Web的攻击，大部分是来自于外部，如Url上添加一些字段注入($_GET输入)，表单的提交注入(一般为$_POST)，所以在接收数据时对数据进行过滤，是很有必要的。
一. 一般php自带的过滤方法有:
1.空过滤
trim过滤字符串首尾空格
$name = trim($_POST[‘name‘]);
2.标签过滤 :
strip_tags会将字符串中的php标签(<?php ?>)Html标签(<h1></h1><script></script>....等)移除。一定程序上阻止了恶意注入。
//for example: $_POST[‘name‘] = "<script>alert(‘hehe‘);</script>"; var_dump($_POST[‘name‘]);//弹出信息框 ‘hehe‘ $name = strip_tags($_POST[‘name‘]); var_dump($name); //string(14) "alert(‘hehe‘);"
3.转数据类型
若知道要接收的数据是整形或浮点形，可以直接转数据类型。
//转整形 $number = intval($_POST[‘number‘]); $price = floatval($_POST[‘price‘]);
4.移除xss攻击（跨站脚本攻击）
xss攻击有时会把标签转换成其他数据，strip_tags防止不了，
ThinkPHP中有个remove_xss方法，可以将大部分xss攻击阻止。这方法在 ./ThinkPHP/Extend/Function/extend.php中，为了方便使用，可以放到项目的common.php里。
方法如下
/**
* @from extend.php
* 过滤xss攻击
* @param str $val
* @return mixed
*/
function remove_xss($val) {
// remove all non-printable characters. CR(0a) and LF(0b) and TAB(9) are allowed
// this prevents some character re-spacing such as <java\0script>
// note that you have to handle splits with \n, \r, and \t later since they *are* allowed in some inputs
$val = preg_replace(‘/([\x00-\x08,\x0b-\x0c,\x0e-\x19])/‘, ‘‘, $val);
// straight replacements, the user should never need these since they‘re normal characters
// this prevents like <IMG [email protected]:alert(‘XSS‘)>
$search = ‘abcdefghijklmnopqrstuvwxyz‘;
$search .= ‘ABCDEFGHIJKLMNOPQRSTUVWXYZ‘;
$search .= ‘[email protected]#$%^&*()‘;
$search .= ‘~`";:?+/={}[]-_|\‘\\‘;
for ($i = 0; $i < strlen($search); $i++) {
// ;? matches the ;, which is optional
// 0{0,7} matches any padded zeros, which are optional and go up to 8 chars
// @ @ search for the hex values
$val = preg_replace(‘/(&#[xX]0{0,8}‘.dechex(ord($search[$i])).‘;?)/i‘, $search[$i], $val); // with a ;
// @ @ 0{0,7} matches ‘0‘ zero to seven times
$val = preg_replace(‘/(�{0,8}‘.ord($search[$i]).‘;?)/‘, $search[$i], $val); // with a ;
}
// now the only remaining whitespace attacks are \t, \n, and \r
$ra1 = array(‘javascript‘, ‘vbscript‘, ‘expression‘, ‘applet‘, ‘meta‘, ‘xml‘, ‘blink‘, ‘link‘, ‘style‘, ‘script‘,
‘embed‘, ‘object‘, ‘iframe‘, ‘frame‘, ‘frameset‘, ‘ilayer‘, ‘layer‘, ‘bgsound‘, ‘title‘, ‘base‘);
$ra2 = array(‘onabort‘, ‘onactivate‘, ‘onafterprint‘, ‘onafterupdate‘, ‘onbeforeactivate‘, ‘onbeforecopy‘, ‘onbeforecut‘,
‘onbeforedeactivate‘, ‘onbeforeeditfocus‘, ‘onbeforepaste‘, ‘onbeforeprint‘, ‘onbeforeunload‘, ‘onbeforeupdate‘,
‘onblur‘, ‘onbounce‘, ‘oncellchange‘, ‘onchange‘, ‘onclick‘, ‘oncontextmenu‘, ‘oncontrolselect‘, ‘oncopy‘, ‘oncut‘,
‘ondataavailable‘, ‘ondatasetchanged‘, ‘ondatasetcomplete‘, ‘ondblclick‘, ‘ondeactivate‘, ‘ondrag‘, ‘ondragend‘,
‘ondragenter‘, ‘ondragleave‘, ‘ondragover‘, ‘ondragstart‘, ‘ondrop‘, ‘onerror‘, ‘onerrorupdate‘, ‘onfilterchange‘,
‘onfinish‘, ‘onfocus‘, ‘onfocusin‘, ‘onfocusout‘, ‘onhelp‘, ‘onkeydown‘, ‘onkeypress‘, ‘onkeyup‘, ‘onlayoutcomplete‘,
‘onload‘, ‘onlosecapture‘, ‘onmousedown‘, ‘onmouseenter‘, ‘onmouseleave‘, ‘onmousemove‘, ‘onmouseout‘, ‘onmouseover‘,
‘onmouseup‘, ‘onmousewheel‘, ‘onmove‘, ‘onmoveend‘, ‘onmovestart‘, ‘onpaste‘, ‘onpropertychange‘,‘onreadystatechange‘,
‘onreset‘, ‘onresize‘, ‘onresizeend‘, ‘onresizestart‘, ‘onrowenter‘, ‘onrowexit‘, ‘onrowsdelete‘, ‘onrowsinserted‘,
‘onscroll‘, ‘onselect‘, ‘onselectionchange‘, ‘onselectstart‘, ‘onstart‘, ‘onstop‘, ‘onsubmit‘, ‘onunload‘);
$ra = array_merge($ra1, $ra2);
$found = true; // keep replacing as long as the previous round replaced something
while ($found == true) {
$val_before = $val;
for ($i = 0; $i < sizeof($ra); $i++) {
$pattern = ‘/‘;
for ($j = 0; $j < strlen($ra[$i]); $j++) {
if ($j > 0) {
$pattern .= ‘(‘;
$pattern .= ‘(&#[xX]0{0,8}([9ab]);)‘;
$pattern .= ‘|‘;
$pattern .= ‘|(�{0,8}([9|10|13]);)‘;
$pattern .= ‘)*‘;
}
$pattern .= $ra[$i][$j];
}
$pattern .= ‘/i‘;
$replacement = substr($ra[$i], 0, 2).‘<x>‘.substr($ra[$i], 2); // add in <> to nerf the tag
$val = preg_replace($pattern, $replacement, $val); // filter out the hex tags
if ($val_before == $val) {
// no replacements were made, so exit the loop
$found = false;
}
}
}
return $val;
}
调用时如下
$name = remove_xss($_POST[‘name‘]);
基本我使用的就这几种方法。如果有其他不错的方法，请一起来分享。
时间： 2024-08-01 07:08:51