I bought a used PC that had a cracked game and several hardware-monitoring tools installed. Malwarebytes detected an activator for one of the tools, and VirusTotal reported 40 out of 66 detections. I haven't signed into any accounts on the machine, but I'm worried about an infostealer or other malware.
I'd like to create a Windows installation USB, boot from it, delete every existing partition, and perform a completely clean installation. The usual advice is to create the installer using another trusted computer, but I currently only have this PC available. Could malware infect the USB while I'm creating the installer? Would Safe Mode with Networking be reliable for this, and can Windows Setup itself be modified or compromised? What is the safest practical approach?
3 Answers
If you have an Android phone that supports USB OTG, it may be possible to download the official ISO or installer files and write them to a USB drive, but compatibility varies and it’s less straightforward than using another computer. A library, repair shop, or someone you trust could also create the installer for you. Avoid using the questionable Windows installation itself to prepare the media if you can.
The most reliable solution is still to create the installer on a different trusted device. If you have two USB drives, one option is to boot this computer from a Linux live USB, download the official Windows ISO, verify it if possible, and create the Windows installer from within Linux. Malware designed to persist into a freshly created Windows installer while you’re running a normal, current Linux live environment is extremely unlikely.
After booting the Windows installer, delete all partitions on the target drive and let Setup recreate them. Then install updates, drivers, and applications only from official sources. Don’t sign into important accounts until the reinstall is complete and fully updated.
A factory reset from inside the existing Windows installation isn’t the same as wiping the disk from external installation media. Boot from the Windows USB, press Shift+F10 if needed to open Command Prompt, use DiskPart carefully to select and clean the correct drive, then install to the unallocated space. Make sure you have network, storage, and other required drivers available first, since some systems may need them during Setup.
That’s what I was planning to do, but my main concern was whether the existing malware could infect the USB while I was creating it. Using a Linux live environment or another trusted device seems safer than relying on the current Windows installation.