When buying a used PC you need to do some preventive checks to avoid putting your personal data at risk
Buying a second-hand PC can be a very convenient option, because if you find the right offer you can take home a machine that is no longer very recent but still more than sufficient for your use, paying a sometimes very advantageous price. However, you also have to consider the risks you might run.
For example, the used PC might be affected by a virus even if the previous owner does not know it. Or, the previous owner may have installed software to mine his cryptocurrencies without your knowledge. In the most extreme cases, he might even have installed software to spy on the new owner and steal his bank account login credentials. Or, more simply, illegal files may still be on your hard drive. So what should you do when buying a used PC to stay safe from these dangers?
Deleting data from the hard drive
Deleting the contents of the hard drive and reinstalling the operating system may not be enough to remove a possible threat. It’s better to proceed to a wipe, that is to say a deep deletion of the data that is performed by writing on each track of the disk a very long series of zeros. There are special utilities, even free ones, that do this job for you: for example the official applications of the disk manufacturer (be it magnetic or SSD), almost always offer the possibility to do the wipe. Sometimes they call this feature “Secure erase”.
Buy another disk
Even more effective than wiping the disk is replacing it altogether: if you change the old disk for a new one, you will not inherit any viruses, malware or other malicious software from the old owner. Moreover, in most cases, the expense of a new drive is also repaid by the increase in PC performance, especially if you mount an SSD instead of a traditional drive.
Flash the BIOS
The last thing you need to do to make sure that your second-hand PC is not infected is to rewrite, or “flash” in technical jargon, the BIOS. In the Basic Input-Output System of the motherboard, in fact, a virus may have injected a dangerous code, which starts even before the operating system. With the new UEFIs equipped with Secure Boot this eventuality is much rarer, but it is still a possibility to be taken into account. By flashing the BIOS/UEFI memory, even if you restore the same official version that is already present, downloaded from the Internet to another computer, the risk is eliminated.