I put my old HDD in my new computer. The main one is partitioned into C: and D:, the old one into E: and F:
Have been running antivirus and antispyware programs only on the C: and D:, as assuming no way a virus could get on the second drive. I keep that only to backup to, and for some older programs may eventually transfer to the new drive. Never backup before running the protective programs.
This safe practice? Any way viruses or spyware could get on the old drive?
If the hard drive is accessible to you, it’s accessible to a virus. Generally, a virus is going to go after your system files first, which will usually be on the C: drive. But there’s no reason to assume that a secondary hard drive is safe.
I’ll agree with that. If a virus is programmed to look for other disks to infect, and your second hard drive is on and connected, it’ll hit that hard disk. (It may need to find suitably vulnerable files on that hard disk first.) Also, if it’s a randomly destructive virus, everything on your secondary may be subject to deletion attacks or the like.
Most viruses run in a hidden/disguised background process. They can infect any file that Windows can access. Some of them wait for a file to be accessed to infect it, others actively scan your system for certain types of files. Files can be infected on floppy disks, hard drives, network drives, and probably writable CD and DVDs.
Bear in mind however that viruses are programs and as such must be executed in order to infect anything. If the virus was just sitting dormant on the second drive and has never been executed in your current setup then all it will do is just sit there. You can run a scan on the drive and clean it easily.
When I say “program” I don’t necessarily mean an EXE file. Viruses can be scripts of almost any flavour as well. (Some script languages, such as Javascript, are exempt as they do not have direct access to network or system functions and so have no way to propagate without the help of an external program or script that does. Some script languages, like MS Word macros are specific to apps like Microsoft Office and must be executed within that environment for them to do any damage)
For exmaple if you have one hard drive and have no viruses on it, and then install a second drive from another system that does have one or more viruses on it, those viruses will not spontaneously start infecting your main drive unless they are executed either by you or another program or script designed to execute the specific files in their present locations that contain the virus. The latter being extremely unlikely unless the program you executed was on the drive with the virus(es), the chances of infection in a case like this is slim to none. It is always best however to run a virus scanner over the drive anyway, just to prevent the possibility.