OWASP API 6 : Unrestricted Access to Sensitive Business Flows


In this blog, we will gain insights about OWASP API 6: 2023 – Unrestricted Access to Sensitive Business Flows.

APIs (Application Programming Interfaces) have become the backbone of modern software development. They enable different applications and systems to communicate and share data seamlessly. However, with the proliferation of APIs, the need for robust security measures has never been greater. The Open Web Application Security Project (OWASP) regularly publishes a list of the top security vulnerabilities to help organizations understand and mitigate risks associated with API security. In this blog post, we will delve into the OWASP Top 10 API Security list, with a particular focus on the replacement of the previous API6:2019 – Mass Assignment vulnerability, which allowed for unrestricted access to sensitive business flows.

The OWASP Top 10 API Security List

The OWASP Top 10 API Security list is a valuable resource for developers, security professionals, and organizations to identify common security vulnerabilities in APIs. These vulnerabilities are critical to address, as they can lead to data breaches, unauthorized access, and other potentially devastating consequences for businesses and their clients.

One of the key updates in the latest OWASP API Security list is the replacement of API6:2019 – Mass Assignment with a more comprehensive and nuanced concept: Unrestricted Access to Sensitive Business Flows. Let’s take a closer look at this vulnerability and understand its implications.

Understanding Unrestricted Access to Sensitive Business Flows

Unrestricted access to sensitive business flows is a sophisticated concept within the realm of API security, which necessitates a deeper understanding of its implications and potential risks. In essence, this vulnerability signifies a situation where an API exposes crucial business processes without the appropriate access controls and restrictions in place. To comprehend the significance of this security concern, let’s delve into it more comprehensively:

What are Sensitive Business Flows?

Sensitive business flows encompass a range of operations and processes that are mission-critical to an organization’s functionality and often involve handling sensitive or valuable data. These could include financial transactions, user data management, administrative tasks, or any other operation integral to a company’s core operations.

The Role of APIs in Modern Systems:

APIs serve as the conduits through which data and operations are shared between different software components, applications, and systems. They have revolutionized the way organizations function by allowing disparate software to work together seamlessly. This, however, introduces the risk of unauthorized access to these sensitive business flows.

Unrestricted Access Explained:

Unrestricted access means that the API endpoints responsible for these sensitive business flows are accessible without adequate safeguards. It allows attackers to potentially manipulate, exploit, or automate actions that can have a devastating impact on an organization. For example, an attacker might gain access to a payment processing API without proper authentication, enabling them to conduct unauthorized transactions.

Automation and Scalability:

One of the major concerns with unrestricted access to sensitive business flows is that it allows attackers to automate their attacks. Automated attacks can be scaled up to impact a large number of transactions or data records in a very short time, multiplying the potential harm to the business.

Implications of Unrestricted Access

  • Financial Loss: Unrestricted access to sensitive business flows can lead to financial losses. Attackers may exploit these vulnerabilities to perform unauthorized financial transactions or manipulate critical financial data.
  • Data Breaches: Sensitive business flows often involve access to user data. An attacker with unrestricted access can steal or manipulate this data, leading to data breaches and privacy violations.
  • Disruption of Services: Attackers could use unrestricted access to disrupt critical business processes, causing service outages, downtime, and reputational damage.
  • Regulatory Compliance Issues: Many industries have strict regulations regarding data protection and access control. Failure to secure sensitive business flows can result in regulatory violations and legal consequences.


To prevent this vulnerability, a two-layered approach is recommended:

Business layer: Identify the business flows that may harm the business if excessively used.

Engineering layer: Implement appropriate protection mechanisms to mitigate the identified risks. This can include techniques such as device fingerprinting, human detection (e.g., captcha), analyzing user flow for non-human patterns, blocking IP addresses of known proxies, and securing and limiting access to APIs consumed directly by machines.

By implementing these preventive measures, organizations can reduce the risk of unrestricted access to sensitive business flows and protect their systems and users from potential harm.

Additionally, some more mitigation techniques are listed below which can be helpful when dealing with API security.

  • Authentication and Authorization: Implement robust authentication and authorization mechanisms to ensure that only authorized users or systems can access sensitive business flows.
  • Role-Based Access Control: Assign roles and permissions to users, allowing them to access only the specific resources and actions necessary for their job functions.
  • API Tokens: Use API tokens for authentication and authorization. Tokens can be revoked or rotated to enhance security.
  • Rate Limiting: Implement rate limiting to prevent abuse and brute force attacks on APIs.
  • Logging and Monitoring: Maintain detailed logs of API access and monitor for any suspicious activity. Anomalies can be detected and addressed promptly.
  • Regular Security Testing: Conduct regular security assessments, including penetration testing and code reviews, to identify and fix vulnerabilities.

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