09 Feb, 2023

Business logic flow 2.0

Vulnerability Assessment as a Service (VAaaS)

Tests systems and applications for vulnerabilities to address weaknesses.

Business logic flow vulnerability is a type of software vulnerability that occurs in the business logic flow of an application. This vulnerability can be exploited by an attacker to manipulate the intended flow of business processes and gain unauthorized access to sensitive information or perform unauthorized actions.

A business logic flow vulnerability can arise from various factors, including poor code design, lack of input validation, and failure to enforce proper access controls. This type of vulnerability can have significant impact on the security of an application, as it can allow an attacker to bypass security controls and carry out malicious actions that affect the confidentiality, integrity, and availability of data and systems.

Examples of vulnerable code on different programming languages

Python:

				
					def transfer_funds(from_account, to_account, amount):
    if from_account.balance >= amount:
        from_account.balance -= amount
        to_account.balance += amount
    else:
        raise ValueError("Insufficient funds")

# Attacker can manipulate the balance of the from_account to be negative, and bypass the check for sufficient funds.
# This can result in the attacker being able to transfer more funds than they have.

				
			

Java:

				
					public void transferFunds(Account fromAccount, Account toAccount, double amount) {
    if (fromAccount.getBalance() >= amount) {
        fromAccount.setBalance(fromAccount.getBalance() - amount);
        toAccount.setBalance(toAccount.getBalance() + amount);
    } else {
        throw new IllegalArgumentException("Insufficient funds");
    }
}

// Attacker can manipulate the balance of the fromAccount to be negative, and bypass the check for sufficient funds.
// This can result in the attacker being able to transfer more funds than they have.

				
			

Javascript:

				
					function transferFunds(fromAccount, toAccount, amount) {
    if (fromAccount.balance >= amount) {
        fromAccount.balance -= amount;
        toAccount.balance += amount;
    } else {
        throw new Error("Insufficient funds");
    }
}

// Attacker can manipulate the balance of the fromAccount to be negative, and bypass the check for sufficient funds.
// This can result in the attacker being able to transfer more funds than they have.

				
			

In all of these examples, the vulnerability is that the check for sufficient funds is done before the transfer, rather than after. An attacker could manipulate the balance property of the from_account or fromAccount to be negative, which would allow them to transfer more funds than they have. This could be done, for example, by using a debugger to change the value of the balance property while the code is running.

Examples of exploitation Business logic flow vulnerabilities

  1. An attacker manipulates the balance of an account to be negative and bypasses the check for sufficient funds in a transfer funds function. This allows the attacker to transfer more funds than they have, which could result in a negative balance and potentially allow the attacker to make additional unauthorized transfers.

  2. An attacker manipulates the input parameters to a function that processes orders to include items that are not available for purchase or are significantly discounted. The function does not validate the inputs and the attacker is able to purchase items for less than their actual cost.

  3. An attacker manipulates the input parameters to a function that calculates the total cost of a purchase. The function does not validate the inputs and the attacker is able to provide a large value for the number of items being purchased, resulting in an inflated total cost.

  4. An attacker manipulates the inputs to a function that performs a sensitive action, such as updating a password or deleting an account. The function does not validate the inputs and the attacker is able to perform the action as an unauthorized user.

  5. An attacker manipulates the inputs to a function that processes user-generated content, such as comments on a blog post. The function does not validate the inputs and the attacker is able to include malicious code, such as JavaScript or HTML, which could be executed by other users who view the content.

In all of these examples, the exploitation of the business logic flow vulnerability is made possible by a lack of proper input validation and an incorrect order of operations in the code. It’s important to thoroughly validate all inputs and perform necessary checks in the correct order to prevent these types of vulnerabilities.

Privilege escalation techniques for Business logic flow vulnerabilities

  • Chaining: An attacker chains together multiple vulnerabilities in different parts of the application to escalate their privileges. For example, an attacker may find a business logic flow vulnerability that allows them to perform an unauthorized action and then leverage that action to bypass additional access controls and escalate their privileges further.

  • Tampering with inputs: An attacker manipulates the inputs to a function to cause it to behave in an unintended way, such as bypassing access controls or escalating their privileges. For example, an attacker may modify the inputs to a function that processes a user’s request for a higher level of access to cause the function to grant the request without proper validation.

  • Using functionality in unintended ways: An attacker takes advantage of functionality in the application that was not designed to be used for malicious purposes, but can be used to escalate their privileges. For example, an attacker may take advantage of a function that is used to update a user’s password to reset the password of an administrative account.

  • Abusing error messages: An attacker takes advantage of error messages or logging information in the application to gather information that can be used to escalate their privileges. For example, an attacker may manipulate the inputs to a function to cause it to throw an error and expose information about the application’s internals, such as the names of tables or columns in a database.

  • Exploiting weak authentication: An attacker exploits weak or nonexistent authentication mechanisms to escalate their privileges. For example, an attacker may find a business logic flow vulnerability that allows them to perform an unauthorized action and then leverage that action to bypass the application’s authentication mechanism and access sensitive information or perform sensitive actions as an administrative user.

In all of these examples, the goal of the attacker is to escalate their privileges and gain access to sensitive information or functionality within the application. It’s important to implement robust access controls and validate inputs thoroughly to prevent these types of attacks.

General methodology and checklist for Business logic flow vulnerabilities

Here is a general methodology and checklist for identifying and mitigating business logic flow vulnerabilities:

  1. Understanding the application: Begin by thoroughly understanding the functionality of the application and the different parts of the code that interact with each other. This includes identifying the functions that process user inputs, perform sensitive actions, and manage access controls.

  2. Input validation: Ensure that all inputs are thoroughly validated and that any unexpected inputs are rejected. This includes checking the type, length, and format of inputs, as well as checking that the inputs are within a valid range or set of values.

  3. Correct order of operations: Ensure that the necessary checks and validations are performed in the correct order. For example, checks for sufficient funds should be performed before performing a transfer, and checks for user authentication should be performed before allowing access to sensitive information.

  4. Robust access controls: Implement robust access controls to prevent unauthorized actions, such as allowing users to perform sensitive actions or access sensitive information. This includes implementing role-based access controls and checking that a user has the necessary permissions before performing an action.

  5. Error handling: Ensure that error messages do not reveal sensitive information or provide attackers with a way to escalate their privileges. For example, error messages should not reveal information about the application’s internals, such as the names of tables or columns in a database.

  6. Monitoring and logging: Implement monitoring and logging mechanisms to detect and respond to potential attacks. This includes logging all sensitive actions and monitoring for unusual or unexpected behavior.

  7. Regular security assessments: Regularly perform security assessments, including code reviews and penetration testing, to identify and mitigate potential vulnerabilities. This includes testing for business logic flow vulnerabilities and ensuring that the necessary checks and validations are in place.

By following this methodology and checklist, you can significantly reduce the risk of business logic flow vulnerabilities in your applications and ensure that they are secure and protected against attacks.

Tools set for exploiting Business logic flow vulnerabilities

Automatic Tools for Detecting Business Logic Flow Vulnerabilities:

  1. Burp Suite: A comprehensive web application security testing tool that includes a suite of tools for testing the security of web applications, including a proxy tool for intercepting and modifying requests, as well as a number of plugins for automating the detection and exploitation of vulnerabilities.

  2. OWASP ZAP: An open-source web application security testing tool that includes a proxy tool for intercepting and modifying requests, as well as a suite of tools for testing the security of web applications. OWASP ZAP includes a number of plugins that can be used to automate the detection and exploitation of business logic flow vulnerabilities.

  3. Acunetix: A web application security testing tool that automates the detection of a wide range of web application vulnerabilities, including business logic flow vulnerabilities.

  4. Nessus: A vulnerability scanning tool that automates the detection of security vulnerabilities in systems and applications, including business logic flow vulnerabilities in web applications.

  5. Qualys: A cloud-based platform for automating the detection and management of vulnerabilities in systems and applications, including business logic flow vulnerabilities in web applications.

  6. AppScan: A web application security testing tool that automates the detection of a wide range of web application vulnerabilities, including business logic flow vulnerabilities.

  7. WebInspect: A web application security testing tool that automates the detection of a wide range of web application vulnerabilities, including business logic flow vulnerabilities.

  8. W3af: An open-source web application security testing tool that automates the detection of a wide range of web application vulnerabilities, including business logic flow vulnerabilities.

  9. NeXpose: A vulnerability scanning tool that automates the detection of security vulnerabilities in systems and applications, including business logic flow vulnerabilities in web applications.

  10. OpenVAS: An open-source vulnerability scanning tool that automates the detection of security vulnerabilities in systems and applications, including business logic flow vulnerabilities in web applications.

Manual Tools for Detecting Business Logic Flow Vulnerabilities:

  1. sqlmap: An open-source tool for automating SQL injection attacks and exploiting business logic flow vulnerabilities in web applications that use SQL databases.

  2. Metasploit: A widely used framework for developing and executing exploits, including those that exploit business logic flow vulnerabilities.

  3. Custom scripts: An attacker can also write custom scripts to exploit business logic flow vulnerabilities. This approach requires a deep understanding of the application and the vulnerability, as well as the ability to write code.

  4. curl: A command-line tool for transferring data over various protocols, including HTTP and HTTPS. curl can be used to test the security of web applications and automate the detection of business logic flow vulnerabilities.

  5. Postman: A tool for testing and documenting APIs, including the APIs of web applications. Postman can be used to automate the detection of business logic flow vulnerabilities in web applications.

  6. Charles Proxy: A web debugging proxy tool that allows you to view and modify requests and responses between your computer and the Internet. Charles Proxy can be used to automate the detection of business logic flow vulnerabilities in web applications.

  7. Telnet: A protocol for communication with a remote computer over the Internet. Telnet can be used to automate the detection of business logic flow vulnerabilities in web applications.

  8. Fiddler: A web debugging proxy tool that allows you to view and modify requests and responses between your computer and the Internet. Fiddler can be used to automate the detection of business logic flow vulnerabilities in web applications.

  9. Wireshark: A network protocol analyzer

Average CVSS score of Business logic flow vulnerabilities

The Common Vulnerability Scoring System (CVSS) is a widely used industry standard for evaluating the severity of security vulnerabilities. The average CVSS score for business logic flow vulnerabilities can vary greatly depending on the specific vulnerability and the impact it has on the affected system.

Business logic flow vulnerabilities can range from low to high severity, with CVSS scores ranging from 2.0 to 9.0. Some common business logic flow vulnerabilities, such as Cross-Site Scripting (XSS) and SQL injection, can have average CVSS scores of around 6.0 to 7.0, while more severe vulnerabilities, such as Remote Code Execution (RCE) and Command Injection, can have CVSS scores of 8.0 to 9.0.

The Common Weakness Enumeration (CWE)

The Common Weakness Enumeration (CWE) is a standardized classification system for software security weaknesses. CWE provides a common language and structure for describing and organizing information about software weaknesses.

Business logic flow vulnerabilities can be classified under various CWEs, depending on the specific type of vulnerability and the underlying cause. Some common CWEs associated with business logic flow vulnerabilities include:

• CWE-89: Improper Neutralization of Special Elements used in an SQL Command (SQL Injection)
• CWE-79: Improper Neutralization of Input During Web Page Generation (Cross-Site Scripting (XSS))
• CWE-94: Improper Control of Generation of Code (Code Injection)
• CWE-120: Buffer Overflow
• CWE-352: Cross-Site Request Forgery (CSRF)
• CWE-306: Missing Authentication for Critical Function
• CWE-77: Improper Neutralization of Special Elements used in an OS Command (Command Injection)
• CWE-250: Execution with Unnecessary Privileges
• CWE-732: Incorrect Permission Assignment for Critical Resource
• CWE-918: Server-Side Request Forgery (SSRF)

Business logic flow vulnerabilities exploits

Business logic flow vulnerabilities are weaknesses in the design or implementation of a system that can be exploited by attackers to carry out malicious activities. Here are some common business logic flow exploits:

  1. Race conditions: A race condition occurs when two or more actions are executed in an unpredictable order, leading to unexpected results. For example, an attacker may place multiple orders for an item in a online store before the stock is updated, leading to the item being oversold.

  2. Input validation bypass: Input validation is the process of ensuring that user-supplied data is valid and secure. Attackers may try to bypass input validation by injecting malicious code into a system, leading to security vulnerabilities such as SQL injection attacks.

  3. Access control bypass: Access control is the process of controlling access to resources based on user roles and permissions. Attackers may try to bypass access controls by finding weaknesses in the implementation of the access control mechanism, leading to unauthorized access to sensitive information.

  4. Cross-Site Request Forgery (CSRF): CSRF attacks exploit the trust that a website has in a user’s browser to carry out malicious actions on behalf of the user. For example, an attacker may create a malicious website that causes a user’s browser to send a request to a vulnerable website, leading to unauthorized actions being taken.

  5. Workflow manipulation: Workflow manipulation involves changing the order or logic of a process to achieve a desired outcome. For example, an attacker may manipulate the approval workflow of a financial transaction to approve a fraudulent transaction.

Practicing in test for Business logic flow vulnerabilities

Testing for business logic flow vulnerabilities is an important part of ensuring the security of a system. Here are some steps you can follow to practice testing for these types of vulnerabilities:

  1. Review the system design and architecture: Start by understanding the design of the system and how it’s intended to work. This will help you identify potential areas where logic flow vulnerabilities may exist.

  2. Conduct black box testing: Black box testing involves testing the system without knowledge of the internal workings. You can use tools like automated web vulnerability scanners to identify potential weaknesses in the system.

  3. Conduct white box testing: White box testing involves testing the system with knowledge of its internal workings. You can manually test the system by reviewing the code and identifying areas where logic flow vulnerabilities may exist.

  4. Test for race conditions: Race conditions occur when two or more actions are executed in an unpredictable order, so you should test for these by attempting to execute actions in parallel to see if the system behaves as expected.

  5. Test for input validation bypass: Try to inject malicious input into the system to see if it can be used to bypass input validation checks.

  6. Test for access control bypass: Attempt to access resources that should be restricted based on user roles and permissions to see if the access control mechanism is implemented correctly.

  7. Test for Cross-Site Request Forgery (CSRF): Try to create a malicious website that causes a user’s browser to send a request to a vulnerable website to see if the system is vulnerable to CSRF attacks.

  8. Test for workflow manipulation: Attempt to change the order or logic of a process to see if it’s possible to manipulate the workflow to achieve a desired outcome.

For study Business logic flow vulnerabilities

If you’re interested in studying business logic flow vulnerabilities, here are some steps you can follow:

  1. Read about software design and architecture: A good understanding of software design and architecture is important for understanding how systems are built and where vulnerabilities may occur.

  2. Learn about web application security: Web applications are a common target for attackers, so it’s important to understand the types of vulnerabilities that can occur in web applications and how they can be exploited.

  3. Read about input validation and access control: Input validation and access control are two key security controls that can be used to prevent business logic flow vulnerabilities. Read about these concepts and how they can be implemented to secure a system.

  4. Study case studies and real-world examples: Studying real-world examples of business logic flow vulnerabilities and the attacks that exploit them will give you a deeper understanding of the types of vulnerabilities that exist and how they can be prevented.

  5. Learn about software testing: Understanding software testing techniques, including both black box and white box testing, is important for finding and preventing business logic flow vulnerabilities.

  6. Practice testing: Try testing different types of systems and applications to gain hands-on experience in finding and preventing business logic flow vulnerabilities.

  7. Stay up to date: The field of software security is constantly evolving, so it’s important to stay up to date with the latest threats, vulnerabilities, and best practices for preventing them. Read articles and attend conferences to stay informed.

Books with review of Business logic flow vulnerabilities

  • “Web Application Hacker’s Handbook” by Dafydd Stuttard and Marcus Pinto: This book provides a comprehensive overview of web application security, including business logic flow vulnerabilities. It covers the latest techniques used by attackers and provides practical advice on how to prevent and remediate these types of vulnerabilities.

  • “The Tangled Web: A Guide to Securing Modern Web Applications” by Michal Zalewski: This book provides a deep dive into the security of web applications, including a chapter on business logic flow vulnerabilities. It covers the most common types of vulnerabilities, including input validation bypass, access control bypass, and workflow manipulation, and provides practical advice on how to prevent and remediate these issues.

  • “Pro PHP Security” by Chris Snyder and Michael Southwell: This book provides a comprehensive overview of PHP security, including a chapter on business logic flow vulnerabilities. It covers the most common types of vulnerabilities in PHP applications and provides practical advice on how to secure PHP code.

  • “Mastering Modern Web Penetration Testing” by Claudio Viviani: This book provides a comprehensive overview of web penetration testing, including a chapter on business logic flow vulnerabilities. It covers the latest techniques used by attackers and provides practical advice on how to test and secure web applications.

These books provide a good starting point for understanding business logic flow vulnerabilities and how to prevent them. It’s important to keep in mind that the field of software security is constantly evolving, so it’s important to stay up to date with the latest threats and best practices.

List of payloads Business logic flow vulnerabilities

A payload is the code or data that is delivered during an attack. In the context of business logic flow vulnerabilities, payloads can be used to exploit these vulnerabilities and carry out malicious actions. Here are a few examples of payloads that are commonly used in attacks that exploit business logic flow vulnerabilities:

  1. SQL injection payloads: SQL injection payloads are used to inject malicious SQL code into a database, allowing an attacker to retrieve or manipulate sensitive data.

  2. Cross-Site Scripting (XSS) payloads: XSS payloads are used to inject malicious scripts into a web page, allowing an attacker to steal sensitive information or carry out other malicious actions.

  3. Command injection payloads: Command injection payloads are used to inject malicious commands into a system, allowing an attacker to execute arbitrary code and take control of a system.

  4. Cross-Site Request Forgery (CSRF) payloads: CSRF payloads are used to cause a user’s browser to send a request to a vulnerable website, allowing an attacker to carry out actions as the user.

  5. Buffer overflow payloads: Buffer overflow payloads are used to overflow a buffer in memory, allowing an attacker to execute arbitrary code and take control of a system.

How to be protected from Business logic flow vulnerabilities

Sigma rules and firewall rules can be used to detect and prevent attacks that exploit business logic flow vulnerabilities. Sigma rules and firewall rules are designed to block or stop malicious traffic, and they can be used to mitigate the risk posed by these types of vulnerabilities.

Sigma rules are used to detect security incidents and anomalies in log data. These rules can be used to identify suspicious activity related to business logic flow vulnerabilities, such as attempts to inject malicious code into a system or manipulate a process flow.

Firewall rules, on the other hand, can be used to block incoming or outgoing traffic based on specific criteria. For example, firewall rules can be used to block incoming traffic from known malicious IP addresses, or to prevent outgoing traffic that contains certain keywords or payloads.

In order to be effective, sigma rules and firewall rules must be regularly updated and maintained to reflect the latest threats and attack patterns. It’s also important to regularly review and audit these rules to ensure that they are functioning as intended and providing adequate protection against business logic flow vulnerabilities.

Keep in mind that while sigma rules and firewall rules can be useful in preventing attacks, they should be used as part of a comprehensive security strategy that includes other security measures such as secure coding practices, input validation, and access controls.

Mitigations for Business logic flow vulnerabilities

Mitigating business logic flow vulnerabilities requires a multi-layered approach that involves several different strategies and techniques. Here are some key steps you can take to reduce the risk posed by these types of vulnerabilities:

  1. Input validation: Ensure that all user input is thoroughly validated before it is processed by a system. This can include checks for proper data type, length, and format.

  2. Access control: Implement strict access controls to limit who has access to sensitive data and functionality. This includes defining clear roles and responsibilities for users and limiting the amount of access each user has to the minimum necessary to perform their job.

  3. Secure coding practices: Ensure that all software is developed with secure coding practices in mind. This includes writing code that is free from common vulnerabilities, such as SQL injection and cross-site scripting (XSS), and properly handling exceptions and error conditions.

  4. Regular security updates: Regularly update software to address known security vulnerabilities and to take advantage of new security features and protections.

  5. Testing: Thoroughly test software for security vulnerabilities, including penetration testing and code review, to identify and address any potential weaknesses before they can be exploited.

  6. Monitoring: Implement monitoring and logging capabilities to detect and respond to security incidents in a timely manner. This includes regularly reviewing log files and using security information and event management (SIEM) tools to identify and respond to potential threats.

  7. Employee training: Regularly train employees on secure coding practices, secure data handling, and the importance of following security protocols.

Implementing these mitigations and following best practices in software security can help reduce the risk posed by business logic flow vulnerabilities and improve the overall security posture of your systems and applications.

Conclusion

In conclusion, business logic flow vulnerabilities are a significant threat to the security of software systems and applications. These vulnerabilities can be exploited by attackers to carry out a range of malicious actions, including data theft, unauthorized access to sensitive information, and the compromise of systems and applications. To reduce the risk posed by these vulnerabilities, it’s important to implement a multi-layered security strategy that includes input validation, access control, secure coding practices, regular security updates, testing, monitoring, and employee training. By following best practices in software security, organizations can improve the security of their systems and reduce the risk of successful attacks.

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