Computer Virus Advice

In spite of years of experience and many good anti virus programs, viruses are still with us. In fact, there are more viruses, and more virus infections, every year. The problem is getting worse. But there are steps we can take to protect ourselves.

Here are my recommendations for keeping virus free. The pointer icon will get you more detail about each one.

	Make frequent backups. Test to make sure you can restore from them.
	Trust no one. Always scan diskettes, executable files, and macro-capable documents. Always write-protect your diskettes.
	Set your CMOS to prevent floppy boot, and to prevent changes to hard disk system areas.
	Install the Word Viewer from Microsoft; set it as your default association for .DOC files. Set your email package to use the Word Viewer rather than Word when you double-click on a .DOC attachment.
	Install a good anti virus program; use its on-demand scanner set to scan file writes. Keep it up to date.
	Do not install large (over 520 MByte) hard disks in computers with IDE controllers. Install EIDE controllers along with the large drives.

Backups are the only sure protection from viruses, hardware failure, program bugs, accidental file deletion, and lots more.
It is always a balance between the aggravation of making a backup and the aggravation of not having made one when you need it. And sooner or later, you will need it. There's an engineering measure - MTBF. Mean Time Between Failures. It is a statistical measure of how soon, on average, a particular component will fail. Floppy disks have lives measures in tens of hours. Hard disks are likely to run tens of thousands of hours. On average. But the WILL fail.

Is the only copy of your Quicken file on your hard disk? Is your IRS audit next week? Then your hard disk will fail. This has nothing to do with MTBF but everything to do with Murphy's Law. The IRS does not accept "my computer ate my records" as an excuse.

Make sure you test your backups to make sure that you can restore the information they contain. Don't take it on faith. Actually DO it to be sure, at least once or twice.

You're only paranoid if they aren't out to get you. And they ARE out to get you. There are over 10,000 viruses. New ones are being written at a rate of over 100 a month. If you receive documents, software, or even new blank diskettes then you are at risk.
You are not safe because you only use new diskettes and only install programs directly from shrink-wrapped boxes. Both of these have been infected. System setup disks direct from computer manufacturers have been infected.

I am not trying to imply that these folks deliberately spread viruses. Anyone you receive these things from could, themselves, be a victim.
When you receive a Word document as an email attachment, scan it.

When you download a program over the Web, scan it.

When you use a diskette to print information at a hotel information center, scan it before you use it again. In fact, any diskette that has been in another computer should be scanned before use.

If you leave your computer in an accessible area at work, assume that it could have been run by someone during off hours. A power-on password is a good idea.

It is altogether too easy to forget a floppy in the A: drive. You just wanted to copy a file so you can bring it to the office tomorrow. But you leave the disk in the computer when you turn it off, and don't notice that it's there when you turn it on again. A message appears on your screen, "Please insert a bootable disk and press any key to continue."
But it is already too late. That message came from a program that sits in the boot sector of the floppy disk. It appeared on your screen when that program was run during power-on. If the floppy disk had a boot sector virus, then your hard disk has it now, too.

Most computers give you a way to prevent all this. You can configure the CMOS options to completely bypass the floppy during the boot process.

Microsoft Word documents can contain Word Macro viruses. These are viruses written in Word Basic. They spread by infecting your Word templates and other Word documents.

Certain of the newest versions of Microsoft Word have a mechanism for detecting macro viruses. But it is too primitive and too ineffective to trust. It does not differentiate between "good macros" and "bad macros" but warns about them all, leaving it up to the user to decide. Under some conditions, for instance when double-clicking an attached document in an email, it does not run at all.

Microsoft provides a Word viewer for free via Web download that will solve these problems. This viewer will let you view Word documents (after all, most of the time you want to view not edit an email message) and is aware of the very latest Word formats. So it can read an Office 97 Word document even if you haven't upgraded yet. If you really DO want to edit the document, you can start Word from within the viewer. And best of all, it is completely immune to Word viruses because it doesn't process macros

The specification for IDE allows for disk sizes up to about 520Mb. Drives larger than that should use an EIDE controller. But most drive manufacturers sell large drives for use with IDE controllers, using software to "fool" things into working. This software is loaded in the portion of the first disk track unused by the Boot Sector and Partition Table. It is loaded during startup and things work fine.

But the way boot sector viruses work makes this arrangement vulnerable to problems. When infecting a computer, boot sector viruses take a "snapshot" of the good boot sector, relocate it to somewhere else on the disk's first track, and replace the boot sector with virus code.

If the disk is an EIDE disk with the special code as described above, this special code (which you need to use the disk in any way) is wiped out by the virus.

EIDE controllers are cheap - in the $25-$35 range. If you're going to get a large disk, get an EIDE controller, too. Not only will you eliminate this virus vulnerability, but you'll pick up some performance, too.