How to check uplaod file is executable file or not in c#

Maharudra Gadekar

Hi,

i am try to check .exe file change extension .jpg and uplaod then upload this file but this file is how to check this is executable file or not in if change the extension in c#

please help me

thanks in advance

8 Replies

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sudipta sanyal9y ago
Accepted answer
Hi
Please Try
------------------------------------------
public static bool IsExeFile(byte[] FileContent)
{
var twoBytes = SubByteArray(FileContent, 0, 2);
return ((Encoding.UTF8.GetString(twoBytes) == "MZ")||(Encoding.UTF8.GetString(twoBytes) == "ZM"));
}
private static byte[] SubByteArray(byte[] data, int index, int length)
{
byte[] result = new byte[length];
Array.Copy(data, index, result, 0, length);
return result;
}

--------------------
Do mark as correct answer, if it resolves your issue.
+2
sudipta sanyal9y ago
Hi @Maharudra

@Rafnas was already answered the solution, Please go throw his post
0
Maharudra Gadekar9y ago
Hi Sudipta sanyal,
please help me.....if i am upload txt file changing extesion in jpg then what is the extension to check

same process of xlsx,xls,csv, docx, png,jpg,gif,jpeg,zip,rar file

help me
thanks in advance
0
sudipta sanyal9y ago
Hi @Rafnas

You right, I do not understand why he needs this requirement which may damage the system.
0
Rafnas T P9y ago
HI@sudipta,
you are right.
then dont change the extension.
if you know this is an .exe file then why you wanted to change the extension.

here he wanted to just change the extension if this is an .exe file
so that mean he wanted to upload .exe file as .jpg but I dont know why he is wanted to do like this, even he can upload .exe file directly.
so according to his requirement he can do like below if he is not worrying about as you said the issue.

string path=FullFilepath;
string fileExtension = System.IO.Path.GetExtension("FullFilepath");
if(fileExtension ==".exe")
{
path= System.IO.Path.ChangeExtension(fileLocation, ".jpeg");
}

0
sudipta sanyal9y ago
Hi @Rafnas
Many times we fall in a situation where we have implemented detection of file type based on file extension. It’s pretty easy to do that on both client as well as server side.

But does it guarantees that file uploaded is not actually an "exe" file.
Well, anyone can rename an "test.exe" to "test.txt" and upload it to your web application which may lead to dangerous results & even security threst.

For this we must validate the file in deeper.

+2
Rafnas T P9y ago
to get the file extension use deolw code
string fileExtension = System.IO.Path.GetExtension("FullFilepath");

to change the file extension directly you can use deolw code

string dest = System.IO.Path.ChangeExtension(fileLocation, ".jpeg");
-1
Amit Kumar9y ago
Hi Dear,
I agree with Sudipta Sanyal's code is running fine.
0

How to check uplaod file is executable file or not in c#

@Rafnas was already answered the solution, Please go throw his post