# **OWASP API top 10**
APIs are the backbone of modern applications, but their exposure to the internet makes them a prime target for attacks. The **OWASP API Security Top 10** outlines the most critical API vulnerabilities and how to mitigate them.
## **1. Broken Object Level Authorization (BOLA)**
When an API fails to properly enforce authorization, a user can access or modify another user's data.
🔹 **Example:**
- A banking API allows user A to access their transactions using `/transactions/12345`.
- User B modifies the request to `/transactions/67890` and retrieves someone else's transaction history.
🔹 **Mitigation:**
- Implement **strict access controls** at the object level.
- Verify user permissions for every API request.
---
## **2. Broken Authentication**
Weak authentication or missing security controls allow attackers to bypass login mechanisms.
🔹 **Example:**
- An API allows logins with only an **email and a weak password** without rate limiting or MFA.
- An attacker brute-forces accounts using leaked passwords.
🔹 **Mitigation:**
- Enforce **strong authentication (OAuth, JWT, MFA)**.
- Implement **rate limiting** to prevent brute-force attacks.
---
## **3. Broken Object Property Level Authorization**
APIs expose or allow modification of sensitive data through insecure endpoints.
🔹 **Example:**
- A user sends a request to update their profile:
```json
{ "name": "John", "role": "admin" }
```
- The API accepts it, granting admin privileges.
🔹 **Mitigation:**
- Restrict access to **sensitive fields** at both request and response levels.
- Enforce **backend validation** to prevent unauthorized modifications.
---
## **4. Unrestricted Resource Consumption**
APIs that lack resource limits are vulnerable to abuse, leading to **Denial of Service (DoS)**.
🔹 **Example:**
- A bot sends **millions of requests per second**, crashing the API.
🔹 **Mitigation:**
- Implement **rate limiting, request throttling, and quota enforcement**.
- Optimize database queries to **handle high loads efficiently**.
---
## **5. Broken Function Level Authorization**
APIs expose **administrative functionalities** to regular users, allowing **privilege escalation**.
🔹 **Example:**
- A user modifies an API request from `GET /user/profile` to `DELETE /user/1234`, deleting someone else's account.
🔹 **Mitigation:**
- Enforce **role-based access control (RBAC)**.
- Use **least privilege** principles for API endpoints.
---
## **6. Unrestricted Access to Sensitive Business Flows**
Attackers exploit business processes through excessive automation.
🔹 **Example:**
- A travel booking API allows unlimited ticket reservations, leading to fraudulent activity.
🔹 **Mitigation:**
- Implement **CAPTCHAs, behavior-based monitoring, and anomaly detection**.
---
## **7. Server-Side Request Forgery (SSRF)**
APIs that fetch external resources based on user input can be tricked into making requests to internal systems.
🔹 **Example:**
- An attacker submits `http://localhost/admin` to an API that fetches URLs, exposing internal services.
🔹 **Mitigation:**
- Restrict external requests to **trusted domains**.
- Validate and sanitize user inputs.
---
## **8. Security Misconfiguration**
Improper API settings expose systems to attacks.
🔹 **Example:**
- A misconfigured API exposes **debugging endpoints** that reveal sensitive data.
- **CORS misconfiguration** allows unauthorized domains to access API resources.
🔹 **Mitigation:**
- Disable **unnecessary features** (e.g., verbose error messages, debug modes).
- Implement **secure default configurations** and **regular security patches**.
---
## **9. Improper Inventory Management**
Exposed, outdated, or undocumented API versions create security risks.
🔹 **Example:**
- An old API endpoint (`/v1/user-data`) remains active while `/v2/user-data` is introduced, allowing attackers to exploit legacy weaknesses.
🔹 **Mitigation:**
- Maintain **an up-to-date API inventory**.
- **Retire old APIs** and remove unused endpoints.
---
## **10. Unsafe Consumption of APIs**
Trusting third-party APIs blindly can introduce vulnerabilities.
🔹 **Example:**
- An API integrates with an external service that **stores data insecurely**, leading to leaks.
🔹 **Mitigation:**
- Validate and sanitize **all responses from third-party APIs**.
- Use **API security gateways** to filter malicious responses.
---
# **Pillars of API Security**
To build **secure APIs**, organizations must focus on:
### **1️⃣ Governance (Secure API Development)**
🔹 Establish **security policies and design guidelines**.
🔹 Ensure **consistent security practices** throughout API development.
### **2️⃣ Testing (Finding API Vulnerabilities)**
🔹 **Automate security testing** (fuzzing, injection, access control checks).
🔹 Test for **business logic flaws** and **API function abuse**.
### **3️⃣ Monitoring (Detecting Threats in Production)**
🔹 Use **runtime protection** to filter traffic.
🔹 Detect and respond to **API abuse and distributed attacks**.
---
# **OpenAPI Specification (Swagger) for Secure API Documentation**
Using **OpenAPI (Swagger)** helps ensure:
✅ **Standardized API documentation**.
✅ **Security policies** (authentication, rate limits).
✅ **Consistent endpoint structures**.
---
# **Conclusion**
APIs are critical but **high-risk attack surfaces**. Understanding the **OWASP API Security Top 10** and implementing **best security practices** helps prevent breaches and protect sensitive data. 🚀
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