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<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');/*** CodeIgniter** An open source application development framework for PHP 5.1.6 or newer** @package CodeIgniter* @author ExpressionEngine Dev Team* @copyright Copyright (c) 2008 - 2011, EllisLab, Inc.* @license http://codeigniter.com/user_guide/license.html* @link http://codeigniter.com* @since Version 1.0* @filesource*/// ------------------------------------------------------------------------/*** Security Class** @package CodeIgniter* @subpackage Libraries* @category Security* @author ExpressionEngine Dev Team* @link http://codeigniter.com/user_guide/libraries/security.html*/class CI_Security {/*** Random Hash for protecting URLs** @var string* @access protected*/protected $_xss_hash = '';/*** Random Hash for Cross Site Request Forgery Protection Cookie** @var string* @access protected*/protected $_csrf_hash = '';/*** Expiration time for Cross Site Request Forgery Protection Cookie* Defaults to two hours (in seconds)** @var int* @access protected*/protected $_csrf_expire = 7200;/*** Token name for Cross Site Request Forgery Protection Cookie** @var string* @access protected*/protected $_csrf_token_name = 'ci_csrf_token';/*** Cookie name for Cross Site Request Forgery Protection Cookie** @var string* @access protected*/protected $_csrf_cookie_name = 'ci_csrf_token';/*** List of never allowed strings** @var array* @access protected*/protected $_never_allowed_str = array('document.cookie' => '[removed]','document.write' => '[removed]','.parentNode' => '[removed]','.innerHTML' => '[removed]','window.location' => '[removed]','-moz-binding' => '[removed]','<!--' => '<!--','-->' => '-->','<![CDATA[' => '<![CDATA[','<comment>' => '<comment>');/* never allowed, regex replacement *//*** List of never allowed regex replacement** @var array* @access protected*/protected $_never_allowed_regex = array('javascript\s*:','expression\s*(\(|&\#40;)', // CSS and IE'vbscript\s*:', // IE, surprise!'Redirect\s+302',"([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?");/*** Constructor** @return void*/public function __construct(){// Is CSRF protection enabled?if (config_item('csrf_protection') === TRUE){// CSRF configforeach (array('csrf_expire', 'csrf_token_name', 'csrf_cookie_name') as $key){if (FALSE !== ($val = config_item($key))){$this->{'_'.$key} = $val;}}// Append application specific cookie prefixif (config_item('cookie_prefix')){$this->_csrf_cookie_name = config_item('cookie_prefix').$this->_csrf_cookie_name;}// Set the CSRF hash$this->_csrf_set_hash();}log_message('debug', "Security Class Initialized");}// --------------------------------------------------------------------/*** Verify Cross Site Request Forgery Protection** @return object*/public function csrf_verify(){// If it's not a POST request we will set the CSRF cookieif (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST'){return $this->csrf_set_cookie();}// Do the tokens exist in both the _POST and _COOKIE arrays?if ( ! isset($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name])){$this->csrf_show_error();}// Do the tokens match?if ($_POST[$this->_csrf_token_name] != $_COOKIE[$this->_csrf_cookie_name]){$this->csrf_show_error();}// We kill this since we're done and we don't want to// polute the _POST arrayunset($_POST[$this->_csrf_token_name]);// Nothing should last foreverunset($_COOKIE[$this->_csrf_cookie_name]);$this->_csrf_set_hash();$this->csrf_set_cookie();log_message('debug', 'CSRF token verified');return $this;}// --------------------------------------------------------------------/*** Set Cross Site Request Forgery Protection Cookie** @return object*/public function csrf_set_cookie(){$expire = time() + $this->_csrf_expire;$secure_cookie = (config_item('cookie_secure') === TRUE) ? 1 : 0;if ($secure_cookie && (empty($_SERVER['HTTPS']) OR strtolower($_SERVER['HTTPS']) === 'off')){return FALSE;}setcookie($this->_csrf_cookie_name, $this->_csrf_hash, $expire, config_item('cookie_path'), config_item('cookie_domain'), $secure_cookie);log_message('debug', "CRSF cookie Set");return $this;}// --------------------------------------------------------------------/*** Show CSRF Error** @return void*/public function csrf_show_error(){show_error('The action you have requested is not allowed.');}// --------------------------------------------------------------------/*** Get CSRF Hash** Getter Method** @return string self::_csrf_hash*/public function get_csrf_hash(){return $this->_csrf_hash;}// --------------------------------------------------------------------/*** Get CSRF Token Name** Getter Method** @return string self::csrf_token_name*/public function get_csrf_token_name(){return $this->_csrf_token_name;}// --------------------------------------------------------------------/*** XSS Clean** Sanitizes data so that Cross Site Scripting Hacks can be* prevented. This function does a fair amount of work but* it is extremely thorough, designed to prevent even the* most obscure XSS attempts. Nothing is ever 100% foolproof,* of course, but I haven't been able to get anything passed* the filter.** Note: This function should only be used to deal with data* upon submission. It's not something that should* be used for general runtime processing.** This function was based in part on some code and ideas I* got from Bitflux: http://channel.bitflux.ch/wiki/XSS_Prevention** To help develop this script I used this great list of* vulnerabilities along with a few other hacks I've* harvested from examining vulnerabilities in other programs:* http://ha.ckers.org/xss.html** @param mixed string or array* @param bool* @return string*/public function xss_clean($str, $is_image = FALSE){/** Is the string an array?**/if (is_array($str)){while (list($key) = each($str)){$str[$key] = $this->xss_clean($str[$key]);}return $str;}/** Remove Invisible Characters*/$str = 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.**/$str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", array($this, '_decode_entity'), $str);/** Remove Invisible Characters Again!*/$str = 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", ' ', $str);}/** Capture converted string for later comparison*/$converted_string = $str;// Remove Strings that are never allowed$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', "<?\\1", $str);}else{$str = str_replace(array('<?', '?'.'>'), array('<?', '?>'), $str);}/** Compact any exploded words** This corrects words like: j a v a s c r i p t* These words are compacted back to their correct state.*/$words = array('javascript', 'expression', 'vbscript', 'script', 'base64','applet', 'alert', 'document', 'write', 'cookie', 'window');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($temp, 0, -3).')(\W)#is', array($this, '_compact_exploded_words'), $str);}/** Remove disallowed Javascript in links or img tags* We used to do some version comparisons and use of stripos for PHP5,* but it is dog slow compared to these simplified non-capturing* preg_match(), especially if the pattern exists in the string*/do{$original = $str;if (preg_match("/<a/i", $str)){$str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", array($this, '_js_link_removal'), $str);}if (preg_match("/<img/i", $str)){$str = preg_replace_callback("#<img\s+([^>]*?)(\s?/?>|$)#si", array($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);// Remove evil attributes such as style, onclick and xmlns$str = $this->_remove_evil_attributes($str, $is_image);/** Sanitize naughty HTML elements** If a tag containing any of the words in the list* below is found, the tag gets converted to entities.** So this: <blink>* Becomes: <blink>*/$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', array($this, '_sanitize_naughty_html'), $str);/** Sanitize naughty scripting elements** Similar to above, only instead of looking for* tags it looks for PHP and JavaScript commands* that are disallowed. Rather than removing the* code, it simply converts the parenthesis to entities* rendering the code un-executable.** For example: eval('some code')* Becomes: eval('some code')*/$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2(\\3)", $str);// Final clean up// This adds a bit of extra precaution in case// something got through the above filters$str = $this->_do_never_allowed($str);/** Images are Handled in a Special Way* - Essentially, we want to know that after all of the character* conversion is done whether any unwanted, likely XSS, code was found.* If not, we return TRUE, as the image is clean.* However, if the string post-conversion does not matched the* string post-removal of XSS, then it fails, as there was unwanted XSS* code found and removed/changed during processing.*/if ($is_image === TRUE){return ($str == $converted_string) ? TRUE: FALSE;}log_message('debug', "XSS Filtering completed");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 $this->_xss_hash;}// --------------------------------------------------------------------/*** HTML Entities Decode** This function is a replacement for html_entity_decode()** The reason we are not using html_entity_decode() by itself is because* while it is not technically correct to leave out the semicolon* at the end of an entity most browsers will still interpret the entity* correctly. html_entity_decode() does not convert entities without* semicolons, so we are left with our own little solution here. Bummer.** @param string* @param string* @return string*/public function entity_decode($str, $charset='UTF-8'){if (stristr($str, '&') === FALSE){return $str;}$str = html_entity_decode($str, ENT_COMPAT, $charset);$str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str);}// --------------------------------------------------------------------/*** Filename Security** @param string* @param bool* @return string*/public function sanitize_filename($str, $relative_path = FALSE){$bad = array("../","<!--","-->","<",">","'",'"','&','$','#','{','}','[',']','=',';','?',"%20","%22","%3c", // <"%253c", // <"%3e", // >"%0e", // >"%28", // ("%29", // )"%2528", // ("%26", // &"%24", // $"%3f", // ?"%3b", // ;"%3d" // =);if ( ! $relative_path){$bad[] = './';$bad[] = '/';}$str = remove_invisible_characters($str, FALSE);return stripslashes(str_replace($bad, '', $str));}// ----------------------------------------------------------------/*** Compact Exploded Words** Callback function for xss_clean() to remove whitespace from* things like j a v a s c r i p t** @param type* @return type*/protected function _compact_exploded_words($matches){return preg_replace('/\s+/s', '', $matches[1]).$matches[2];}// --------------------------------------------------------------------/** 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, $is_image){// All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns$evil_attributes = array('on\w*', 'style', 'xmlns', 'formaction');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', $evil_attributes)]);}do {$count = 0;$attribs = array();// find occurrences of illegal attribute strings with quotes (042 and 047 are octal quotes)preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*(\042|\047)([^\\2]*?)(\\2)/is', $str, $matches, PREG_SET_ORDER);foreach ($matches as $attr){$attribs[] = preg_quote($attr[0], '/');}// find occurrences of illegal attribute strings without quotespreg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*([^\s>]*)/is', $str, $matches, PREG_SET_ORDER);foreach ($matches as $attr){$attribs[] = preg_quote($attr[0], '/');}// replace illegal attribute strings that are inside an html tagif (count($attribs) > 0){$str = preg_replace('/(<?)(\/?[^><]+?)([^A-Za-z<>\-])(.*?)('.implode('|', $attribs).')(.*?)([\s><]?)([><]*)/i', '$1$2 $4$6$7$8', $str, -1, $count);}} while ($count);return $str;}// --------------------------------------------------------------------/*** Sanitize Naughty HTML** Callback function for xss_clean() to remove naughty HTML elements** @param array* @return string*/protected function _sanitize_naughty_html($matches){// encode opening brace$str = '<'.$matches[1].$matches[2].$matches[3];// encode captured opening or closing brace to prevent recursive vectors$str .= str_replace(array('>', '<'), array('>', '<'),$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(array('<', '>'), '', $match[1]))),$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(array('<', '>'), '', $match[1]))),$match[0]);}// --------------------------------------------------------------------/*** Attribute Conversion** Used as a callback for XSS Clean** @param array* @return string*/protected function _convert_attribute($match){return str_replace(array('>', '<', '\\'), array('>', '<', '\\\\'), $match[0]);}// --------------------------------------------------------------------/*** Filter Attributes** Filters tag attributes for consistency and safety** @param string* @return string*/protected function _filter_attributes($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], strtoupper(config_item('charset')));}// --------------------------------------------------------------------/*** 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;",$str);/** Un-Protect GET variables in URLs*/$str = str_replace($this->xss_hash(), '&', $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 $str;}// --------------------------------------------------------------------/*** Set Cross Site Request Forgery Protection Cookie** @return string*/protected function _csrf_set_hash(){if ($this->_csrf_hash == ''){// If the cookie exists we will use it's value.// We don't necessarily want to regenerate it with// each page load since a page could contain embedded// sub-pages causing this feature to failif (isset($_COOKIE[$this->_csrf_cookie_name]) &&preg_match('#^[0-9a-f]{32}$#iS', $_COOKIE[$this->_csrf_cookie_name]) === 1){return $this->_csrf_hash = $_COOKIE[$this->_csrf_cookie_name];}return $this->_csrf_hash = md5(uniqid(rand(), TRUE));}return $this->_csrf_hash;}}/* End of file Security.php *//* Location: ./system/libraries/Security.php */