Despite advancements in API security, access control vulnerabilities, such as broken object-level authentication (BOLA) and broken function-level authentication (BFLA), remain almost impossible to detect.
This blog will explore why these vulnerabilities are so difficult to detect, the limitations of current security tools, and the implications for businesses relying on API-driven applications. It will also discuss potential approaches for improving API security posture.
What are API Access Control Vulnerabilities?
Access control vulnerabilities arise when an application fails to enforce proper authorization. BOLA and BFLA are two of the most common types. Let’s briefly explore how they work.
- BOLA occurs when an API fails to verify whether a requester is permitted to access a specific data object. For example, changing a user ID in an API request to view another user’s profile.
- BFLA is when an API does not properly restrict access to sensitive functions based on user roles. For example, allowing a regular user to invoke an admin-only action like deleting an account.
The key thing to understand is that while both BOLA and BFLA stem from insufficient authorization controls, they differ in what they allow attackers to do: BOLA exposes data objects, while BLFA exposes sensitive functions.
Why is it Important to Protect Against API Access Control Vulnerabilities?
Access control vulnerabilities can have serious consequences if organizations fail to detect and address them. Allowing attackers to bypass authentication and authorization controls grants them access to sensitive data or lets them perform unauthorized actions. The consequences of this should be obvious: data breaches, financial fraud, compliance and regulatory penalties, reputational damage, and operational disruption can all result from these vulnerabilities.
Why Are API Access Control Vulnerabilities So Difficult to Detect?
API Access control vulnerabilities like BOLA and BFLA are notoriously difficult to detect because they arise out of an application’s specific business logic – details that traditional security tools like web application firewalls (WAFs) and vulnerability scanners don’t understand. Three factors contribute to this gap:
- Lack of Business Context: Traditional security tools are unaware of an application’s internal rules. They don’t know, for example, who should be considered a regular user or an admin or which endpoints are meant for each role.
- Role-Dependent Behavior: An API endpoint might return different data depending on each user’s role. Without knowing the intended behavior for each role, automated tools struggle to determine what’s normal and what’s a vulnerability.
- Varied Application Logic: Applications have differing access control rules, meaning that a solution suitable for one application might trigger false positives or negatives in another because the business logic is different.
The main challenge is spotting anomalies or abuses of business logic. For example, a sudden spike in requests might be an attacker trying to abuse business logic to withdraw money from a digital wallet, but it could also be routine communication between applications. To determine whether this high traffic is a problem, you must understand the context behind it. But what does this mean for organizations that rely on API-driven applications?
| Limitation | Description | Implication |
| Limited Visibility | Traditional tools like firewalls and Intrusion Detection Systems (IDS) primarily focus on network and perimeter security, lacking deep visibility into API traffic. | Difficult to detect unauthorized or anomalous API interactions, leading to potential undetected breaches. |
| Inadequate Authentication and Authorization | Conventional security measures may not enforce API-specific policies, increasing the risk of broken authentication and privilege escalation attacks. | Unauthorized users might gain access to sensitive data or functionalities. |
| Insufficient Threat Detection | Traditional security solutions often rely on predefined signatures and static rule-based detection, which are ineffective against zero-day API threats and business logic abuse. | New or evolving attack vectors may go unnoticed, leaving APIs vulnerable. |
| Lack of API Governance and Compliance Enforcement | Traditional security lacks API-specific governance, making it challenging for organizations to monitor, audit, and enforce compliance across their API ecosystem. | Increased risk of non-compliance with regulations like GDPR, leading to legal repercussions. |
| Failure to Prevent API Data Exposure | Traditional security tools do not provide adequate controls to detect and mitigate over-permissioned APIs or improper data sharing. | Sensitive data may be exposed inadvertently, leading to data breaches. |
| Inability to Detect Business Logic Attacks | Traditional tools are designed to detect common vulnerabilities like SQL injection but are not effective against business logic attacks that exploit legitimate API functions. | Attackers can manipulate API workflows to perform unauthorized actions without detection. |
| Incompatibility with Modern Technologies | Traditional DAST tools struggle with the complexities of modern applications, including microservices and GraphQL APIs, often focusing on surface-level vulnerabilities without scanning deeper business logic. | Critical vulnerabilities within complex API architectures may be missed. |
| Reactive Rather Than Proactive | Conventional security measures often react to known threats rather than proactively identifying potential vulnerabilities through behavioral analysis. | Organizations remain vulnerable to novel attack strategies until after an exploit occurs. |
Caption: Why traditional API security tools fail to address access control vulnerabilities
How Wallarm Does It
Wallarm helps organizations detect and mitigate API access control vulnerabilities like BOLA and BFLA by combining automated discovery, traffic analysis, and adaptive security measures. Here’s how it works.
Automatic Discovery of Vulnerable Endpoints
Wallarm’s API Discovery module maps endpoints and identifies which ones are associated with sensitive business functions like authentication, user management, billing, and transactions. This additional business context means our platform can flag high-risk endpoints requiring stricter API access controls.
Real-Time Traffic Analysis and Anomaly Detection
Wallarm analyzes API traffic to identify unusual request patterns that may indicate access control abuse. For example, if a user sends multiple requests to trigger SMS-based authentication codes, or a user attempts to manipulate the sequence of steps in an online checkout process to alter pricing. By detecting these abnormal sequences in real time, Wallarm can recognize when an attacker is exploiting business logic.
BOLA Protection and Custom Defense Mechanisms
By offering both automatic and manual BOLA protection, Wallarm allows organizations to restrict unauthorized access to API objects and define custom rules for API protection based on their specific business logic. With Wallarm, organizations can even create user-defined threat definitions to tailor protection against API access control violations unique to their environment.
Vulnerability Scanning and Threat Replay Testing
Wallarm performs passive vulnerability detection, active scanning, and threat replay testing to uncover access control weaknesses. By analyzing API responses, our platform identifies endpoints where unauthorised access may be possible, helping to prioritize remediation efforts.
Continuous Monitoring and Adaptive Security
What’s more, to stay ahead of evolving threats, our analysts:
- Track trending vulnerabilities with CVE identifiers to ensure coverage.
- Perform self-assessments to identify gaps in its detection capabilities.
- Monitor social media for bypass methods used by attackers and update defenses accordingly.
- Address detection gaps by systematically improving protection against real-world attack techniques.
Wallarm provides a complete solution for API security, from detection to mitigation. Want to find out more about how we ensure your APIs are secure? Check out our info page here.
The post Unsolved Challenge: Why API Access Control Vulnerabilities Remain a Major Security Risk appeared first on Wallarm.
