preferably cardboard disk mailers.

stamps (available from any post office). Please use sturdy envelopes,

the U.S. may send an international postal reply coupon instead of US

the author at the address given at the end of this manual. People outside

self-addressed stamped envelope and a floppy disk (800K or 1440K) to

shareware software may obtain a copy of Disinfectant by sending a

Macintosh users who do not have access to electronic sources of free and



services.

commercial services such as telephone support, mailing lists, or upgrade

Disinfectant is not a commercial product. We cannot offer typical



   ftp://ftp.nwu.edu/pub/disinfectant/



within a few days. The official anonymous FTP site is:

we usually release a new version of Disinfectant to recognize the virus

Disinfectant is distributed electronically. When a new virus is discovered,



to the comparatively meaningless damage caused by computer viruses.

compare the enormous suffering caused by biological viruses such as HIV

they never occur naturally. Most importantly, it is not possible to

never created by people. Computer viruses are always created by people;

organisms. Biological viruses usually occur naturally and are almost

between biological and computer viruses too far. Computers are not living

As with all analogies, however, it is possible to carry the analogy



inoculate or vaccinate the system to protect it against future infection.

the infection without damaging the system and it is sometimes possible to

damaged. With both kinds of viruses, it is sometimes possible to remove

survive. In both cases, the infected system is sometimes severely

Both of them replicate and they both require the assistance of a host to

The analogy between biological viruses and computer viruses is striking.



revolution.

let the virus problem and other security concerns endanger this

rules and regulations imposed by the corporate MIS priesthood. We cannot

are extensions of each individual’s imagination, unfettered by arbitrary

is the empowerment of the individual. At their best, personal computers

of the personal computer revolution (especially the Macintosh revolution)

are completely unnecessary and are, in fact, very dangerous. The heart

employees from joining bulletin boards or user groups! These restrictions

software. Some companies have even gone so far as to prohibit their

in locked rooms and do not permit their employees to use unapproved

doing more harm than good. For example, some companies keep computers

on the use of personal computers and personal computer software are

overreact to the threat. Organizations which impose severe restrictions

The virus problem is serious, but even more serious is the tendency to



of freeware and shareware software are remarkably virus-free.

infected commercial software, while most of the major national sources

from the truth. There have been many reported cases of (inadvertently)

viruses by merely avoiding shareware and freeware software. This is far

There is a misconception that you can protect your Macintosh against



simple things we suggest you do to protect your Mac.

viruses. See the section titled “Recommendations” for a short list of the

minutes per week to effectively protect your Macintosh against the known

should take the problem seriously. Using Disinfectant, it only takes a few

There is no need to panic over the current virus situation. However, you



Trojan horses.

Disinfectant does not attempt to address the problems of worms and



replicate.

the background while you used the program. Trojan horses do not

would be game or other program which quietly erased your hard drive in

additionally does something destructive behind your back. An example

A “Trojan horse” is a program which appears to do something useful, yet



computers in a single day.

infected and disabled several thousand government and university UNIX

The most well-known example is the Fall 1988 Internet worm, which

computers. They are not spread through the sharing of software or disks.

survive and replicate. Worms usually propagate over a network of

itself to other programs. Unlike a virus, it does not require a host to

A “worm” is a program which replicates and spreads, but does not attach



such as “worms” and “Trojan horses.”

Viruses should not be confused with other types of destructive software



against infection by any of the known Mac system viruses.

properly installed, the Disinfectant INIT will protect an uninfected system

Disinfectant also includes a virus protection extension (INIT). When



Northwestern University to attempt to combat them in Disinfectant.

so many new ones keep appearing, we do not have the resources at

Unfortunately, because there are so many Microsoft macro viruses, and



to worry about these viruses if you do not use Word 6 or Excel 5.

recommend a commercial Macintosh anti-viral program. You do not need

for Word 6 users. If you need protection against these viruses, we

The Microsoft macro viruses are currently a major problem, especially



Microsoft Word 6 and Excel 5 macro viruses.

“MerryXMas” HyperCard viruses and the many cross-platform

language viruses. These include the “Dukakis,” “Three Tunes,” and

Disinfectant does not recognize application-specific scripting or macro



have to get a new copy of the program.

appears, we will have to modify the program to recognize it, and you will

been configured and programmed to recognize. If a new virus or strain

Disinfectant will not recognize all possible viruses: only the ones it has



possible, repair files which have been infected by the viruses.

unknown variations and clones. It will both detect the viruses and, when

viruses. Furthermore, Disinfectant also recognizes many possible

viruses. It also recognizes all the known variations and clones of these

Disinfectant recognizes all of the currently known Macintosh system



crashes and strange behavior.

also discovered errors in most viruses which can cause unexplained

interfere in unexpected ways with other parts of the system. We have

They also live at very low levels in the operating system and can

memory and disk space and this is enough to cause problems all by itself.

problems with the normal operation of their Macintosh. Viruses occupy

unintentional. Many people who have experienced infections have reported

non-malicious viruses are always damaging, even if the damage is

are non-malicious. It is very important to realize, however, that even

We are very fortunate that to date most of the known Macintosh viruses



damage or delete files or destroy the contents of hard drives.

damage something. For example, malicious viruses often intentionally

other hand, malicious viruses, in addition to replicating, do attempt to

else innocuous, but they do not intentionally try to do any damage. On the

example, they may beep, display messages on the screen, or do something

replicate, but they do not attempt to do anything destructive. For

Viruses may be malicious or non-malicious. Non-malicious viruses



and distribution of infected software or infected disks.

computer. Viruses spread from one Macintosh to another via the sharing

files. Viruses quickly propagate to other files and disks as you use your

A virus is a piece of software which attaches itself to other programs or



continue to cause problems for some time.

years ago, viruses continue to spread rapidly and widely. Viruses will

community, although the problem is not as serious as it was several

increasingly serious problem in the computing world. In the Macintosh

Viruses and other kinds of destructive computer software have become an








åIntroduction



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,