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SELECT * FROM db_user WHERE username='<USERNAME>' AND 
                            password='<PASSWORD>'

class Login {
  public Connection getConnection() throws SQLException {
    DriverManager.registerDriver(new
            com.microsoft.sqlserver.jdbc.SQLServerDriver());
    String dbConnection = 
      PropertyManager.getProperty("db.connection");
    // can hold some value like
    // "jdbc:microsoft:sqlserver://<HOST>:1433,<UID>,<PWD>"
    return DriverManager.getConnection(dbConnection);
  }

  String hashPassword(char[] password) {
    // create hash of password
  }

  public void doPrivilegedAction(String username, char[] password)
                                 throws SQLException {
    Connection connection = getConnection();
    if (connection == null) {
      // handle error
    }
    try {
      String pwd = hashPassword(password);

      String sqlString = "SELECT * FROM db_user WHERE username = '" 
                         + username +
                         "' AND password = '" + pwd + "'";
      Statement stmt = connection.createStatement();
      ResultSet rs = stmt.executeQuery(sqlString);

      if (!rs.next()) {
        throw new SecurityException(
          "User name or password incorrect"
        );
      }

      // Authenticated; proceed
    } finally {
      try {
        connection.close();
      } catch (SQLException x) {
        // forward to handler
      }
    }
  }
}

class XXE {
  private static void receiveXMLStream(InputStream inStream,
                                       DefaultHandler defaultHandler)
      throws ParserConfigurationException, SAXException, IOException {
    SAXParserFactory factory = SAXParserFactory.newInstance();
    SAXParser saxParser = factory.newSAXParser();
    saxParser.parse(inStream, defaultHandler);
  }

  public static void main(String[] args)
      throws ParserConfigurationException, SAXException, IOException {
    receiveXMLStream(new FileInputStream("evil.xml"), 
                     new DefaultHandler());
  }
}