CWE-234: Failure to Handle Missing Parameter

What is Failure to Handle Missing Parameter?

• Overview: This vulnerability occurs when a function is called with fewer arguments than it expects, causing it to improperly handle the missing parameters. This can lead to unpredictable behavior and potential security risks.

• Exploitation Methods:

• Attackers can exploit this vulnerability by intentionally providing fewer parameters to functions, possibly manipulating the program's control flow or causing unintended behavior.
• Common attack patterns include function hijacking or causing the program to access unintended memory locations, which could result in data leakage or corruption.

• Security Impact:

• Direct consequences of successful exploitation include application crashes, unauthorized access to sensitive data, and execution of arbitrary code.
• Potential cascading effects include broader system compromise, data integrity issues, and service disruptions.
• Business impact can involve loss of customer trust, legal ramifications, and financial damage due to data breaches or service downtime.

• Prevention Guidelines:

• Specific code-level fixes include implementing strict parameter validation and using default values for optional parameters.
• Security best practices involve thorough testing, code reviews, and static analysis to ensure all functions handle parameters correctly.
• Recommended tools and frameworks include linters, static code analyzers, and languages that provide built-in mechanisms for parameter validation.

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Technical Details

Likelihood of Exploit: High

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

function getUserInfo(userId, includeEmail = false) {
    // Vulnerable code: Fails to handle missing parameters
    // If `userId` is not provided, `userId` will be `undefined`
    console.log(`Fetching info for user: \${userId}`);
    if (includeEmail) {
        console.log("Including email in the response");
    }
}

// Example usage
getUserInfo();  // This will execute without error, but userId is undefined

How to fix Failure to Handle Missing Parameter?

In JavaScript, it is crucial to explicitly check for missing required parameters to prevent unintended behavior. We can utilize default parameters or perform a manual check to raise an error if a required parameter is not provided. By doing this, we ensure that the function is executed only with valid inputs, thereby improving the robustness and reliability of the code.

Fixed Code Example

function getUserInfo(userId, includeEmail = false) {
    // Fixed code: Checks if the required parameter is missing
    if (userId === undefined || userId === null) {
        throw new Error("Missing required parameter: userId");
    }
    
    console.log(`Fetching info for user: \${userId}`);
    if (includeEmail) {
        console.log("Including email in the response");
    }
}

// Example usage
try {
    getUserInfo();  // This will throw an Error
} catch (error) {
    console.error(`Error: \${error.message}`);
}

Explanation

1. Vulnerable Code: The vulnerable code fails to check if the userId parameter is provided. This can lead to unintended behavior, such as logging undefined values or causing downstream errors if the userId is used in further processing.

2. Fixed Code: The fixed code includes a check to ensure that the userId parameter is neither undefined nor null. If the parameter is missing, an error is thrown, preventing the function from proceeding with invalid input. This ensures that the function operates correctly and only with valid input, thereby preventing potential runtime errors and improving code reliability.