Improving parameter security in xss clean
diff --git a/system/libraries/Security.php b/system/libraries/Security.php
index 58db4e7..ceef977 100644
--- a/system/libraries/Security.php
+++ b/system/libraries/Security.php
@@ -22,44 +22,44 @@
* @subpackage Libraries
* @category Security
* @author ExpressionEngine Dev Team
- * @link http://codeigniter.com/user_guide/libraries/sessions.html
+ * @link http://codeigniter.com/user_guide/libraries/security.html
*/
class CI_Security {
-
- public $xss_hash = '';
- public $csrf_hash = '';
- public $csrf_expire = 7200; // Two hours (in seconds)
- public $csrf_token_name = 'ci_csrf_token';
- public $csrf_cookie_name = 'ci_csrf_token';
+
+ protected $_xss_hash = '';
+ protected $_csrf_hash = '';
+ protected $_csrf_expire = 7200; // Two hours (in seconds)
+ protected $_csrf_token_name = 'ci_csrf_token';
+ protected $_csrf_cookie_name = 'ci_csrf_token';
/* never allowed, string replacement */
- public $never_allowed_str = array(
- 'document.cookie' => '[removed]',
- 'document.write' => '[removed]',
- '.parentNode' => '[removed]',
- '.innerHTML' => '[removed]',
- 'window.location' => '[removed]',
- '-moz-binding' => '[removed]',
- '<!--' => '<!--',
- '-->' => '-->',
- '<![CDATA[' => '<![CDATA['
- );
- /* never allowed, regex replacement */
- public $never_allowed_regex = array(
- "javascript\s*:" => '[removed]',
- "expression\s*(\(|&\#40;)" => '[removed]', // CSS and IE
- "vbscript\s*:" => '[removed]', // IE, surprise!
- "Redirect\s+302" => '[removed]'
- );
+ protected $_never_allowed_str = array(
+ 'document.cookie' => '[removed]',
+ 'document.write' => '[removed]',
+ '.parentNode' => '[removed]',
+ '.innerHTML' => '[removed]',
+ 'window.location' => '[removed]',
+ '-moz-binding' => '[removed]',
+ '<!--' => '<!--',
+ '-->' => '-->',
+ '<![CDATA[' => '<![CDATA['
+ );
+ /* never allowed, regex replacement */
+ protected $_never_allowed_regex = array(
+ "javascript\s*:" => '[removed]',
+ "expression\s*(\(|&\#40;)" => '[removed]', // CSS and IE
+ "vbscript\s*:" => '[removed]', // IE, surprise!
+ "Redirect\s+302" => '[removed]'
+ );
+
+ /**
+ * Constructor
+ */
public function __construct()
{
- $this->csrf_token_name = (config_item('csrf_token_name')) ? config_item('csrf_token_name') : 'csrf_token_name';
- $this->csrf_cookie_name = (config_item('csrf_cookie_name')) ? config_item('csrf_cookie_name') : 'csrf_cookie_name';
- $this->csrf_expire = (config_item('csrf_expire')) ? config_item('csrf_expire') : 7200;
-
// Append application specific cookie prefix to token name
- $this->csrf_cookie_name = (config_item('cookie_prefix')) ? config_item('cookie_prefix').$this->csrf_token_name : $this->csrf_token_name;
+ $this->_csrf_cookie_name = (config_item('cookie_prefix')) ? config_item('cookie_prefix').$this->_csrf_token_name : $this->_csrf_token_name;
// Set the CSRF hash
$this->_csrf_set_hash();
@@ -72,8 +72,7 @@
/**
* Verify Cross Site Request Forgery Protection
*
- * @access public
- * @return null
+ * @return object
*/
public function csrf_verify()
{
@@ -84,26 +83,30 @@
}
// Do the tokens exist in both the _POST and _COOKIE arrays?
- if ( ! isset($_POST[$this->csrf_token_name]) OR ! isset($_COOKIE[$this->csrf_cookie_name]))
+ if ( ! isset($_POST[$this->_csrf_token_name]) OR
+ ! isset($_COOKIE[$this->_csrf_cookie_name]))
{
$this->csrf_show_error();
}
// Do the tokens match?
- if ($_POST[$this->csrf_token_name] != $_COOKIE[$this->csrf_cookie_name])
+ 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[$this->csrf_token_name]);
+ // We kill this since we're done and we don't want to
+ // polute the _POST array
+ unset($_POST[$this->_csrf_token_name]);
// Nothing should last forever
- unset($_COOKIE[$this->csrf_cookie_name]);
+ unset($_COOKIE[$this->_csrf_cookie_name]);
$this->_csrf_set_hash();
$this->csrf_set_cookie();
log_message('debug', "CSRF token verified ");
+
+ return $this;
}
// --------------------------------------------------------------------
@@ -111,44 +114,28 @@
/**
* Set Cross Site Request Forgery Protection Cookie
*
- * @access public
- * @return null
+ * @return object
*/
public function csrf_set_cookie()
{
- $expire = time() + $this->csrf_expire;
+ $expire = time() + $this->_csrf_expire;
$secure_cookie = (config_item('cookie_secure') === TRUE) ? 1 : 0;
- setcookie($this->csrf_cookie_name, $this->csrf_hash, $expire, config_item('cookie_path'), config_item('cookie_domain'), $secure_cookie);
-
- log_message('debug', "CRSF cookie Set");
- }
-
- // --------------------------------------------------------------------
-
- /**
- * Set Cross Site Request Forgery Protection Cookie
- *
- * @access private
- * @return null
- */
- private function _csrf_set_hash()
- {
- if ($this->csrf_hash == '')
+ if ($secure_cookie)
{
- // If the cookie exists we will use it's value. We don't necessarily want to regenerate it with
- // each page load since a page could contain embedded sub-pages causing this feature to fail
- if (isset($_COOKIE[$this->csrf_cookie_name]) AND $_COOKIE[$this->csrf_cookie_name] != '')
+ $req = isset($_SERVER['HTTPS']) ? $_SERVER['HTTPS'] : FALSE;
+
+ if ( ! $req OR $req == 'off')
{
- $this->csrf_hash = $_COOKIE[$this->csrf_cookie_name];
- }
- else
- {
- $this->csrf_hash = md5(uniqid(rand(), TRUE));
+ return FALSE;
}
}
- return $this->csrf_hash;
+ setcookie($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;
}
// --------------------------------------------------------------------
@@ -156,8 +143,7 @@
/**
* Show CSRF Error
*
- * @access public
- * @return null
+ * @return void
*/
public function csrf_show_error()
{
@@ -167,6 +153,34 @@
// --------------------------------------------------------------------
/**
+ * 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
@@ -188,7 +202,6 @@
* harvested from examining vulnerabilities in other programs:
* http://ha.ckers.org/xss.html
*
- * @access public
* @param mixed string or array
* @return string
*/
@@ -213,35 +226,8 @@
*/
$str = remove_invisible_characters($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);
+ // Validate Entities in URLs
+ $str = $this->_validate_entities($str);
/*
* URL Decode
@@ -265,7 +251,7 @@
*/
$str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);
-
+
$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", array($this, '_decode_entity'), $str);
/*
@@ -278,9 +264,8 @@
*
* This prevents strings like this: ja vascript
* NOTE: we deal with spaces between characters later.
- * NOTE: preg_replace was found to be amazingly slow here on large blocks of data,
- * so we use str_replace.
- *
+ * NOTE: preg_replace was found to be amazingly slow here on
+ * large blocks of data, so we use str_replace.
*/
if (strpos($str, "\t") !== FALSE)
@@ -293,34 +278,23 @@
*/
$converted_string = $str;
- /*
- * Not Allowed Under Any Conditions
- */
-
- foreach ($this->never_allowed_str as $key => $val)
- {
- $str = str_replace($key, $val, $str);
- }
-
- foreach ($this->never_allowed_regex as $key => $val)
- {
- $str = preg_replace("#".$key."#i", $val, $str);
- }
+ // Remove Strings that are never allowed
+ $str = $this->_do_never_allowed($str);
/*
* Makes PHP tags safe
*
- * Note: XML tags are inadvertently replaced too:
+ * Note: XML tags are inadvertently replaced too:
*
- * <?xml
+ * <?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.
+ // 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
@@ -333,9 +307,12 @@
*
* 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', 'applet', 'alert', 'document', 'write', 'cookie', 'window');
+ $words = array(
+ 'javascript', 'expression', 'vbscript', 'script',
+ 'applet', 'alert', 'document', 'write', 'cookie', 'window'
+ );
+
foreach ($words as $word)
{
$temp = '';
@@ -352,8 +329,9 @@
/*
* 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
+ * 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
{
@@ -374,30 +352,12 @@
$str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str);
}
}
- while ($original != $str);
+ while($original != $str);
unset($original);
- /*
- * Remove JavaScript Event Handlers
- *
- * Note: This code is a little blunt. It removes
- * the event handler and anything up to the closing >,
- * but it's unlikely to be a problem.
- *
- */
- $event_handlers = array('[^a-z_\-]on\w*','xmlns');
-
- if ($is_image === TRUE)
- {
- /*
- * Adobe Photoshop puts XML metadata into JFIF images, including namespacing,
- * so we have to allow this for images. -Paul
- */
- unset($event_handlers[array_search('xmlns', $event_handlers)]);
- }
-
- $str = preg_replace("#<([^><]+?)(".implode('|', $event_handlers).")(\s*=\s*[^><]*)([><]*)#i", "<\\1\\4", $str);
+ // Remove evil attributes such as style, onclick and xmlns
+ $str = $this->_remove_evil_attributes($str, $is_image);
/*
* Sanitize naughty HTML elements
@@ -407,7 +367,6 @@
*
* 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);
@@ -423,45 +382,28 @@
*
* 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)", $str);
- /*
- * Final clean up
- *
- * This adds a bit of extra precaution in case
- * something got through the above filters
- *
- */
- foreach ($this->never_allowed_str as $key => $val)
- {
- $str = str_replace($key, $val, $str);
- }
- foreach ($this->never_allowed_regex as $key => $val)
- {
- $str = preg_replace("#".$key."#i", $val, $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.
+ * 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 ($is_image === TRUE)
{
- if ($str == $converted_string)
- {
- return TRUE;
- }
- else
- {
- return FALSE;
- }
+ return ($str == $converted_string) ? TRUE: FALSE;
}
log_message('debug', "XSS Filtering completed");
@@ -473,157 +415,25 @@
/**
* Random Hash for protecting URLs
*
- * @access public
* @return string
*/
public function xss_hash()
{
- if ($this->xss_hash == '')
+ if ($this->_xss_hash == '')
{
if (phpversion() >= 4.2)
- mt_srand();
- else
- mt_srand(hexdec(substr(md5(microtime()), -8)) & 0x7fffffff);
-
- $this->xss_hash = md5(time() + mt_rand(0, 1999999999));
- }
-
- return $this->xss_hash;
- }
-
- // --------------------------------------------------------------------
-
- /**
- * Compact Exploded Words
- *
- * Callback function for xss_clean() to remove whitespace from
- * things like j a v a s c r i p t
- *
- * @access private
- * @param type
- * @return type
- */
- private function _compact_exploded_words($matches)
- {
- return preg_replace('/\s+/s', '', $matches[1]).$matches[2];
- }
-
- // --------------------------------------------------------------------
-
- /**
- * Sanitize Naughty HTML
- *
- * Callback function for xss_clean() to remove naughty HTML elements
- *
- * @access private
- * @param array
- * @return string
- */
- private 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 $str;
- }
-
- // --------------------------------------------------------------------
-
- /**
- * JS Link Removal
- *
- * Callback function for xss_clean() to sanitize links
- * This limits the PCRE backtracks, making it more performance friendly
- * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
- * PHP 5.2+ on link-heavy strings
- *
- * @access private
- * @param array
- * @return string
- */
- private function _js_link_removal($match)
- {
- $attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));
- return str_replace($match[1], preg_replace("#href=.*?(alert\(|alert&\#40;|javascript\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
- }
-
- /**
- * JS Image Removal
- *
- * Callback function for xss_clean() to sanitize image tags
- * This limits the PCRE backtracks, making it more performance friendly
- * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
- * PHP 5.2+ on image tag heavy strings
- *
- * @access private
- * @param array
- * @return string
- */
- private function _js_img_removal($match)
- {
- $attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));
- return str_replace($match[1], preg_replace("#src=.*?(alert\(|alert&\#40;|javascript\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
- }
-
- // --------------------------------------------------------------------
-
- /**
- * Attribute Conversion
- *
- * Used as a callback for XSS Clean
- *
- * @access private
- * @param array
- * @return string
- */
- private function _convert_attribute($match)
- {
- return str_replace(array('>', '<', '\\'), array('>', '<', '\\\\'), $match[0]);
- }
-
- // --------------------------------------------------------------------
-
- /**
- * Filter Attributes
- *
- * Filters tag attributes for consistency and safety
- *
- * @access private
- * @param string
- * @return string
- */
- private function _filter_attributes($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);
+ mt_srand();
}
+ else
+ {
+ mt_srand(hexdec(substr(md5(microtime()), -8)) & 0x7fffffff);
+ }
+
+ $this->_xss_hash = md5(time() + mt_rand(0, 1999999999));
}
- return $out;
- }
-
- // --------------------------------------------------------------------
-
- /**
- * HTML Entity Decode Callback
- *
- * Used as a callback for XSS Clean
- *
- * @access private
- * @param array
- * @return string
- */
- private function _decode_entity($match)
- {
- return $this->entity_decode($match[0], strtoupper(config_item('charset')));
+ return $this->_xss_hash;
}
// --------------------------------------------------------------------
@@ -642,7 +452,6 @@
* character set, and the PHP developers said they were not back porting the
* fix to versions other than PHP 5.x.
*
- * @access public
* @param string
* @param string
* @return string
@@ -657,7 +466,8 @@
// correctly. html_entity_decode() does not convert entities without
// semicolons, so we are left with our own little solution here. Bummer.
- if (function_exists('html_entity_decode') && (strtolower($charset) != 'utf-8' OR is_php('5.0.0')))
+ if (function_exists('html_entity_decode') &&
+ (strtolower($charset) != 'utf-8'))
{
$str = html_entity_decode($str, ENT_COMPAT, $charset);
$str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);
@@ -682,7 +492,6 @@
/**
* Filename Security
*
- * @access public
* @param string
* @return string
*/
@@ -721,16 +530,289 @@
"%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
+ $evil_attributes = array('on\w*', 'style', 'xmlns');
+
+ if ($is_image === TRUE)
+ {
+ /*
+ * Adobe Photoshop puts XML metadata into JFIF images,
+ * including namespacing, so we have to allow this for images.
+ */
+ unset($evil_attributes[array_search('xmlns', $evil_attributes)]);
+ }
+
+ do {
+ $str = preg_replace(
+ "#<(/?[^><]+?)([^A-Za-z\-])(".implode('|', $evil_attributes).")(\s*=\s*)([\"][^>]*?[\"]|[\'][^>]*?[\']|[^>]*?)([\s><])([><]*)#i",
+ "<$1$6",
+ $str, -1, $count
+ );
+ } while ($count);
+
+ return $str;
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Sanitize Naughty HTML
+ *
+ * Callback function for xss_clean() to remove naughty HTML elements
+ *
+ * @param array
+ * @return string
+ */
+ protected function _sanitize_naughty_html($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)
+ {
+ $attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));
+
+ return str_replace($match[1], preg_replace("#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * JS Image Removal
+ *
+ * Callback function for xss_clean() to sanitize image tags
+ * This limits the PCRE backtracks, making it more performance friendly
+ * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
+ * PHP 5.2+ on image tag heavy strings
+ *
+ * @param array
+ * @return string
+ */
+ protected function _js_img_removal($match)
+ {
+ $attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));
+
+ return str_replace($match[1], preg_replace("#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Attribute Conversion
+ *
+ * Used as a callback for XSS Clean
+ *
+ * @param array
+ * @return string
+ */
+ protected function _convert_attribute($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)
+ {
+ foreach ($this->_never_allowed_str as $key => $val)
+ {
+ $str = str_replace($key, $val, $str);
+ }
+
+ foreach ($this->_never_allowed_regex as $key => $val)
+ {
+ $str = preg_replace("#".$key."#i", $val, $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]) &&
+ $_COOKIE[$this->_csrf_cookie_name] != '')
+ {
+ return $this->_csrf_hash = $_COOKIE[$this->_csrf_cookie_name];
+ }
+
+ return $this->_csrf_hash = md5(uniqid(rand(), TRUE));
+ }
+
+ return $this->_csrf_hash;
+ }
+
}
// END Security Class