What is Function Call With Incorrect Number (CWE-685)?

TL;DR: Function Call With Incorrect Number of Arguments (CWE-685) is a vulnerability that occurs when functions are called with incorrect arguments, leading to undefined behavior and quality degradation. Ensuring strict adherence to parameter requirements fixes this issue.

What is Function Call With Incorrect Number of Arguments?

Function Call With Incorrect Number of Arguments (CWE-685) is a type of vulnerability that occurs when a function, procedure, or routine is called with an incorrect number of arguments. As defined by the MITRE Corporation under CWE-685.

Quick Summary

This weakness can lead to undefined behavior and quality degradation in applications. It matters because it affects the reliability and security of software systems. Jump to: What is Function Call With Incorrect Number of Arguments? · Overview · How It Works · Business Impact · Attack Scenario · Detection · Fixing · Framework Fixes · AI Check Prompt · Best Practices Checklist · FAQ · Related Vulnerabilities

Jump to: Quick Summary · Function Call With Incorrect Number of Arguments Overview · How Function Call With Incorrect Number of Arguments Works · Business Impact of Function Call With Incorrect Number of Arguments · Function Call With Incorrect Number of Arguments Attack Scenario · How to Detect Function Call With Incorrect Number of Arguments · How to Fix Function Call With Incorrect Number of Arguments · Framework-Specific Fixes for Function Call With Incorrect Number of Arguments · How to Ask AI to Check Your Code for Function Call With Incorrect Number of Arguments · Function Call With Incorrect Number of Arguments Best Practices Checklist · Function Call With Incorrect Number of Arguments FAQ · Vulnerabilities Related to Function Call With Incorrect Number of Arguments · References · Scan Your Own Site

Function Call With Incorrect Number of Arguments Overview

What: This vulnerability occurs when a function call has too many or too few arguments, leading to undefined behavior.

Why it matters: It can cause unexpected application behavior and lead to security issues.

Where it occurs: In any programming language where functions are called with incorrect parameters.

Who is affected: Developers who write code that includes function calls without proper parameter validation.

Who is NOT affected: Systems already using robust testing mechanisms to ensure correct function call arguments.

How Function Call With Incorrect Number of Arguments Works

Root Cause

The root cause lies in the misuse or incorrect usage of functions, where the number of provided arguments does not match what the function expects.

Attack Flow

1. An attacker identifies a function that is called with an incorrect number of arguments.
2. The application’s behavior becomes unpredictable and may lead to undefined results.
3. This can cause security issues such as data corruption or unexpected system behavior.

Prerequisites to Exploit

• A function must be called with an incorrect number of arguments.
• The application must not have proper validation mechanisms in place.

Vulnerable Code

def process_data(data, flag):
    # Process the data based on the flag

# Incorrect call
process_data("data")

This code is vulnerable because it calls process_data with only one argument instead of two.

Secure Code

def process_data(data, flag=None):
    if not isinstance(flag, bool) or flag is None:
        raise ValueError("Flag must be a boolean value.")
    # Process the data based on the flag

# Correct call
process_data("data", True)

This code ensures that flag is always provided and validated before proceeding.

Business Impact of Function Call With Incorrect Number of Arguments

Quality Degradation:

• Unexpected behavior can lead to application crashes or incorrect functionality.

Availability:

• The system may become unstable, leading to downtime.

Function Call With Incorrect Number of Arguments Attack Scenario

1. An attacker identifies a function that is called with an incorrect number of arguments.
2. They exploit this by manipulating the input data to trigger undefined behavior.
3. This results in unexpected application crashes or security vulnerabilities.

How to Detect Function Call With Incorrect Number of Arguments

Manual Testing

• Ensure all function calls adhere strictly to their defined parameter requirements.
• Test edge cases where functions may be called with incorrect arguments.

Automated Scanners (SAST / DAST)

Static analysis can detect instances where functions are called without the correct number of arguments. Dynamic testing is necessary for runtime behavior verification.

PenScan Detection

PenScan’s scanner engines such as ZAP, Nuclei, and Wapiti actively identify function calls with incorrect arguments during automated scans.

False Positive Guidance

False positives may occur if a function call appears to be incorrect but is actually part of an expected workflow. Ensure that the context of the function call matches the application’s design.

How to Fix Function Call With Incorrect Number of Arguments

• Ensure all function calls adhere strictly to their defined parameter requirements.
• Implement validation mechanisms for function arguments during development and testing phases.
• Use linters or automated tools to enforce correct argument usage in code.

Framework-Specific Fixes for Function Call With Incorrect Number of Arguments

Python/Django

def process_data(data, flag):
    if not isinstance(flag, bool) or flag is None:
        raise ValueError("Flag must be a boolean value.")
    # Process the data based on the flag

This ensures that flag is always provided and validated before proceeding.

How to Ask AI to Check Your Code for Function Call With Incorrect Number of Arguments

Function Call With Incorrect Number of Arguments Best Practices Checklist

✅ Ensure all function calls adhere strictly to their defined parameter requirements. ✅ Implement validation mechanisms for function arguments during development and testing phases. ✅ Use linters or automated tools to enforce correct argument usage in code. ✅ Test edge cases where functions may be called with incorrect arguments.

Function Call With Incorrect Number of Arguments FAQ

How does a function call with incorrect number of arguments lead to vulnerabilities?

When a function is called with too many or too few arguments, it can result in undefined behavior, leading to security issues and quality degradation.

Can you provide an example of how this vulnerability occurs in real-world code?

A developer might mistakenly pass the wrong number of parameters to a function, causing unexpected behavior that could be exploited by attackers.

How can developers prevent Function Call With Incorrect Number of Arguments vulnerabilities during testing?

Developers should thoroughly test all possible control paths and ensure functions are called with the correct number of arguments to avoid undefined behavior.

How does Function Call With Incorrect Number of Arguments affect data integrity in applications?

Incorrect function calls can lead to unintended modifications or corruptions of application data, compromising its integrity.

Can you explain how PenScan detects Function Call With Incorrect Number of Arguments vulnerabilities?

PenScan uses static and dynamic analysis techniques to identify instances where functions are called with an incorrect number of arguments.

What is the best practice for fixing Function Call With Incorrect Number of Arguments in Python code?

Ensure that all function calls adhere strictly to their defined parameter requirements, using linters or automated tools to enforce this rule.

Vulnerabilities Related to Function Call With Incorrect Number of Arguments

| CWE | Name | Relationship | |—|—|—| | CWE-628 | Function Call with Incorrectly Specified Arguments | ChildOf |

References

• MITRE
• NVD

Scan Your Own Site

Manual code review catches what you know to look for. An automated scan catches what you didn’t. Scan your own website using PenScan to find Function Call With Incorrect Number of Arguments and other risks before an attacker does.