Mitigating OWASP API Security Risks: Broken Authentication using BIG-IP

Introduction:

In today’s API-centric sector, authentication is the first line of defense against unauthorized access. However, it continues to be one of the most exploited vulnerabilities. As highlighted in the OWASP API Security Top 10, Broken Authentication is a critical risk. It can expose sensitive data, compromising user identities, and enabling large-scale attacks.

This vulnerability often stems from misconfigured or weak authentication mechanisms, including inadequate password policies, poor token handling, and the lack of multi-factor authentication (MFA). When these flaws exist, attackers can impersonate users, hijack active sessions, or escalate their privileges within the system.

In this article, we delve into the root causes of Broken Authentication in APIs and demonstrate how F5 BIG-IP can be leveraged to effectively mitigate these risks. Through features such as robust token validation, session control, and seamless integration with identity providers, BIG-IP helps enforce secure, scalable authentication for modern APIs.

What is Broken Authentication?

It is a critical security vulnerability that occurs when authentication mechanisms are weak, misconfigured, or improperly implemented. This enables attackers to gain unauthorized access to user accounts or sensitive information.

This risk is particularly severe in API security. Authentication-related elements such as session tokens, credentials, and identity verification are often directly exposed to clients, which makes them attractive targets for exploitation.

Root Causes Behind Broken Authentication:

Use of weak or easily guessable passwords, making accounts vulnerable to simple attacks.
Absence of Multi-Factor Authentication (MFA), reducing the security barrier for unauthorized access.
Exposed or predictable login endpoints, which attackers can easily discover and target.
Poor session token management, such as not setting expiration times or allowing token reuse.
Publicly accessible authentication endpoints without proper access controls.
Lack of protections against brute-force and credential stuffing attacks, enabling automated login attempts.

Problem Statement:

Consider a login endpoint that is publicly accessible to support user authentication across multiple client platforms. This endpoint is often targeted due to its exposure. This makes attackers a prime target for brute-force attacks, credential stuffing, and other forms of Broken Authentication exploits.

Without proper controls such as rate limiting or restrictions on the number of authentication attempts per user or IP address, attackers can exploit the system by automating repeated login attempts. This increases the risk of account compromise and unauthorized access to sensitive data.

Demonstration with Example:

This demonstration showcases how BIG-IP can seamlessly mitigate such risks and enhance application security. For this setup, we’re using the Petstore Swagger JSON as the API definition to apply protection to the API endpoints.

As the first step, configure BIG-IP with a virtual server and associate it with the demo application, which in this case is represented by the Petstore Swagger API.Now let’s start mitigating this risk by associating a rate-limiting profile to the virtual server.

Mitigation steps:

-Configuration:

Log in to the BIG-IP console and navigate to Access > API Protection > Profile, then click Create to set up a new profile.
Enter a name for the profile and upload the Swagger file to define the API schema.
Under the Rate Limiting section, create a new rate-limiting profile and specify the allowed number of requests per user per second.
Next, navigate to the Access Control section and configure the Per-Request Policy to define how incoming requests are evaluated and handled.
Apply the rate-limiting profile and configure the necessary headers for the specific endpoints you intend to test or protect.

Save the profile, then associate it with the virtual server and apply the updates to finalize the configuration.

-Verification:

Now, let's access the Petstore endpoint multiple times to observe the applied protections in action.

Conclusion:

As shown, F5 BIG-IP’s rate-limiting feature is a key way to protect against broken authentication attacks. It finds and controls abnormal request patterns before they can be used to attack the system. By enforcing request thresholds, it effectively mitigates risks such as brute-force and credential stuffing attempts. This proactive security measure enhances overall API resilience and complements broader authentication strategies. When integrated into a comprehensive API security framework, BIG-IP not only protects the integrity of authentication processes but also contributes to a more robust and secure API environment.