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How can I avoid infection?
There is no way to guarantee that you will avoid infection. However, the potential
damage can be minimized by taking the following precautions:
- make sure you have a clean boot disk - test with whatever (up-to-date!)
antivirus software you can get hold of and make sure it is (and stays) write-protected.
Boot from it and make a couple of copies.
- use reputable, up-to-date and properly-installed anti-virus software regularly.
(See below) If you use a shareware package for which payment and/or registration
is required, do it. Not only does it encourage the writer and make you feel
virtuous, it means you can legitimately ask for technical support in a crisis.
- do some reading (see below). If you're a home user, you may well get an
infection sooner or later. If you're a business user, it'll be sooner. Either
way you'll benefit from a little background. If you're a business user you
(or your enterprise) need a policy.
- don't rely solely on newsgroups like this to get you out of trouble:
it may be a while before you get a response (especially from a moderated group
like comp.virus), and the first response you act upon may not offer the most
appropriate advice for your particular problem.
- if you use a shareware/freeware package, make sure you have hard copy of
the documentation before your system falls apart!
- always run a memory-resident scanner to monitor disk access and executable
files before they're run.
- if you run Windows, a reputable anti-virus package which includes DOS and
Windows components is likely to offer better protection than a DOS only package.
If you run Windows 95, you need a proper Win95 32-bit package for full protection.
- make sure your home system is protected, as well as your work PC.
- check all new systems and all floppy disks when they're brought in (from
any source) with a good virus-scanning program.
- acquire software from reputable sources: 2nd-hand software is frequently
unchecked and sometimes infected. Bear in mind that shrinkwrapped software
isn't necessarily unused. In any case, reputable firms have shipped viruses
unknowingly.
- once formatted, keep floppies write-disabled except when you need to write
a file to them: then write-disable them again.
- make sure your data is backed up regularly and that the procedures for restoring
archived data work properly.
- scan pre-formatted diskettes before use.
- Get to know all the components of the package you're using and consider
which bits to use and how best to use them. Different packages have different
strengths: diversifying and mixing and matching can, if carefully and properly
done, be a good antivirus strategy, especially in a corporate environment
- if your PC can be prevented with a CMOS setting from booting with a disk
in drive A, do it (and re-enable floppy booting temporarily when you need
to clean-boot).
CMOS settings
Some CMOSes come with special anti-virus settings. These are normally vague about
what they do but typically they write-protect your hard disk's boot sector and
partition sector (MBR). This can be some use against boot sector viruses but may
false alarm when you upgrade your operating system.
One sensible setting to make (if your CMOS allows) is to adjust the boot sequence
of your PC. Changing the default boot-up drive order from A: C: to C: will mean
that the PC will attempt to boot from drive C: even if a floppy disk has been
left in drive A:. This way boot sector virus infection can often be avoided.
Remember, however, to set your CMOS back temporarily if you ever do want
to boot clean from floppy (for example, when running a cryptographical checksummer
after a cold boot).
SCSI controllers have their own BIOS. On some systems, this will override the
boot sequence set in CMOS. It's always a good idea to check with a (known clean)
bootable floppy after you've disabled floppy booting that it really is disabled.
I don't think it's necessary to use the Rosenthal Simulator to do this, thank
you, Doren.
