How do I use my USB memory stick safely when copying files from and to infected computers?
For example, I have a Word-document on my clean laptop's HDD. I right-click on this Word-document, choose to 'Send to...' and choose as target my USB memory stick (without having to open it).
Then, I go to a public computer where I need to have this Word-document printed out. I have to assume this public computer is infected with virus. The USB memory stick has to be opened to view and locate my Word-document, then it's copied onto the public computer's HDD and printed out. I also have a document that I need scanned, so I do that and get a file sent from this infected public computer onto my USB memory stick.
Back home, how should I now safely handle this USB memory stick, and the scanned document from the infected public computer?
I have a laptop and a netbook (my laptop is most important that I keep 100 % clean all the time, the netbook is of secondary importance). I assume I have to open the USB memory stick in order to locate the scanned image. And isn't this the occasion when virus and malware get the opportunity to spread onto my system, the moment I open the root folder on a removable device?
Or I could virus-scan the USB memory stick first, but to be very certain it's clean, I would need to use several different search applications (for virus, for malware etc), right? How certain could I be after doing multiple virus-scans for virus and malware that it's as close to 100 % clean as possible?
Anyhow, if I don't scan it but open on my netbook (which is of secondary security importance), could I then choose to virus-scan only this document (the scanned image) and then choose 'Send to...' to another of my USB memory stick (which I always use only this way, that is, as 'intermediate' transfer tool and I always keep this 2nd USB memory stick empty of files, just for the purpose of momentarily transfering files)?
Finally, I plug this 2nd USB memory stick (which is 100 % clean) into my laptop (which is primary security priority, it must absolutely be kept clean of virus and malware) and open the folder with the scanned image and copy onto my laptop's HDD.
To summarize, one of the two choices would be to do thorough searches with several anti-virus and anti-malware applications etc. on my 1st USB memory stick and trust that all viruses are found. I would then use only this 1st USB memory stick, on both my netbook and my laptop.
Or, the second choise is that I use my netbook and my 1st USB memory stick as 'higher-risk' devices, and my laptop and 2nd USB memory stick as 'secure' devices.
A final question: I've already disabled auto-play on my 'secure' laptop. I wouldn't need to disable auto-play also on my 'higher-risk' netbook, would I? My 'higher-risk' netbook would auto-play my 'secure' 2nd USB memory stick, but in that moment no virus or malware would be given the opportunity to spread onto my 2nd USB memory stick, would it? It must be the other way around, virus and malware could only spread from the 2nd USB memory stick onto netbook's HDD during auto-play.
Or do I make everyting too complicated? Is there no risk for spreading of virus and malware when I open root folder of my infected 1st USB memory stick?
Also, is there any difference between different OS, such as Windows XP, Linux Kubuntu, Windows Vista, and Windows 7?