Ya'll ain't seen nothing yet. For a time the leading UEFI vendor, Phoenix Technologies, had a web browser in their UEFI BIOS. Some photos from WinHEC 2005 can be seen here: https://www.anandtech.com/show/1670/8
tl;dr version: UEFI can download software from the internet, copy it to the Windows partition, edit the registry, and even add desktop icons and IE bookmarks. Phoenix sought to productize this.
If you've ever seen a Windows PC where you just couldn't get rid of certain pieces of software or icons, it may have been eBetween at work. This is effectively the same thing as the persistent malware attacks described in numerous security blogs. Phoenix has since rebranded their UEFI codebase to (irony alert!) SecureCore.
This was part of their "eBetween" UEFI BIOS that enabled them to show ads during boot-up (seriously) and also install software to Windows with what they called "Virtual Bundling Technology": https://indexarticles.com/business/business-wire/phoenix-tec... and https://www.cnet.com/tech/tech-industry/phoenix-jumps-on-web...
tl;dr version: UEFI can download software from the internet, copy it to the Windows partition, edit the registry, and even add desktop icons and IE bookmarks. Phoenix sought to productize this.
If you've ever seen a Windows PC where you just couldn't get rid of certain pieces of software or icons, it may have been eBetween at work. This is effectively the same thing as the persistent malware attacks described in numerous security blogs. Phoenix has since rebranded their UEFI codebase to (irony alert!) SecureCore.