CWE-164: Improper Neutralization of Internal Special Elements

What is Improper Neutralization of Internal Special Elements?

• Overview: Improper Neutralization of Internal Special Elements (CWE-164) occurs when software receives input containing special characters that are not correctly sanitized. These characters can be misinterpreted by downstream components, leading to unexpected behaviors or vulnerabilities.

• Exploitation Methods:

• Attackers can exploit this vulnerability by injecting special characters into inputs that are processed by different components, causing them to behave unexpectedly.
• Common attack patterns include injecting script tags, SQL commands, or other code snippets that exploit the improper handling of special elements.

• Security Impact:

• Direct consequences of successful exploitation can include unauthorized data access, data corruption, or control over application behavior.
• Potential cascading effects may involve cross-site scripting (XSS), SQL injection, or other injection-based attacks.
• Business impact includes data breaches, loss of customer trust, legal liabilities, and financial losses due to remediation efforts.

• Prevention Guidelines:

• Specific code-level fixes involve validating and sanitizing inputs by escaping or removing special characters before processing.
• Security best practices include adopting a whitelist approach for input validation and consistently using parameterized queries for database access.
• Recommended tools and frameworks include static analysis tools to detect vulnerabilities during development and utilizing security libraries or frameworks that automate input sanitization.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

JavaScript Example

const express = require('express');
const app = express();

// Vulnerable code: Accepts user input and uses it to construct a database query without proper sanitization
app.get('/search', (req, res) => {
    const userInput = req.query.q; // User input is directly used
    const query = `SELECT * FROM users WHERE name = '\${userInput}'`; // Constructing a query with raw user input
    database.execute(query, (err, results) => {
        if (err) {
            res.status(500).send('Server error');
        } else {
            res.json(results);
        }
    });
});

app.listen(3000);

Explanation:

• Direct User Input Usage: The user input from req.query.q is directly embedded into the SQL query, which makes the application vulnerable to SQL injection. An attacker could manipulate the input to alter the SQL command structure.

How to fix Improper Neutralization of Internal Special Elements?

Fixed Code Example

JavaScript Example

const express = require('express');
const app = express();

// Fixed code: Uses parameterized queries to prevent SQL injection
app.get('/search', (req, res) => {
    const userInput = req.query.q;
    const query = 'SELECT * FROM users WHERE name = ?'; // Use a placeholder for user input
    database.execute(query, [userInput], (err, results) => { // Pass user input as a parameter
        if (err) {
            res.status(500).send('Server error');
        } else {
            res.json(results);
        }
    });
});

app.listen(3000);

Key Changes:

• Parameterized Queries: Instead of directly embedding user input in the SQL query, a placeholder (?) is used, and the user input is passed as a parameter to the database.execute function. This approach ensures that user input is treated strictly as data, not executable parts of the SQL command.
• Secure Database Interaction: By using parameterized queries or prepared statements, we ensure that all user inputs are safely incorporated into the query, regardless of their content, thus neutralizing any special elements or SQL syntax that could be abused.

Best Practices:

• Always validate and sanitize user inputs even when using parameterized queries to add an extra layer of security.
• Regularly update dependencies and libraries to patch any known vulnerabilities.
• Implement logging and monitoring to detect and respond to potential injection attempts.