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<?php |
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/** |
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* Created by PhpStorm. |
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* User: mfrancois |
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* Date: 04/07/2016 |
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* Time: 11:32 |
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*/ |
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namespace Distilleries\Security\Helpers; |
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class Security |
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{ |
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/** |
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* Random Hash for protecting URLs |
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* |
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* @var string |
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* @access protected |
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*/ |
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protected $_xss_hash = ''; |
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/** |
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* List of never allowed strings |
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* |
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* @var array |
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* @access protected |
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*/ |
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protected $_never_allowed_str = [ |
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'document.cookie' => '[removed]', |
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'document.write' => '[removed]', |
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'.parentNode' => '[removed]', |
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'.innerHTML' => '[removed]', |
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'window.location' => '[removed]', |
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'-moz-binding' => '[removed]', |
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'<!--' => '<!--', |
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'-->' => '-->', |
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'<![CDATA[' => '<![CDATA[', |
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'<comment>' => '<comment>' |
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]; |
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/* never allowed, regex replacement */ |
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/** |
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* List of never allowed regex replacement |
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* |
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* @var array |
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* @access protected |
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*/ |
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protected $_never_allowed_regex = [ |
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'javascript\s*:', |
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'expression\s*(\(|&\#40;)', // CSS and IE |
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'vbscript\s*:', // IE, surprise! |
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'Redirect\s+302', |
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"([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?" |
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]; |
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/** |
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* XSS Clean |
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* |
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* Sanitizes data so that Cross Site Scripting Hacks can be |
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* prevented. This function does a fair amount of work but |
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* it is extremely thorough, designed to prevent even the |
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* most obscure XSS attempts. Nothing is ever 100% foolproof, |
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* of course, but I haven't been able to get anything passed |
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* the filter. |
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* |
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* Note: This function should only be used to deal with data |
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* upon submission. It's not something that should |
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* be used for general runtime processing. |
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* |
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* This function was based in part on some code and ideas I |
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* got from Bitflux: http://channel.bitflux.ch/wiki/XSS_Prevention |
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* |
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* To help develop this script I used this great list of |
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* vulnerabilities along with a few other hacks I've |
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* harvested from examining vulnerabilities in other programs: |
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* http://ha.ckers.org/xss.html |
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* |
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* @param mixed string or array or boolean |
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* @return string | array |
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*/ |
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public function xss_clean($str, $is_image = false, $evilAttribute = true) |
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{ |
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/* |
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* Is the string an array? |
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* |
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*/ |
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if (is_array($str)) { |
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return $this->xssCleanFromArray($str, $is_image, $evilAttribute); |
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} |
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//Remove Invisible Characters |
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$str = $this->remove_invisible_characters($str); |
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// Validate Entities in URLs |
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$str = $this->_validate_entities($str); |
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/** |
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* URL Decode |
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* |
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* Just in case stuff like this is submitted: |
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* |
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* <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a> |
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* |
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* Note: Use rawurldecode() so it does not remove plus signs |
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* |
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**/ |
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$str = rawurldecode($str); |
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/** |
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* Convert character entities to ASCII |
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* |
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* This permits our tests below to work reliably. |
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* We only convert entities that are within tags since |
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* these are the ones that will pose security problems. |
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* |
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**/ |
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$str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", [$this, '_convert_attribute'], $str); |
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$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", [$this, '_decode_entity'], $str); |
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/** |
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* Remove Invisible Characters Again! |
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**/ |
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$str = $this->remove_invisible_characters($str); |
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/** |
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* Convert all tabs to spaces |
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* |
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* This prevents strings like this: ja vascript |
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* NOTE: we deal with spaces between characters later. |
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* NOTE: preg_replace was found to be amazingly slow here on |
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* large blocks of data, so we use str_replace. |
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**/ |
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if (strpos($str, "\t") !== false) { |
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$str = str_replace("\t", ' ', $str); |
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} |
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// Remove Strings that are never allowed |
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$str = $this->_do_never_allowed($str); |
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/* |
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* Makes PHP tags safe |
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* |
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* Note: XML tags are inadvertently replaced too: |
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* |
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* <?xml |
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* |
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* But it doesn't seem to pose a problem. |
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*/ |
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if ($is_image === true) { |
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// Images have a tendency to have the PHP short opening and |
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// closing tags every so often so we skip those and only |
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// do the long opening tags. |
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$str = preg_replace('/<\?(php)/i', "<?\\1", $str); |
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} else { |
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$str = str_replace(['<?', '?' . '>'], ['<?', '?>'], $str); |
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} |
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$str = $this->compactedWords([ |
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'javascript', |
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'expression', |
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'vbscript', |
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'script', |
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'applet', |
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'alert', |
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'document', |
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'write', |
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'cookie', |
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'window' |
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], $str); |
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$str = $this->disallowedJavascriptInLinks($str); |
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// Remove evil attributes such as style, onclick and xmlns |
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$str = $this->_remove_evil_attributes($str, $is_image, $evilAttribute); |
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/* |
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* Sanitize naughty HTML elements |
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* |
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* If a tag containing any of the words in the list |
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* below is found, the tag gets converted to entities. |
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* |
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* So this: <blink> |
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* Becomes: <blink> |
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*/ |
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$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'; |
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$str = preg_replace_callback('#<(/*\s*)(' . $naughty . ')([^><]*)([><]*)#is', [$this, '_sanitize_naughty_html'], |
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$str); |
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/* |
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* Sanitize naughty scripting elements |
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* |
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* Similar to above, only instead of looking for |
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* tags it looks for PHP and JavaScript commands |
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* that are disallowed. Rather than removing the |
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* code, it simply converts the parenthesis to entities |
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* rendering the code un-executable. |
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* |
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* For example: eval('some code') |
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* Becomes: eval('some code') |
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*/ |
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$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', |
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"\\1\\2(\\3)", $str); |
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// Final clean up |
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// This adds a bit of extra precaution in case |
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// something got through the above filters |
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$str = $this->_do_never_allowed($str); |
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return $str; |
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} |
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/** |
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* Compact any exploded words |
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* |
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* This corrects words like: j a v a s c r i p t |
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* These words are compacted back to their correct state. |
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**/ |
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protected function compactedWords($words, $str) |
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{ |
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foreach ($words as $word) { |
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$temp = ''; |
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for ($i = 0, $wordlen = strlen($word); $i < $wordlen; $i++) { |
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$temp .= substr($word, $i, 1) . "\s*"; |
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} |
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// We only want to do this when it is followed by a non-word character |
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// That way valid stuff like "dealer to" does not become "dealerto" |
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$str = preg_replace_callback('#(' . substr($temp, 0, -3) . ')(\W)#is', [$this, '_compact_exploded_words'], |
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$str); |
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} |
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return $str; |
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} |
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/** |
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* @param $str |
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* @param bool $is_image |
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* @param bool $evilAttribute |
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* @return array |
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*/ |
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protected function xssCleanFromArray($str, $is_image = false, $evilAttribute = true) |
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{ |
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foreach ($str as $key => $value) { |
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$str[$key] = $this->xss_clean($str[$key], $is_image, $evilAttribute); |
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} |
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return $str; |
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} |
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/* |
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* Remove disallowed Javascript in links or img tags |
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* We used to do some version comparisons and use of stripos for PHP5, |
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* but it is dog slow compared to these simplified non-capturing |
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* preg_match(), especially if the pattern exists in the string |
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*/ |
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protected function disallowedJavascriptInLinks($str) |
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{ |
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do { |
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$original = $str; |
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if (preg_match("/<a/i", $str)) { |
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$str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", [$this, '_js_link_removal'], $str); |
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} |
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if (preg_match("/<img/i", $str)) { |
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$str = preg_replace_callback("#<img\s+([^>]*?)(\s?/?>|$)#si", [$this, '_js_img_removal'], $str); |
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} |
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if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str)) { |
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$str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str); |
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} |
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} while ($original != $str); |
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unset($original); |
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return $str; |
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} |
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// -------------------------------------------------------------------- |
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/* |
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* Remove Evil HTML Attributes (like evenhandlers and style) |
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* |
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* It removes the evil attribute and either: |
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* - Everything up until a space |
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* For example, everything between the pipes: |
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* <a |style=document.write('hello');alert('world');| class=link> |
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* - Everything inside the quotes |
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* For example, everything between the pipes: |
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* <a |style="document.write('hello'); alert('world');"| class="link"> |
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* |
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* @param string $str The string to check |
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* @param boolean $is_image TRUE if this is an image |
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* @return string The string with the evil attributes removed |
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*/ |
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protected function _remove_evil_attributes($str, $is_image, $evilAttribute) |
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{ |
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// All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns |
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if ($evilAttribute) { |
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$evil_attributes = ['on\w*', 'style', 'xmlns']; |
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} else { |
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$evil_attributes = ['on\w*', 'xmlns']; |
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} |
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if ($is_image === true) { |
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/* |
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* Adobe Photoshop puts XML metadata into JFIF images, |
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* including namespacing, so we have to allow this for images. |
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*/ |
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unset($evil_attributes[array_search('xmlns', $evil_attributes)]); |
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} |
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do { |
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$str = preg_replace( |
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"#<(/?[^><]+?)([^A-Za-z\-])(" . implode('|', |
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$evil_attributes) . ")(\s*=\s*)([\"][^>]*?[\"]|[\'][^>]*?[\']|[^>]*?)([\s><])([><]*)#i", |
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"<$1$6", |
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$str, -1, $count |
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); |
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} while ($count); |
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return $str; |
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} |
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// -------------------------------------------------------------------- |
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/** |
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* HTML Entities Decode |
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* |
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* This function is a replacement for html_entity_decode() |
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* |
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* The reason we are not using html_entity_decode() by itself is because |
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* while it is not technically correct to leave out the semicolon |
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* at the end of an entity most browsers will still interpret the entity |
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* correctly. html_entity_decode() does not convert entities without |
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* semicolons, so we are left with our own little solution here. Bummer. |
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* |
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* @param string |
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* @param string |
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* @return string |
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*/ |
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public function entity_decode($str, $charset = 'UTF-8') |
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{ |
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if (stristr($str, '&') === false) { |
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return $str; |
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} |
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$str = html_entity_decode($str, ENT_COMPAT, $charset); |
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$str = preg_replace_callback('~&#x(0*[0-9a-f]{2,5})~i', function ($matches) { |
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return chr(hexdec($matches[1])); |
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2 |
|
}, $str); |
361
|
|
|
return preg_replace_callback('~&#([0-9]{2,4})~', function ($matches) { |
362
|
|
|
return chr($matches[1]); |
363
|
2 |
|
}, $str); |
364
|
|
|
} |
365
|
|
|
|
366
|
|
|
// -------------------------------------------------------------------- |
367
|
|
|
|
368
|
|
|
/** |
369
|
|
|
* Filename Security |
370
|
|
|
* |
371
|
|
|
* @param string |
372
|
|
|
* @param bool |
373
|
|
|
* @return string |
374
|
|
|
*/ |
375
|
4 |
|
public function sanitize_filename($str, $relative_path = false) |
376
|
|
|
{ |
377
|
|
|
$bad = [ |
378
|
4 |
|
"../", |
379
|
|
|
"<!--", |
380
|
|
|
"-->", |
381
|
|
|
"<", |
382
|
|
|
">", |
383
|
|
|
"'", |
384
|
|
|
'"', |
385
|
|
|
'&', |
386
|
|
|
'$', |
387
|
|
|
'#', |
388
|
|
|
'{', |
389
|
|
|
'}', |
390
|
|
|
'[', |
391
|
|
|
']', |
392
|
|
|
'=', |
393
|
|
|
';', |
394
|
|
|
'?', |
395
|
|
|
"%20", |
396
|
|
|
"%22", |
397
|
|
|
"%3c", // < |
398
|
|
|
"%253c", // < |
399
|
|
|
"%3e", // > |
400
|
|
|
"%0e", // > |
401
|
|
|
"%28", // ( |
402
|
|
|
"%29", // ) |
403
|
|
|
"%2528", // ( |
404
|
|
|
"%26", // & |
405
|
|
|
"%24", // $ |
406
|
|
|
"%3f", // ? |
407
|
|
|
"%3b", // ; |
408
|
|
|
"%3d" // = |
409
|
|
|
]; |
410
|
|
|
|
411
|
4 |
|
if (!$relative_path) { |
412
|
2 |
|
$bad[] = './'; |
413
|
2 |
|
$bad[] = '/'; |
414
|
|
|
} |
415
|
|
|
|
416
|
4 |
|
$str = $this->remove_invisible_characters($str, false); |
417
|
|
|
|
418
|
4 |
|
return stripslashes(str_replace($bad, '', $str)); |
419
|
|
|
} |
420
|
|
|
|
421
|
|
|
// ---------------------------------------------------------------- |
422
|
|
|
|
423
|
|
|
/** |
424
|
|
|
* Compact Exploded Words |
425
|
|
|
* |
426
|
|
|
* Callback function for xss_clean() to remove whitespace from |
427
|
|
|
* things like j a v a s c r i p t |
428
|
|
|
* |
429
|
|
|
* @param type |
430
|
|
|
* @return type |
|
|
|
|
431
|
|
|
*/ |
432
|
6 |
|
protected function _compact_exploded_words($matches) |
433
|
|
|
{ |
434
|
6 |
|
return preg_replace('/\s+/s', '', $matches[1]) . $matches[2]; |
|
|
|
|
435
|
|
|
} |
436
|
|
|
|
437
|
|
|
// -------------------------------------------------------------------- |
438
|
|
|
|
439
|
|
|
/** |
440
|
|
|
* Sanitize Naughty HTML |
441
|
|
|
* |
442
|
|
|
* Callback function for xss_clean() to remove naughty HTML elements |
443
|
|
|
* |
444
|
|
|
* @param array |
445
|
|
|
* @return string |
446
|
|
|
*/ |
447
|
4 |
|
protected function _sanitize_naughty_html($matches) |
448
|
|
|
{ |
449
|
|
|
// encode opening brace |
450
|
4 |
|
$str = '<' . $matches[1] . $matches[2] . $matches[3]; |
451
|
|
|
|
452
|
|
|
// encode captured opening or closing brace to prevent recursive vectors |
453
|
4 |
|
$str .= str_replace(['>', '<'], ['>', '<'], |
454
|
4 |
|
$matches[4]); |
455
|
|
|
|
456
|
4 |
|
return $str; |
457
|
|
|
} |
458
|
|
|
|
459
|
|
|
// -------------------------------------------------------------------- |
460
|
|
|
|
461
|
|
|
/** |
462
|
|
|
* JS Link Removal |
463
|
|
|
* |
464
|
|
|
* Callback function for xss_clean() to sanitize links |
465
|
|
|
* This limits the PCRE backtracks, making it more performance friendly |
466
|
|
|
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in |
467
|
|
|
* PHP 5.2+ on link-heavy strings |
468
|
|
|
* |
469
|
|
|
* @param array |
470
|
|
|
* @return string |
471
|
|
|
*/ |
472
|
2 |
|
protected function _js_link_removal($match) |
473
|
|
|
{ |
474
|
2 |
|
return str_replace( |
475
|
2 |
|
$match[1], |
476
|
2 |
|
preg_replace( |
477
|
2 |
|
'#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si', |
478
|
2 |
|
'', |
479
|
2 |
|
$this->_filter_attributes(str_replace(['<', '>'], '', $match[1])) |
480
|
|
|
), |
481
|
2 |
|
$match[0] |
482
|
|
|
); |
483
|
|
|
} |
484
|
|
|
|
485
|
|
|
// -------------------------------------------------------------------- |
486
|
|
|
|
487
|
|
|
/** |
488
|
|
|
* JS Image Removal |
489
|
|
|
* |
490
|
|
|
* Callback function for xss_clean() to sanitize image tags |
491
|
|
|
* This limits the PCRE backtracks, making it more performance friendly |
492
|
|
|
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in |
493
|
|
|
* PHP 5.2+ on image tag heavy strings |
494
|
|
|
* |
495
|
|
|
* @param array |
496
|
|
|
* @return string |
497
|
|
|
*/ |
498
|
2 |
|
protected function _js_img_removal($match) |
499
|
|
|
{ |
500
|
2 |
|
return str_replace( |
501
|
2 |
|
$match[1], |
502
|
2 |
|
preg_replace( |
503
|
2 |
|
'#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si', |
504
|
2 |
|
'', |
505
|
2 |
|
$this->_filter_attributes(str_replace(['<', '>'], '', $match[1])) |
506
|
|
|
), |
507
|
2 |
|
$match[0] |
508
|
|
|
); |
509
|
|
|
} |
510
|
|
|
|
511
|
|
|
// -------------------------------------------------------------------- |
512
|
|
|
|
513
|
|
|
/** |
514
|
|
|
* Attribute Conversion |
515
|
|
|
* |
516
|
|
|
* Used as a callback for XSS Clean |
517
|
|
|
* |
518
|
|
|
* @param array |
519
|
|
|
* @return string |
520
|
|
|
*/ |
521
|
4 |
|
protected function _convert_attribute($match) |
522
|
|
|
{ |
523
|
4 |
|
return str_replace(['>', '<', '\\'], ['>', '<', '\\\\'], $match[0]); |
524
|
|
|
} |
525
|
|
|
|
526
|
|
|
// -------------------------------------------------------------------- |
527
|
|
|
|
528
|
|
|
/** |
529
|
|
|
* Filter Attributes |
530
|
|
|
* |
531
|
|
|
* Filters tag attributes for consistency and safety |
532
|
|
|
* |
533
|
|
|
* @param string |
534
|
|
|
* @return string |
535
|
|
|
*/ |
536
|
2 |
|
protected function _filter_attributes($str) |
537
|
|
|
{ |
538
|
2 |
|
$out = ''; |
539
|
|
|
|
540
|
2 |
|
if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches)) { |
541
|
2 |
|
foreach ($matches[0] as $match) { |
542
|
2 |
|
$out .= preg_replace("#/\*.*?\*/#s", '', $match); |
543
|
|
|
} |
544
|
|
|
} |
545
|
|
|
|
546
|
2 |
|
return $out; |
547
|
|
|
} |
548
|
|
|
|
549
|
|
|
// -------------------------------------------------------------------- |
550
|
|
|
|
551
|
|
|
/** |
552
|
|
|
* HTML Entity Decode Callback |
553
|
|
|
* |
554
|
|
|
* Used as a callback for XSS Clean |
555
|
|
|
* |
556
|
|
|
* @param array |
557
|
|
|
* @return string |
558
|
|
|
*/ |
559
|
8 |
|
protected function _decode_entity($match) |
560
|
|
|
{ |
561
|
8 |
|
return $this->entity_decode($match[0]); |
562
|
|
|
} |
563
|
|
|
|
564
|
|
|
// -------------------------------------------------------------------- |
565
|
|
|
|
566
|
|
|
/** |
567
|
|
|
* Validate URL entities |
568
|
|
|
* |
569
|
|
|
* Called by xss_clean() |
570
|
|
|
* |
571
|
|
|
* @param string |
572
|
|
|
* @return string |
573
|
|
|
*/ |
574
|
12 |
|
protected function _validate_entities($str) |
575
|
|
|
{ |
576
|
|
|
/* |
577
|
|
|
* Protect GET variables in URLs |
578
|
|
|
*/ |
579
|
|
|
|
580
|
|
|
// 901119URL5918AMP18930PROTECT8198 |
581
|
|
|
|
582
|
12 |
|
$str = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-]+)|i', $this->xss_hash() . "\\1=\\2", $str); |
583
|
|
|
|
584
|
|
|
/* |
585
|
|
|
* Validate standard character entities |
586
|
|
|
* |
587
|
|
|
* Add a semicolon if missing. We do this to enable |
588
|
|
|
* the conversion of entities to ASCII later. |
589
|
|
|
* |
590
|
|
|
*/ |
591
|
12 |
|
$str = preg_replace('#(&\#?[0-9a-z]{2,})([\x00-\x20])*;?#i', "\\1;\\2", $str); |
592
|
|
|
|
593
|
|
|
/* |
594
|
|
|
* Validate UTF16 two byte encoding (x00) |
595
|
|
|
* |
596
|
|
|
* Just as above, adds a semicolon if missing. |
597
|
|
|
* |
598
|
|
|
*/ |
599
|
12 |
|
$str = preg_replace('#(&\#x?)([0-9A-F]+);?#i', "\\1\\2;", $str); |
600
|
|
|
|
601
|
|
|
|
602
|
12 |
|
return $str; |
603
|
|
|
} |
604
|
|
|
|
605
|
|
|
// ---------------------------------------------------------------------- |
606
|
|
|
|
607
|
|
|
/** |
608
|
|
|
* Do Never Allowed |
609
|
|
|
* |
610
|
|
|
* A utility function for xss_clean() |
611
|
|
|
* |
612
|
|
|
* @param string |
613
|
|
|
* @return string |
614
|
|
|
*/ |
615
|
12 |
|
protected function _do_never_allowed($str) |
616
|
|
|
{ |
617
|
12 |
|
$str = str_replace(array_keys($this->_never_allowed_str), $this->_never_allowed_str, $str); |
618
|
|
|
|
619
|
12 |
|
foreach ($this->_never_allowed_regex as $regex) { |
620
|
12 |
|
$str = preg_replace('#' . $regex . '#is', '[removed]', $str); |
621
|
|
|
} |
622
|
|
|
|
623
|
12 |
|
return $str; |
624
|
|
|
} |
625
|
|
|
|
626
|
|
|
|
627
|
16 |
|
protected function remove_invisible_characters($str, $url_encoded = true) |
628
|
|
|
{ |
629
|
16 |
|
$non_displayables = []; |
630
|
|
|
|
631
|
|
|
// every control character except newline (dec 10) |
632
|
|
|
// carriage return (dec 13), and horizontal tab (dec 09) |
633
|
|
|
|
634
|
16 |
|
if ($url_encoded) { |
635
|
12 |
|
$non_displayables[] = '/%0[0-8bcef]/'; // url encoded 00-08, 11, 12, 14, 15 |
636
|
12 |
|
$non_displayables[] = '/%1[0-9a-f]/'; // url encoded 16-31 |
637
|
|
|
} |
638
|
|
|
|
639
|
16 |
|
$non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S'; // 00-08, 11, 12, 14-31, 127 |
640
|
|
|
|
641
|
|
|
do { |
642
|
16 |
|
$str = preg_replace($non_displayables, '', $str, -1, $count); |
643
|
16 |
|
} while ($count); |
644
|
|
|
|
645
|
16 |
|
return $str; |
646
|
|
|
} |
647
|
|
|
|
648
|
|
|
/** |
649
|
|
|
* Random Hash for protecting URLs |
650
|
|
|
* |
651
|
|
|
* @return string |
652
|
|
|
*/ |
653
|
12 |
|
public function xss_hash() |
654
|
|
|
{ |
655
|
12 |
|
if ($this->_xss_hash == '') { |
656
|
12 |
|
mt_srand(); |
657
|
12 |
|
$this->_xss_hash = md5(time() + mt_rand(0, 1999999999)); |
658
|
|
|
} |
659
|
|
|
|
660
|
12 |
|
return $this->_xss_hash; |
661
|
|
|
} |
662
|
|
|
|
663
|
|
|
|
664
|
2 |
|
public static function escapeLike($str, $escape = '\'\'') |
665
|
|
|
{ |
666
|
|
|
|
667
|
2 |
|
return str_replace( |
668
|
2 |
|
['%', '_', '\'', '"', '<', '>', '(', ')', '{', ']', ':', '/', '\\'], |
669
|
2 |
|
['\%', '\_', $escape, '\"', '\<', '\>', '\(', '\)', '\{', '\}', '\:', '\/', '\\\\'], $str); |
670
|
|
|
} |
671
|
|
|
} |