viruses are emerging but there are ways to avoid catching them
by Alan Zisman (c) 1996 First published
in Business in Vancouver
, Issue #357 August 27, 1996 High Tech Office column
used to be
that, despite media hype such as the Michelangelo scare a couple of
years ago, computer viruses were relatively rare--especially among
businesses that used some common sense. It wasn't impossible for your
company's computer to get infected, but a much more typical victim
was a kid swapping floppies with pirated copies of games.
a new type of virus has emerged, aimed specifically at users of common
business applications. And while traditional viruses either required
that you run an infected application, or start up your computer with
an infected floppy in the disk drive, all it takes to infect your
computer with one of these new-style viruses is to read an infected
data file. And because they're passed on in your data, some of these
viruses can even pass between different types of computers--from a
PC to a Mac, for example.
viruses have been
made possible because many applications include powerful
Sophisticated users can use them to create customized macros--add-ins
that let your word processor, for example, do much more than simply
display a business letter.
allows virus creators to use those same macro-languages to hide code
in a document that allows the virus to spread itself onto your
and to copy itself into any new document that you read or write. As
a result, the virus can spread to still more users, as your document
is shared over your network.
Concept, infected Microsoft Word documents, and appeared about
a year ago. Since then, there have been several more viruses infecting
Word files. Recently, a new virus named Laroux became the first to
infect spreadsheet files created with Microsoft Excel. However, it
only affects Windows Excel versions 5.0 through 7.0--earlier versions
of the program, along with Macintosh versions, are currently safe.
Microsoft and virus
specialist McAfee are distributing tools to detect and remove
the Laroux virus from Excel data files, and these are available for
free from their Web sites (www.microsoft.com and www.mcafee.com).
As well, Microsoft says that you can manually identify infected data
files by holding down the shift key when opening files in Excel (this
prevents auto-load macros from being run). From the Tools menu, you
would then choose Macros, and check for any of the following macros: Auto_Open;
Check_files; PERSONAL. XLS!auto_open;
or PERSONAL.XLS!check_files. If any macros with those names
are found, they should be deleted from that menu item, with the changes
saved to your file.
steps can be
used in Word to check the macros listed there. If any seem unfamiliar
to you, you may want to delete them.
a number of
other steps you can take to minimize the risk of infecting your
with these sorts of viruses.
example, if you
receive a document, you may want to view it rather than immediately
opening it in an application like Word or Excel. Windows 95, for
includes a QuickView option, which you may already have installed.
If you do, all you have to do is use the right mouse button to click
on the file name, and QuickView will be one of the options in the
pop-up menu. This allows you to view the contents of a file without
loading it into its parent application. Windows 95's QuickView supports
a dozen or so file types. QuickView Plus, a much more sophisticated
utility, supports more than 200 different PC and Mac file types, and
costs about $30. (Check their free, time-limited version at http://www.inso.com/).
For Word documents only, Microsoft also distributes a free WordView
utility on its Web site.
have added the detection of most Word macro viruses. Get one and use
it. Note, however, that these programs are always a month or so behind
the latest viruses. And with new strains of viruses every week or
so, it's important to update your program's data regularly. Symantec's
Norton AntiVirus posts a free update on-line each month; shareware
programs like McAfee's VirusScan or Frisk F-Prot are updated every
two or three months. Make sure that you have the latest version for the
most complete protection.
viruses seem to be limited to Microsoft Office applications. Perhaps
this is the result of Office owning 90 per cent of the market for
you shouldn't let these viruses keep you from using your computer
to get your work done. Do take the necessary precautions.