The first rule of dealing with malware and exploits, don’t panic, you’ll make things worse, the second rule is, isolate the machine from your other machines ( so make sure it doesn’t communicate with anything, Bluetooth, Hotspots, and obviously the Internet ), thirdly, boot into safe mode with networking off, and delete the files… check the event viewer, check the task manager, check the installed apps, check for hidden files in the C directory, check for installed Extensions in your browser, if anything seem unusual, revert the changes, by restoring to a previous restore point ( you do have a restore point set right ? )
If the problem ( the change that has been done by the malware ) doesn’t go away, it’s time to backup your data to an external drive, and reimage the machine
Edit : don’t blindly trust files from Z Lib, some uploaders are evil, unfortunately… If the file seem bigger than it should be then it’s shady, also read the reviews, as far as opening PDFs in Firefox goes, Firefox PDF viewer is secure as far as I know, the last major vulnerability was in 2015
The first rule of dealing with malware and exploits, don’t panic, you’ll make things worse, the second rule is, isolate the machine from your other machines ( so make sure it doesn’t communicate with anything, Bluetooth, Hotspots, and obviously the Internet ), thirdly, boot into safe mode with networking off, and delete the files… check the event viewer, check the task manager, check the installed apps, check for hidden files in the C directory, check for installed Extensions in your browser, if anything seem unusual, revert the changes, by restoring to a previous restore point ( you do have a restore point set right ? )
If the problem ( the change that has been done by the malware ) doesn’t go away, it’s time to backup your data to an external drive, and reimage the machine
Edit : don’t blindly trust files from Z Lib, some uploaders are evil, unfortunately… If the file seem bigger than it should be then it’s shady, also read the reviews, as far as opening PDFs in Firefox goes, Firefox PDF viewer is secure as far as I know, the last major vulnerability was in 2015