如何php防止XSS攻击
什么是XSS：这里通俗的讲，就像是SQL注入一样，XSS攻击也可以算是对HTML和JS的一种注入。你本来希望得到是从用户那得到一段有用的文本文字，但用户提交给你的却是别有用心的可执行javascript或者其他脚本，当你再把这些提交的内容显示到页面上时，xss攻击就发生了。
关于xss的攻击方式和场景层出不穷，以下是一些解决的方法，各位可以借鉴，如果有不准确的在下方评论，忘各位大神Coder不吝赐教
方法一
PHP htmlentities()函数 htmlentities() 函数把字符转换为 HTML 实体。语法为htmlentities(string,flags,character-set,double_encode)
实例把一些字符转换成HTML实体
<?php $str = "Jane & "Tarzan""; echo htmlentities($str, ENT_COMPAT); // Will only convert double quotes echo "<br>"; echo htmlentities($str, ENT_QUOTES); // Converts double and single quotes echo "<br>"; echo htmlentities($str, ENT_NOQUOTES); // Does not convert any quotes ?>上面代码的 HTML 输出如下（查看源代码）：
<!DOCTYPE html> <html> <body> Jane & "Tarzan"<br> Jane & "Tarzan"<br> Jane & "Tarzan" </body> </html>上面代码的浏览器输出如下
Jane & "Tarzan"
Jane & "Tarzan"
Jane & "Tarzan"
方法二 对COOKIE进行IP绑定
cookie里面一般有自动登录信息和session_id,就算对cookie里面的内容全部加了密，cookie的信息一但被别人通过XSS攻击获取后也一样等同于把自己的帐号密码给了别人。
对cookie进行IP绑定，（当然也可以获取用户客户端更多的其它信息进行同时绑定）可以根据用户的IP来判断这个cookie是不是来原始授权用户。代码案例如下
用户设置了自动登录时保存自动登录信息:
$auto=I("post.auto");//用户设置了自动登录
if(!empty($auto)){
cookie("auto",encrypt(serialize($data)));//将登录信息保存到cookie,其中$data里含有加密后的帐号，密码，和用户的IP，这里的cookie已在全局中设置过期日期为一周
}
用户关闭浏览器再次访问网站时，进行自动登录
if (!is_login()) {//是否未登录状态?
$auth=cookie("auto");
if(!empty($auth)){//是否未有自动登录cookie?
$data=unserialize(decrypt($auth));
if(!empty($data) && !empty($data["username"]) && !empty($data["password"]) && !empty($data["last_login_ip"])){
$user=M("Member")->where(array("username"=>$data["username"],"password"=>$data["password"]))->find();
if(!empty($user["id"])&&($user["last_login_ip"]==get_client_ip())){//cookie帐号密码是否有效?//IP来源是否相同?
login_session($user["id"], $user["username"], $data["last_login_ip"]);//用户自动登录成功
}
}
}
}优点：大多数场景下可使被XSS攻击盗取的cookie失效。缺点：由于IP存在多台电脑共用的可能，对绑定做不到十分精细。
方法三 HTML5值得观注的新特性：
方法四 这有一个remove—xss方法，可以调用
function remove_xss($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 script>
// note that you have to handle splits with
,
, and 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 SRC=@avascript:alert("XSS")>
$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 ,
, and
$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;
}
以上是本人个人经验积累，具体解决办法还要根据每个人编程的情况具体分析。请多指教~声明：该文观点仅代表作者本人，牛骨文系教育信息发布平台，牛骨文仅提供信息存储空间服务。
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