Question Best way to clean a hacked computer

[cb6731]

Hello,
I am pretty certain that my sons computer has been hacked. He is a teenager using it mainly for video games so I have no idea what crazy sites he's gone to or what he's downloaded that he shouldn't have. Recently one of his video game accounts was hacked and an email account. We have since added 2 factor authentication but continued to have issues which makes be believe the hacker must have access to the trusted computer. Malwarebytes found something in the registry that it deleted and it currently has McAfee that says its fine however we've gotten security notices with the email account since the antivirus scans. If the computer wasn't fairly new I would just scrap it so I don't have to worry but that is not an option. If I download the USB Windows 11 to reinstall the OS will it be 100% certain that the hacker cannot access the computer or is it possible that they loaded something in the BIOS or boot files that will come back? We currently have the computer powered off until this can be resolved. Thank you for your help.

 

[USAFRet]

Full wipe and reinstall, with known good install USB.

How To - Windows 10 clean install tutorial

If you are looking for the Windows 11 Clean install tutorial, you can find that here: Windows 11 Clean install tutorial (Click here) Otherwise, welcome to the Windows 10 Clean install tutorial This tutorial is intended to help you, step by step, to perform a clean install of Windows...

forums.tomshardware.com

How To - Windows 11 clean install tutorial

Windows 11 Clean install tutorial This tutorial is intended to help you, step by step, to perform a clean install of Windows 11, version 23H2 or newer but can be equally applied to earlier versions which may have some basic differences in the screens you see but will largely remain similar in...

forums.tomshardware.com

 

[cb6731]

Full wipe and reinstall, with known good install USB.

How To - Windows 10 clean install tutorial

If you are looking for the Windows 11 Clean install tutorial, you can find that here: Windows 11 Clean install tutorial (Click here) Otherwise, welcome to the Windows 10 Clean install tutorial This tutorial is intended to help you, step by step, to perform a clean install of Windows...

forums.tomshardware.com

How To - Windows 11 clean install tutorial

Windows 11 Clean install tutorial This tutorial is intended to help you, step by step, to perform a clean install of Windows 11, version 23H2 or newer but can be equally applied to earlier versions which may have some basic differences in the screens you see but will largely remain similar in...

forums.tomshardware.com

Thank you for your response. I downloaded the Windows 11 to USB but the computer does not recognize it. In BIOS my only boot options are Windows Boot, Onboard NIC (IPV4 PXE) and Onboard NIC (IPV6 PXE). I don't see any way to force it to read the USB. I disabled Windows Boot and it went into Support Assist and somehow eventually Install Windows 11 came up, but it was only seeing my USB as the partition available to install it on and did not see my hard drive. If I set BIOS back to windows boot it still boots fine. Any suggestions?

 

[punkncat]

Be aware that if network sharing was on and this infection is bad enough, or the son used other house computers then anything can/may also be infected. Where and how did you get the installer USB?

 

[USAFRet]

I downloaded the Windows 11 to USB but the computer does not recognize it.

How, exactly, did you do this?

 

[cb6731]

How, exactly, did you do this?

I downloaded it at a completely different location on a computer that I believe to be safe

 

[COLGeek]

Did you download an ISO and then use something like Rufus to write the image to your USB drive?

Or, did you use the Media Creation Tool from MS?

 

[cb6731]

Be aware that if network sharing was on and this infection is bad enough, or the son used other house computers then anything can/may also be infected. Where and how did you get the installer USB?

I cannot be sure about Network Sharing being on. If that's a windows default I would assume so. My son did not use any other computers but we have a few laptops that connect to our home network via WiFi occasionally. I downloaded the USB install at a completely different location on what I believe is a safe computer.

 

[USAFRet]

I downloaded it at a completely different location on a computer that I believe to be safe

What "it"?

Exactly...start to finish. Starting from a blank flash drive, to boot attempt.

 

[cb6731]

Did you download an ISO and then use something like Rufus to write the image to your USB drive?

Or, did you use the Media Creation Tool from MS?

I used the media creation tool

 

[cb6731]

What "it"?

Exactly...start to finish. Starting from a blank flash drive, to boot attempt.

 

[punkncat]

I used the media creation tool

You mean you went to the Microsoft site and used it to download and create the bootable USB?

Are you aware how (what key sequence) to get to the boot menu on this laptop?
Does this happen to be an HP machine?

 

[cb6731]

I followed the steps for the Media Creation Tool for Windows 11 install in the above post. I first downloaded the Media Creation tool, then ran that to create the files that were then added to a new blank 32GB USB Drive. On the hacked computer I first tried plugging in the USB and restarting but it went right into windows as normal, so then I went into the BIOS to change the boot sequence. There was not an option for USB only windows boot and the NIC drives as I mentioned above. I moved the first and 2nd boots to the NIC drives and 3rd to windows boot, after restart it still loaded into windows as normal. I went back into BIOS and set the 3rd boot to disabled to windows boot is not available. After restart it went into Support Assist, said it found nothing wrong, then somehow it came up to install windows 11 but I don't believe that was coming from the USB because when it asked me to choose a drive to install on the only option showing is the USB 32GB
All of this was being done while the computer was disconnected from the internet.

 

[cb6731]

You mean you went to the Microsoft site and used it to download and create the bootable USB?

Are you aware how (what key sequence) to get to the boot menu on this laptop?
Does this happen to be an HP machine?

Yes I used the post above to create the media creation tool which I then ran to create a bootable USB. No this is not an HP. This is a Dell Alienware Aurora R16

 

[punkncat]

So, if you insert that, turn the machine on, spam F12 what is happening?

The reason I asked about HP is I have had multiple issues with the Pavilion models not wanting to do anything aside from its own recovery partition (or back in the day) disks.