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Data Sanitization

The CakePHP Sanitize class can be used to rid user-submitted data of malicious data and other unwanted information. Sanitize is a core library, so it can be used anywhere inside of your code, but is probably best used in controllers or models.

CakePHP already protects you against SQL Injection if you use CakePHP’s ORM methods (such as find() and save()) and proper array notation (ie. array(‘field’ => $value)) instead of raw SQL. For sanitization against XSS its generally better to save raw HTML in database without modification and sanitize at the time of output/display.

All you need to do is include the Sanitize core library (e.g. before the controller class definition):

App::import('Sanitize');

class MyController extends AppController {
    ...
    ...
}

Once you’ve done that, you can make calls to Sanitize statically.

paranoid

paranoid(string $string, array $allowedChars);

This function strips anything out of the target $string that is not a plain-jane alphanumeric character. The function can be made to overlook certain characters by passing them in $allowedChars array.

$badString = ";:<script><html><   // >@@#";
echo Sanitize::paranoid($badString);
// output: scripthtml
echo Sanitize::paranoid($badString, array(' ', '@'));
// output: scripthtml    @@

html

html(string $string, array $options = array())

This method prepares user-submitted data for display inside HTML. This is especially useful if you don’t want users to be able to break your layouts or insert images or scripts inside of your HTML pages. If the $remove option is set to true, HTML content detected is removed rather than rendered as HTML entities.

$badString = '<font size="99" color="#FF0000">HEY</font><script>...</script>';
echo Sanitize::html($badString);
// output: &lt;font size=&quot;99&quot; color=&quot;#FF0000&quot;&gt;HEY&lt;/font&gt;&lt;script&gt;...&lt;/script&gt;
echo Sanitize::html($badString, array('remove' => true));
// output: HEY...

escape

escape(string $string, string $connection)

Used to escape SQL statements by adding slashes, depending on the system’s current magic_quotes_gpc setting. $connection is the name of the database to quote the string for, as named in your app/config/database.php file.

clean

Sanitize::clean(mixed $data, mixed $options)

This function is an industrial-strength, multi-purpose cleaner, meant to be used on entire arrays (like $this->data, for example). The function takes an array (or string) and returns the clean version. The following cleaning operations are performed on each element in the array (recursively):

  • Odd spaces (including 0xCA) are replaced with regular spaces.

  • Double-checking special chars and removal of carriage returns for increased SQL security.

  • Adding of slashes for SQL (just calls the sql function outlined above).

  • Swapping of user-inputted backslashes with trusted backslashes.

The $options argument can either be a string or an array. When a string is provided it’s the database connection name. If an array is provided it will be merged with the following options:

  • connection

  • odd_spaces

  • encode

  • dollar

  • carriage

  • unicode

  • escape

  • backslash

  • remove_html (must be used in conjunction with the encode parameter)

All of these options except connection are boolean values which are set to true by default; to customize your results you can pass an array that sets the unwanted options to false. Usage of clean() with options looks something like the following:

$this->data = Sanitize::clean($this->data, array('encode' => false));