如何限制扩展名为.exe，.zip等的文件 [英] How to restrict files with extensions like .exe, .zip etc

问题描述

如果我上传文件test.exe，那么我的应用程序会限制它并发出警告消息。

但是，如果我将文件重命名为test.exe.txt，应用程序会将其上传到数据库中成功。



如何限制test.exe.txt或test.zip.txt的上传？



请建议。



谢谢，

Sneha。



< b>我尝试了什么：



我试过限制文件的内容类型但是它没有按要求工作。



for ex：

If i upload a file test.exe, then my application restricts it and give an alert message.
But, if i rename the file as test.exe.txt the application uploads it in database successfully.

How to restrict the upload for test.exe.txt or test.zip.txt?

Please suggest.

Thanks,
Sneha.

What I have tried:

I have tried restricting the contenttype of a file but it is not working as required.

for ex:

If (fuAttachment.PostedFile.ContentType <> "text/HTML" And fuAttachment.PostedFile.ContentType <> "text/plain" And fuAttachment.PostedFile.ContentType <> "Application/msword" And fuAttachment.PostedFile.ContentType <> "image/jpeg" And fuAttachment.PostedFile.ContentType <> "image/GIF" And fuAttachment.PostedFile.ContentType <> "application/pdf" And fuAttachment.PostedFile.ContentType <> "Application/x-msexcel" And fuAttachment.PostedFile.ContentType <> "image/bmp" And fuAttachment.PostedFile.ContentType <> "application/vnd.ms-outlook" And fuAttachment.PostedFile.ContentType <> "image/tiff" And fuAttachment.PostedFile.ContentType <> "video/mp4" And fuAttachment.PostedFile.ContentType <> "application/rar" And fuAttachment.PostedFile.ContentType <> "video/mpeg") Then
                    lblMsg.Visible = True
                    lblMsg.Text = "Upload JPG / BMP / JPEG / TIF / PDF / Doc / Excel / Zip format / MP4 / MPEG / MPG/ RAR / TXT / HTML / MSG files only"
                    Return False
                    Exit Try

推荐答案

由于您无法信任文件扩展名，因此您必须至少阅读二进制文件的一些字节来告诉它的确切性质。例如，请参阅：文件签名列表 - 维基百科 [ ^ ]和可执行文件 - 如何判断文件是EXE还是DLL？ - 堆栈溢出 [ ^ ]。

Since you cannot trust the file extension, then you have to read at least some bytes of the binary file to tell its exact nature. See, for instance: List of file signatures - Wikipedia[^] and executable - How to tell if a file is an EXE or a DLL? - Stack Overflow[^].

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