Difference in browsers detecting extension type C#

Question

Currently using a file.contentType validation method to verify the extension type of an image uploaded to my application. Issue however if I download a .jpg image from the internet and rename it with a .png extension then try to upload it using my application, IE is detecting that it is not really a .png and rejects it. Chrome on the other hand uploads and displays it correctly.

I would like to know what is causing IE to notice this extension change and Chrome not to. Or does Chrome notice and just not care? I would either need to make IE accept the changed .jpeg --> .png OR, have Chrome pull the same error.

Thanks for any advice.

Answer 1

Credit goes to this post I found while doing some research.

http://www.aaronstannard.com/how-to-securely-verify-and-validate-image-uploads-in-aspnet-and-aspnet-mvc/