back it up, back it up

May 20, 2009 9:27 AM

Can a virus on my desktop infect my external HD? Solutions needed for backing up data on a computer I'm about to nuke.

Last nite a virus slipped past Avast! and infected my desktop computer. I'd like to backup a few more things before I nuke the box.

Is it safe to plug in my external HD and copy some specific files? I can't boot into safe mode (I get an "NTLDR is missing" message). I've already unplugged the computer from the network.

posted by gnutron to computers & internet (7 comments total)

Yes, it is entirely possible. You should always disable auto-run on any Windows system for exactly this reason.
posted by odinsdream at 9:45 AM on May 20

Do you have a spare computer with a disk burner? If so, then d/l and burn some free live-distro like Ubuntu. Boot with the Ubuntu CD in the drive, choose the "live" option, then copy over whatever files you'd like from your internal hd to the external.
posted by philomathoholic at 9:51 AM on May 20

If you haven't cleaned the virus, I'd only connect only an empty external HD, as any existing files on the external drive might become infected. Connect it to another computer and scan the files ASAP.
posted by wongcorgi at 9:55 AM on May 20

Last nite a virus slipped past Avast! and infected my desktop computer. I'd like to backup a few more things before I nuke the box.

No. Oh, god, no.

The time to back-up your data is BEFORE a virus hits. If you do it after, you're just backing up potentially infected files. There's no point in doing that.

A backup is meant to recover your system. The point of recovering a system is to revert to a known-good state. Backing up infected files means your backup is known-bad.

You certainly can backup the files anyway. Then, when you restore them to your new, clean computer that you spent hours installing, you can savor the satisfaction of having one infected file ruin all your work.

You don't want that. You don't want to backup your data after being infected. You do have a backup from before then, right? Because if not, you're doing it wrong. Backups are for before the disaster hits, not after.
posted by splice at 11:17 AM on May 20

If anyone still cares, I managed to repair Windows using my XP disk. I followed instructions from this page.

I hear you, Splice. I am not backing up any program files....just saving music, documents, photos and such. I know it's less than ideal, but there is a lot of data I'm not willing to write off as a loss.
posted by gnutron at 11:23 AM on May 20

It is extremely common for viruses to affect data files, so even saving music and documents may carry the virus over. My advice would be to follow philo's suggestion about a Linux distro, copy all your data, reinstall Windows, and when you plug the drive with the copied data back in, scan it before transferring anything.
posted by fearnothing at 2:37 PM on May 20

We had a virus here at work that was propagating 1) through network security loopholes and 2) through USB external drives (thumb drives and larger backup drives). When plugging the external drive into the infected machine the virus service would download itself into a hidden folder on the root drive (something like x:/Recycler/97849237849/blahblah).

Make sure you run a virus check of your external drive when you run one on your entire system (use Free AVG or ClamAV if you need something free that should do the trick). Also, in Windows Explorer in Windows XP (or any other version for that matter) go to "Tools > Folder Options > View" and check the box "Show Hidden Files and Folders" and uncheck the box "Hide Protected Operating System Files (Recommended)" ... this will let you see everything on your drive (the viruses like to hide themselves).

If you want a great tool to do a final analysis of your drive in order to root out any other little hidden boogers, check out WinDirStat. It'll break things up in a way that you just can't do with Windows Explorer alone. And best of all, it's also open source (free).

Oh... also... since basically I'm answering your question with "Yes. Viruses can spread this way" ... make sure you run a scan on any computer that you have attached your external drive / USB thumb drive to AFTER you had used it on the machine that you knew was infected.
posted by eli_d at 5:58 PM on May 20