What is business logic, and why it's important for application security

What is business logic, and why it's important for application security

Is understanding business logic a critical component of application security? Absolutely. In the world of cybersecurity, business logic is more than just a set of operational directives. It serves as the crucial bridge between an application's technical function and its alignment with strategic business goals.

More than that, it's important not only to understand but also to properly secure applications from business logic attacks.

A striking example of this was the breach experienced by USPS, where attackers exploited business logic vulnerabilities to gain unauthorized access and 60 Million user records were exposed. This incident underscores the importance of understanding and securing business logic within application security frameworks.

Understanding business logic issues will be paramount for security engineers in the future:

"So I think there's going to be a long time before that happens, and I suspect that we're going to have a lot more like us, as security folks, we'll probably stop focusing on the foundational issues. And we'd be looking at much more difficult issues that our tooling has a hard time to find. Like business logic issues in itself very difficult or even AI-related issues securing AI and LLM  in itself. " - Jeevan Singh, Senior Staff Security Engineer at Rippling at The Elephant in AppSec Podcast

In this blog post, we dive into the significance of business logic, its faults, potential vulnerabilities, and best practices for securing your applications from business logic attacks.

What is business logic

Business logic refers to the custom rules or algorithms that handle the exchange, processing, and management of data in an application. It dictates the core functionality of a software system, defining how it operates in various scenarios to fulfill specific business requirements. Business logic is responsible for executing the operational policies of a business within its software applications. It's the backbone of any software application, driving its operational efficiency and effectiveness. At its core, business logic is about ensuring that an application behaves as intended, under every conceivable scenario.

For example, in an e-commerce application, the business logic would determine how items are added to a cart, the application of discounts, calculation of taxes, and the processing of payments. It is distinct from the application's user interface and database management, focusing instead on how the application processes data and makes decisions in line with the business's objectives and workflows.

Effective business logic is critical for ensuring that an application behaves as intended, enhances user experience, and aligns with the business's goals and compliance requirements. It's a key component in the overall architecture of any software application, instrumental in defining the success and efficiency of the application's operations.

Examples of business logic

In e-commerce platforms, business logic is skillfully designed to manage a large range of functions. This includes sophisticated pricing rules that may vary based on market demand, customer behavior, or promotional strategies. Inventory management systems are governed by business logic that tracks stock levels in real-time, triggers reorder processes, and manages supply chain logistics. Additionally, discount calculations are implemented, often involving complex algorithms that take into account customer loyalty, seasonal promotions, and dynamic pricing models.

In the financial sector, business logic plays a vital role in ensuring secure and efficient operations. This encompasses robust transaction processing systems that handle a multitude of transaction types while ensuring accuracy and compliance with financial regulations. Fraud detection algorithms, a critical component, utilize advanced analytics and pattern recognition to identify and mitigate fraudulent activities. Furthermore, customer credit evaluations are conducted using business logic that assesses creditworthiness through a variety of data points, including credit scores, transaction history, and income.

Healthcare applications rely heavily on business logic for sensitive and critical operations. This includes patient data management systems that securely store and manage patient records, ensuring compliance with healthcare regulations like HIPAA.


Appointment scheduling systems are designed to optimize healthcare provider time and resource allocation. Business logic is also employed in treatment planning, which involves algorithms that aid in diagnosing diseases, suggesting treatment options, and monitoring patient progress.

In each of these industries, business logic is customized to meet specific operational needs and objectives, ensuring that the applications not only perform tasks efficiently but also align with the strategic goals of the business.

Business logic flaws

Despite its critical role, business logic can be a vulnerability hotspot. Flaws in business logic arise when developers fail to anticipate how users (or attackers) might interact with the application in unanticipated ways. These flaws can lead to significant security breaches, data theft, or service disruptions.

Most of the companies do not start by looking immediately at business logic flaws, leaving them the most vulnerable for the hackers. And they might take a very long time to be fixed. It also took USPS a year to fix their 60 million user data breach according to the Verge.

Jeevan Singh, Senior Staff Security Engineer at Rippling, in "The Elephant in AppSec Podcast," highlighted this issue:

"But those large companies do focus on the foundations and the fundamentals a lot initially. And once they get into a good place, they are able to sort of move up that chain of challenging security issues. Where, once the foundations are done, they can start looking at some of the things that more focused on the business logic stuff where there isn't tooling.
And you have to really sit down and map out how exactly you're going to be fixing those things."

Business logic vs application logic

While often used interchangeably, it's open to highlight the differences between business and application logic. Business logic and application logic definitions are distinct. Application logic deals with the technical aspects of an application, like user interface and database interactions. Business logic, on the other hand, is about the business-specific operations within the application.

It's essential to acknowledge that while business logic and application logic are distinct, they function collaboratively within an application. To ensure that an application adheres to both its inherent functionality and the specified business criteria, the integration of both types of logic is necessary.

Business logic vulnerabilities

Vulnerabilities in business logic are indeed unique in their nature and impact. They exploit the normal, intended functionalities of an application, rather than relying on code-based flaws. This involves manipulating the application to behave in ways unforeseen by its creators, leading to unintended outcomes.

For instance, attackers might manipulate input fields in ways that were not anticipated, such as entering unexpected values or sequences that cause the application to reveal sensitive information or grant unauthorized access. They might also abuse application workflows, exploiting the logic of how the application is supposed to work.

For example, a flaw in an e-commerce site's purchasing logic could be exploited to bypass payment processes, or in a banking application, to conduct unauthorized transactions. These vulnerabilities are challenging to detect and mitigate because they arise from the legitimate use of the application's features, requiring a deep understanding of both the application's business logic and potential threat actors' tactics.

This year, in OWASP Top 10 2023, unrestricted access to sensitive business flows is one of the 10 critical vulnerabilities. It's easily exploitable and exploitation might hurt the business in different ways, for example: prevent legitimate users from purchasing a product, or lead to inflation in the internal economy of a game.

How to prevent business logic attacks

Preventing business logic attacks requires a multi-faceted approach:

  • Conduct thorough threat modeling to understand potential attack vectors.
  • Implement robust input validation and authentication checks.
  • Regularly review and update business logic rules.
  • Employ continuous security testing and monitoring.
Discover a Feedback-driven API exploration algorithm developed by Escape to tackle business logic vulnerabilities. It's a new technique that quickly asses the underlying business logic of an API by analyzing responses and dependencies between requests.

Protect yourself by fixing business logic vulnerabilities with Escape

Escape is the only API Security solution that combines the capabilities of API inventory, API Security testing, and business logic security testing with a shift-left approach. Unlike DAST and classic API Security tools, Escape does not only find vulnerabilities but also helps security teams automate their API inventory without any agent.

To protect against business logic vulnerabilities, it's crucial to employ advanced security solutions like Escape.

Enhanced by AI, Escape protects not only against OWASP Top 10 vulnerabilities (included unrestricted access to sensitive business flows), but also runs advanced business logic tests:

  • Automated tenant isolation control: When two users are configured, this test ensures strict tenant isolation, preventing unauthorized cross-tenant access.
  • Sensitive endpoint brute force: Targets critical endpoints like login and reset-password, protecting against brute force attacks.
  • Broken Object Level Authorization (IDOR) checks: Identifies vulnerabilities in object-level authorizations, an essential aspect of access control.
  • Enhanced access control checks: Overall improvements in access control validations, providing a more robust security posture.
  • Public state altering operation identification: Ensures that operations altering application data (like REST READ, UPDATE, DELETE requests, and GraphQL mutations) are adequately protected by authentication middleware

💡 Want to learn more about application security? Check out the following articles: