Because of the wide range of demands, zero trust has often been used as a north star, rather than an individual security tooling. This has changed with the introduction of next-gen API threat detection solutions.

#5. Runtime Security

Most security controls covered here operate at design time – static scans, configuration reviews, and authentication checks implemented before release. Once APIs go live, however, it can be harder to detect logic flaws, token misuse, and data exfiltration attempts. This gap gave rise to runtime API security – protection that activates while the API is actively serving requests.

API runtime security embeds runtime sensors directly into the execution path of API traffic. These components inspect live requests and responses and correlate the corresponding metadata, such as tokens, payloads, endpoints, and timestamps. Implementing behavioral analysis also allows these datapoints to be pooled into a baseline of API behavior. From there, anomalies in request rates, injection patterns, privilege escalations, and token reuse can be detected – and automated responses like rate limiting, session termination, or alert generation triggered.

How Check Point CloudGuard Addresses Key API Vulnerabilities

Today’s threats run the gamut from high-volume reused attacks, to bespoke zero days: to keep an organization secure on all fronts, Check Point CloudGuard utilizes a WAF architecture using two complementary AI engines. One is a supervised attack-indicator engine trained on known malicious traffic; the other is an unsupervised contextual analysis engine that learns the patterns of normal behavior. This dual approach ensures that well-known vulnerabilities and novel attacks alike are blocked before they can compromise an API, or its underlying application.

To better reinforce your own security capabilities, CloudGuard automatically discovers all APIs and applications in your environment. By examining URLs, headers, and full bodies of payloads, it’s able to generate schema definitions and expected input formats. These are then used to validate incoming requests; any mismatches are blocked, giving security teams early protection against misuse or injection attacks. Explore the full suite of CloudGuard’s capabilities for yourself and schedule a demo today.