API Security Best Practices: Top 10 Tips for a Secure API

Being an API testing company ourselves, we know how crucial it is to keep your APIs sane all the time. Since they’re the ones carrying over 85% of the business logic of an app- essentially running the app themselves.

It is our standard practice to do our own API Regression Report every year. But it was staggering for even us to know 8,661,895 regressions were reported last year on our own platform. This number is increasing as more apps are making use of APIs without taking proper measures to test them.

API security is equally critical. As applications become increasingly dependent on APIs, they grow more vulnerable to security breaches. This guide will help you properly test and secure your APIs to avoid making headlines—whether for system outages like Twitter's or airline booking failures caused by breached APIs.

We’re going to divide the best practices under two categories:

• one is more on the general lines of it,

• and the second will have all the technicalities involved if you plan to implement them.

Let’s get started with the common practices first. If you feel you already know them, here’s the thing you’re looking for then.

Common Practices to Keep Your APIs Secure

1. Trust no one

Zero Trust is a security concept centered on the belief that organizations should not automatically trust anything inside or outside their perimeters and instead must verify anything and everything trying to connect to its systems before granting access. This approach applies to API security by enforcing:

• Authentication and authorization for every API call, regardless of the source.

• Continuous validation of security configurations and policies.

• Segmentation of network access to minimize lateral movement in case of a breach.

2. Protect all APIs

Every API, regardless of how minor it may seem, represents a potential gateway into your system. It's essential to:

• Apply consistent security measures across all APIs.

• Ensure that internal APIs have the same level of security as external APIs, as internal systems are often the most vulnerable to attacks.

• Document and routinely update security policies that apply to all APIs.

3. Always use a Gateway:

An API Gateway acts as a middle layer that intercepts all incoming and outgoing API calls, providing an additional layer of security, such as:

• Rate limiting to prevent abuse.

• Authentication and authorization to ensure that only legitimate requests are processed.

• Logging and monitoring of all API traffic to detect and respond to potential security incidents.

4. Regression tests your APIs

Regression testing your APIs is crucial to ensure that any new change in the code has not introduced new bug in the code. And automating this whole process is of utmost value. It ensures that tests are run automatically whenever changes are made, preventing the integration of potentially harmful code into the main codebase.

✅ test for each endpoint and method (GET, POST, PUT, DELETE)

✅ regularly review and update your test cases to cover new API features and scenarios as your application evolves

These screenshots are from HyperTest's dashboard. Whenever a new code change occurs, tests run automatically and update you on any discrepancies detected between the two versions.

✅ use data that closely mirrors the real data your API will handle in production.

5. Regularly Update and Patch

The security landscape is constantly evolving, and so are the methods attackers use to exploit vulnerabilities. To protect APIs from known vulnerabilities, it’s vital to:

• Regularly update API management software, libraries, and dependencies to their latest versions.

• Apply security patches promptly to mitigate vulnerabilities.

• Monitor security advisories for the technologies you use in your API stack.

6. Implement comprehensive Logging and Monitoring

Effective monitoring can alert you to potential security incidents before they cause significant damage. Implementing comprehensive logging and monitoring involves:

• Detailed logging of all API interactions to provide an audit trail that can be analyzed after an incident.

• Real-time monitoring systems to alert on suspicious activities.

• Regularly reviewing logs and adapting monitoring tools to evolving security needs.

  
  

These general best practices form the cornerstone of a robust API security strategy, helping ensure the integrity, confidentiality, and availability of your API services.

Advanced API Security Tips

As the reliance on APIs increases, so does the attack surface they present. Let’s discuss some ways you can implement immediately to keep your APIs and thus your apps secure.

1. Implement Robust Authentication and Authorization Measures

Authentication verifies that users are who they say they are, and authorization determines if they have the right to access a resource. For APIs, implementing OAuth 2.0 for authorization is a gold standard, leveraging bearer tokens to maintain secure access.

// Example of securing an API endpoint using OAuth 2.0
app.get('/api/resource', oauth.authenticate(), (req, res) => {
  res.send('This is a secure resource');
});

2. Use HTTPS to Secure Data in Transit

Encrypting data in transit using HTTPS is non-negotiable in today's API security landscape. Ensure all data exchanged with your API is encrypted using TLS (Transport Layer Security) to protect against interception attacks.

# Enforce HTTPS by redirecting all HTTP traffic
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

3. Employ Rate Limiting to Mitigate DoS Attacks

Rate limiting controls the number of requests a user can make to your API in a given time frame, protecting your API from denial-of-service (DoS) attacks and service abuse.

# Example using Flask-Limiter to add rate limiting
from flask import Flask
from flask_limiter import Limiter
from flask_limiter.util import get_remote_address

app = Flask(__name__)
limiter = Limiter(app, key_func=get_remote_address, default_limits=["200 per day", "50 per hour"])

@app.route("/api")
@limiter.limit("10 per minute")
def access_api():
    return "API response"

4. Validate and Sanitize All Input

Input validation prevents improperly formatted data from entering your system, where it could potentially trigger unwanted behavior. Sanitization further ensures that any dangerous characters or scripts are removed before processing.

// Example of input validation in Java
public boolean validateUserInput(String input) {
    return input.matches("^[a-zA-Z0-9_]*$");
}

6. Implement Proper Error Handling

Secure API error handling means not exposing too much information to the user, which could be leveraged by an attacker. Always log errors internally and present generic error messages externally.

// Proper API error handling in Node.js
app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).send('Something broke!');
});

7. Use Token Expiry and Rotation Strategies

Using tokens with expiration and rotation policies helps limit the damage of a token being leaked. JWT (JSON Web Tokens) is a popular choice for implementing secure, expirable tokens.

// Implementing JWT token expiry
const jwt = require('jsonwebtoken');
const token = jwt.sign({ user_id: user.id }, process.env.JWT_SECRET, { expiresIn: '1h' });

8. Implement Logging and Monitoring

Effective logging and monitoring strategies are vital for detecting and responding to security incidents in real time. Use tools like ELK (Elasticsearch, Logstash, Kibana) or Splunk to monitor API usage and spot unusual activities.

# Example log entry for monitoring API access
LOG: User 123 accessed /api/resource at 2023-12-06T12:00:00

Conclusion

Securing your APIs is not just about adding layers of security but integrating these practices into the very fabric of your API development and maintenance workflows. With these top 10 security practices, you can significantly enhance the security posture of your APIs, protect your data, and ensure a safe user experience.

By consistently applying these measures and staying informed on the latest security trends, your API ecosystem will not only be robust but also resilient against emerging threats.

Thorough API testing plays a crucial role in defending against cyber-attacks. Keep your APIs updated and consistently tested to prevent many potential failures.

Discover how we help teams ensure their APIs are thoroughly tested and secure.