Security::xssCleanFromArray() - Code Metrics - Inspection of ":recycle: Refactoring code to explode in some meth..." - Distilleries/Security - Measure and Improve Code Quality continuously with Scrutinizer

Completed
Push — master ( 9c631a...fcb278 )

by Maxime
created 2019-02-20 17:52 UTC
Security::xssCleanFromArray() A

↳ Parent: Security
Complexity

Conditions	2
Paths	2
Size

Total Lines	7
Code Lines	3
Duplication

Lines	0
Ratio	0 %
Code Coverage

Tests	0
CRAP Score	6
Importance

Changes
Metric	Value
cc	2
eloc	3
nc	2
nop	3
dl	0
loc	7
ccs	0
cts	4
cp	0
crap	6
rs	10
c	0
b	0
f	0
<?php
/**
 * Created by PhpStorm.
 * User: mfrancois
 * Date: 04/07/2016
 * Time: 11:32
 */

namespace Distilleries\Security\Helpers;


class Security
{


    /**
     * Random Hash for protecting URLs
     *
     * @var string
     * @access protected
     */
    protected $_xss_hash = '';

    /**
     * List of never allowed strings
     *
     * @var array
     * @access protected
     */
    protected $_never_allowed_str = [
        'document.cookie' => '[removed]',
        'document.write' => '[removed]',
        '.parentNode' => '[removed]',
        '.innerHTML' => '[removed]',
        'window.location' => '[removed]',
        '-moz-binding' => '[removed]',
        '<!--' => '&lt;!--',
        '-->' => '--&gt;',
        '<![CDATA[' => '&lt;![CDATA[',
        '<comment>' => '&lt;comment&gt;'
    ];

    /* never allowed, regex replacement */
    /**
     * List of never allowed regex replacement
     *
     * @var array
     * @access protected
     */
    protected $_never_allowed_regex = [
        'javascript\s*:',
        'expression\s*(\(|&\#40;)', // CSS and IE
        'vbscript\s*:', // IE, surprise!
        'Redirect\s+302',
        "([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?"
    ];


    /**
     * XSS Clean
     *
     * Sanitizes data so that Cross Site Scripting Hacks can be
     * prevented.  This function does a fair amount of work but
     * it is extremely thorough, designed to prevent even the
     * most obscure XSS attempts.  Nothing is ever 100% foolproof,
     * of course, but I haven't been able to get anything passed
     * the filter.
     *
     * Note: This function should only be used to deal with data
     * upon submission.  It's not something that should
     * be used for general runtime processing.
     *
     * This function was based in part on some code and ideas I
     * got from Bitflux: http://channel.bitflux.ch/wiki/XSS_Prevention
     *
     * To help develop this script I used this great list of
     * vulnerabilities along with a few other hacks I've
     * harvested from examining vulnerabilities in other programs:
     * http://ha.ckers.org/xss.html
     *
     * @param    mixed    string or array or boolean
     * @return    string | array
     */
    public function xss_clean($str, $is_image = false, $evilAttribute = true)
    {
        /*
           * Is the string an array?
           *
           */
        if (is_array($str)) {
            return $this->xssCleanFromArray($str, $is_image, $evilAttribute);
        }

        //Remove Invisible Characters
        $str = $this->remove_invisible_characters($str);

        // Validate Entities in URLs
        $str = $this->_validate_entities($str);

        /**
         * URL Decode
         *
         * Just in case stuff like this is submitted:
         *
         * <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a>
         *
         * Note: Use rawurldecode() so it does not remove plus signs
         *
         **/
        $str = rawurldecode($str);

        /**
         * Convert character entities to ASCII
         *
         * This permits our tests below to work reliably.
         * We only convert entities that are within tags since
         * these are the ones that will pose security problems.
         *
         **/

        $str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", [$this, '_convert_attribute'], $str);
        $str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", [$this, '_decode_entity'], $str);

        /**
         * Remove Invisible Characters Again!
         **/
        $str = $this->remove_invisible_characters($str);

        /**
         * Convert all tabs to spaces
         *
         * This prevents strings like this: ja    vascript
         * NOTE: we deal with spaces between characters later.
         * NOTE: preg_replace was found to be amazingly slow here on
         * large blocks of data, so we use str_replace.
         **/
        if (strpos($str, "\t") !== false) {
            $str = str_replace("\t", ' ', $str);
        }

        // Remove Strings that are never allowed
        $str = $this->_do_never_allowed($str);

        /*
           * Makes PHP tags safe
           *
           * Note: XML tags are inadvertently replaced too:
           *
           * <?xml
           *
           * But it doesn't seem to pose a problem.
           */
        if ($is_image === true) {
            // Images have a tendency to have the PHP short opening and
            // closing tags every so often so we skip those and only
            // do the long opening tags.
            $str = preg_replace('/<\?(php)/i', "&lt;?\\1", $str);
        } else {
            $str = str_replace(['<?', '?' . '>'], ['&lt;?', '?&gt;'], $str);
        }

        $str = $this->compactedWords([
            'javascript',
            'expression',
            'vbscript',
            'script',
            'applet',
            'alert',
            'document',
            'write',
            'cookie',
            'window'
        ], $str);


        $str = $this->disallowedJavascriptInLinks($str);

        // Remove evil attributes such as style, onclick and xmlns
        $str = $this->_remove_evil_attributes($str, $is_image, $evilAttribute);

        /*
           * Sanitize naughty HTML elements
           *
           * If a tag containing any of the words in the list
           * below is found, the tag gets converted to entities.
           *
           * So this: <blink>
           * Becomes: &lt;blink&gt;
           */
        $naughty = 'alert|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|isindex|layer|link|meta|object|plaintext|style|script|textarea|title|video|xml|xss';
        $str = preg_replace_callback('#<(/*\s*)(' . $naughty . ')([^><]*)([><]*)#is', [$this, '_sanitize_naughty_html'],
            $str);

        /*
           * Sanitize naughty scripting elements
           *
           * Similar to above, only instead of looking for
           * tags it looks for PHP and JavaScript commands
           * that are disallowed.  Rather than removing the
           * code, it simply converts the parenthesis to entities
           * rendering the code un-executable.
           *
           * For example:	eval('some code')
           * Becomes:		eval&#40;'some code'&#41;
           */
        $str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si',
            "\\1\\2&#40;\\3&#41;", $str);


        // Final clean up
        // This adds a bit of extra precaution in case
        // something got through the above filters
        $str = $this->_do_never_allowed($str);

        return $str;
    }

    /**
     * Compact any exploded words
     *
     * This corrects words like:  j a v a s c r i p t
     * These words are compacted back to their correct state.
     **/
    protected function compactedWords($words, $str)
    {
        foreach ($words as $word) {
            $temp = '';

            for ($i = 0, $wordlen = strlen($word); $i < $wordlen; $i++) {
                $temp .= substr($word, $i, 1) . "\s*";
            }

            // We only want to do this when it is followed by a non-word character
            // That way valid stuff like "dealer to" does not become "dealerto"
            $str = preg_replace_callback('#(' . substr($temp, 0, -3) . ')(\W)#is', [$this, '_compact_exploded_words'],
                $str);
        }

        return $str;
    }

    /**
     * @param $str
     * @param bool $is_image
     * @param bool $evilAttribute
     * @return array
     */
    protected function xssCleanFromArray($str, $is_image = false, $evilAttribute = true)
    {
        foreach ($str as $key => $value) {
            $str[$key] = $this->xss_clean($str[$key], $is_image, $evilAttribute);
        }

        return $str;
    }

    /*
     * Remove disallowed Javascript in links or img tags
     * We used to do some version comparisons and use of stripos for PHP5,
     * but it is dog slow compared to these simplified non-capturing
     * preg_match(), especially if the pattern exists in the string
     */
    protected function disallowedJavascriptInLinks($str)
    {
        do {
            $original = $str;

            if (preg_match("/<a/i", $str)) {
                $str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", [$this, '_js_link_removal'], $str);
            }

            if (preg_match("/<img/i", $str)) {
                $str = preg_replace_callback("#<img\s+([^>]*?)(\s?/?>|$)#si", [$this, '_js_img_removal'], $str);
            }

            if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str)) {
                $str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str);
            }
        } while ($original != $str);

        unset($original);

        return $str;
    }

    // --------------------------------------------------------------------

    /*
      * Remove Evil HTML Attributes (like evenhandlers and style)
      *
      * It removes the evil attribute and either:
      * 	- Everything up until a space
      *		For example, everything between the pipes:
      *		<a |style=document.write('hello');alert('world');| class=link>
      * 	- Everything inside the quotes
      *		For example, everything between the pipes:
      *		<a |style="document.write('hello'); alert('world');"| class="link">
      *
      * @param string $str The string to check
      * @param boolean $is_image TRUE if this is an image
      * @return string The string with the evil attributes removed
      */
    protected function _remove_evil_attributes($str, $is_image, $evilAttribute)
    {
        // All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns
        if ($evilAttribute) {
            $evil_attributes = ['on\w*', 'style', 'xmlns'];
        } else {
            $evil_attributes = ['on\w*', 'xmlns'];
        }

        if ($is_image === true) {
            /*
                * Adobe Photoshop puts XML metadata into JFIF images,
                * including namespacing, so we have to allow this for images.
                */
            unset($evil_attributes[array_search('xmlns', $evil_attributes)]);
        }

        do {
            $str = preg_replace(
                "#<(/?[^><]+?)([^A-Za-z\-])(" . implode('|',
                    $evil_attributes) . ")(\s*=\s*)([\"][^>]*?[\"]|[\'][^>]*?[\']|[^>]*?)([\s><])([><]*)#i",
                "<$1$6",
                $str, -1, $count
            );
        } while ($count);

        return $str;
    }



    // --------------------------------------------------------------------

    /**
     * HTML Entities Decode
     *
     * This function is a replacement for html_entity_decode()
     *
     * The reason we are not using html_entity_decode() by itself is because
     * while it is not technically correct to leave out the semicolon
     * at the end of an entity most browsers will still interpret the entity
     * correctly.  html_entity_decode() does not convert entities without
     * semicolons, so we are left with our own little solution here. Bummer.
     *
     * @param    string
     * @param    string
     * @return    string
     */
    public function entity_decode($str, $charset = 'UTF-8')
    {
        if (stristr($str, '&') === false) {
            return $str;
        }

        $str = html_entity_decode($str, ENT_COMPAT, $charset);
        $str = preg_replace_callback('~&#x(0*[0-9a-f]{2,5})~i', function ($matches) {
            return chr(hexdec($matches[1]));
            return chr(/** @scrutinizer ignore-type */ hexdec($matches[1]));
        }, $str);
        return preg_replace_callback('~&#([0-9]{2,4})~', function ($matches) {
            return chr($matches[1]);
        }, $str);
    }

    // --------------------------------------------------------------------

    /**
     * Filename Security
     *
     * @param    string
     * @param    bool
     * @return    string
     */
    public function sanitize_filename($str, $relative_path = false)
    {
        $bad = [
            "../",
            "<!--",
            "-->",
            "<",
            ">",
            "'",
            '"',
            '&',
            '$',
            '#',
            '{',
            '}',
            '[',
            ']',
            '=',
            ';',
            '?',
            "%20",
            "%22",
            "%3c", // <
            "%253c", // <
            "%3e", // >
            "%0e", // >
            "%28", // (
            "%29", // )
            "%2528", // (
            "%26", // &
            "%24", // $
            "%3f", // ?
            "%3b", // ;
            "%3d"        // =
        ];

        if (!$relative_path) {
            $bad[] = './';
            $bad[] = '/';
        }

        $str = $this->remove_invisible_characters($str, false);

        return stripslashes(str_replace($bad, '', $str));
    }

    // ----------------------------------------------------------------

    /**
     * Compact Exploded Words
     *
     * Callback function for xss_clean() to remove whitespace from
     * things like j a v a s c r i p t
     *
     * @param    type
     * @return    type
filter:
    dependency_paths: ["lib/*"]
     */
    protected function _compact_exploded_words($matches)
    {
        return preg_replace('/\s+/s', '', $matches[1]) . $matches[2];

    }

    // --------------------------------------------------------------------

    /**
     * Sanitize Naughty HTML
     *
     * Callback function for xss_clean() to remove naughty HTML elements
     *
     * @param    array
     * @return    string
     */
    protected function _sanitize_naughty_html($matches)
    {
        // encode opening brace
        $str = '&lt;' . $matches[1] . $matches[2] . $matches[3];

        // encode captured opening or closing brace to prevent recursive vectors
        $str .= str_replace(['>', '<'], ['&gt;', '&lt;'],
            $matches[4]);

        return $str;
    }

    // --------------------------------------------------------------------

    /**
     * JS Link Removal
     *
     * Callback function for xss_clean() to sanitize links
     * This limits the PCRE backtracks, making it more performance friendly
     * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
     * PHP 5.2+ on link-heavy strings
     *
     * @param    array
     * @return    string
     */
    protected function _js_link_removal($match)
    {
        return str_replace(
            $match[1],
            preg_replace(
                '#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si',
                '',
                $this->_filter_attributes(str_replace(['<', '>'], '', $match[1]))
            ),
            $match[0]
        );
    }

    // --------------------------------------------------------------------

    /**
     * JS Image Removal
     *
     * Callback function for xss_clean() to sanitize image tags
     * This limits the PCRE backtracks, making it more performance friendly
     * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
     * PHP 5.2+ on image tag heavy strings
     *
     * @param    array
     * @return    string
     */
    protected function _js_img_removal($match)
    {
        return str_replace(
            $match[1],
            preg_replace(
                '#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si',
                '',
                $this->_filter_attributes(str_replace(['<', '>'], '', $match[1]))
            ),
            $match[0]
        );
    }

    // --------------------------------------------------------------------

    /**
     * Attribute Conversion
     *
     * Used as a callback for XSS Clean
     *
     * @param    array
     * @return    string
     */
    protected function _convert_attribute($match)
    {
        return str_replace(['>', '<', '\\'], ['&gt;', '&lt;', '\\\\'], $match[0]);
    }

    // --------------------------------------------------------------------

    /**
     * Filter Attributes
     *
     * Filters tag attributes for consistency and safety
     *
     * @param    string
     * @return    string
     */
    protected function _filter_attributes($str)
    {
        $out = '';

        if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches)) {
            foreach ($matches[0] as $match) {
                $out .= preg_replace("#/\*.*?\*/#s", '', $match);
            }
        }

        return $out;
    }

    // --------------------------------------------------------------------

    /**
     * HTML Entity Decode Callback
     *
     * Used as a callback for XSS Clean
     *
     * @param    array
     * @return    string
     */
    protected function _decode_entity($match)
    {
        return $this->entity_decode($match[0]);
    }

    // --------------------------------------------------------------------

    /**
     * Validate URL entities
     *
     * Called by xss_clean()
     *
     * @param    string
     * @return    string
     */
    protected function _validate_entities($str)
    {
        /*
         * Protect GET variables in URLs
         */

        // 901119URL5918AMP18930PROTECT8198

        $str = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-]+)|i', $this->xss_hash() . "\\1=\\2", $str);

        /*
         * Validate standard character entities
         *
         * Add a semicolon if missing.  We do this to enable
         * the conversion of entities to ASCII later.
         *
         */
        $str = preg_replace('#(&\#?[0-9a-z]{2,})([\x00-\x20])*;?#i', "\\1;\\2", $str);

        /*
         * Validate UTF16 two byte encoding (x00)
         *
         * Just as above, adds a semicolon if missing.
         *
         */
        $str = preg_replace('#(&\#x?)([0-9A-F]+);?#i', "\\1\\2;", $str);


        return $str;
    }

    // ----------------------------------------------------------------------

    /**
     * Do Never Allowed
     *
     * A utility function for xss_clean()
     *
     * @param    string
     * @return    string
     */
    protected function _do_never_allowed($str)
    {
        $str = str_replace(array_keys($this->_never_allowed_str), $this->_never_allowed_str, $str);

        foreach ($this->_never_allowed_regex as $regex) {
            $str = preg_replace('#' . $regex . '#is', '[removed]', $str);
        }

        return $str;
    }


    protected function remove_invisible_characters($str, $url_encoded = true)
    {
        $non_displayables = [];

        // every control character except newline (dec 10)
        // carriage return (dec 13), and horizontal tab (dec 09)

        if ($url_encoded) {
            $non_displayables[] = '/%0[0-8bcef]/'; // url encoded 00-08, 11, 12, 14, 15
            $non_displayables[] = '/%1[0-9a-f]/'; // url encoded 16-31
        }

        $non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S'; // 00-08, 11, 12, 14-31, 127

        do {
            $str = preg_replace($non_displayables, '', $str, -1, $count);
        } while ($count);

        return $str;
    }

    /**
     * Random Hash for protecting URLs
     *
     * @return    string
     */
    public function xss_hash()
    {
        if ($this->_xss_hash == '') {
            mt_srand();
            $this->_xss_hash = md5(time() + mt_rand(0, 1999999999));
        }

        return $this->_xss_hash;
    }


    public static function escapeLike($str, $escape = '\'\'')
    {

        return str_replace(
            ['%', '_', '\'', '"', '<', '>', '(', ')', '{', ']', ':', '/', '\\'],
            ['\%', '\_', $escape, '\"', '\<', '\>', '\(', '\)', '\{', '\}', '\:', '\/', '\\\\'], $str);
    }
}
Distilleries / Security

Push — master ( 9c631a...fcb278 )

Security::xssCleanFromArray() A

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