So yesterday I was downloading Cave Story from cavestory.org and so I had to go to my downloads folder to get it and move it to a DVD that I was going to give to a friend so he could play the game. I know that the game and website are virus free. Anyway, as I was heading to my downloads folder, I found strange files on my computer that said they were created from either the 12th or 13th to the 15th, the day I found out about the virus. All of the folders were hidden (good thing that I have it set to where I can see hidden folders!) They were not windows update folders, as they all were 5 character, seemingly random, alphabetical characters. (uppercase and lowercase) Inside of the folders were files that seemed randomly named gibberish, but some of them seemed like two dictionary words. (There were files named strange things like 'bomber breeds', 'unfortunately', and other things about a report or something.) Whenever I tried to open these files, it said they were corrupted or something. A few .txt files could be opened, but they looked corrupted, like they wee written in some computer language or something. These folders were under C:/ and also under C:/Users/ I went to run a scan with MBAM, and when I went to the custom scan option I saw that there was another drive, (A:) that I do not have on the computer. The icon of it was like a normal hard drive, but with a red X over it. It had one of these random folders in it, and I selected scan. (I only scanned that drive, as I had plans to restore my hard drive to factory default.) 20 minutes later, MBAM said that it found one PUM called 'PUM.Optional.NoDrives' I then checked WinDirStat, which I know can view partitions and has lots of information about them. WinDirStat said that it had zero folders, zero files, and was created on 1/1/1601 at 12:00:00, which was obviously bogus. I then went into file explorer, and it said that it was a Disconnected Network Drive. One of these folders had spread to my recovery partition. I had backups of my documents and app data and everything taken a few weeks ago, which was fine except for the app data, which I needed recent versions of because I had been playing Cave Story+ on steam for about 48 hours since that backup, and I didn't want to lose that data. (I ended up losing it anyway, apparently Steam doesn't save game save data to the AppData folder.) Another one of these gibberish folders appeared, I deleted it, then unplugged the drive immediately. While I was backing up things, I was very careful to only backup files for games and programs I knew about. I then reset to factory default, and afterwards I ran a scan with HitmanPro, (will run a scan with even more av soon.) and it said it found some suspicious things. They turned out to be bloatware that came with the PC, (a false positive) but I removed them anyway. I have checked my 2 drives several times a day now, and have found no signs of the virus. My question is, though, what virus did I have? It seemed very mysterious and creepy and I am very worried that it still may be on my PC somehow. I have searched up on it and have found nothing about it.
Also, I do not go to weird websites or open spam or anything like that. The only things I can think of is that I wanted to return a controller from a chinese company called 8BITDO. I emailed them about it and they gave me an attachment with a return label. I opened it, and it printed just fine and everything, and it didn't seem to come with anything else. I even deleted it afterwards.
The other possibility is that a found a file in my downloads called 'unconfirmed291971.crdownload' on my computer that seemed to be created at around the same time as the virus.
Thanks for any help, I am scared, as I said. Earlier I was shaking, now I have calmed down a bit but I am still worried. Computer viruses and hackers terrify me.