How to detect if a file is a favicon in PHP?

I need to check if an uploaded file is a favicon type and I need do it in a secure way.

If I upload a favicon file through an input file and print the $_FILES variable, I can see that the variable has the following type value:

image/vnd.microsoft.icon

I know that I can check if that value matches that, but I think that the user can dumper it. If someone could give me some tip I'd be grateful

Solution

If you want avoid using any external tools, https://github.com/lordelph/icofileloader provides a native PHP method for parsing .ico files

$loader = new Elphin\IcoFileLoader\IcoFileService;
try {
    /** @var Elphin\IcoFileLoader\Icon $icon */
    $icon = $loader->fromFile('/path/to/icon.ico');

    //perform further inspection or render the icon as an image here...

} catch (\Exception $e) {
    //not an .ico file
}