PHP清理跨站XSS xss_clean 函数 整理自codeigniter Security
PHP清理跨站XSS xss_clean 函数 整理自codeigniter Security
由Security Class 改编成函数xss_clean 单文件直接调用。BY吠品。
//来自codeigniter 清理跨站XSS xss_clean
//Security Class 改编成函数
function remove_invisible_characters($str, $url_encoded = TRUE)
{
$non_displayables = array();
if ($url_encoded) {
$non_displayables[] = '/%0[0-8bcef]/';
$non_displayables[] = '/%1[0-9a-f]/';
}
$non_displayables[] = '/[\\x00-\\x08\\x0B\\x0C\\x0E-\\x1F\\x7F]+/S';
do {
$str = preg_replace($non_displayables, '', $str, -1, $count);
} while ($count);
return $str;
}
function _convert_attribute($match){
return str_replace(array('>', '<', '\\'), array('>', '<', '\\\\'), $match[0]);
}
function _decode_entity($match){
$str = $match[0];
if (stristr($str, '&') === FALSE){
return $str;
}
$str = html_entity_decode($str, ENT_COMPAT, 'UTF-8');
$str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);
return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str);
}
function _compact_exploded_words($matches)
{
return preg_replace('/\s+/s', '', $matches[1]).$matches[2];
}
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 $out;
}
function _js_link_removal($match){
return str_replace(
$match[1],
preg_replace(
'#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si',
'',
_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
),
$match[0]
);
}
function _js_img_removal($match){
return str_replace(
$match[1],
preg_replace(
'#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si',
'',
_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
),
$match[0]
);
}
function _sanitize_naughty_html($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 $str;
}
//调用这个函数
//from http://www.cnblogs.com/osfipin/
function xss_clean($str, $is_image = FALSE){
/*
* Is the string an array?
*
*/
if (is_array($str))
{
while (list($key) = each($str))
{
$str[$key] = xss_clean($str[$key]);
}
return $str;
}
$str = remove_invisible_characters($str);
// Validate Entities in URLs
$hash = md5(time() + mt_rand(0, 1999999999));
$str = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-]+)|i', $hash."\\1=\\2", $str);
$str = preg_replace('#(&\#?[0-9a-z]{2,})([\x00-\x20])*;?#i', "\\1;\\2", $str);
$str = preg_replace('#(&\#x?)([0-9A-F]+);?#i',"\\1\\2;",$str);
$str = str_replace($hash, '&', $str);
$str = rawurldecode($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", '_convert_attribute', $str);
$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", '_decode_entity', $str);
/*
* Remove Invisible Characters Again!
*/
$str = remove_invisible_characters($str);
/*
* Convert all tabs to spaces
*
* This prevents strings like this: ja vascript
* NOTE: we deal with spaces between characters later.
* NOTE: preg_replace was found to be amazingly slow here on
* large blocks of data, so we use str_replace.
*/
if (strpos($str, "\t") !== FALSE)
{
$str = str_replace("\t", ' ', $str);
}
/*
* Capture converted string for later comparison
*/
$converted_string = $str;
// Remove Strings that are never allowed
$_never_allowed_str = array(
'document.cookie' => '[removed]',
'document.write' => '[removed]',
'.parentNode' => '[removed]',
'.innerHTML' => '[removed]',
'window.location' => '[removed]',
'-moz-binding' => '[removed]',
'<!--' => '<!--',
'-->' => '-->',
'<![CDATA[' => '<![CDATA[',
'<comment>' => '<comment>'
);
$str = str_replace(array_keys($_never_allowed_str), $_never_allowed_str, $str);
$_never_allowed_regex = array(
'javascript\s*:',
'expression\s*(\(|&\#40;)', // CSS and IE
'vbscript\s*:', // IE, surprise!
'Redirect\s+302',
"([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?"
);
foreach ($_never_allowed_regex as $regex)
{
$str = preg_replace('#'.$regex.'#is', '[removed]', $str);
}
/*
* Makes PHP tags safe
*
* Note: XML tags are inadvertently replaced too:
*
* <?xml
*
* But it doesn't seem to pose a problem.
*/
if ($is_image === TRUE)
{
// Images have a tendency to have the PHP short opening and
// closing tags every so often so we skip those and only
// do the long opening tags.
$str = preg_replace('/<\?(php)/i', "<?\\1", $str);
}
else
{
$str = str_replace(array('<?', '?'.'>'), array('<?', '?>'), $str);
}
/*
* Compact any exploded words
*
* This corrects words like: j a v a s c r i p t
* These words are compacted back to their correct state.
*/
$words = array(
'javascript', 'expression', 'vbscript', 'script', 'base64',
'applet', 'alert', 'document', 'write', 'cookie', 'window'
);
foreach ($words as $word)
{
$temp = '';
for ($i = 0, $wordlen = strlen($word); $i < $wordlen; $i++)
{
$temp .= substr($word, $i, 1)."\s*";
}
// We only want to do this when it is followed by a non-word character
// That way valid stuff like "dealer to" does not become "dealerto"
$str = preg_replace_callback('#('.substr($temp, 0, -3).')(\W)#is', '_compact_exploded_words', $str);
}
/*
* Remove disallowed Javascript in links or img tags
* We used to do some version comparisons and use of stripos for PHP5,
* but it is dog slow compared to these simplified non-capturing
* preg_match(), especially if the pattern exists in the string
*/
do
{
$original = $str;
if (preg_match("/<a/i", $str))
{
$str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", '_js_link_removal', $str);
}
if (preg_match("/<img/i", $str))
{
$str = preg_replace_callback("#<img\s+([^>]*?)(\s?/?>|$)#si", '_js_img_removal', $str);
}
if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str))
{
$str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str);
}
}
while($original != $str);
unset($original);
// Remove evil attributes such as style, onclick and xmlns
// All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns
$evil_attributes = array('on\w*', 'style', 'xmlns', 'formaction');
if ($is_image === TRUE)
{
/*
* Adobe Photoshop puts XML metadata into JFIF images,
* including namespacing, so we have to allow this for images.
*/
unset($evil_attributes[array_search('xmlns', $evil_attributes)]);
}
do {
$count = 0;
$attribs = array();
// find occurrences of illegal attribute strings with quotes (042 and 047 are octal quotes)
preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*(\042|\047)([^\\2]*?)(\\2)/is', $str, $matches, PREG_SET_ORDER);
foreach ($matches as $attr)
{
$attribs[] = preg_quote($attr[0], '/');
}
// find occurrences of illegal attribute strings without quotes
preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*([^\s>]*)/is', $str, $matches, PREG_SET_ORDER);
foreach ($matches as $attr)
{
$attribs[] = preg_quote($attr[0], '/');
}
// replace illegal attribute strings that are inside an html tag
if (count($attribs) > 0)
{
$str = preg_replace('/(<?)(\/?[^><]+?)([^A-Za-z<>\-])(.*?)('.implode('|', $attribs).')(.*?)([\s><]?)([><]*)/i', '$1$2 $4$6$7$8', $str, -1, $count);
}
} while ($count);
/*
* Sanitize naughty HTML elements
*
* If a tag containing any of the words in the list
* below is found, the tag gets converted to entities.
*
* So this: <blink>
* Becomes: <blink>
*/
$naughty = 'alert|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|isindex|layer|link|meta|object|plaintext|style|script|textarea|title|video|xml|xss';
$str = preg_replace_callback('#<(/*\s*)('.$naughty.')([^><]*)([><]*)#is','_sanitize_naughty_html', $str);
/*
* Sanitize naughty scripting elements
*
* Similar to above, only instead of looking for
* tags it looks for PHP and JavaScript commands
* that are disallowed. Rather than removing the
* code, it simply converts the parenthesis to entities
* rendering the code un-executable.
*
* For example: eval('some code')
* Becomes: eval('some code')
*/
$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2(\\3)", $str);
// Final clean up
// This adds a bit of extra precaution in case
// something got through the above filters
$str = str_replace(array_keys($_never_allowed_str), $_never_allowed_str, $str);
foreach ($_never_allowed_regex as $regex)
{
$str = preg_replace('#'.$regex.'#is', '[removed]', $str);
}
/*
* Images are Handled in a Special Way
* - Essentially, we want to know that after all of the character
* conversion is done whether any unwanted, likely XSS, code was found.
* If not, we return TRUE, as the image is clean.
* However, if the string post-conversion does not matched the
* string post-removal of XSS, then it fails, as there was unwanted XSS
* code found and removed/changed during processing.
*/
if ($is_image === TRUE)
{
return ($str == $converted_string) ? TRUE: FALSE;
}
return $str;
}
///测试
function show($r){
echo $r;
echo '<br/>';
echo xss_clean($r);
echo '<br/><br/>';
}
show('%3Cscript%3Ealert(’XSS’)%3C/script%3E');
show('%3c/a%3e%3cscript%3ealert(%22xss%22)%3c/script%3e');
show('<IMG SRC="javascript:alert(’XSS’);">');
show('<STYLE type="text/css">BODY{background:url("javascript:alert(’XSS’)")}</STYLE>');
可以测试下效果如何