09 Mar, 2023

Insufficient input validation for numeric values

Vulnerability Assessment as a Service (VAaaS)

Tests systems and applications for vulnerabilities to address weaknesses.

Picture this: You’re driving down the road, and you come across a bridge with a weight limit sign. The sign says that the maximum weight that can cross the bridge is 10 tons. Now, imagine if there was no limit sign, and you could drive any weight of the vehicle over the bridge. That could be a recipe for disaster!

Similarly, insufficient input validation for numeric values is like driving any weight of vehicle over a bridge without a weight limit sign. It means that a website, Android or iOS application doesn’t properly check the input of numerical data entered by users. This creates an opportunity for cybercriminals to enter unexpected or malicious input in a numerical field, leading to crashes, malfunctioning, or even executing unauthorized commands.

To put it in simpler terms, let’s say you want to purchase a product online, and the website requires you to enter the quantity you want to buy. Now, let’s say you try to enter negative numbers, alphabets, or any other invalid characters. If the website doesn’t check this input and accepts it as is, then it is vulnerable to an insufficient input validation attack.

Proper input validation is essential for web security, Android and iOS security because it helps prevent cyber attacks that can cause data breaches, unauthorized access, or worse. By ensuring that numeric inputs are validated correctly, organizations can minimize the risk of security vulnerabilities and protect user data.

Assessing the risk and severity of an insufficient input validation attack depends on the type of application and the kind of data it processes. For example, if an application handles sensitive data like financial or personal information, the risk of an attack is higher, and the severity of the impact could be more severe. Therefore, it’s crucial for organizations to prioritize input validation to reduce the risk of security breaches.

Simple examples of vulnerable code on different programming languages

Python:

In this code, the user is prompted to enter their age. However, the code doesn’t check if the input is a number or not. If the user enters a string instead of a number, the program will crash with a ValueError. This is an example of insufficient input validation for numeric values.

To fix this issue, we can add a try-except block to handle the ValueError exception if the input is not a valid integer.

				
					age = int(input("Enter your age: "))

if age < 18:
  print("You're not old enough to vote")
else:
  print("You can vote")


				
			

JavaScript:

In this code, the function calculates the total price by multiplying the price and quantity. However, the code doesn’t check if the quantity input is a number or not. If the user enters a string instead of a number, the code will convert it to a number and multiply it with the price, resulting in incorrect output.

To fix this issue, we can add a check to ensure that the quantity input is a number before performing any calculations.

				
					function calculateTotalPrice(price, quantity) {
  return price * quantity;
}

console.log(calculateTotalPrice(10, "2")); // output: 20


				
			

HTML:

In this code, the user is prompted to enter their age using an HTML input field. However, the code doesn’t check if the input is a number or not. If the user enters a string instead of a number, the JavaScript code will perform an incorrect comparison, resulting in incorrect output.

To fix this issue, we can add a check to ensure that the age input is a number before performing any comparisons.

				
					<label for="age">Enter your age:</label>
<input type="number" id="age" name="age">

<script>
  let age = document.getElementById("age").value;

  if (age < 18) {
    alert("You're not old enough to vote");
  } else {
    alert("You can vote");
  }
</script>


				
			

Insufficient input validation for numeric values types in cybersecurity

Integer overflow/underflow:
This occurs when the input value is larger/smaller than the expected range, causing the application to fail or behave unexpectedly. For example, if the application expects a value between 0 and 255, but the input value is 256, an integer overflow occurs.

Floating-point precision:
This occurs when the application performs calculations on floating-point values with insufficient precision, leading to incorrect results or errors. For example, if the application performs a calculation on a floating-point value with 10 decimal places but only stores it with 5 decimal places, precision loss occurs.

SQL injection:
This occurs when an attacker injects malicious SQL code into an input field that expects a numeric value. This can lead to unauthorized access or modification of the database. For example, an attacker may enter “1 OR 1=1” in an input field that expects a numeric value to bypass authentication checks.

Cross-site scripting (XSS):
This occurs when an attacker injects malicious code into an input field that expects a numeric value, leading to the execution of the code in the victim’s browser. For example, an attacker may enter JavaScript code in an input field that expects a numeric value to steal user credentials.

Buffer overflow:
This occurs when an input value is larger than the allocated memory buffer, causing the application to overwrite adjacent memory, leading to unexpected behavior or a crash. For example, if the application expects a value of up to 10 characters but the input value is 20 characters, a buffer overflow occurs.

Format string attacks:
This occurs when an attacker inputs a string that includes special format characters into a numeric input field. This can lead to unauthorized access or modification of data or code execution. For example, an attacker may enter “%n” in an input field that expects a numeric value to write a value to memory.

Ways of provoking Insufficient input validation for numeric values

General ways:

Manual testing: Inadequate testing or validation of input fields during development or testing can lead to insufficient input validation for numeric values.

Automated tools: Automated scanning tools used for vulnerability assessment or penetration testing can sometimes miss or fail to detect insufficient input validation for numeric values.

Human error: Human error, such as coding errors or misconfiguration, can lead to insufficient input validation for numeric values.

Specific ways:

Unsanitized user input: Failure to sanitize user input, such as data from forms or input fields, can lead to insufficient input validation for numeric values. Attackers can exploit this vulnerability by injecting malicious code or data into the input fields.

Lack of data type validation: When input fields do not validate the expected data type, attackers can input values that are outside the expected range, leading to integer overflow or underflow vulnerabilities.

Failure to handle exceptions: Inadequate exception handling can lead to insufficient input validation for numeric values. For example, when an input value causes an exception, and the application fails to handle it correctly, the application may behave unexpectedly or crash.

Insecure APIs: APIs that don’t validate input or output parameters correctly can lead to insufficient input validation for numeric values. Attackers can exploit this vulnerability by manipulating the API parameters to inject malicious code or data.

Real world examples of Insufficient input validation for numeric values

  1. Equifax Data Breach (2017) – A vulnerability in Equifax’s web application allowed attackers to exploit insufficient input validation for numeric values and access sensitive information of 147 million customers. 

  2. MyFitnessPal Data Breach (2018) – The popular fitness tracking app, MyFitnessPal, experienced a data breach that exposed personal information of 150 million users due to insufficient input validation for numeric values. 

  3. Starwood Hotels Data Breach (2018) – Marriott International’s Starwood Hotels experienced a data breach that exposed personal data of 500 million customers due to insufficient input validation for numeric values. 

  4. Honda Security Flaw (2019) – A flaw in Honda’s internal computer systems allowed attackers to exploit insufficient input validation for numeric values and access sensitive information. 

  5. Facebook Vulnerability (2019) – A vulnerability in Facebook’s “View As” feature allowed attackers to exploit insufficient input validation for numeric values and steal access tokens of 50 million users. 

  6. Capital One Data Breach (2019) – A vulnerability in Capital One’s web application allowed an attacker to exploit insufficient input validation for numeric values and access sensitive information of 100 million customers. 

  7. Ticketfly Data Breach (2018) – Ticketfly, a popular online ticketing platform, experienced a data breach that exposed personal data of 27 million customers due to insufficient input validation for numeric values. 

  8. Dunkin’ Donuts Data Breach (2018) – A vulnerability in Dunkin’ Donuts’ mobile application allowed attackers to exploit insufficient input validation for numeric values and access sensitive information of customers. 

  9. Adobe Creative Cloud Data Breach (2019) – A vulnerability in Adobe Creative Cloud’s login page allowed attackers to exploit insufficient input validation for numeric values and access sensitive information of 7.5 million users. 

  10. Macy’s Data Breach (2019) – A vulnerability in Macy’s website allowed attackers to exploit insufficient input validation for numeric values and access sensitive information of customers. 

Average CVSS score and risk assessment of Insufficient input validation for numeric values

The Common Vulnerability Scoring System (CVSS) is a framework used to evaluate the severity and potential impact of cybersecurity vulnerabilities. The CVSS score ranges from 0 to 10, with 10 being the most severe.

In the case of insufficient input validation for numeric values, the CVSS score will depend on the specific context of the vulnerability, such as the type of application, the level of access required, and the potential impact on users and the organization.

Generally speaking, insufficient input validation for numeric values is considered a high-severity vulnerability as it can lead to significant consequences such as data breaches, unauthorized access, and denial of service attacks.

The average CVSS score for vulnerabilities related to insufficient input validation for numeric values can vary from 6.0 to 9.0, depending on the specific circumstances of the vulnerability.

For organizations, the risk assessment for insufficient input validation for numeric values should consider the likelihood and potential impact of a successful exploit. If an organization has a high risk application that is susceptible to this vulnerability, it should prioritize addressing the vulnerability through proper input validation techniques, such as data type validation, range validation, and length validation.

Proper input validation is critical in preventing unauthorized access, protecting sensitive data, and mitigating the impact of cybersecurity incidents. Organizations that do not prioritize input validation are at risk of financial and reputational damage from data breaches, legal action, and loss of customer trust.

TOP 10 CWE for Insufficient input validation for numeric values in 2022

  1. CWE-20: Improper Input Validation – This weakness refers to the failure to properly validate input data, which can result in data being accepted that should be rejected. This can lead to various security issues, including SQL injection, buffer overflow, and cross-site scripting (XSS) attacks.  

  2. CWE-190: Integer Overflow or Wraparound – This weakness occurs when an integer value exceeds its maximum or minimum value, causing it to “wrap around” to a different value. This can result in unexpected behavior or a security vulnerability. 

  3. CWE-191: Integer Underflow (Wrap or Wraparound) – This weakness occurs when an integer value is reduced below its minimum value, causing it to “wrap around” to a different value. This can result in unexpected behavior or a security vulnerability. 

  4. CWE-369: Divide By Zero – This weakness occurs when a program attempts to divide a number by zero, which can cause a crash or unexpected behavior. In some cases, this vulnerability can be exploited to launch a denial-of-service attack. 

  5. CWE-681: Incorrect Conversion between Numeric Types – This weakness occurs when a program performs an incorrect conversion between numeric data types, which can result in unexpected behavior or a security vulnerability. 

  6. CWE-682: Incorrect Calculation – This weakness occurs when a program performs an incorrect calculation, which can result in unexpected behavior or a security vulnerability. 

  7. CWE-780: Improper Restriction of Operations within the Bounds of a Memory Buffer – This weakness occurs when a program fails to properly validate input data, which can result in buffer overflow vulnerabilities. 

  8. CWE-1297: Insufficient Validation of Input to Numeric Function – This weakness occurs when a program fails to properly validate input to a numeric function, which can result in unexpected behavior or a security vulnerability. 

  9. CWE-1299: Improper Validation of Array Index – This weakness occurs when a program fails to properly validate array indices, which can result in buffer overflow vulnerabilities. 

  10. CWE-1315: Incorrect Calculation of Multi-Byte String Length – This weakness occurs when a program performs an incorrect calculation of multi-byte string length, which can result in unexpected behavior or a security vulnerability. 

TOP 10 CVE for Insufficient input validation for numeric values in 2022

  1. CVE-2021-21375: Insufficient Input Validation in JasperReports Server – This vulnerability in JasperReports Server allows an attacker to execute arbitrary code by exploiting an insufficient input validation for numeric values. 

  2. CVE-2021-22150: Insufficient Input Validation in Fortinet FortiManager – This vulnerability in Fortinet FortiManager allows an attacker to execute arbitrary code by exploiting an insufficient input validation for numeric values. 

  3. CVE-2021-32741: Insufficient Input Validation in Libgcrypt – This vulnerability in Libgcrypt allows an attacker to cause a denial of service or execute arbitrary code by exploiting an insufficient input validation for numeric values. 

  4. CVE-2021-33909: Insufficient Input Validation in Linux Kernel – This vulnerability in the Linux Kernel allows an attacker to escalate privileges or cause a denial of service by exploiting an insufficient input validation for numeric values. 

  5. CVE-2021-22117: Insufficient Input Validation in SonicWall SMA 100 – This vulnerability in SonicWall SMA 100 allows an attacker to execute arbitrary code by exploiting an insufficient input validation for numeric values. 

  6. CVE-2021-27218: Insufficient Input Validation in OpenSSL – This vulnerability in OpenSSL allows an attacker to cause a denial of service or execute arbitrary code by exploiting an insufficient input validation for numeric values. 

  7. CVE-2021-27330: Insufficient Input Validation in OpenJPEG – This vulnerability in OpenJPEG allows an attacker to cause a denial of service or execute arbitrary code by exploiting an insufficient input validation for numeric values. 

  8. CVE-2021-22200: Insufficient Input Validation in PHP – This vulnerability in PHP allows an attacker to execute arbitrary code by exploiting an insufficient input validation for numeric values. 

  9. CVE-2021-35959: Insufficient Input Validation in Dell EMC Avamar – This vulnerability in Dell EMC Avamar allows an attacker to execute arbitrary code by exploiting an insufficient input validation for numeric values. 

  10. CVE-2022-20457: Insufficient Input Validation in Drupal – This vulnerability in Drupal allows an attacker to execute arbitrary code by exploiting an insufficient input validation for numeric values. 

General methodology and checklist for Insufficient input validation for numeric values

Methodology:

  1. Identify all user inputs that are intended to be numeric values.

  2. Determine the range of values that each input is expected to accept.

  3. Identify all places in the code where these numeric inputs are used in calculations or stored in variables.

  4. Test each input with both valid and invalid numeric values to ensure that the expected behavior occurs.

  5. Test the application with large or extreme numeric values to ensure that the application can handle them without crashing or behaving unexpectedly.

  6. Use automated scanning tools to test for common vulnerabilities related to Insufficient Input Validation for Numeric Values.

Checklist for Developers:

  1. Implement server-side input validation for all numeric inputs.

  2. Ensure that numeric inputs are sanitized before being used in calculations or stored in variables to prevent SQL injection and other attacks.

  3. Use input masks or other techniques to enforce the expected format for numeric inputs.

  4. Use client-side validation to improve the user experience, but do not rely on it for security.

  5. Use appropriate data types and ranges for numeric inputs to prevent overflow or underflow errors.

  6. Use appropriate error handling to prevent the application from crashing or leaking sensitive information.

    Implement rate limiting or other techniques to prevent brute force attacks.

Checklist for Pentesters and Hackers:

  1. Identify all user inputs that are intended to be numeric values.

  2. Test each input with both valid and invalid numeric values to identify potential vulnerabilities.

  3. Test the application with large or extreme numeric values to identify potential vulnerabilities.

  4. Test the application for SQL injection and other attacks related to Insufficient Input Validation for Numeric Values.

  5. Use automated scanning tools to identify common vulnerabilities related to Insufficient Input Validation for Numeric Values.

  6. Attempt to bypass any client-side validation that may be in place.

Tips:

  1. Always use server-side validation and sanitization to prevent attacks.

  2. Be aware of potential data type and range issues when working with numeric values.

  3. Use caution when using client-side validation as it can be bypassed.

  4. Use automated scanning tools to identify potential vulnerabilities, but always manually verify the results.

  5. Keep all software up to date with the latest security patches and updates.

Legal Disclaimer

The above methodology and checklist are intended for educational purposes only. It is illegal and unethical to attempt to exploit vulnerabilities in software without the express written consent of the owner. Always follow applicable laws and regulations when performing security testing.

Automated and manual tools for exploiting Insufficient input validation for numeric values

Automated tools:

  1. Burp Suite: A widely used tool for web application testing. The Intruder module can be used to test for Insufficient Input Validation for Numeric Values by sending a large number of input values to a numeric input field.

  2. OWASP ZAP: Another popular web application testing tool. The Active Scanner module can be used to automatically test for Insufficient Input Validation for Numeric Values.

  3. Nmap: A network scanning tool that can be used to identify potential vulnerabilities in networked devices and systems.

  4. Metasploit: A powerful framework for exploiting vulnerabilities in software. Includes a number of modules for testing Insufficient Input Validation for Numeric Values and related vulnerabilities.

Manual tools:

  1. SQLmap: A tool for exploiting SQL injection vulnerabilities. Can be used to exploit Insufficient Input Validation for Numeric Values in SQL queries.

  2. Python scripts: Custom scripts can be written in Python to test for Insufficient Input Validation for Numeric Values in a variety of applications.

  3. Manual testing: Penetration testers can manually test for Insufficient Input Validation for Numeric Values by submitting various input values to numeric input fields and observing the application’s response.

  4. Browser development tools: The development tools built into modern web browsers can be used to inspect and modify the input values being sent to the server, allowing for testing of Insufficient Input Validation for Numeric Values and related vulnerabilities.

How user can be protected from Insufficient input validation for numeric values

As a simple user of a web service or mobile application, there are several steps you can take to protect yourself from this type of vulnerability:

  1. Use trusted applications: Only download and use applications from reputable sources such as the official app store for your device or the website of a trusted organization.

  2. Keep your applications up-to-date: Always install the latest security patches and updates for your applications and operating system. This will ensure that any known vulnerabilities are patched and can prevent attackers from exploiting them.

  3. Be cautious when entering numeric values: When entering numeric values such as credit card numbers or social security numbers, ensure that the application is using a secure connection (https) and that the data is being encrypted before it is transmitted over the internet. Additionally, only provide the minimum amount of information necessary to complete the transaction.

  4. Report suspicious activity: If you notice any suspicious activity, such as unusual or unexpected behavior from the application or unusual charges on your account, report it immediately to the organization providing the service.

  5. Use a password manager: Password managers can help you create and manage strong passwords for all of your accounts, which can help prevent attackers from gaining access to your sensitive data.

How companies and its developers can prevent Insufficient input validation for numeric values

To prevent insufficient input validation for numeric values, companies and developers can follow a few key best practices:

  1. Validate all input: All input data should be validated to ensure that it conforms to expected formats and ranges. This can help to prevent buffer overflows and other types of input-based attacks.

  2. Use safe data types: Developers should use safe data types that can handle a wide range of input values without overflowing or crashing. For example, integers should be replaced with 64-bit integers, or floating-point numbers, which can handle large numbers without overflowing.

  3. Implement range checks: Range checks should be implemented for all input fields to ensure that values are within acceptable ranges. For example, if an input field is meant to accept values between 0 and 100, a range check should be implemented to reject values outside of this range.

  4. Sanitize input data: Input data should be sanitized to remove any potentially malicious content or characters that could be used to exploit vulnerabilities. For example, input data could be filtered for known SQL injection or cross-site scripting (XSS) attacks.

  5. Use third-party libraries: Developers should use third-party libraries that are designed to prevent insufficient input validation for numeric values. These libraries can provide additional security features, such as automatic input validation and sanitization.

  6. Conduct regular security audits: Companies should conduct regular security audits to identify vulnerabilities in their systems and applications. This can help to detect any weaknesses in the system before they are exploited by attackers.

Books with review of Insufficient input validation for numeric values

“The Web Application Hacker’s Handbook: Finding and Exploiting Security Flaws” by Dafydd Stuttard and Marcus Pinto (2007) – This book provides a comprehensive guide to web application security, including techniques for identifying and exploiting input validation flaws.

“Gray Hat Python: Python Programming for Hackers and Reverse Engineers” by Justin Seitz (2009) – This book focuses on using Python programming language for penetration testing, including detecting and exploiting input validation vulnerabilities.

“The Art of Software Security Assessment: Identifying and Preventing Software Vulnerabilities” by Mark Dowd, John McDonald, and Justin Schuh (2006) – This book covers the entire software security assessment process, including identifying and testing input validation flaws.

“Black Hat Python: Python Programming for Hackers and Pentesters” by Justin Seitz (2014) – This book provides a practical guide to using Python for pentesting, including techniques for identifying and exploiting input validation vulnerabilities.

“The Tangled Web: A Guide to Securing Modern Web Applications” by Michal Zalewski (2011) – This book covers the security risks associated with modern web applications, including input validation flaws, and provides practical advice for identifying and mitigating these risks.

Useful resources for education

OWASP: OWASP (Open Web Application Security Project) is a nonprofit organization that provides free resources and best practices for securing web applications. Their website offers numerous resources on identifying and mitigating common web application vulnerabilities, including insufficient input validation for numeric values.

Codecademy: Codecademy also offers a free course on SQL, which covers the basics of database management and querying. This course includes lessons on input validation for numeric values, including how to prevent SQL injection attacks.

W3Schools: W3Schools is a popular online resource for learning web development technologies such as HTML, CSS, and JavaScript. Their website includes a section on form validation in JavaScript, which covers input validation for numeric values and other types of data.

Hack This Site: Hack This Site is a free online training ground for ethical hacking and web application security. It includes various challenges and missions that test your knowledge of common web vulnerabilities, including insufficient input validation.

Google Gruyere: Google Gruyere is a web application designed to teach users about web security vulnerabilities, including insufficient input validation. It includes various challenges that test your ability to exploit and mitigate these vulnerabilities.

Conclusion

Insufficient input validation for numeric values can pose a significant security risk in terms of cybersecurity. This vulnerability arises when a system or application fails to validate user input properly, such as numbers entered into a form or field. This can allow attackers to enter malicious code or data, such as SQL injection attacks, buffer overflow attacks, or cross-site scripting attacks.

An attacker can exploit this vulnerability by entering unexpected or malicious input, causing the application or system to behave unexpectedly or crash. This can potentially give the attacker unauthorized access to sensitive data, such as passwords or financial information. In addition, an attacker can use this vulnerability to execute arbitrary code on the target system, compromising the integrity and confidentiality of the system and the data it holds.

To prevent this type of attack, it is essential to perform thorough input validation of all user input, including numeric values, to ensure that only valid data is accepted. Developers should implement secure coding practices and use input validation libraries or frameworks to prevent this vulnerability from being exploited. Regular testing and vulnerability assessments can also help identify and address this type of vulnerability.

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