So, I was trying to do a backup with my USB drive on my teachers laptop because her laptop is infected but I have a question first. How do you even prevent getting the clean USB drive infected before plugging it into the infected computer? Because I am risking my flash drive and I want to know how. Despite, on her USB flash drive. Files turned into shortcuts and folders turned into .bat extension. Also her laptop doesn't even have an antivirus because the virus prevents it from being installed. Even if it has one before the virus even came, it wouldn't even open.
Well, there is no other way around I know, you have to clear the PC with an antivirus software. You can install a portable antivirus software on the USB or download one to the infected laptop. Logged in as an administrator you must be able to install and run antivirus software.
Try avira anti maleware and calmwin https/portableapps.com/apps/security/clamwin_portable
1) Install the portable anti virus and anti maleware softrware onto the usb drive (use the link or look for other free portable solutions)
2) Try to clean the laptop
3) do not connect any media that has been plugged into the infected device unless you have antivirus on the other PC
Also try to burn the installer of the operating system onto a non-rewritable CD or DVD when making the clean install. Viruses may hide in system memory, so once you got the new operating system running, try to install an antivirus
If those steps are not possible, ask for professional help. Infecting other devices would be useless.
The safest way to backup files from an infected system is to have an external dock on a clean system. Boot the clean system, make sure it is set to do absolutely nothing with external media (ALL autoplay disabled). Then turn on the dock with the infected drive. From there you can recover files. Antivirus and anti-malware SCAN the recovered files in case the malware has slipped something nasty in. Something NAMED *.jpg or .ppt, etc may not actually be one.
If the infected OS is in control, many things it could do.
If you change the bios to allow booting from external media, you could always try a toolset like parted magic, which runs a unix OS, bootable from USB or CD. This also would allow you to bypass the installed windows OS.