Trojan principle: The intruder uses such tools such as ASP Picture Trojan Generator to merge a normal picture with an ASP Trojan file into a picture file (will be harmful to the site
The ASP code inserts in the picture code, although the picture still can display normally, but the file content and the size has been changed, then uploads this one by the website file upload function
' FA ' picture, and then realize the purpose of uploading ASP Trojan horse.
' Precautionary method: because this kind of Trojan horse is a picture and the two in one, so need to check the file before uploading pictures, if the contents of the file is not legal (that is, contain malicious code in the inside),
' It is forbidden to upload, thus blocking the origin of the Trojan attack, this is the first of the Trojan attack, vital, must be blocked.
'***************************************************************************
Copy Code code as follows:
' Begin------------------------------------------------------------------------------------------------------------------- -------
function Checkfilecontent (FileName)
Dim clientfile,clienttext,clientcontent,dangerstring,dsarray,attackflag,k
Set Clientfile=server.createobject ("Scripting.FileSystemObject")
Set Clienttext=clientfile.opentextfile (Server.MapPath (FileName), 1)
Clientcontent=lcase (Clienttext.readall)
Set clienttext=nothing
Set clientfile=nothing
Attackflag=false
Dangerstring= ". getfolder|. createfolder|. deletefolder|. createdirectory|. deletedirectory|. Saveas|wscript.shell|script.encode|server.|. Createobject|execute|activexobject|language=|include|filesystemobject|shell.application "
Dsarray=split (dangerstring, "|")
For k=0 to UBound (Dsarray)
If InStr (Clientcontent,dsarray (k)) >0 then ' determines whether the contents of the file contain dangerous action characters, and if so, you must delete the file.
Attackflag=true
Exit For
End If
Next
Checkfilecontent=attackflag
End Function
' End--------------------------------------------------------------------------------------------------------------------- -------
