Almost a year ago, I dual-booted Windows 10 and Linux Mint. And since then, I haven't booted into my Windows 10 OS.

I still remember that the Wi-Fi adapter was off when I shut my Windows 10 down.

Now, since my Windows 10 OS is not up to date with the latest security updates, is it vulnerable to malware even though it is not connected to the Internet?

Note: I can't delete my Windows 10 partition yet, because I have all my important files (more than 400 GB) on it and I don't have a 400 GB thumb drive or external HDD or external SSD to back up those files and delete the Windows partition. (I have two 32 GB thumb drives and a 4 GB thumb drive.)

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    If Windows is not needed to backup your files, then you can mount the win partition into Linux and cleanup all the files that are not important for you including the system files. – elsadek Jun 5 at 13:45
  • Do you mean "running but not connected to the Internet?" or do you mean "not running?" You say that you have not booted it and that you shut it down. Are you concerned about it in a shutdown state or when you run it? – schroeder Jul 6 at 6:39

I have been in the situation many times, but usually it is not a problem. Just connect it to a secure internet connection behind a router and start downloading the updates. The updates are usually signed and if you connect directly to the ISP then the outgoing connections are unlikely to be attacked.

One way to be moderately more secure is to boot Windows to safe mode, then connect and install the Windows updates. That way applications that start automatically in normal mode cannot interfere or be attacked. Updating your browsers would be next, because they are sometimes used by other applications for connecting to the web.

Whatever you do, don't start using mail or browse the web before the Windows updates have been performed. I would also first update the OS and browsers and only then allow application specific updates to be run, as those may use the Windows / browser functionality.

It is a good idea to have everything wired up if you're on a mobile device: use a LAN with Native Address Translation (NAT). A NAT commonly drops all incoming traffic. You might want to temporarily deactivate UPnP though.

As for using a cable: you might want to connect to a power source anyway; you don't want the battery to drain during updates. If you're on the go, use a mobile phone connection and / or a VPN. Do not use public Wifi without a VPN and firewall installed.

  • There will be random attacks against public IPv4 addresses. It's the background radiation of the Internet. – vidarlo Jul 5 at 20:30
  • True, fortunately computers don't open that many ports by default anymore, and the fact that routers are commonly using NAT will generally also help. However, if you start services or start connecting yourself you're still vulnerable. I don't know exactly how this works with IPv6; it's probably complicated :) I've removed the part about active attacks though, I don't understand why I wrote it the way I did. Anyway, the trick is to make sure you don't allow incoming connections and only rely on outgoing ones for the updates. – Maarten Bodewes Jul 5 at 20:45
  • Indeed, it's not a very common risk, and it can somewhat be mitigated by booting the device in disconnected mode and ensure that as few services as possible are running, and that the software firewall drops all incoming :) IPv6 basically makes IP enumeration a ting of the past; the address space is too vast to map out or probe at random with any chance of success. – vidarlo Jul 5 at 20:51
  • @vidarlo I would not say that, in cryptography 128 bits is fine for e.g. an AES key. But that said, it is not infeasibly large if you consider multi-target attacks. And the IPv6 space if of course segmented just like IPv4. – Maarten Bodewes Jul 5 at 20:53
  • It's segmented, but the smallest subnet is a /64, which is 2^32 times bigger than the entire IPv4 Internet. If you can probe a billion IP's per second, that's still hundreds of years just to enumerate one subnet. You can constrain it somewhat because addresses are not entirely random, but it's still a different beast, and I've not yet seen random ssh attempts over IPv6 for hosts that isn't published in DNS. – vidarlo Jul 5 at 20:56

Systems can be vulnerable even though they are not connected to the internet, e.g. through the use of compromised media like USB thumb drives or the like.

I understand you have the Windows partition around because you are not able to move your files from that partition to your Linux partition. But you do not need a big external medium for that. Here is a thread that might help you with moving your data: https://unix.stackexchange.com/questions/498322/how-do-i-access-windows-files-from-linux-mint-and-vice-versa-if-possible-i-ha

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