Hi, roughly 2 years ago someone decided to get very very upset online with me, this person knew my exact hardware and what software I ran.
Do you know this person personally? If not, then it is
extremely unlikely they knew as much about your system as you fear. They probably just had a lucky guess based on some information you posted about your system before.
And just because and even if someone knows which motherboard, CPU, RAM, graphics solution, operating system and other programs you run, that
IN NO WAY means they can access first your network, then your computer and then plant malware on your computer. That would be very challenging, even for a pro who is specifically and personally targeting you.
I am not saying it is impossible, but essentially, you would have to allow them access to your computer. This would have to be done by you clicking on an unsolicited link in an spam email they intentionally sent to you. Or they would have to be a next door neighbor or a stranger sitting in a car out front on your street pointing a directional antenna at your house AND you didn't change your wifi passphrase from the default. And note, that would only get them into your network, not your computer. Or they would need to physically connect via Ethernet cable to your network and hopefully you would notice a bad guy sitting in your house doing that. Or last, you left your computer unattended at a coffee shop and this person, who was following you around town, sat down at your computer when you went to the bathroom.
The most likely scenario, if it happened at all, is you fell victim to a "
socially engineered" con that tricked you into clicking on an unsolicited link, letting the malware in. This is commonly done by the bad guy sending spam that looks like it came from a legitimate source, like your bank or Walmart, etc. They send it to millions of people, hoping someone will take the bait. The email will claim your account was some how messed up and you need to click some link. That link then infects your computer or asks you to provide your log-in credentials, passwords, account numbers, etc. That information is then sent back to the bad guys.
Even if you were tricked to click on such an unsolicited link, fully updated operating systems and anti-malware programs, and even current browsers are pretty good at blocking the malicious activity.
Sadly, you have not told us anything about this computer - such as the OS. Hopefully it is Windows 10 (or at least W7) and you keep it fully updated. And hopefully, you didn't disable Microsoft Defender (formally Windows Defender) and then didn't install a capable alternative security solution. And you keep your security solution fully updated AND you are not "click-happy" on unsolicited downloads, attachments, links and popups. And finally, you changed the default passwords and passphrases to your computer and network to something not obvious. If you did that, then I highly doubt a person you knew infected your computer. It is just not that simple.
I recommend you make sure your operating system and security are fully updated. Change your wifi passphrase, computer passwords, and passwords to your banks and other important sites. Use a password manager so you only have to remember the password to the password manager. Don't write passwords down.
Use a supplemental scanner to verify you (the user and ALWAYS weakest link in security), or your primary solution didn't let something slip by. I typically recommend Malwarebytes for that.
Roughly a couple months ago I suspect a file I had received was a rootkit from them;
Back to this. How did you receive it? Did you open and run it?