What is Incorrect Type Conversion or Cast (CWE-704)?

TL;DR: Incorrect Type Conversion or Cast (CWE-704) is a vulnerability that occurs when an object is incorrectly converted from one type to another, leading to potential security risks. Proper type checking and validation are essential for prevention.

What is Incorrect Type Conversion or Cast?

Incorrect Type Conversion or Cast (CWE-704) is a type of vulnerability that occurs when an object, resource, or structure is incorrectly converted from one type to another. As defined by the MITRE Corporation under CWE-704, and classified by the OWASP Foundation as not directly mapped.

Quick Summary

Incorrect Type Conversion or Cast leads to unexpected behavior such as crashes, data corruption, and security vulnerabilities due to improper handling of different data types. Jump to: Overview · How It Works · Business Impact · Attack Scenario · Detection · Fixing · Framework Fixes · Ask AI · Best Practices · FAQ · Related Vulnerabilities · References

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

Incorrect Type Conversion or Cast Overview

What: Incorrect type conversion occurs when an object, resource, or structure is incorrectly converted from one type to another.

Why it matters: This can cause data corruption, system instability, and security vulnerabilities due to unexpected behavior.

Where it occurs: In applications that handle external inputs and perform type conversions without proper validation.

Who is affected: Developers using programming languages that allow for dynamic or unsafe type casting.

Who is NOT affected: Applications with strict typing enforced by the language or runtime environment.

How Incorrect Type Conversion or Cast Works

Root Cause

Incorrect type conversion occurs when an object, resource, or structure is incorrectly converted from one type to another without proper validation and error handling.

Attack Flow

1. An attacker inputs a value that triggers incorrect type conversion.
2. The system performs the type conversion without proper checks.
3. Unexpected behavior occurs, leading to potential security vulnerabilities.

Prerequisites to Exploit

• External input capable of triggering incorrect type conversion.
• Lack of validation and error handling for type conversions.

Vulnerable Code

def convert_type(value):
    return int(value)

This code attempts to cast an external value directly to an integer without proper checks, leading to potential issues if the value is not a valid number.

Secure Code

def convert_type(value):
    try:
        return int(value)
    except ValueError:
        raise ValueError("Invalid input type")

The secure version includes validation and error handling to ensure that only valid values are converted.

Business Impact of Incorrect Type Conversion or Cast

Confidentiality: Data integrity issues may lead to unauthorized access if sensitive data is corrupted.

• Example: Sensitive information becomes corrupted due to incorrect type conversion, leading to potential exposure.

Integrity: System instability and crashes can result from improper handling of different data types.

• Example: Incorrect type conversion causes a system crash, disrupting normal operations.

Availability: Potential security vulnerabilities can lead to unauthorized access or control over the system.

• Example: An attacker exploits incorrect type conversion to gain unauthorized access to sensitive resources.

Business consequences:

• Financial losses due to system downtime and recovery efforts.
• Compliance penalties for data breaches caused by improper handling of sensitive information.
• Damage to reputation from public disclosure of security vulnerabilities.

Incorrect Type Conversion or Cast Attack Scenario

1. The attacker inputs a value that triggers incorrect type conversion in the application.
2. The system performs the type conversion without proper checks, leading to unexpected behavior.
3. The attacker exploits this behavior to cause data corruption or system instability.
4. Unauthorized access is gained due to improper handling of sensitive information.

How to Detect Incorrect Type Conversion or Cast

Manual Testing

• [-] Review code for direct type conversions without validation.
• [-] Test with invalid input values to see if proper error handling occurs.
• [-] Verify that all type conversions are properly validated and checked before execution.

Automated Scanners (SAST / DAST)

Static analysis can detect potential CWE-704 issues by identifying unvalidated type conversions. Dynamic testing is required to confirm actual vulnerabilities in runtime scenarios.

PenScan Detection

PenScan’s scanner engines such as ZAP, Nuclei, Wapiti, Nikto, SSLyze, and Dalfox can identify incorrect type conversion vulnerabilities during automated scans.

False Positive Guidance

A real finding will show a direct type conversion without proper validation. A false positive may occur if the code includes robust error handling mechanisms that prevent issues from occurring.

How to Fix Incorrect Type Conversion or Cast

• Ensure proper type checking and validation before performing any type conversions.
• Use appropriate casting methods that ensure data integrity during type conversions.
• Implement defensive programming techniques such as explicit type checks and error handling.
• Test the code thoroughly with various input values to verify robustness against incorrect type conversion.

Framework-Specific Fixes for Incorrect Type Conversion or Cast

Python

def convert_type(value):
    try:
        return int(value)
    except ValueError:
        raise ValueError("Invalid input type")

Java

public static Integer convertType(String value) {
    try {
        return Integer.parseInt(value);
    } catch (NumberFormatException e) {
        throw new IllegalArgumentException("Invalid input type");
    }
}

Node.js

function convertType(value) {
    if (!isNaN(parseInt(value))) {
        return parseInt(value);
    } else {
        throw new Error('Invalid input type');
    }
}

PHP

function convert_type($value) {
    if (filter_var($value, FILTER_VALIDATE_INT)) {
        return intval($value);
    } else {
        throw new Exception("Invalid input type");
    }
}

How to Ask AI to Check Your Code for Incorrect Type Conversion or Cast

Incorrect Type Conversion or Cast Best Practices Checklist

✅ Ensure proper type checking before performing any type conversions. ✅ Use appropriate casting methods that ensure data integrity during type conversions. ✅ Implement defensive programming techniques such as explicit type checks and error handling. ✅ Test the code thoroughly with various input values to verify robustness against incorrect type conversion.

Incorrect Type Conversion or Cast FAQ

How does incorrect type conversion lead to security issues?

Incorrect type conversion can cause unexpected behavior, such as data corruption or crashes, leading to potential security vulnerabilities.

What are the common consequences of CWE-704 in applications?

The impact varies but often includes data integrity issues and system instability due to improper handling of different data types.

How can I detect incorrect type conversion in my code?

Use static analysis tools like SAST or manual testing with specific checks for type conversions between incompatible types.

What are the best practices to prevent CWE-704 vulnerabilities?

Ensure proper type checking and validation before performing any type conversions, especially when dealing with external inputs.

How can I fix incorrect type conversion in my application code?

Implement robust type-checking mechanisms and use appropriate casting methods that ensure data integrity during type conversions.

What are the common mistakes developers make when handling type conversions?

Use defensive programming techniques such as explicit type checks, validation, and error handling to mitigate incorrect type conversion risks.

Vulnerabilities Related to Incorrect Type Conversion or Cast

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 Incorrect Type Conversion or Cast and other risks before an attacker does.