ASP防止图片木马上传的代码

有时候通过程序上传木马，一般都是伪装成图片,下面是asp下检测图片木马的代码，需要的朋友可以参考下。ASP木马防御：

复制代码代码如下:

const adTypeBinary=1

dim jpg(1):jpg(0)=CByte(&HFF):jpg(1)=CByte(&HD8)

dim bmp(1):bmp(0)=CByte(&H42):bmp(1)=CByte(&H4D)

dim png(3):png(0)=CByte(&H89):png(1)=CByte(&H50):png(2)=CByte(&H4E):png(3)=CByte(&H47)

dim gif(5):gif(0)=CByte(&H47):gif(1)=CByte(&H49):gif(2)=CByte(&H46):gif(3)=CByte(&H39):gif(4)=CByte(&H38):gif(5)=CByte(&H61)

Response.Write CheckFileType(Server.MapPath(2.gif))

function CheckFileType(filename)

on error resume next

CheckFileType=false

dim fstream,fileExt,stamp,i

fileExt=mid(filename,InStrRev(filename,.)+1)

set fstream=Server.createobject(ADODB.Stream)

fstream.Open

fstream.Type=adTypeBinary

fstream.LoadFromFile filename

fstream.position=0

select case fileExt

case jpg,jpeg

stamp=fstream.read(2)

for i=0 to 1

if ascB(MidB(stamp,i+1,1))=jpg(i) then CheckFileType=true else CheckFileType=false

next

case gif

stamp=fstream.read(6)

for i=0 to 5

if ascB(MidB(stamp,i+1,1))=gif(i) then CheckFileType=true else CheckFileType=false

next

case png

stamp=fstream.read(4)

for i=0 to 3

if ascB(MidB(stamp,i+1,1))=png(i) then CheckFileType=true else CheckFileType=false

next

case bmp

stamp=fstream.read(2)

for i=0 to 1

if ascB(MidB(stamp,i+1,1))=bmp(i) then CheckFileType=true else CheckFileType=false

next

end select

fstream.Close

set fseteam=nothing

if err.number<>0 then CheckFileType=false

end function

%>