API Security Best Practices for Businesses

APIs are a valuable tool for app developers as they open the door to improved data sharing and powerful functionality. Good, well-designed and coded APIs help you to create innovative and integrated solutions.

But, there are potential downsides – especially if they’re not secured properly and run the risk of leaking sensitive data.

Poorly secured APIs are susceptible to attacks like injection, denial of service, data breaches and more. A single vulnerability can be catastrophic, allowing hackers to access information or crippling your systems with traffic floods.

The good news is – as long as you make security a priority, follow API security best practices, and only use APIs that apply industry standards, you can be confident that your app data is in safe hands.

Read on to find out how to benefit from the convenience of APIs, while making sure that your app or platform is safe and secure.

Authentication

Proper authentication is the first line of defense for your APIs.

Authentication is like a gatekeeper that lets you verify who is accessing your APIs before allowing them in. Follow these authentication best practices to manage logins:

• Understand and implement OAuth 2.0 standards: OAuth 2.0 is a widely-accepted standard for authorizing API access. Understanding OAuth 2.0 and how it works can help you to build secure applications that delegate access rights without risking the exposure of user credentials.
• Validate access tokens on every API request: Ensuring the validation of access tokens with every API request is critical. Without this step, a stolen or otherwise compromised token could potentially be used to gain unauthorized access. This could compromise user data and the integrity of the application.
• Use an identity provider service to externalize authentication: These services manage the complex aspects of identity and access management, so you can focus on other aspects of the app. They allow you to streamline authentication and add features like social logins that can enhance the user experience and potentially increase user adoption.

Authorization

Proper authorization design is crucial for securing your app's backend and data. Here are some user-friendly practices to consider while setting up authorization:

• Personalize Roles and Permissions: Do away with role-based permissions that may unintentionally grant excessive access. Tailor-make roles such as "admin", "manager", or "customer", each representing a specific use case. Grant these roles just the right amount of access to maintain functional efficiency while promoting role clarity and security.
• Limit API Access and Actions: Each of your app's API endpoints should cross-check a user's role and permissions before carrying out requested tasks. Remember, CREATE, READ, UPDATE, and DELETE operations should be exclusive to users with the appropriate permissions.
• Employ Access Control Lists: Create and maintain access control lists. These lists connect user accounts or roles to specific data entities and app resources, enabling you to enforce permissions on a fine-grained level.
• Monitor Access and Changes: Keep track of user access and actions in your app and through your API. Regularly assess these logs to detect any unauthorized or suspicious activities swiftly.

Encryption

Robust encryption is a necessity for securing user data, shielding against unauthorized access and ensuring confidentiality. Apply the following encryption strategies to strengthen data protection and build user trust:

• Full-Spectrum Encryption: Always enable transport encryption (think TLS/SSL) for all connections to your app and API. This ensures data security while it traverses the network. Don't forget to encrypt sensitive data stored in your databases and servers too.
• HTTPS: The Standard Protocol: Insist on HTTPS connections instead of the unencrypted HTTP. This adds an extra layer of encryption to user traffic. Additionally, activating HSTS can further ensure HTTPS connections are the norm.
• Guard Sensitive Data: Store passwords, financial details, personal information, or any sensitive data in an encrypted format. This keeps the data unreadable even if your servers are breached.
• Secure Your Backups: Encrypt backups to prevent unauthorized restoration of data. This security measure applies to both recent backups and older archives.
• Manage Keys Intelligently: The crux of encryption is key management. Store keys securely, change them regularly, and have strict access control policies for key use.

Input Validation

Securing your app's backend is important to prevent attacks. One essential aspect is proper input validation and sanitation. Here are some key things to consider for effective input validation:

• Validate Every API Input: Ensure that each parameter, header, URL, and body payload from API requests meets your expectations before proceeding. Check for the correct formatting, size, and data type.
• Defend Against Injection Attacks: Be cautious of user inputs which could house harmful code or commands. To prevent code injection attacks like SQLi, XSS or OS command injection, make sure to encode or escape special characters.
• Detect and Block DDoS: Stay alert for abnormal repeated requests, malformed payloads, or other patterns indicative of a DDoS attack. Tools such as rate limiting and anomaly detection can help you identify and stop these attacks.
• Avoid Data Corruption: Check for illegal characters, strings, or improper syntax that could corrupt your data. This ensures the integrity of data in your app backend and databases.
• Limit Input Sizes: Curb potential overflows by validating input lengths against reasonable maximums before acceptance.
• Implement Whitelisting: When feasible, create whitelists of known good or acceptable values that inputs should match. Inputs that don't conform should be rejected outright.

Rate Limiting

Implementing rate limiting is essential to prevent abusive requests. By controlling the number of requests from individual clients, rate limiting helps protect your backend from potential overload and malicious intent such as DDoS attacks. Here are some rate limiting best practices to implement:

• Create Throttling Policies: Define sensible request quotas for each endpoint and user that align with expected usage patterns. Common techniques involve allowing a specific number of requests per minute/hour or a daily maximum.
• Limit Per User and IP Address: Consider limiting requests based on both the IP address and authenticated user accounts. This tactic curbs abusive behavior from a single IP or user.
• Employ Exponential Backoff: If quotas are exceeded, progressively increase timeouts in responses to encourage clients to slow down, instead of entirely blocking access. This approach helps avoid accidental lockouts.
• Study Usage Patterns: Keep analyzing request patterns and adjust throttling policies accordingly. Remember, usage trends may shift over time or vary among user segments. Whenever possible, set dynamic rather than static limits.
• Monitor and Alert: Keep an eye on analytics like dropped requests and exceeded quotas. Set alerts for sudden spikes, which could signal emerging abuse.

Monitoring

Robust monitoring and alerting are crucial elements in detecting and responding to security incidents promptly and effectively. Here are some tips to make sure you’re effectively monitoring API usage:

• Observe API Usage Patterns: Collect data on average API traffic volumes, response times, error rates, etc. to establish a baseline for anomaly detection.
• Record Authentication Attempts: Log all successful and failed login attempts. Watch out for sudden spikes in failed logins, which could indicate credential stuffing attacks.
• Set Threshold Alerts: Create alerts that trigger when unusual activities, such as sudden increases in error rates, traffic, or authorization failures, are detected.
• Monitor Server Performance: Keep track of CPU, memory, and storage usage across backend servers. Unexpected surges may signal an impending DDoS attack.
• Collect Security Events: Centralize logs from firewalls, APIs, endpoints, etc., in a SIEM system for correlation and analysis. Even events that do not trigger immediate alerts, like blocked IPs, should be collected.
• Perform Log Analysis: Regularly review logs using security analytics tools to spot unusual behavior patterns or suspicious access attempts, which may be early indicators of a breach.

Testing

Thorough testing is needed to prevent the vulnerabilities and ensure the robustness of your APIs. Here are some strategies to test your application's security effectively:

• Embrace Unit and Integration Testing: Develop automated tests that confirm the expected behavior of individual components and their combined interactions. Whenever changes are made, re-run these tests to ensure everything still works as intended.
• Load and Performance Testing: Simulate heavy traffic on your APIs to identify potential bottlenecks. This approach verifies that performance remains satisfactory, even under peak conditions.
• Engage in Penetration Testing: Enlist the help of ethical hackers to actively probe your APIs for vulnerabilities, such as injection flaws or inadequate access controls. Prioritize remediation of all medium and high-severity findings.
• Scan for Open Ports and Misconfigurations: Regularly examine servers for exposed ports, default credentials, and other security-risk configurations. Utilize static and dynamic application security testing tools to aid this process.
• Test Endpoints Rigorously: Every API endpoint requires thorough testing to ensure proper input validation, error handling, rate limiting, and access authorization. Make sure to account for both positive and negative scenarios in your testing.
• Continually Expand Testing Coverage: As your app evolves, perpetually extend your test cases to cover new scenarios, error conditions, edge cases, and unintended usage. High coverage minimizes blind spots and maximizes security.

Summary

While hackers will continually evolve their tactics, following security fundamentals will make their job much harder.

With vigilance and regular reviews of your practices against the latest threats, you can use robust APIs that avoid exposing user data. Security requires continued focus, but the effort pays dividends in the trust you build with customers.

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If you’d like to see Sceyt in action, check out our demo app today.

Dan Martin

Dan is a an experienced B2B tech writer with a background in engineering.

He specializes in writing about IT, software, SaaS, and engineering.