APIs allow different software systems to communicate with each other, serving as the gateway to an application‘s functionality and data. As adoption of APIs accelerates, so does the need for adequate security to prevent breaches. This guide explains API vulnerabilities and provides actionable recommendations on locking down your APIs.
Why API Security Matters
Like any application, APIs can contain vulnerabilities that attackers exploit to steal data, execute malicious code or overwhelm systems. Unprotected APIs put the entire application at risk.
Some common API attack methods include:
- Injecting malicious code through inputs like URLs or payloads
- Stealing or modifying data through flaws in authentication or access controls
- Flooding requests to trigger denial-of-service
- Exploiting known vulnerabilities in API code or dependencies
Implementing security best practices is crucial for any API, public or private. Let‘s examine key areas to focus on.
Authentication: Verify User Identities
Authentication confirms a user‘s identity before allowing access to the API. Some options:
- OAuth 2.0: Delegate authentication to authorization servers like Google, Facebook, etc.
- JSON Web Tokens (JWT): Encode user credentials in a digitally signed token
- API Keys: Generate unique keys to identify applications rather than users specifically
Require authentication for every request. The server should verify tokens or keys on each call before responding.
Authorization: Control Access
Once authenticated, applying authorization rules determines what data and functions a user can access. For example:
- User A can GET order data only for their account
- Admins can GET all order data and POST to create orders
Define and enforce authorization policies based on roles and permissions. Don‘t rely solely on authentication.
Encryption: Protect Data
Encryption safeguards data in transit between client and server:
TLS: Implement TLS 1.2+ and disable outdated versions like SSLv2. TLS establishes an encrypted tunnel protected from eavesdropping/tampering.
Sensitive data: Fields like passwords, Social Security numbers, etc. may need extra encryption even inside TLS tunnels. The data should remain unreadable in storage as well.
Input Validation
Scrutinize all inputs from URLs, headers, payloads and anywhere else, assuming they contain malicious code by default.
- Validate data types, length, format, range and business logic
- Sanitize to remove executable code like JavaScript
- Use allowlists over denylists to specify exactly what is permitted
Input validation prevents attacks like code injections, unauthorized access or buffer overflows.
Rate Limiting
Rate limiting establishes thresholds like:
- Maximum 1000 requests per hour
- No more than 10 requests per minute
When thresholds are exceeded, requests get blocked. This technique prevents abuse and protects availability.
Apply intelligent rate limiting policies tailored to your expected traffic patterns.
Monitoring & Logs
- Activity logs provide visibility into all requests for tracing problems and detecting anomalies
- Monitoring dashboards track usage volumes, response times, error rates and more
- Alerting immediately notifies teams about potential incidents
Use logging, monitoring and alerting tooling to stay ahead of issues.
Secure Dependencies
Scan dependencies like libraries and SDKs for known vulnerabilities regularly:
- Subscribe to mailing lists and services that disclose vulnerabilities
- Patch dependencies promptly when fixes are available
- Enforce version pinning to avoid accidental dependency upgrades
Vulnerabilities get introduced via dependencies alarmingly often. Manage them closely.
Security Testing
Continuously test APIs to reveal weaknesses:
Static analysis: Inspect code for flaws without executing it
DAST: Test running APIs by actively manipulating inputs to find holes
Pen testing: Launch controlled attacks against APIs to uncover real-world risks
Fix issues before attackers discover and target them.
Compliance Checks
Adhere to API security standards like OWASP API Security Top 10 and NIST 800-203 for coverage of all major risk categories.
Review compliance status frequently to avoid gaps as methods evolve.
Zero Trust Mindset
Adopt a zero trust security model with the mantra "never trust, always verify." Implement controls assuming breaches will occur via any channel.
Strive to create layered defenses across your people, processes and technology.
Conclusion
Securing APIs requires vigilance across numerous fronts. Apply these best practices to lock down the gateways to your applications. Protect your customers and your business from threats.
