Mitigating OWASP API Security Top 10 Risks – 2023 using F5 BIG-IP
Introduction
APIs (Application Programming Interfaces) are critical components of modern software architectures. They allow different systems and services to communicate with each other, whether it’s a mobile app retrieving user data or a payment gateway processing transactions. However, as APIs grow in functionality and exposure, they also become prime targets for attackers.
To help developers and security teams address these challenges, the Open Worldwide Application Security Project (OWASP) publishes a regularly updated list of the Top 10 API Security Risks. The 2023 edition focuses on the most common and impactful vulnerabilities seen in real-world applications. In this article, we’ll walk through each risk in a clear and structured way to help you understand what can go wrong and how to avoid such risks using F5 BIG-IP solution.
1. Broken Object Level Authorization
This risk arises when an API doesn’t properly verify whether a user is authorized to access a specific object, like a user ID, document, or order. Attackers can exploit this by manipulating the object identifier in the API request (e.g., changing a user ID in the URL) to access someone else’s data. It’s one of the most commonly exploited API flaws.
2. Broken Authentication
Authentication is how APIs confirm a user’s identity, usually via tokens, API keys, or credentials. When authentication mechanisms are weak or misconfigured, attackers can gain unauthorized access by exploiting token reuse, missing rate limits, or predictable credential patterns. For instance, if an API does not enforce session expiration or supports weak password recovery flows, an attacker could hijack accounts. Secure APIs use industry-standard authentication methods (like OAuth 2.0), enforce token expiration, and protect login endpoints from brute-force attacks.
For detailed information and mitigation strategies for this attack using F5 BIG-IP, please refer to this article.
3. Broken Object Property Level Authorization
While object-level authorization checks whether a user can access an object, property-level authorization ensures they can only access specific parts of that object. For example, a regular user might be able to view their profile but should not see sensitive attributes like “isAdmin” or “accountBalance.” If these fields are included in API responses or allowed to be edited through update endpoints, attackers can gain insights into system structure—or worse, escalate their privileges. APIs must validate not just what objects a user can access, but also what properties within those objects they are allowed to view or modify.
For detailed information and mitigation strategies for this attack using F5 BIG-IP, please refer to this article.
4. Unrestricted Resource Consumption
Some APIs allow clients to make large or repeated requests without limits, potentially consuming excessive server resources. This could involve uploading huge files, requesting large datasets, or making too many calls in a short time. Attackers can exploit this to perform denial-of-service (DoS) attacks or drive up cloud costs. Real-world examples include APIs without pagination or input size limits. To mitigate this, developers should implement request throttling, enforce size limits, and apply quotas per user or IP address.
For detailed information and mitigation strategies for this attack using F5 BIG-IP, please refer to this article.
5. Broken Function Level Authorization
Beyond object-level permissions, APIs often expose various functions or actions (like creating users, deleting data, or updating roles). This risk arises when APIs fail to enforce proper checks on who can perform which actions. For example, if the endpoint /api/user/delete is not restricted to admin users, any authenticated user might be able to delete accounts. Attackers often discover these endpoints through API documentation or guesswork. Proper role-based access control and consistent authorization logic across functions are essential to preventing abuse.
For detailed information and mitigation strategies for this attack using F5 BIG-IP, please refer to this article.
6. Unrestricted Access to Sensitive Business Flows
APIs sometimes expose operations critical to business logic, such as checkout processes, promotional code redemption, or loyalty point claims, without limiting how frequently these flows can be triggered. An attacker can abuse this to gain a financial or competitive advantage. For example, automating reward claims could let someone drain a loyalty program. These flows should include anti-automation protections like rate-limiting, CAPTCHA, or usage thresholds to prevent abuse without affecting legitimate users.
For detailed information and mitigation strategies for this attack using F5 BIG-IP, please refer to this article.
7. Server-Side Request Forgery (SSRF)
SSRF occurs when an API allows users to input URLs or resource locations that the server fetches on their behalf, such as in image previews or webhook validators. If the server doesn't validate the target URL, attackers can trick it into making requests to internal systems (e.g., http://localhost:8000/admin) or cloud metadata services. This can reveal sensitive information or open the door for lateral attacks. Preventing SSRF involves whitelisting allowed domains, avoiding internal network access, and using secure request libraries.
For detailed information and mitigation strategies for this attack using F5 BIG-IP, please refer to this article.
8. Security Misconfiguration
Misconfigurations are often the result of rushed deployments, lack of environment-specific settings, or forgotten default settings. This includes issues like exposed stack traces, verbose error messages, overly permissive CORS settings, and default credentials. These flaws can make it easier for attackers to understand how the system works and exploit it.
For detailed information and mitigation strategies for this attack using F5 BIG-IP, please refer to this article.
9. Improper Inventory Management
As systems evolve, organizations often lose track of all their deployed APIs, especially when teams move quickly or infrastructure becomes decentralized. Forgotten or undocumented APIs and deprecated but still accessible endpoints can still be present in production environments. These APIs often lack monitoring or up-to-date security controls, making them attractive targets. Maintaining a complete API inventory with versioning and automated discovery tools can help mitigate this risk.
For detailed information and mitigation strategies for this attack using F5 BIG-IP, please refer to this article.
10. Unsafe Consumption of APIs
APIs often rely on data from third-party services such as payment processors, external databases, or public APIs. If these sources are blindly trusted, they can become a weak link in the chain. For instance, an attacker could compromise a third-party API that your service depends on and inject harmful data. Developers should validate and sanitize data from all external APIs, apply schema validation, and build fallback mechanisms in case third-party services are unavailable or compromised.
Conclusion
APIs continue to power our digital world, enabling fast, flexible integration between services. But with that power comes responsibility. The OWASP API Top 10 (2023) serves as a practical guide to the most common and damaging vulnerabilities in API security today.
By understanding these risks and applying secure development practices such as proper authentication, access control, input validation, and monitoring, organizations can protect sensitive data, ensure reliable service delivery, and maintain user trust.
Additional Resources
Employee