How to verify: MS XLS is what it is supposed to be

securing uploading to a dir

[henry0]

I need to allow a site admin to upload MS XL files
To an xl_dir, then I have a script that performs DB insert by grabbing data from the XL file.

I might be over cautious knowing that only logged user with top admin level will be able to reach that upload area.
(I know how PW are handeled in an office environment!)
Aside verifying the file extension how may I make sure that the file is harmless?
Regex is not an option knowing MS file spaghetti code :)
I looked around but am still clueless

[venelin13]

While uploading the file, check its type:

$_FILES['my_file']['type']

If you upload an MS Excel file, you should expect the mime type to be "application/vnd.ms-excel" or similar.

[henry0]

Ahhh why didn't I think about the obvious!
going to hide behind my desk for a while :)