'[removed]', 'document.write' => '[removed]', '.parentNode' => '[removed]', '.innerHTML' => '[removed]', '-moz-binding' => '[removed]', '' => '-->', ' '<![CDATA[', '' => '<comment>' ); /* never allowed, regex replacement */ /** * List of never allowed regex replacement * * @var array * @access protected */ protected $_never_allowed_regex = array( 'javascript\s*:', '(document|(document\.)?window)\.(location|on\w*)', 'expression\s*(\(|&\#40;)', // CSS and IE 'vbscript\s*:', // IE, surprise! 'wscript\s*:', // IE 'jscript\s*:', // IE 'vbs\s*:', // IE 'Redirect\s+30\d:', "([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?" ); /** * Constructor * * @return void */ public function __construct() { // Is CSRF protection enabled? if (config_item('csrf_protection') === TRUE) { // CSRF config foreach (array('csrf_expire', 'csrf_token_name', 'csrf_cookie_name') as $key) { if (FALSE !== ($val = config_item($key))) { $this->{'_'.$key} = $val; } } // Append application specific cookie prefix if (config_item('cookie_prefix')) { $this->_csrf_cookie_name = config_item('cookie_prefix').$this->_csrf_cookie_name; } // Set the CSRF hash $this->_csrf_set_hash(); } log_message('debug', "Security Class Initialized"); } // -------------------------------------------------------------------- /** * Verify Cross Site Request Forgery Protection * * @return object */ public function csrf_verify() { // If it's not a POST request we will set the CSRF cookie if (strtoupper($_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]) { $this->csrf_show_error(); } // We kill this since we're done and we don't want to // polute the _POST array unset($_POST[$this->_csrf_token_name]); // Nothing should last forever unset($_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); /* * URL Decode * * Just in case stuff like this is submitted: * * Google * * Note: Use rawurldecode() so it does not remove plus signs */ do { $str = rawurldecode($str); } while (preg_match('/%[0-9a-f]{2,}/i', $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. */ $str = preg_replace_callback("/[^a-z0-9>]+[a-z0-9]+=([\'\"]).*?\\1/si", array($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. */ $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: * * '), 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. */ $words = array( 'javascript', 'expression', 'vbscript', 'jscript', 'wscript', 'vbs', 'script', 'base64', 'applet', 'alert', 'document', 'write', 'cookie', 'window', 'confirm', 'prompt', 'eval' ); foreach ($words as $word) { $word = implode('\s*', str_split($word)).'\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" $str = preg_replace_callback('#('.substr($word, 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(), * but it is dog slow compared to these simplified non-capturing * preg_match(), especially if the pattern exists in the string * * Note: It was reported that not only space characters, but all in * the following pattern can be parsed as separators between a tag name * and its attributes: [\d\s"\'`;,\/\=\(\x00\x0B\x09\x0C] * ... however, remove_invisible_characters() above already strips the * hex-encoded ones, so we'll skip them below. */ do { $original = $str; if (preg_match('/]+([^>]*?)(?:>|$)#si', array($this, '_js_link_removal'), $str); } if (preg_match('/]*?)(?:\s?/?>|$)#si', array($this, '_js_img_removal'), $str); } if (preg_match('/script|xss/i', $str)) { $str = preg_replace('##si', '[removed]', $str); } } while($original !== $str); unset($original); /* * 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: * Becomes: <blink> */ $pattern = '#' .'<((?/*\s*)(?[a-z0-9]+)(?=[^a-z0-9]|$)' // tag start and name, followed by a non-tag character .'[^\s\042\047a-z0-9>/=]*' // a valid attribute character immediately after the tag would count as a separator // optional attributes .'(?(?:[\s\042\047/=]*' // non-attribute characters, excluding > (tag close) for obvious reasons .'[^\s\042\047>/=]+' // attribute characters // optional attribute-value .'(?:\s*=' // attribute-value separator .'(?:[^\s\042\047=><`]+|\s*\042[^\042]*\042|\s*\047[^\047]*\047|\s*(?U:[^\s\042\047=><`]*))' // single, double or non-quoted value .')?' // end optional attribute-value group .')*)' // end optional attributes group .'[^>]*)(?\>)?#isS'; // Note: It would be nice to optimize this for speed, BUT // only matching the naughty elements here results in // false positives and in turn - vulnerabilities! do { $old_str = $str; $str = preg_replace_callback($pattern, array($this, '_sanitize_naughty_html'), $str); } while ($old_str !== $str); unset($old_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|prompt|confirm|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); } 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, $charset='UTF-8') { if (strpos($str, '&') === FALSE) { return $str; } static $_entities; isset($charset) OR $charset = strtoupper(config_item('charset')); $flag = is_php('5.4') ? ENT_COMPAT | ENT_HTML5 : ENT_COMPAT; do { $str_compare = $str; // Decode standard entities, avoiding false positives if (preg_match_all('/\&[a-z]{2,}(?![a-z;])/i', $str, $matches)) { if ( ! isset($_entities)) { $_entities = array_map( 'strtolower', is_php('5.3.4') ? get_html_translation_table(HTML_ENTITIES, $flag, $charset) : get_html_translation_table(HTML_ENTITIES, $flag) ); // If we're not on PHP 5.4+, add the possibly dangerous HTML 5 // entities to the array manually if ($flag === ENT_COMPAT) { $_entities[':'] = ':'; $_entities['('] = '('; $_entities[')'] = ')'; $_entities["\n"] = '&newline;'; $_entities["\t"] = '&tab;'; } } $replace = array(); $matches = array_unique(array_map('strtolower', $matches[0])); foreach ($matches as &$match) { if (($char = array_search($match.';', $_entities, TRUE)) !== FALSE) { $replace[$match] = $char; } } $str = str_ireplace(array_keys($replace), array_values($replace), $str); } // Decode numeric & UTF16 two byte entities $str = html_entity_decode( preg_replace('/(&#(?:x0*[0-9a-f]{2,5}(?![0-9a-f;])|(?:0*\d{2,4}(?![0-9;]))))/iS', '$1;', $str), $flag, $charset ); } while ($str_compare !== $str); return $str; } // -------------------------------------------------------------------- /** * Filename Security * * @param string * @param bool * @return string */ public function sanitize_filename($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); do { $old = $str; $str = str_replace($bad, '', $str); } while ($old !== $str); return stripslashes($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]; } // -------------------------------------------------------------------- /** * Sanitize Naughty HTML * * Callback function for xss_clean() to remove naughty HTML elements * * @param array * @return string */ protected function _sanitize_naughty_html($matches) { static $naughty_tags = array( 'alert', 'prompt', 'confirm', 'applet', 'audio', 'basefont', 'base', 'behavior', 'bgsound', 'blink', 'body', 'embed', 'expression', 'form', 'frameset', 'frame', 'head', 'html', 'ilayer', 'iframe', 'input', 'button', 'select', 'isindex', 'layer', 'link', 'meta', 'keygen', 'object', 'plaintext', 'style', 'script', 'textarea', 'title', 'math', 'video', 'svg', 'xml', 'xss' ); static $evil_attributes = array( 'on\w+', 'style', 'xmlns', 'formaction', 'form', 'xlink:href', 'FSCommand', 'seekSegmentTime' ); // First, escape unclosed tags if (empty($matches['closeTag'])) { return '<'.$matches[1]; } // Is the element that we caught naughty? If so, escape it elseif (in_array(strtolower($matches['tagName']), $naughty_tags, TRUE)) { return '<'.$matches[1].'>'; } // For other tags, see if their attributes are "evil" and strip those elseif (isset($matches['attributes'])) { // We'll need to catch all attributes separately first $pattern = '#' .'([\s\042\047/=]*)' // non-attribute characters, excluding > (tag close) for obvious reasons .'(?[^\s\042\047>/=]+)' // attribute characters // optional attribute-value .'(?:\s*=(?[^\s\042\047=><`]+|\s*\042[^\042]*\042|\s*\047[^\047]*\047|\s*(?U:[^\s\042\047=><`]*)))' // attribute-value separator .'#i'; if ($count = preg_match_all($pattern, $matches['attributes'], $attributes, PREG_SET_ORDER | PREG_OFFSET_CAPTURE)) { // Since we'll be using substr_replace() below, we // need to handle the attributes in reverse order, // so we don't damage the string. for ($i = $count - 1; $i > -1; $i--) { if ( // Is it indeed an "evil" attribute? preg_match('#^('.implode('|', $evil_attributes).')$#i', $attributes[$i]['name'][0]) // Or an attribute not starting with a letter? Some parsers get confused by that OR ! ctype_alpha($attributes[$i]['name'][0][0]) // Does it have an equals sign, but no value and not quoted? Strip that too! OR (trim($attributes[$i]['value'][0]) === '') ) { $matches['attributes'] = substr_replace( $matches['attributes'], ' [removed]', $attributes[$i][0][1], strlen($attributes[$i][0][0]) ); } } // Note: This will strip some non-space characters and/or // reduce multiple spaces between attributes. return '<'.$matches['slash'].$matches['tagName'].' '.trim($matches['attributes']).'>'; } } return $matches[0]; } // -------------------------------------------------------------------- /** * JS Link Removal * * Callback function for xss_clean() to sanitize links * This limits the PCRE backtracks, making it more performance friendly * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in * PHP 5.2+ on link-heavy strings * * @param array * @return string */ protected function _js_link_removal($match) { return str_replace( $match[1], preg_replace( '#href=.*?(?:(?:alert|prompt|confirm)(?:\(|&\#40;)|javascript:|livescript:|mocha:|charset=|window\.|document\.|\.cookie|_filter_attributes($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|prompt|confirm|eval)(?:\(|&\#40;)|javascript:|livescript:|mocha:|charset=|window\.|document\.|\.cookie|_filter_attributes($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) { // Protect GET variables in URLs // 901119URL5918AMP18930PROTECT8198 $match = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-/]+)|i', $this->xss_hash().'\\1=\\2', $match[0]); // Decode, then un-protect URL GET vars return str_replace( $this->xss_hash(), '&', $this->entity_decode($match, strtoupper(config_item('charset'))) ); } // ---------------------------------------------------------------------- /** * 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 fail if (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/core/Security.php */