可能潜在安全漏洞，如跨站脚本攻击（XSS）、跨站请求伪造（CSRF）、代码注入漏洞、字符编码循环漏洞等，如何在代码中避免呢?
对于XSS, 前辈早有精品, 如 http://kallahar.com/smallprojects/php_xss_filter_function.php
function RemoveXSS($val) {
// remove all non-printable characters. CR(0a) and LF(0b) and TAB(9) are allowed
// this prevents some character re-spacing such as
// 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
$search = ‘abcdefghijklmnopqrstuvwxyz’;
$search .= ‘ABCDEFGHIJKLMNOPQRSTUVWXYZ’;
$search .= ‘1234567890!@#$%^&*()’;
$search .= ‘~`”;:?+/={}[]-_|’\';
for ($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[$i], 0, 2).”.substr($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 $val;
}
跨站请求伪造（CSRF）:
http://www.codewalkers.com/c/a/Miscellaneous/Stopping-CSRF-Attacks-in-Your-PHP-Applications/
不过想想php 模拟QQ Mail 登录，好像这招不一定灵的!
代码注入就不用说了，$_GET 、$_POST 、$_REQUEST 这些前记得根据具体情况, 加个 intval 、htmlspecialchars、 htmlentities 、addslashes小心为上
再就是字符转换后的漏洞了 http://www.sai52.com/archives/493/
想想不少网站用email 作为用户登录名，还是蛮安全的
