How can check double extensions in file while file uploading

Question

 

Hello, 

How can restrict files like Index.php.png. sample.aspx.cs.txt 

i need a solution for asp.net mvc5

 

 

My code below

 

here iam checking for single extension. but somebody can upload files like index.php.png

making critical security issue.

 

if any body know how i can modify this code for double extension checking, give me an answer.

 

 

var fileType = "";

if (files != null)

{

foreach (var file in files)

{

if (!string.IsNullOrEmpty(file.FileName) && !string.IsNullOrWhiteSpace(file.FileName))

{

string ext = System.IO.Path.GetExtension(file.FileName);

if (BasePage.CheckFileType(ext))

{

fileType = BasePage.FileRename(Path.GetExtension(file.FileName));

var physicalPath = Path.Combine(Server.MapPath("~/Uploads"), fileType);

file.SaveAs(physicalPath);

}

}

}

}

public bool CheckFileType(string ext)

{

string[] validFileTypes = { "PDF", "pdf", "png","PNG", "jpg","JPG","JPEG", "jpeg" };

bool isValidFile = false;

for (int i = 0; i < validFileTypes.Length; i++)

{

if (ext == "." + validFileTypes[i])

{

isValidFile = true;

break;

}

}

return isValidFile;

}

 

 

mohammed jaseefar

mohdjaseefar2gmail.com