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  1. cheatsheetseries.owasp.org

    This cheat sheet will help you prevent SQL injection flaws in your applications. It will define what SQL injection is, explain where those flaws occur, and provide four options for defending against SQL injection attacks. ... For example, MySQL runs as system on Windows by default! Change the DBMS's OS account to something more appropriate ...
  2. stackoverflow.com

    Escaping is inadequate to prevent SQL injection, use prepared statements instead. Use the strategy outlined below at your own risk. (Also, mysql_real_escape_string() was removed in PHP 7.) IMPORTANT. The best way to prevent SQL Injection is to use Prepared Statements instead of escaping, as the accepted answer demonstrates.
  3. slingacademy.com

    Jan 26, 2024In conclusion, preventing SQL injection in MySQL 8 is about being stringent with the inputs your application allows, employing best practices in query formation, and knowing the tools at your disposal. By sticking to prepared statements, validating and sanitizing user inputs, and using stored procedures, you can enforce a strong security policy ...
  4. cheatsheetseries.owasp.org

    SQL injection attacks are a type of injection attack, in which SQL commands are injected into data-plane input in order to affect the execution of predefined SQL commands. SQL Injection attacks can be divided into the following three classes: Inband: data is extracted using the same channel that is used to inject the SQL code. This is the most ...
  5. geeksforgeeks.org

    So, as you can see the above-mentioned poisoned string can make any user login in the geeksforgeeks username so this is called SQL Injection. Now to avoid this type of SQL injection, we need to sanitize the password input and username input using mysqli_real_escape_string() function.. The mysqli_real_escape_string() function takes the special characters as they were as an input from the user ...
  6. acunetix.com

    If you scan the application using the SQL Injection scan type in Acunetix, it confirms the vulnerability.. SQL Injection Prevention in PHP Parameterized queries. To prevent and/or fix SQL Injection vulnerabilities, start by reading advice in our Defence in Depth series: Parameterize SQL queries.Parameterized queries are simple to write and understand.
  7. code-boxx.com

    Nov 12, 2023Welcome to a tutorial and example of PHP MYSQL injection, plus how to prevent it. So you have heard of this "SQL injection" thing from all over the Internet, and wonder why it is such a big deal? In simple terms, SQL injection is an attempt to change the original statement to do something else entirely.
  8. cloudflare.com

    How to prevent SQL injection. While SQL injection is one of the most prevalent API threats, it can be effectively avoided with the right prevention strategies. Helpful approaches for preventing SQL injection include restricting database procedures, sanitizing database inputs, and enforcing least-privilege access. Restrict database procedures ...
  9. This cheat sheet will help you prevent SQL injection flaws in your applications. It will define what SQL injection is, explain where those flaws occur, and provide four options for defending against SQL injection attacks. ... For example, MySQL runs as system on Windows by default! Change the DBMS's OS account to something more appropriate ...
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  1. The correct way to avoid SQL injection attacks, no matter which database you use, is to separate the data from SQL, so that data stays data and will never be interpreted as commands by the SQL parser. It is possible to create an SQL statement with correctly formatted data parts, but if you don't fully understand the details, you should always use prepared statements and parameterized queries. These are SQL statements that are sent to and parsed by the database server separately from any parameters. This way it is impossible for an attacker to inject malicious SQL.

    You basically have two options to achieve this:

    1. Using PDO (for any supported database driver):

      $stmt = $pdo->prepare('SELECT * FROM employees WHERE name = :name');
      $stmt->execute([ 'name' => $name ]);
      
      foreach ($stmt as $row) {
          // Do something with $row
      }
    2. Using MySQLi (for MySQL):
      Since PHP 8.2+ we can make use of execute_query() which prepares, binds parameters, and executes SQL statement in one method:

      $result = $db->execute_query('SELECT * FROM employees WHERE name = ?', [$name]);
       while ($row = $result->fetch_assoc()) {
           // Do something with $row
       }

      Up to PHP8.1:

       $stmt = $db->prepare('SELECT * FROM employees WHERE name = ?');
       $stmt->bind_param('s', $name); // 's' specifies the variable type => 'string'
       $stmt->execute();
       $result = $stmt->get_result();
       while ($row = $result->fetch_assoc()) {
           // Do something with $row
       }

    If you're connecting to a database other than MySQL, there is a driver-specific second option that you can refer to (for example, pg_prepare() and pg_execute() for PostgreSQL). PDO is the universal option.

    Correctly setting up the connection PDO

    Note that when using PDO to access a MySQL database real prepared statements are not used by default. To fix this you have to disable the emulation of prepared statements. An example of creating a connection using PDO is:

    $dbConnection = new PDO('mysql:dbname=dbtest;host=127.0.0.1;charset=utf8mb4', 'user', 'password');
    
    $dbConnection->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
    $dbConnection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    In the above example, the error mode isn't strictly necessary, but it is advised to add it. This way PDO will inform you of all MySQL errors by means of throwing the PDOException.

    What is mandatory, however, is the first setAttribute() line, which tells PDO to disable emulated prepared statements and use real prepared statements. This makes sure the statement and the values aren't parsed by PHP before sending it to the MySQL server (giving a possible attacker no chance to inject malicious SQL).

    Although you can set the charset in the options of the constructor, it's important to note that 'older' versions of PHP (before 5.3.6) silently ignored the charset parameter in the DSN.

    Mysqli

    For mysqli we have to follow the same routine:

    mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT); // error reporting
    $dbConnection = new mysqli('127.0.0.1', 'username', 'password', 'test');
    $dbConnection->set_charset('utf8mb4'); // charset
    Explanation

    The SQL statement you pass to prepare is parsed and compiled by the database server. By specifying parameters (either a ? or a named parameter like :name in the example above) you tell the database engine where you want to filter on. Then when you call execute, the prepared statement is combined with the parameter values you specify.

    The important thing here is that the parameter values are combined with the compiled statement, not an SQL string. SQL injection works by tricking the script into including malicious strings when it creates SQL to send to the database. So by sending the actual SQL separately from the parameters, you limit the risk of ending up with something you didn't intend.

    Any parameters you send when using a prepared statement will just be treated as strings (although the database engine may do some optimization so parameters may end up as numbers too, of course). In the example above, if the $name variable contains 'Sarah'; DELETE FROM employees the result would simply be a search for the string "'Sarah'; DELETE FROM employees", and you will not end up with an empty table.

    Another benefit of using prepared statements is that if you execute the same statement many times in the same session it will only be parsed and compiled once, giving you some speed gains.

    Oh, and since you asked about how to do it for an insert, here's an example (using PDO):

    $preparedStatement = $db->prepare('INSERT INTO table (column) VALUES (:column)');
    
    $preparedStatement->execute([ 'column' => $unsafeValue ]);
    Can prepared statements be used for dynamic queries?

    While you can still use prepared statements for the query parameters, the structure of the dynamic query itself cannot be parametrized and certain query features cannot be parametrized.

    For these specific scenarios, the best thing to do is use a whitelist filter that restricts the possible values.

    // Value whitelist
    // $dir can only be 'DESC', otherwise it will be 'ASC'
    if (empty($dir) || $dir !== 'DESC') {
       $dir = 'ASC';
    }

    --Theo

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