Business Logic Vulnerabilities | Complete Guide

Summary

In this video, the presenter covers the fundamentals of business logic vulnerabilities, offering insights into their causes, types, and real-world examples. Key topics include how business logic flaws can allow attackers to bypass security measures, such as unauthorized password changes, fraudulent transactions, and exploiting application design flaws. The video explains how to find and exploit these vulnerabilities through testing, while emphasizing the importance of thorough documentation, clear code, and security-focused code reviews to prevent such vulnerabilities. Hands-on labs will further explore these concepts, with actionable advice for developers and security testers.

Takeaways

• 😀 Business logic vulnerabilities (BLVs) are flaws in an application's design that allow attackers to perform malicious actions, such as accessing sensitive data or compromising user accounts.
• 😀 Unlike typical security vulnerabilities, BLVs are specific to an application’s logic, making them difficult to categorize, detect, and prevent through standard tools or scanners.
• 😀 Business logic flaws often stem from assumptions made by developers about how users will interact with an application. These assumptions can lead to significant vulnerabilities.
• 😀 One common BLV example is when an attacker can change arbitrary user passwords by exploiting flaws in how the system handles the password change request for administrators versus regular users.
• 😀 Another example of a BLV is in e-commerce applications where users can bypass payment steps by manipulating the sequence of requests sent to the backend, resulting in orders without payment.
• 😀 A banking application flaw could allow users to bypass fraud prevention by submitting negative amounts in transactions, which are incorrectly accepted as valid transfers.
• 😀 A discount-related BLV in an e-commerce site can allow attackers to remove discounted items from their cart after the discount has been applied, thus buying products at a lower price without meeting purchase requirements.
• 😀 The impact of BLVs can vary depending on the vulnerability, but typically they affect the C Triad (Confidentiality, Integrity, Availability) in critical ways, especially when it comes to user data or financial transactions.
• 😀 Business logic vulnerabilities are often not listed separately in security risks assessments like the OWASP Top 10, but they fall under the 'Insecure Design' category, ranked as a high-risk issue.
• 😀 Identifying and exploiting BLVs involves mapping the application, reviewing the business flow, and testing each component with use cases outside the intended flow to find design flaws or incorrect assumptions.
• 😀 To prevent BLVs, developers should ensure detailed documentation of application design, write clear code with proper comments, and conduct thorough security-focused code reviews to minimize the risk of logic flaws being introduced.

Q & A

What are business logic vulnerabilities?

Business logic vulnerabilities are flaws in the design and implementation of an application that allow an attacker to perform malicious actions. These could include actions like viewing sensitive data or compromising user accounts, and they are typically related to assumptions made during application development.

Why are business logic vulnerabilities difficult to detect using automated scanners?

Automated scanners are ineffective at detecting business logic vulnerabilities because these flaws are based on the specific logic and assumptions of an application. Scanners focus on technical issues like XSS or SQL injection but don't account for the complex business rules that govern user interactions.

What was the critical flaw in the password change functionality example?

The flaw in the password change functionality was that the backend code incorrectly assumed that if the 'existing password' field was empty, the user was an administrator. This allowed regular users to bypass the requirement for an existing password and change any user's password.

In the e-commerce checkout flow example, how did an attacker exploit the system?

An attacker could exploit the e-commerce checkout by skipping the payment step in the checkout flow. By directly submitting delivery information, the attacker could bypass the payment step and receive the items without paying.

What was the issue with the banking application that allowed users to bypass the fraud prevention mechanism?

The banking application allowed users to transfer funds greater than the $10,000 limit by submitting a negative amount. Since the application only checked if the transfer was below the threshold value, a negative number was incorrectly approved, allowing users to transfer large sums without approval.

How did the bulk discount vulnerability work in the e-commerce site example?

The bulk discount vulnerability allowed users to receive a discount by adding an item to the cart that triggered the discount. They could then remove that item from the cart after the discount was applied and purchase the remaining items at the discounted price without actually buying the item that triggered the discount.

Why are business logic vulnerabilities considered critical in web application security?

Business logic vulnerabilities can have severe consequences because they often lead to unauthorized access, data manipulation, financial loss, or a complete compromise of a system. Since they are highly specific to the business logic of an application, they are not easily detected with automated tools and require manual testing.

What steps should a security tester take to find business logic vulnerabilities in an application?

To find business logic vulnerabilities, a security tester should map the application's functionality, identify business flows, and review any assumptions made during the design phase. They should test components by attempting to exploit edge cases and use cases outside the intended flow, such as trying requests in a different order or submitting unusual inputs.

How can businesses reduce the risk of introducing business logic vulnerabilities into their applications?

To reduce the risk, businesses should ensure that their application design is thoroughly documented, with clear descriptions of the assumptions made during development. The code should include detailed comments, particularly about assumptions and business flows. Regular security-focused code reviews are also essential to catch potential logic flaws before they make it into production.

What is the role of human testers in identifying business logic vulnerabilities?

Human testers play a critical role in identifying business logic vulnerabilities because they can understand the business requirements and logic behind an application. Unlike automated tools, human testers can evaluate complex scenarios, question design assumptions, and explore unusual or non-obvious user interactions to uncover vulnerabilities.