Can a virus spread to my computer?

[EggyRepublic]

I have a laptop which has a few files that may contain a virus. I have done the following:

 

1) connected an external disk to the laptop

2) dragged the potentially malicious files directly over from my laptop to the external drive, but the MS Office documents keep saying "properties not found" so I deleted everything that has already been copied over

3) zipped the files up with 7-zip while on the laptop

4) moved the zipped file over to the external disk

5) removed the external disk

6) factory reset the laptop (giving it away later to someone)

 

I do not care if the zipped files are gone forever, they weren't important and I didn't realize that they may have had a virus until after I copied them over to the disk.

 

Right now, I have this disk sitting beside me, not connected to anything. There are other kinda important files on the disk other than that zip file, would it be safe for me to connect the disk to my desktop and delete that zip file? Would that external drive be virus-free?

 

Basically, can a virus be executed or spread to other files by zipping it or by connecting that disk to another computer? How reliable is Bitdefender (my antivirus on my desktop)?

[homeap5]

If you have autorun disabled it's safe, but your AV may alarm you anyway. If you have enabled autorun it's safe too unless you choose to run anything after plug in drive.

 

Virus, like any other program, must be executed somehow to be active, otherwise it's just harmless file.

[john01dav]

Usually antivirus is pretty good, but it isn't perfect. If I were you, I would do this:

 - Get a live Linux USB stick (these are pretty easy to make -- all you need is a USB stick that you can overwrite. When one boots to it, it runs Linux off the USB stick.).

 - Temporarily remove *all* storage from a computer (eg. all hard drives, ssds, etc.).

 - Boot the computer into Linux using the live usb stick.

 - Attach the external disk
 - Delete the files

 - Run clamtk (a Linux virus scanner), optional
 - Shut down Linux and reformat the live USB
 - Run a Windows virus scanner on the external drive

 

That should get rid of 99.99% of viruses as it usually isn't worth the virus-maker's effort to write the code to get around that, but it is theoretically possible. The reason to use Linux is that there are far fewer viruses for Linux, and you're almost certainly on Windows so you probably don't have one that is able to do anything under Linux. For a bit of extra security, you can copy the important files (copy as few as possible) to a different drive using Linux.

 

EDIT: Regarding homeap5's comment about autorun. If you decide to look at the drive in Windows, definitely disable autorun, but be aware that it isn't a perfect solution. There are many ways that a program can start running, eg. if it infected a word document without you realizing and added macros.

[homeap5]

@john01dav: This is not different opinion - I said about general rule that virus must be activated, is no difference if you activate it by clicking exe or doc - it's still user interaction.

 

And macros don't start without user permission since Excel7.