User-provided data, such as URL parameters, should always be considered untrusted and tainted. Constructing SQL queries directly from tainted data enables attackers to inject specially crafted values that change the initial meaning of the query itself. Successful database query injection attacks can read, modify, or delete sensitive information from the database and sometimes even shut it down or execute arbitrary operating system commands.


Typically, the solution is to use prepared statements and to bind variables to SQL query parameters with dedicated methods like ``++setString++``, which ensures that user-provided data will be properly escaped. Another solution is to validate every parameter used to build the query. This can be achieved by transforming string values to primitive types or by validating them against a white list of accepted values.


This rule supports: JDBC, Java EE Entity Manager, Spring Framework, Hibernate, JDO, Android Database, Apache Torque, Apache Turbine, MyBastis, Rapidoid.

== Noncompliant Code Example

[source,java]
----
public boolean authenticate(javax.servlet.http.HttpServletRequest request, java.sql.Connection connection) throws SQLException { 
  String user = request.getParameter("user"); 
  String pass = request.getParameter("pass"); 

  String query = "SELECT * FROM users WHERE user = '" + user + "' AND pass = '" + pass + "'"; // Unsafe 

  // If the special value "foo' OR 1=1 --" is passed as either the user or pass, authentication is bypassed 
  // Indeed, if it is passed as a user, the query becomes: 
  // SELECT * FROM users WHERE user = 'foo' OR 1=1 --' AND pass = '...' 
  // As '--' is the comment till end of line syntax in SQL, this is equivalent to: 
  // SELECT * FROM users WHERE user = 'foo' OR 1=1 
  // which is equivalent to: 
  // SELECT * FROM users WHERE 1=1 
  // which is equivalent to: 
  // SELECT * FROM users 

  java.sql.Statement statement = connection.createStatement(); 
  java.sql.ResultSet resultSet = statement.executeQuery(query); // Noncompliant 
  return resultSet.next(); 
} 
----

== Compliant Solution

[source,java]
----
public boolean authenticate(javax.servlet.http.HttpServletRequest request, java.sql.Connection connection) throws SQLException { 
  String user = request.getParameter("user"); 
  String pass = request.getParameter("pass"); 

  String query = "SELECT * FROM users WHERE user = ? AND pass = ?"; // Safe even if authenticate() method is still vulnerable to brute-force attack in this specific case

  java.sql.PreparedStatement statement = connection.prepareStatement(query); 
  statement.setString(1, user); // Will be properly escaped 
  statement.setString(2, pass); 
  java.sql.ResultSet resultSet = statement.executeQuery();
  return resultSet.next(); 
} 
----

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