'[removed]',
'document.write' => '[removed]',
'.parentNode' => '[removed]',
'.innerHTML' => '[removed]',
'window.location' => '[removed]',
'-moz-binding' => '[removed]',
'' => '-->',
' '<![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]'
);
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;
// Set the CSRF hash
$this->_csrf_set_hash();
log_message('debug', "Security Class Initialized");
}
// --------------------------------------------------------------------
/**
* Verify Cross Site Request Forgery Protection
*
* @access public
* @return null
*/
public function csrf_verify()
{
// If no POST data exists we will set the CSRF cookie
if (count($_POST) == 0)
{
return $this->csrf_set_cookie();
}
// Do the tokens exist in both the _POST and _COOKIE arrays?
if ( ! isset($_POST[$this->csrf_token_name]) OR ! isset($_COOKIE[$this->csrf_cookie_name]))
{
$this->csrf_show_error();
}
// Do the tokens match?
if ($_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 ");
}
// --------------------------------------------------------------------
/**
* Set Cross Site Request Forgery Protection Cookie
*
* @access public
* @return null
*/
public function csrf_set_cookie()
{
$expire = time() + $this->csrf_expire;
setcookie($this->csrf_cookie_name, $this->csrf_hash, $expire, config_item('cookie_path'), config_item('cookie_domain'), 0);
log_message('debug', "CRSF cookie Set");
}
// --------------------------------------------------------------------
/**
* Set Cross Site Request Forgery Protection Cookie
*
* @access private
* @return null
*/
private function _csrf_set_hash()
{
if ($this->csrf_hash == '')
{
// If 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] != '')
{
$this->csrf_hash = $_COOKIE[$this->csrf_cookie_name];
}
else
{
$this->csrf_hash = md5(uniqid(rand(), TRUE));
}
}
return $this->csrf_hash;
}
// --------------------------------------------------------------------
/**
* Show CSRF Error
*
* @access public
* @return null
*/
public function csrf_show_error()
{
show_error('The action you have requested is not allowed.');
}
// --------------------------------------------------------------------
/**
* XSS Clean
*
* Sanitizes data so that Cross Site Scripting Hacks can be
* prevented. This function does a fair amount of work but
* it is extremely thorough, designed to prevent even the
* most obscure XSS attempts. Nothing is ever 100% foolproof,
* of course, but I haven't been able to get anything passed
* the filter.
*
* Note: This function should only be used to deal with data
* upon submission. It's not something that should
* be used for general runtime processing.
*
* This function was based in part on some code and ideas I
* got from Bitflux: http://channel.bitflux.ch/wiki/XSS_Prevention
*
* To help develop this script I used this great list of
* vulnerabilities along with a few other hacks I've
* harvested from examining vulnerabilities in other programs:
* http://ha.ckers.org/xss.html
*
* @access public
* @param mixed string or array
* @return string
*/
public function xss_clean($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);
/*
* 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);
/*
* URL Decode
*
* Just in case stuff like this is submitted:
*
* Google
*
* 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 = $str;
/*
* Not Allowed Under Any Conditions
*/
foreach ($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);
}
/*
* 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.
*
*/
$words = array('javascript', 'expression', 'vbscript', 'script', 'applet', 'alert', 'document', 'write', 'cookie', 'window');
foreach ($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 = $str;
if (preg_match("/]*?)(>|$)#si", array($this, '_js_link_removal'), $str);
}
if (preg_match("/![]()
]*?)(\s?/?>|$)#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 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);
/*
* 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: