Need to install Avast on machine with broken internet access

[tsc_chazz]

I have a machine with truly horrible access to the internet and I need to install some antivirus on it. I half suspect that the reason for the network difficulty is a rootkit left by a previous owner, though it could be physical damage - the owner was having mental difficulties and when they were unable to open the laptop, they threw it across the room. I'm figuring it has to be a rootkit / boot virus, if it exists, because this is a fresh Windows 10 install at this point. In any event a normal Avast install fails saying that it can't reach the Avast servers or that internet access is not available, even though I can quite handily surf on that same machine... albeit with an occasional delay. What I'd like to do is install Avast and trigger a boot-time full scan. Is there any way to retrieve an off-line copy of Avast that I can load onto this machine when it's being stubborn about connecting?

[Dinobot2]

You can grab the latest offline install file from this link.

https://forum.avast.com/index.php?topic=322019.0

That's the latest version of Avast, small enough to throw on a USB from another computer. Though without internet access you won't be able to update the definitions, so they'll be a couple of weeks outdated.

[tsc_chazz]

Thank you, that looks like it will work.

I'm hoping that if there is a virus, it hasn't updated itself while I was trying to get things installed... but if it hasn't, a couple of weeks delay on the virus definitions won't be a big deal, the machine has been sitting idle for some months.

[tsc_chazz]

Okay, that didn't work. It said it had installed and I needed to reboot. So I rebooted... and it isn't there. The installation seems to have silently failed, or been reverted when the machine restarted. So I guess the only recourse now is a full nuke and pave.

[Rundvleeskroket]

That's probably the best way to go. You might even consider a fresh drive.

[tsc_chazz]

If I can get one to fit this machine. I'm not sure I'd trust a Darik's full-surface mil-spec wipe... but this machine may take one of the super low-profile drives, meaning I'd have to spring for an SSD on a possibly damaged machine.

[Dinobot2]

Have you tried using Windows Defender? You can do a full scan from the Windows Security section.

[Rundvleeskroket]

There's the option to run a Live CD (or USB these days) with an AV baked in. Update definitions and scan the suspect disk. Might clear things up. Worth a shot.

Also check the hosts file for weird entries blocking Avast's servers.

Even then you have to hope it isn't an UEFI rootkit.