Booting into a windows 8 or 10

[trinidad]

It is ridiculously unlikely that EFI has a virus. The only quirk in windows8 that I know of, is the requirement of dual signing keys, one EFI boot, the other kernel, but this is an OEM spec and HP has never enabled it to my knowledge on home desktops. You may want to provide specific information, mobo, cpu, OEM to a RHEL forum. They would know if the dual key is the issue though I doubt HP has ever done this. EFI is not new, except to MS, the opposite of what you may think. The problems of OEM specificity do not exist with windows10, and Ubuntu trusty provides dual signing keys anyway. I suspect you have gone through your steps incorrectly. Depending on your BIOS version, you may be able to raise a shell to correct the EFI, unless of course you deleted the partition on your drive that contains the logs and shell. Check for that with HP. Finally, some windows8 machines did not contain the CSM for legacy booting from the factory, and some versions of windows8 software, did not allow EFI to legacy options even if they did actually exist on the HDD. Again I doubt any of these things are your problem here. Some windows security features transfer to some USB sticks. You can avoid this by partitioning the USB first, before copying the ISO to USB. The very first thing you must do, when attempting a dual boot with windows8 is disable windows quick boot, then you must check to see if windows quick return from suspend is enabled, and disable that. Certain versions of Windwos8 are the only ones I know of where this is necessary, but there are patches available for this from MS, at least there were a couple of years ago. Again I am not aware of HP ever manufacturing a home desktop machine without legacy options, and/or obtainable shell options for BIOS and EFI even those preloaded with windows8. It was commonly only a low-end laptop issue, and was actually rare. Again some windows8 laptop machines ran EFI with their own windows proprietary binaries, and the only way around that is working from an EFI shell to make changes and additions which you will have to obtain from HP if it is not present. Provide your mobo, cpu, ram numbers, and versions of BIOS and/or EFI, HP model and date, and then your problem can be solved. You are correct in only one supposition. The problem is windows related and you have obviously compounded it into the EFI. I'm not sure of the odds, but about 1 in several trillions that you actually have an EFI virus. You need to be more specific.
Trinidad