546 lines
18 KiB
PHP
Executable File
546 lines
18 KiB
PHP
Executable File
<?php if(!defined('APP_ROOT')) exit('No direct script access allowed');
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/** Security Class
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* Pretty heavily based on the CodeIgniter Security Class
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*/
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class Security {
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/* Random Hash for protecting URLs */
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protected $_xss_hash = '';
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/* Random Hash for Cross-Site Request Forgery Protection Cookie (CSRFPC) */
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protected $_csrf_hash = '';
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/* Expiration time for CSRFPC */
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protected $_csrf_expire = 7200;
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/* Token name for CSRFPC */
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protected $_csrf_token_name = 'anvil_csrf_token';
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/* Cookie name for CSRFPC */
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protected $_csrf_cookie_name = 'anvil_csrf_token';
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/* List of never allowed strings */
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protected $_never_allowed_str = array(
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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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/* List of never allowed regex replacement */
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protected $_never_allowed_regex = array(
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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]*?\\1?"
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);
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protected $_anvil;
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/* Constructor */
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public function __construct($a) {
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$this->_anvil = $a;
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// Is CSRF protection enabled?
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if($this->_anvil->config->item('csrf_protection')===TRUE) {
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// Set the CSRF hash
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$this->_csrf_set_hash();
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}
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// Security class initialized
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}
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/**
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* Verify CSRF Protection
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*/
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public function csrf_verify() {
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// If it's not a POST request we will set the CSRF cookie
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if($this->_anvil->request->type !== 'POST') {
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return $this->csrf_set_cookie();
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}
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// Do the tokens exist in both the POST params and COOKIE array?
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if(isset($this->_anvil->request->parameters[$this->_csrf_token_name],
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$this->_anvil->cookie[$this->_csrf_cookie_name])) {
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$this->csrf_show_error();
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}
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// Do the tokens match?
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if($this->_anvil->request->parameters[$this->_csrf_token_name] !=
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$this->_anvil->request->cookie[$this->_csrf_cookie_name]) {
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$this->csrf_show_error();
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}
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// We kill this since we're done and we don't want to polute the POST array
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unset($this->_anvil->request->parameters[$this->_csrf_token_name]);
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// None of these things should last forever
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unset($this->_anvil->request->cookie[$this->_csrf_cookie_name]);
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$this->_csrf_set_hash();
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$this->csrf_set_cookie();
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return $this;
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}
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/** Set CSRF Protection Cookie */
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public function csrf_set_cookie() {
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$expire = time() + $this->_csrf_expire;
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$secure_cookie = ($this->_anvil->config->item('cookie_secure') === TRUE ? 1 : 0);
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if($secure_cookie && !$this->_anvil->request->isSecure()) {
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return FALSE;
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}
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$this->_anvil->request->setCookie($this->_csrf_cookie_name, $this->_csrf_hash, $expire, NULL, NULL, $secure_cookie);
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return $this;
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}
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/* Get CSRF Hash */
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public function get_csrf_hash() {
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return $this->_csrf_hash;
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}
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/* Get CSRF Token Name */
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public function get_csrf_token_name() {
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return $this->_csrf_token_name;
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}
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/**
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* XSS Clean
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* Sanitizes data so that CSS hacks can be prevented.
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* This function does a fair amount of work but it is
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* extremely thorough, designed to prevent even the
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* most obscure XSS attempts. Nothing is ever 100%
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* foolproof, of course, but I haven't been able to
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* get anything passed the filter.
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*
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* Note: This function should only be used to deal
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* with data upon submission. It's not something that
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* should be used for general runtime processing.
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*
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* @param mixed string or array
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* @param bool
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* @return string
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*/
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public function xss_clean($str, $is_image = FALSE) {
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/* Is the string an array? */
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if(is_array($str)) {
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while(list($key) = each($str)) {
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$str[$key] = $this->xss_clean($str[$key]);
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}
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return $str;
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}
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/* Remove Invisible Characters */
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$str = 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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/* URL Decode
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* Note: Use rawurldecode() so it does not remove plus signs
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*/
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$str = rawurldecode($str);
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/* Convert character entities to ASCII
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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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$str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);
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$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", array($this, '_decode_entity'), $str);
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/* Remove Invisible Characters AGAIN! */
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$str = remove_invisible_characters($str);
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/* Convert all tabs to spaces
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* This prevents strings like this: ja vascript
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* NOTE: we deal with spaces between characters later.
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* NOTE: preg_replace was found to be amazingly slow here on
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* large blocks of data, so we use str_replace.
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*/
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if(strpos($str, "\t") !== FALSE) {
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$str = str_replace("\t", ' ', $str);
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}
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/* Capture converted string for later comparison */
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$converted_string = $str;
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/* Remove Strings that are never allowed */
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$str = $this->_do_never_allowed($str);
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/* Makes PHP tags safe
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* Note: XML tags are inadvertently replaced too:
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* <?xml
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* But it doesn't seem to pose a problem.
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*/
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if($is_image === TRUE) {
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/* Images have a tendency to have the PHP short opening and
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* closing tags every so often so we skip those and only
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* do the long opening tags.
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*/
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$str = preg_replace('/<\?(php)/i', "<?\\1", $str);
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} else {
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$str = str_replace(array('<?', '?'.'>'), array('<?', '?>'), $str);
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}
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/* Compact any exploded words
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* This corrects words like: j a v a s c r i p t
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* These words are compacted back to their correct state.
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*/
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$words = array(
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'javascript', 'expression', 'vbscript', 'script', 'base64',
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'applet', 'alert', 'document', 'write', 'cookie', 'window'
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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($temp, 0, -3).')(\W)#is', array($this, '_compact_exploded_words'), $str);
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}
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/* Remove disallowed Javascript in links or img tags */
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do {
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$original = $str;
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if(preg_match("/<a/i", $str)) {
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$str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", array($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?/?\>|$)#si", array($this, '_js_img_removal'), $str);
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}
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if(preg_match("/script/i", $str) || 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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// Remove evil attributes such as style, onclick and xmlns
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$str = $this->_remove_evil_attributes($str, $is_image);
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/* Sanitize naughty HTML elements
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* If a tag containing any of the words in the list
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* below is found, the tag gets converted to entities.
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* so this: <blink>
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* becoms: <blink>
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*/
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$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', array($this, '_sanitize_naughty_html'), $str);
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/* Sanitize naughty scripting elements
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* Similar to above, only instead of looking for
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* tags it looks for PHP and JavaScript commands
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* that are disallowed. Rather than removing the
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* code, it simply converts the parenthesis to
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* entities rendering the code un-executable.
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* so this: eval('some code')
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* becomes: eval('some code')
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*/
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$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2(\\3)", $str);
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/* Final clean up
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* This adds a bit of extra precaution in case
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* something got through the above filters
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*/
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$str = $this->_do_never_allowed($str);
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/* Images are handled in a special way
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* - Essentially, we want to know that after all of the character
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* conversion is done whether any unwanted, likely XSS, code was found.
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* If not, we return TRUE, as the image is clean.
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* However, if the string post-conversion does not match the
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* string post-removal of XSS, then it fails, as there was unwanted XSS
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* code found and removed/changed during processing
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*/
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if($is_image === TRUE) {
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return ($str == $converted_string)?TRUE:FALSE;
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}
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return $str;
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}
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/**
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* Random Hash for protecting URLs
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* @return string
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*/
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public function xss_hash() {
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if($this->_xss_hash == '') {
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mt_srand();
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$this->_xss_hash = md5(time() + mt_rand(0, 1999999999));
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}
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return $this->_xss_hash;
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}
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/**
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* HTML Entities Decode
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* This function is a replacement for html_entity_decode()
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* The reason we are not using html_entity_decode() by itself is
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* because while it is not technically correct to leave out the
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* semicolon at the end of an entity most browsers will still interpret
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* the entity correctly. html_entity_decode() does not convert entities
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* without semicolons, so we are left with our own little solution here.
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*
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* @param string
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* @param string
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* @return string
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*/
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public function entity_decode($str, $charset='UTF-8') {
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if(stristr($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('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);
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return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str);
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}
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/**
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* Filename Security
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*
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* @param string
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* @param bool
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* @return string
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*/
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public function sanitize_filename($str, $relative_path = FALSE) {
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$bad = array( "../", "<!--", "-->", "<",
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">", "'", '"', '&', '$', '#',
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'{', '}', '[', ']', '=', ';',
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'?', "%20", "%22", "%3c", "%253c",
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"%3e", "%0e", "%28", "%29", "%2528",
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"%26", "%24", "%3f", "%3b", "%3d"
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);
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if(!$relateive_path) {
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$bad[] = './';
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$bad[] = '/';
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}
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$str = remove_invisible_characters($str, FALSE);
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return stripslashes(str_replace($bad, '', $str));
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}
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/**
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* Compact Exploded Words
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* Callback function for xss_clean() to remove whitespace from
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* things like j a v a s c r i p t
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*
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* @param type
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* @return type
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*/
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protected function _compact_exploded_words($matches) {
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return preg_replace('/\s+/s', '', $matches[1]).$matches[2];
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}
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/**
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* Remove Evil HTML Attributes (like eventhandlers and style)
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* 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, $is_image) {
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// All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns
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$evil_attributes = array('on\w*', 'style', 'xmlns', 'formaction');
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if($is_image===TRUE) {
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/* Adobe Photoshop puts XML metadata into JFIF images,
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* including namespacing, so we have to allow this for images.
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*/
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unset($evil_attributes[array_search('xmlns', $evil_attributes)]);
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}
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do {
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$count = 0;
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$attribs = array();
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// Find occurrences of illegal attribute string with quotes (042 and 047 are octal quotes)
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preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*(\042|\047)([^\\2]*?)(\\2)/is', $str, $matches, PREG_SET_ORDER);
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foreach ($matches as $attr) {
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$attribs[] = preg_quote($attr[0], '/');
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}
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// find occurrences of illegal attribute strings without quotes
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preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*([^\s>]*)/is', $str, $matches, PREG_SET_ORDER);
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foreach ($matches as $attr) {
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$attribs[] = preg_quote($attr[0], '/');
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}
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// replace illegal attribute strings that are inside an html tag
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if (count($attribs) > 0) {
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$str = preg_replace('/(<?)(\/?[^><]+?)([^A-Za-z<>\-])(.*?)('.implode('|', $attribs).')(.*?)([\s><]?)([><]*)/i', '$1$2 $4$6$7$8', $str, -1, $count);
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}
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} while($count);
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return $str;
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}
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/**
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* Sanitize Naughty HTML
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* Callback function for xss_clean() to remove naughty HTML elements
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*
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* @param array
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* @return string
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*/
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protected function _sanitize_naughty_html($matches) {
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// encode opening brace
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$str = '<'.$matches[1].$matches[2].$matches[3];
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// encode captured opening or closing brace to prevent recursive vectors
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$str .= str_replace(array('>', '<'), array('>', '<'),
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$matches[4]);
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return $str;
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}
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/**
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* JS Link Removal
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* Callback function for xss_clean() to sanitize links
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* This limits the PCRE backtracks, making it more performance friendly
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* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
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* PHP 5.2+ on link-heavy strings
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*
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* @param array
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* @return string
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*/
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protected function _js_link_removal($match) {
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return str_replace(
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$match[1],
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preg_replace(
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'#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si',
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'',
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$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
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),
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$match[0]
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);
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}
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/**
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* JS Image Removal
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* Callback function for xss_clean() to sanitize image tags
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* This limits the PCRE backtracks, making it more performance friendly
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* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
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* PHP 5.2+ on image tag heavy strings
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*
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* @param array
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* @return string
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*/
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protected function _js_img_removal($match) {
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return str_replace(
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$match[1],
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preg_replace(
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'#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si',
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'',
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$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
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),
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$match[0]
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);
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}
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/**
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* Attribute Conversion
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* Used as a callback for XSS Clean
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*
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* @param array
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* @return string
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*/
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protected function _convert_attribute($match) {
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return str_replace(array('>', '<', '\\'), array('>', '<', '\\\\'), $match[0]);
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}
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/**
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* Filter Attributes
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* Filters tag attributes for consistency and safety
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*
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* @param string
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* @return string
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*/
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protected function _filter_attributes($str) {
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$out = '';
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if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches)) {
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foreach ($matches[0] as $match) {
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$out .= preg_replace("#/\*.*?\*/#s", '', $match);
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}
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}
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return $out;
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}
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/**
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* HTML Entity Decode Callback
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* Used as a callback for XSS Clean
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*
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* @param array
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* @return string
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*/
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protected function _decode_entity($match) {
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return $this->entity_decode($match[0], strtoupper(config_item('charset')));
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}
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/**
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* Validate URL entities
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* 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 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;
|
|
}
|
|
} |