CWE-89: Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

What is Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')?

• Overview: Improper Neutralization of Special Elements used in an SQL Command, also known as SQL Injection, occurs when an application includes user input in SQL statements without proper sanitization. This allows attackers to manipulate the SQL query, potentially accessing, modifying, or deleting data within a database.

• Exploitation Methods:

• Attackers can inject malicious SQL code into input fields such as login forms or search boxes.
• Common attack patterns include using operators like 'OR' to bypass authentication, appending UNION queries to extract data, or employing tautology-based injections to manipulate query logic.

• Security Impact:

• Direct consequences include unauthorized data access, data manipulation, and possible data deletion.
• Potential cascading effects may involve complete database compromise, unauthorized privilege escalation, and theft of sensitive information.
• Business impact can range from loss of customer trust and legal penalties to significant financial damage and operational disruption.

• Prevention Guidelines:

• Specific code-level fixes include using prepared statements and parameterized queries that separate SQL logic from data inputs.
• Security best practices involve consistent input validation, escaping user inputs, and implementing least privilege principles for database access.
• Recommended tools and frameworks include using ORM (Object-Relational Mapping) frameworks like Hibernate or Entity Framework, and employing static code analysis tools to detect vulnerabilities in the codebase.

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Technical Details

Likelihood of Exploit: High

Affected Languages: Not Language-Specific, SQL

Affected Technologies: Database Server

Vulnerable Code Example

Certainly! Let's improve the code examples following the specified guidelines.

const mysql = require('mysql');

const connection = mysql.createConnection({
  host: 'localhost',
  user: 'root',
  password: 'password',
  database: 'users'
});

function getUserData(username) {
  // Vulnerable code: Directly embedding user input into SQL query
  const query = `SELECT * FROM users WHERE username = '\${username}'`;  // Vulnerable to SQL Injection
  connection.query(query, (error, results) => {
    if (error) throw error;
    console.log(results);
  });
}

// This function is vulnerable to SQL injection attacks.
// An attacker could pass in the username as "'; DROP TABLE users;--"
// This would execute the SQL command: "SELECT * FROM users WHERE username = ''; DROP TABLE users;--"

How to fix Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')?

In JavaScript, especially when using the mysql module, you should use placeholders (also known as parameterized queries) to mitigate SQL injection risks. Placeholders ensure that user inputs are treated as data, not executable SQL code. This is done by using ? in the SQL query and providing an array of input data that corresponds to the placeholders.

Fixed Code Example

const mysql = require('mysql');

const connection = mysql.createConnection({
  host: 'localhost',
  user: 'root',
  password: 'password',
  database: 'users'
});

function getUserData(username) {
  // Fixed code: Use parameterized queries to prevent SQL injection
  const query = 'SELECT * FROM users WHERE username = ?';  // Secure against SQL Injection
  connection.query(query, [username], (error, results) => {
    if (error) throw error;
    console.log(results);
  });
}

// Now the user input is safely handled, and SQL injection is prevented.
// The username is treated as a parameter, not part of the SQL command.

Key Improvements Made:

1. Syntax Highlighting: Ensured proper syntax highlighting by specifying the language in the code block.
2. Line Number Highlighting: Corrected line number formatting to be next to the file name.
3. Realistic Example: Clarified the vulnerable example with a realistic attack scenario.
4. Comprehensive Comments: Expanded comments for clarity on the vulnerability and the fix.
5. Best Practices: Followed JavaScript best practices for database query execution.

These changes ensure that the examples are clear, realistic, and educational, demonstrating both the problem and the solution effectively.