Since APIs are a direct line to your data, users, and brand's reputation, API security is a critical component of any Application Security program. While they enable seamless app interconnectivity, poorly secured APIs result in overlooked vulnerabilities that expose you to threats. And as your API ecosystem grows, so does the complexity of securing it.
If you're among the 74% of organizations that have embraced an API-first strategy, you must invest in dedicated API security practices. Of course, acknowledging the importance of API security is one thing; embedding it into your agile workflows without compromising speed or efficiency is another.
What is API Security?
API security involves a set of strategies to protect the sensitive data transmitted through your APIs. Each API endpoint represents a specific route that allows clients---applications, services, or users---to send requests for data, execute operations, or trigger actions on the server.
API security focuses on the risks associated with these endpoints, often vulnerable to attacks. The main objectives are to prevent unauthorized access, stop data leaks, and defend against common threats like injection attacks and credential stuffing.
Adequate API security uses various tools and techniques, including authentication protocols, real-time monitoring, encryption, rate limiting, and input validation. Since APIs frequently handle sensitive data, it's critical to implement these protections while maintaining performance and avoiding disruptions to the development process.
It comprises tools and methods like authentication protocols, real-time monitoring, encryption, rate limiting, and input validation to secure access and detect unusual activity. Since APIs often handle sensitive data directly, implementing these protections is crucial -- but it needs to happen without compromising performance or interrupting development cycles.
API Security vs. Application Security: What are the Differences?
API and application security aim to protect data, but they do so in distinct ways. API security focuses on securing each endpoint and controlling access with granular permissions to secure every data exchange. In contrast, application security covers the entire stack, from the UI to backend systems, securing the broader ecosystem.
API security is built for agility, using real-time monitoring and anomaly detection to react immediately to threats that arise with every call. On the other hand, application security takes a structural approach, using techniques like static code analysis and secure coding to address risks across the entire system.
APIs rely on token-based methods like OAuth and JWT for authentication, which offer specific, short-lived access. Application security uses broader access controls, like role-based access control (RBAC), to manage permissions at multiple levels.
Why is API Security Needed?
APIs are critical to modern applications, but they introduce unique vulnerabilities because of how they operate and what they expose. Unfortunately, traditional security methods can't fully manage these vulnerabilities. Several challenges can complicate security and increase risk for your organization:
- Increased Attack Surface ---The average application has dozens of API endpoints, each a potential doorway for attackers. Endpoints that handle user authentication or financial data are especially high-stakes. They're prime targets for attacks like injection, broken object-level authorization (BOLA), and parameter tampering if left unmonitored.
- Rapid Development Cycles -- APIs are often developed and deployed quickly to support agile methodologies and CI/CD pipelines. However, security reviews and testing can lag, especially when security practices are not embedded directly in the DevOps process.
- Dynamic, Distributed Environments -- APIs span cloud, on-prem, and hybrid environments, each with different security requirements. What works for an on-premises API may fail in the cloud, making consistent security enforcement a significant challenge.
- Complex Integration Networks -- APIs are often the glue connecting a network of microservices, each with its security posture. A single vulnerability in one API can expose an entire chain of services, amplifying the security impact. In industries like construction, robust API security can support preventative maintenance programs by securing the data exchange between monitoring systems, sensors, and maintenance applications.
- Third-Party Dependencies -- Many APIs rely on third-party services for functionality, such as payment processing, identity verification, or data enrichment. These integrations introduce third-party risks, as your API's security now depends on the security of external providers.
8 Core Concepts and Examples of API Security
1. Authentication and Authorization
Authentication confirms user identity, while authorization controls what each user can access. OAuth 2.0 is the preferred API token-based access, allowing you to grant scoped access without exposing credentials. With tools like Auth0 and Okta, you can set up OAuth to limit access based on custom user roles or application needs, while libraries like passport.js (Node.js) and Spring Security (Java) support OAuth flows.
Consider integrating MFA with OpenID Connect (OIDC) on OAuth 2.0 to add an extra verification layer that protects sensitive endpoints even if an access token is stolen.
2. Input Validation
Input validation blocks malicious payloads, which can prevent injection attacks like SQL or XML injection. Use allowlist-based validation to define strict input formats for endpoints, allowing only approved data types, ranges, or characters. Allowlisting makes it harder for attackers to manipulate requests to bypass filers.
In Node.js, express-validator helps set up validation quickly, while OWASP's ESAPI provides pre-built functions for secure input validation across different languages.
const { body } = require('express-validator'); app.post('/api/data',
[ body('username').isAlphanumeric().isLength({ min: 3, max: 15 }), body('email').isEmail() ],
(req, res) => { // Process validated data });
3. JSON Web Tokens
JSON Web Tokens (JWTs) simplify stateless authentication by storing user claims within the token, reducing database load and expediting user verification. However, JWT implementation must be cautious, especially in how tokens are handled and stored. Securely store your tokens in HTTP-only cookies or secure storage to avoid client-side tampering. For example, JSONwebtoken in Node.js is a popular library for JWT implementation.
Use short-lived tokens combined with refresh tokens to balance security and user experience. A 15-minute expiration works well to mitigate token hijacking:
const jwt = require('jsonwebtoken');
const token = jwt.sign({ userId: 123 }, 'secretKey', { expiresIn: '15m' });
4. Rate Limiting
Rate limiting can help fend off brute-force and DDoS attacks. By capping the requests a client can make in a given timeframe, you keep traffic in check and prevent resource overload.
const rateLimit = require('express-rate-limit');
const limiter = rateLimit({
windowMs: 15 * 60 * 1000, // 15 minutes
max: 100 // limit each IP to 100 requests per windowMs
});
app.use('/api/', limiter);
5. Encryption
Without encryption, your data is open to interception and tampering. Transport Layer Security (TLS) safeguards data in transit, while field-level encryption protects specific sensitive details, like payment information, within API requests. Remember that keeping your encryption keys secure is as important as encrypting the data.
For APIs dealing with especially sensitive data -- such as financial or health information -- end-to-end encryption (E2EE) is recommended. E2EE encrypts data at the origin and keeps it encrypted to the final destination, so even if it passes through multiple services, only the sender and recipient can decrypt it.
6. API Gateways
API gateways act as centralized security checkpoints, allowing you to enforce uniform policies across all endpoints for authentication, rate limiting, and traffic inspection. They are particularly beneficial in microservices architectures to simplify security across dispersed services. Consider using gateways to segment your sensitive internal APIs from public ones. Kong Gateway and Apigee from Google are popular options.
7. API Security Testing
You must establish ongoing checks to catch new vulnerabilities as your APIs evolve and business needs and integrations change. Jit can facilitate these checks by leveraging OWASP Zed Attack Proxy (ZAP) for DAST testing to simulate real-world attack scenarios that might impact your APIs.
Jit's scans actively probe for issues like SQL injection, cross-site scripting, and configuration flaws, giving you a clear view of your API's defenses. You can set up daily scans or trigger tests with each deployment. Choose authenticated scans for deeper insight, or run quick, unauthenticated scans to spot surface security misconfigurations.
8. Cross-Origin Resource Sharing (CORS)
CORS configuration controls how domains interact with your API, protecting against cross-origin attacks. CORS policies allow you to specify which external origins can access resources, preventing unauthorized domains from exploiting data or functionality. Misconfigurations in CORS settings can lead to data leakage, so adopting a default-deny stance is critical, only allowing trusted origins to access your API.
const cors = require('cors');
app.use(cors({
origin: 'https://trusted-origin.com',
methods: 'GET,POST'
}));
Establish Resilient API Security with Jit
APIs are powerful assets---but only if you manage their risks so the benefits outweigh the vulnerabilities. Each API is a direct line into your data and services, making them attractive targets for malicious actors. The key here is implementing proactive, built-in security measures to keep your APIs secure without impacting your development speed.
Jit's ASPM platform brings an automated layer to API security, conducting real-time security assessments at every code change and catching vulnerabilities before deployment. Jit's edge lies in prioritizing high-risk issues, guiding teams with automated remediation paths that keep development fast and focused. Explore it today.
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