CWE-1287: Improper Validation of Specified Type of Input

What is Improper Validation of Specified Type of Input?

• Overview: CWE-1287 refers to a situation where a software application receives input expected to be of a specific type but fails to validate it properly. This can lead to unexpected behavior if the input is not of the expected type, potentially introducing vulnerabilities.

• Exploitation Methods:

• Attackers can exploit this vulnerability by providing input that mimics other types, causing the application to behave unpredictably.
• Common attack patterns include type confusion attacks, where input is crafted to be interpreted as a different type than intended, leading to potential execution of malicious code or triggering logic errors.

• Security Impact:

• Direct consequences of successful exploitation include application crashes, execution of unintended operations, or unauthorized access to sensitive data.
• Potential cascading effects include deeper penetration into the system, elevation of privileges, or further exploitation of other latent vulnerabilities.
• Business impact may involve data breaches, loss of customer trust, financial loss, and damage to brand reputation.

• Prevention Guidelines:

• Specific code-level fixes include implementing strict type-checking and validation routines to ensure input conforms to expected types before processing.
• Security best practices entail using type-safe programming languages or employing type enforcement mechanisms where possible.
• Recommended tools and frameworks involve utilizing static analysis tools to detect type-related issues and applying input validation libraries to enforce strict type constraints.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

function calculateTotal(input) {
    // Vulnerable code: Assumes input is always an array
    // This assumption can lead to runtime errors and potential security issues
    return input.reduce((acc, num) => acc + num, 0);  // If 'input' is not an array, this will error
}

// Example usage
const userInput = "Not an array!";
calculateTotal(userInput);  // This will crash

How to fix Improper Validation of Specified Type of Input?

In JavaScript, improper input type validation can lead to unexpected behavior and runtime errors. The solution is to explicitly check the input type using Array.isArray() to ensure that the input is an array before attempting to process it. This prevents the function from executing operations on incorrect data types, thereby avoiding errors and potential vulnerabilities.

Fixed Code Example

function calculateTotal(input) {
    // Secure code: Validate input type is array
    if (!Array.isArray(input)) {
        throw new TypeError("Expected input to be an array");
    }
    
    // Now it's safe to perform array operations
    return input.reduce((acc, num) => acc + num, 0);
}

// Example usage
const userInput = [1, 2, 3, 4];  // Correct input type
console.log(calculateTotal(userInput));  // This will output 10

By implementing these checks, you ensure that your code is robust against improper input types, reducing the potential for security vulnerabilities and runtime errors.