While browsing https://www.quovadisglobal.ch/Repository/DownloadRootsAndCRL.aspx site I noticed right after that when I browsed my trusted CA certificates it had automatically downloaded the trusted root CA without asking for my confirmation.
To reproduce the isue just perform the following steps: - Ensure you have no QuaVadis trusted root CA. - Open the site https://www.quovadisglobal.ch/Repository/DownloadRootsAndCRL.aspx. - Close the browser - Open again browser and check root CA certificate.
You will find the QuoVadis trusted root CA that was installed without asking for confirmation from the user.
I tried this with both IE8 and FF.