What is API Security?

API Security refers to the protection of APIs from unauthorized access, misuse, and attacks. Since APIs expose sensitive data and business logic, they are a prime target for attackers.

Why APIs Are Vulnerable?

• Direct exposure to the internet
• Improper authentication mechanisms
• Lack of input validation
• Misconfigured access controls
• Rapid development without security testing

Common API Attacks

1.  Broken Authentication Attack

Occurs when authentication mechanisms are weak or improperly implemented.

Example:

• Weak passwords
• Tokens not expiring
• No MFA (Multi-Factor Authentication)

Prevention:

• Use strong authentication (OAuth 2.0, JWT)
• Implement MFA
• Use secure token storage

2.  Broken Object Level Authorization (BOLA)

Attackers manipulate object IDs to access unauthorized data.

 Example:

Changing: 

Attackers manipulate object IDs to access unauthorized data.

???? Example:

Changing:

/api/user/123 → /api/user/124

to access another user's data.

 Prevention:

• Implement proper authorization checks
• Use indirect object references
• Validate user permissions

to access another user's data

3.  Injection Attacks (SQL/Command Injection)

Malicious input is injected into API requests to execute unintended commands.

 Example:

username=admin' OR '1'='1

 Prevention:

• Input validation & sanitization
• Use prepared statements
• Avoid dynamic queries

4.  Rate Limiting & DoS Attack

Attackers send massive requests to overload the API server.

 Example:

• Bot sending thousands of requests per second

 Prevention:

• Implement rate limiting
• Use API gateways
• Deploy WAF (Web Application Firewall)

5.  Data Exposure Attack

APIs return excessive or sensitive data unnecessarily.

 Example:

• Returning password hashes or internal data in response

 Prevention:

• Filter response data
• Encrypt sensitive data
• Follow least privilege principle

6.  Business Logic Attacks

Attackers exploit flaws in application logic.

 Example:

• Applying unlimited discount coupons
• Skipping payment verification

 Prevention:

• Thorough testing of workflows
• Implement logic validation checks

Tools Used in API Security Testing

 Testing Tools:

• Postman – API testing
• Burp Suite – Intercept & modify API traffic
• OWASP ZAP – Automated vulnerability scanning
• Wireshark – Network analysis
• Fiddler – HTTP debugging

API Security Best Practices

 Authentication & Authorization

• Use OAuth 2.0, JWT
• Implement role-based access control (RBAC)

 Input Validation

• Validate all inputs
• Use allowlists instead of blocklists

 Encryption

• Use HTTPS (TLS)
• Encrypt sensitive data

 Rate Limiting

• Prevent abuse & brute force attacks

 Logging & Monitoring

• Monitor API usage
• Detect anomalies

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