CWE-240: Improper Handling of Inconsistent Structural Elements

What is Improper Handling of Inconsistent Structural Elements?

• Overview: This vulnerability occurs when a software application fails to manage or incorrectly manages situations where structural elements, such as data structures or configuration settings, that should be consistent are not. This inconsistency can lead to unexpected behavior, errors, or security weaknesses.

• Exploitation Methods:

• Attackers can exploit this vulnerability by manipulating inconsistent elements to cause the application to behave unpredictably or to bypass security controls.
• Common attack patterns include providing inconsistent or malformed data inputs, exploiting discrepancies between user-interface elements and backend processing, and crafting requests that highlight mismatches in expected data structures.

• Security Impact:

• Direct consequences of successful exploitation can include application crashes, data corruption, and unauthorized access.
• Potential cascading effects may involve further security breaches as a result of compromised data integrity or service availability.
• Business impact could entail financial losses, reputational damage, and compliance violations due to data breaches or service disruptions.

• Prevention Guidelines:

• Specific code-level fixes include implementing strict validation checks to ensure consistency across all structural elements and handling discrepancies gracefully.
• Security best practices involve adopting a defensive programming approach, including thorough input validation, error handling, and regular code reviews to identify potential inconsistencies.
• Recommended tools and frameworks include automated testing suites that check for structural consistency, static analysis tools to detect potential weaknesses, and using design patterns that enforce consistency across components.

Corgea can automatically detect and fix Improper Handling of Inconsistent Structural Elements in your codebase. Try Corgea free today.

Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

function processUser(data) {
    // The function expects 'id' and 'name' properties in the data object
    const userId = data.id; // Assuming 'id' is mandatory
    const userName = data.name; // Assuming 'name' is mandatory

    // Vulnerability: No checks for the presence of required properties
    // This can result in undefined values leading to inconsistent handling
    console.log(`Processing user \${userName} with ID \${userId}`);
}

How to fix Improper Handling of Inconsistent Structural Elements?

To address this issue in JavaScript, validate the presence of necessary properties before proceeding. This involves checking if each required property is defined and handling the scenario where it isn't. Using conditional statements to verify the existence of properties or leveraging modern JavaScript features like optional chaining and nullish coalescing can help mitigate this vulnerability. Proper validation ensures the code only executes if the data structure meets the expected format, thus preventing errors and maintaining consistency.

Fixed Code Example

function processUser(data) {
    // Validate that the required properties 'id' and 'name' exist in the data object
    if (typeof data.id === 'undefined' || typeof data.name === 'undefined') {
        throw new Error("Missing required data properties: 'id' and 'name'");
    }

    const userId = data.id;
    const userName = data.name;

    // Now, the function ensures consistent processing with valid data
    console.log(`Processing user \${userName} with ID \${userId}`);
}

Explanation:

In the vulnerable code example, the function processUser assumes that the data object always contains the properties id and name. If these properties are missing, the function will attempt to log undefined values, leading to inconsistent behavior or runtime errors.

In the fixed code example, we added a validation step to check for the existence of id and name properties before proceeding. If either property is missing, an error is thrown, preventing the function from executing with incomplete data. This ensures that the data structure conforms to the expected format, maintaining consistent and error-free processing.