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Viruses and the Mac FAQ

David Harley
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      12-31-2003, 01:50 AM
Archive-name: computer-virus/macintosh-faq
Posting-Frequency: Fortnightly
Last-modified: Fri, 1 Jan 2000 19:14 GMT
Copyright: Copyright 1996-2000 by David Harley and contributors
Maintainer: David Harley <(E-Mail Removed)>

Viruses and the Macintosh
by David Harley
Version 1.6b: 7th January 2000

Significant changes from the previous version are flagged with +
symbols in the first two columns at the start of the relevant line
or section. Amendments of minor grammatical or syntactical errors
are not flagged unless they affect factual accuracy or clarity.

Sections tagged with [DH] or [SL] are hangovers from the time when
maintenance of the FAQ was shared between David Harley and Susan Lesch,
and usually denote personal opinions the originator didn't feel the other
maintainer should be held responsible for. Untagged sections using
the first person are usually attributable to David Harley.

This version of the FAQ primarily reflects my involvement in setting
up an information resource at ICSA. This will affect the availability
of the FAQ. The next version will require extensive URL checking,
and will probably introduce major formatting changes.

David Harley

Table of Contents

1.0 Copyright Notice
2.0 Preface
3.0 Availability of this FAQ
4.0 Mission Statement
5.0 Where to get further information
5.1 Computer Virus FAQs
5.3 "Robert Slade's Guide to Computer Viruses"
5.4 Web sites
5.5 Virus Bulletin
5.6 Macro virus information resources
5.7 Other resources
6.0 How many viruses affect the Macintosh?
7.0 What viruses can affect Mac users?
7.1 Mac-specific system and file infectors
7.2 HyperCard Infectors
7.3 Mac Trojan Horses
7.4 Macro viruses, trojans, variants
7.5 Other Operating Systems, emulation on a Mac
7.6 AutoStart 9805 Worms
7.7 Esperanto.4733
8.0 What's the best antivirus package for the Macintosh?
8.1 Microsoft's Protection Tools
8.2 Disinfectant Retired
8.3 Demo Software
8.4 Other freeware/shareware packages
8.5 Commercial Packages
8.6 Contact Details
9.0 Welcome Datacomp
10.0 Hoaxes and myths
10.1 Good Times virus
10.2 Modems and Hardware viruses
10.3 Email viruses
10.4 JPEG/GIF viruses
10.5 Hoaxes Help
11.0 Glossary
12.0 General Reference Section
12.1 Mac Newsgroups
12.2 References and Publications
13.0 Mac Troubleshooting

1.0 Copyright Notice

Copyright on this document remains with the author(s), and all
rights are reserved. However, it may be freely distributed and
quoted - accurately, and with due credit.

It may not be reproduced for profit or distributed in part or as a
whole with any product for which a charge is made, except with the
prior permission of the copyright holder(s). To obtain such
permission, please contact the maintainer of the FAQ.

Primary author and maintainer of this document is David Harley,
Comments and additional material have been received with gratitude
from Ronnie Sutherland, Henri Delger, Mike Groh and Eugene Spafford.
Thanks to Bruce Burrell, Michael Wright, Peter Gersmann, David Miller,
Ladd Van Tol, Eric Hildum, Jeremy Goldman, Kevin White, Bill
Jackson, Robert Slade, Robin Dover, and John Norstad for their
comments and suggestions. Special thanks to Susan Lesch for her
contributions, editing, and maintenance chores as co-maintainer.

2.0 Preface

This document is intended to help individuals with computer
virus-related problems and queries, and clarify the issue
of computer viruses on Macintosh platforms. It should *not* be
regarded as being in any sense authoritative, and has no legal
standing. The authors accept no responsibility for errors or
omissions, or for any ill effects resulting from the use of any
information contained in this document.

Corrections and additional material are welcome, especially if
kept polite.... Contributions will, if incorporated, remain the
copyright of the contributor, and credited accordingly within
the FAQ.

David Harley <(E-Mail Removed)>

3.0 Availability of this FAQ

++The reference site for this FAQ is now However, my own
site at <> will be the
first place new versions will be posted.

It's also available from Henri Delger's Prodigy Anti-Virus Center
file library, as is the alt.comp.virus FAQ. It will probably be available
shortly from <>

There are HTML versions at:

I have no control over the content of these sites, and can't guarantee
that they're up-to-date.

4.0 Mission Statement

This document is a little different to the alt.comp.virus FAQ,
which David Harley also co-maintains (at time of writing). It is
concerned with one platform only, and though it deals with the
Macintosh platform at more length than the alt.comp.virus FAQ can
be expected to, it is a great deal shorter. Nor is there the same
degree of urgency about the Mac virus field, though the risk
element may be somewhat underestimated in general, at present. This
FAQ originated from a concern over the spread of macro viruses, a
theme that is taken up below. Since questions about Macs and
viruses tend to appear more often in the Mac groups than
alt.comp.virus or Virus-L, distribution of this FAQ is wider.

5.0 Where to get further information

5.1 Computer Virus FAQs
Computer Virus FAQ for New Users
A mainly non-Mac virus FAQ posted to news.newusers.questions,
alt.newbie, alt.newbies, alt.answers, and news.answers.

alt.comp.virus FAQ
This is posted to alt.comp.virus approximately fortnightly. It
includes a document that summarizes and gives contact information
for a number of other virus-related FAQs; (not much Mac-specific
material). The latest version is available from:
<> but the reference version will
eventually be the one at (page currently under construction).

VIRUS-L/comp.virus FAQ
The Virus-L/comp.virus FAQ (also fairly low on Mac-specific
information) is regularly posted to the comp.virus newsgroup
(version 2.0 at time of writing). This FAQ is very long and very
thorough. The document is subject to revision, so the file name may
change. The latest version may be found at:

++Dr Solomon's Anti-Virus Toolkit, Virex, and NAV (Norton AntiVirus
for Macintosh) now support the EICAR test. This article by
Paul Ducklin of Sophos explains the EICAR test file:
<>. [SL]

5.3 "Robert Slade's Guide to Computer Viruses"
The disk included with the 2nd Edition of this excellent general
resource includes most of the information available at the
University of Hamburg (see 5.5). The book also contains a
reasonable quantity of Mac-friendly information. The disk includes
a copy of Disinfectant 3.6, which is now out-of-date -- 3.7.1 is
the latest and final release. For more information about this book:
<> [Springer]

++Very few books primarily about computer viruses deal at any length
with Mac viruses (I can't think of one, at present). Some general
books on the Mac touch on the subject, but none I can think of add
anything useful. Some of the "Totally Witless User's Guide
to......." books dealing with security in general include
information on PC -and- Mac viruses. Unfortunately, the quality of
virus-related information in such publications is generally low, and
there are few or no books on computer viruses in general which are
both recent -and- accurate.

5.4 Web sites
Many major vendors have a virus information database online on
their Web sites. Symantec (, Network Associates
(, Sophos ( and Dr. Solomon's
( include Macintosh virus information.

Precise URLs tend to come and go, but you might like to try the

Symantec Antivirus Research Center
Virus Encyclopedia based on Project VGrep: huge, and now has a
search engine. Probably the most complete [SL]. But not always the
most accurate [DH]. ;-)

Network Associates, formerly McAfee Associates:
Virus Information Library
Macintosh Viruses

Sophos Plc
<> "Macintosh Virus Desriptions"
Part of work in progress by Ken Dunham
+ <> (new domain name)

Mac Virus
++[Site closed 5th September 1999]

Dr Solomon's "Mac Viral Zoo"
Starting to go out of date

++Keep watching <>

5.5 Virus Bulletin
The expensive (but, for the professional, essential) periodical
Virus Bulletin includes Mac-specific information from time to time.
However, if you have no interest in PC issues, you probably won't
consider it worth the expense.

Virus Bulletin Ltd
The Pentagon
OX14 3YP

+44 1235 555139

The proceedings of the 1997 Virus Bulletin conference contained a
paper by David Harley which significantly expands on many of the
issues addressed in this FAQ. Contact Virus Bulletin for further
information on the annual conference and on obtaining the
proceedings. The paper can also be found (by permission of Virus
Bulletin) at the author's website <>
and at <>

5.6 Macro virus information resources
++University of Hamburg Virus Test Center Macro Virus List is the
definitive listing. All known macro viruses, some only found in
research labs, some in the wild. Doesn't include information on
individual viruses apart from name and platform, and somewhat
irregularly maintained.

Other Sources:
<> (under Virus Information)

[The following absolute URLs may change: such is the way of Web
administrators..... If you get an error message, try the first part
of the URL, e.g. <> and drill down from there.]

Dr Solomon's Software Ltd.

Central Command

Network Associates

Data Fellows

++Richard Martin put together an FAQ on the subject of Word viruses.
It's well out-of-date, though, and was always inaccurate in some
++N.B.This URL may be out of date. There is a copy of what I believe
to be the last released version at SherpaSoft:

5.7 Other resources

There are excellent pages on HyperCard viruses at HyperActive
Software. There is information on HyperCard infectors, a link to
Bill Swagerty's free Vaccine utility for detecting and cleaning
them, a note on false positives reported by commercial software,
inoculation, and a free HyperCard virus detection service.

The CIAC virus database includes entries for PC, Macintosh, and a
number of other platforms. The Macintosh section also includes a
number of joke programs and one or two apparent hoaxes.

Virus Test Center, Hamburg: AntiVirus Catalog/CARObase early work
These links may be out-of-date: if they don't work, try

Last we checked [03-Sep-97], these sites probably need updating,
though some older files do have historical value. Info-Mac mirrors
have Macintosh information, but includes some outdated virus
information and software at this writing; still, always worth a

Also of interest, again sometimes outdated:

Kevin Harris's Virus Reference was last updated 31-Aug-95. This
HyperCard stack requires HyperCard 2.1 or later.

6.0 How many viruses affect the Macintosh?

There are around 40 Mac-specific viruses and related threats.

++Mac users with Word 6 or versions of Word/Excel supporting Visual Basic
for Applications, however, are vulnerable to infection by macro
viruses which are specific to these applications. Indeed, these
viruses can, potentially, infect other files on any hardware
platform supporting these versions of these applications. I don't
know of a macro virus with a Mac-specific payload that actually
works at present, but such a payload is entirely possible.
++Office 98 applications are in principle vulnerable to most of the
threats to which Office 97 applications are vulnerable. I'll return
to this subject when and if time allows. [DH]

Word Mac version 5.1 and below do not support WordBasic, and are
not, therefore, vulnerable to direct infection. Not only do these
versions not only understand embedded macros, but they can't read
the Word 6 file format unaided. There is, however, at least one
freeware utility which allows Word 5.x users to read Word 6 files.
This will not support execution of Word 6 (or WinWord 2) macros in
Word 5.x, so I would not expect either an infection routine or a
payload routine to be able to execute within this application.

However, Word 5.x users may contribute indirectly to the spread of
infected files across platforms and systems, since it is perfectly
possible for a user whose own system is uninfectable to act as a
conduit for the transmission of infected documents, whether or not
s/he reads it personally.

Files infected with a PC-specific file virus (this excludes macro
viruses) can only execute on a Macintosh running DOS or DOS/Windows
emulation, if then. They can, of course, spread across platforms
simply by copying infected files from one system to another.

DOS diskettes infected with a boot sector virus can be read on a
Mac with Apple File Exchange, PC Exchange, DOS Mounter etc. without
(normally) risk to the Mac. However, leaving such an infected disk
in the drive while booting an emulator such as SoftPC can mean that
the virus attempts to infect the logical PC drive with
unpredictable results.

I am aware of at least one instance of a Mac diskette which, when
read on a PC running a utility for reading Mac-formatted disks
after being infected with a boot-sector infector, became unreadable
as a consequence of the boot track infection.

Some Mac viruses may damage files on Sun systems running MAE or

7.0 What viruses can affect Mac users?

Not all variants are listed here. It was originally intended to
reference all the major variants at least by name eventually, but
since the information is of academic interest at best to most users
(and available elsewhere anyway), it's no longer considered a
priority. The main problem affecting Mac users nowadays is the
spread of macro viruses, and I can't possibly find time to
catalogue them individually, so they are only considered generally.
Native Mac viruses are rather rarely seen nowadays, and most people
don't need to know about them in detail -- in fact, what they need
most is to know that their favoured antivirus software will deal
with them. Note that I'm not primarily in the business of hands-on
virus analysis, and cannot accept responsibility for descriptive errors
based on third-party information. [DH]

The following varieties are listed below:
7.1 Mac-specific system and file infectors
7.2 HyperCard Infectors
7.3 Mac Trojans
7.4 Macro viruses, trojans, variants
7.5 Other Operating Systems, emulation on a Mac
7.6 AutoStart 9805 Worms
7.7 Esperanto 4733

7.1 Mac-specific system and file infectors
AIDS - infects application and system files. No intentional damage.
(nVIR B strain)

Aladin - close relative of Frankie

Anti (Anti-A/Anti-Ange, Anti-B, Anti Variant) - can't spread under
system 7.x, or System 6 under MultiFinder. Can damage applications
so that they can't be 100% repaired.

CDEF - infects desktop files. No intentional damage, and doesn't
spread under system 7.x.

CLAP: nVIR variant that spoofs Disinfectant to avoid detection
(Disinfectant 3.6 recognizes it).

Code 1: file infector. Renames the hard drive to "Trent Saburo".
Accidental system crashes possible.

Code 252: infects application and system files. Triggers when run
between June 6th and December 31st. Runs a gotcha message ("You
have a virus. Ha Ha Ha Ha Ha Ha Ha Now erasing all disks...
[etc.]"), then self-deletes. Despite the message, no intentional
damage is done, though shutting down the Mac instead of clicking to
continue could cause damage. Can crash System 7 or damage files,
but doesn't spread beyond the System file. Doesn't spread under
System 6 with MultiFinder beyond System and MultiFinder. Can cause
various forms of accidental damage.

Code 9811: hides applications, replacing them with garbage files
named "something like 'FIDVCXWGJKJWLOI'." According to Ken Dunham
who reported this virus in November, "The most obvious symptom of
the virus is a desktop that looks like electronic worms and a
message that reads 'You have been hacked by the Pretorians.'"

Code 32767: once a month tries to delete documents. This virus is
not known to be in circulation.

Flag: unrelated to WDEF A and B, but was given the name WDEF-C in
some anti-virus software. Not intentionally damaging but when
spreading it overwrites any existing 'WDEF' resource of ID '0', an
action which might damage some files. This virus is not known to be
in circulation.

Frankie: only affects the Aladdin emulator on the Atari or Amiga.
Doesn't infect or trigger on real Macs or the Spectre emulator.
Infects application files and the Finder. Draws a bomb icon and
displays 'Frankie says: No more piracy!"

****: infects application and System files. No intentional damage.
(nVIR B strain)

Init 17: infects System file and applications. Displays message
"From the depths of Cyberspace" the first time it triggers.
Accidental damage, especially on 68K machines.

Init 29 (Init 29 A, B): Spreads rapidly. Infects system files,
applications, and document files (document files can't infect other
files, though). May display a message if a locked floppy is
accessed on an infected system 'The disk "xxxxx" needs minor
repairs. Do you want to repair it?'. No intentional damage, but can
cause several problems - Multiple infections, memory errors, system
crashes, printing problems, MultiFinder problems, startup document

Init 1984: Infects system extensions (INITs). Works under Systems 6
and 7. Triggers on Friday 13th. Damages files by renaming them,
changing file TYPE and file CREATOR, creation and modification
dates, and sometimes by deleting them.

Init-9403 (SysX): Infects applications and Finder under systems 6
and 7. Attempts to overwrite whole startup volume and disk
information on all connected hard drives. Only found on Macs
running the Italian version of MacOS.

Init-M: Replicates under System 7 only. Infects INITs and
application files. Triggers on Friday 13th. Similar damage
mechanisms to INIT-1984. May rename a file or folder to "Virus
MindCrime". Rarely, may delete files.

MacMag (Aldus, Brandow, Drew, Peace): first distributed as a
HyperCard stack Trojan, but only infected System files. Triggered
(displayed a peace message and self-deleted on March 2nd 1988, so
very rarely found.

MBDF (A,B): originated from the Tetracycle, Tetricycle or
"tetris-rotating" Trojan. The A strain was also distributed in
Obnoxious Tetris and Ten Tile Puzzle. Infect applications and
system files including System and Finder. Can cause accidental
damage to the System file and menu problems. A minor variant of
MBDF B appeared in summer 1997: Disinfectant and Virex have been
updated accordingly.

MDEF (MDEF A/Garfield, MDEF B/Top Cat, C, D): infect System file
and application files (D doesn't infect System). No intentional
damage, but can cause crashes and damaged files.

MDEF-E and MDEF-F: described as simple and benign. They infect
applications and system files with an 'MDEF' resource ID '0', not
otherwise causing file damage. These viruses are not known to be in

nCAM: nVIR variant

nVIR (nVIR A, B, C - AIDS, ****, Hpat, Jude, MEV#, nFlu): infect
System and any opened applications. Extant versions don't cause
intentional damage. Payload is either beeping or (nVIR A) saying
"Don't panic" if MacInTalk is installed.

nVIR-f: nVIR variant.

prod: nVIR variant

Scores (Eric, Vult, NASA, San Jose Flu): aimed to attack two
applications that were never generally released. Can cause
accidental damage, though - system crashes, problems printing or
with MacDraw and Excel. Infects applications, Finder, DA Handler.

SevenDust-A through G (MDEF 9806-A through D, also known as 666, E
was at first called "Graphics Accelerator"): a family of five
viruses which spread both through 'MDEF' resources and a System
extension created by that resource. The first four variants are not
known to be in circulation. Two of these viruses cause no other
damage. On the sixth day of the month, MDEF 9806-B may erase all
non-application files on the current volume. The SARC encyclopedia
calls MDEF 9806-C, "polymorphic and encrypted, no payload," and
MDEF 9806-D, "encrypting, polymorphic, symbiotic," and says the
symbiotic part, "alters a 'WIND' resource from the host
application." SevenDust E, not to be confused with the legitimate
ATI driver "Graphics Accelerator", began as a trojan horse released
to Info-Mac and deleted there on or about September 26, 1998. Takes
two forms, 'INIT' resource ID '33' in an extension named
"\001Graphics Accelerator" and an 'MDEF' resource ID '1' to '255'.
Between 6:00 a.m. and 7:00 a.m. on the sixth and twelfth day of any
month, the virus will try to delete all non-application files on
the startup disk. John Dalgliesh describes "Graphics Accelerator"
on his Web page for AntiGax, a free anti-SevenDust E utility; any
errors here in translation are not his. SevenDust F uses a trojan
"ExtensionConflict", common extensions names, and creator 'ACCE'.[SL]

T4 (A, B, C, D): infects applications, Finder, and tries to modify
System so that startup code is altered. Under System 6 and 7.0,
INITs and system extensions don't load. Under 7.0.1, the Mac may be
unbootable. Damage to infected files and altered System is not
repairable by Disinfectant. The virus masquerades as Disinfectant,
so as to spoof behaviour blockers such as Gatekeeper. Originally
included in versions 2.0/2.1 of the public domain game GoMoku.

T4-D spreads from application to application on launch by appending
itself to the 'CODE' resource. Deletes files other than the System
file from the System Folder, and documents, and is termed dangerous.
The D strain is not known to be in circulation [SL].

WDEF (A,B): infects desktop file only. Doesn't spread under System
7. No intentional damage, but causes beeping, crashes, font
corruption and other problems.

zero: nVIR variant.

Zuc (A, B, C): infects applications. The cursor moves diagonally
and uncontrollably across the screen when the mouse button is held
down when an infected application is run. No other intentional
damage is done.

7.2 HyperCard infectors
These are a somewhat esoteric breed, but a couple have been seen
since Disinfectant was last upgraded in 1995, and most of the
commercial scanners detect them.

Dukakis - infects the Home stack, then other stacks used
subsequently. Displays the message "Dukakis for President", then
deletes itself, so not often seen.

HC 9507 - infects the Home stack, then other running stacks and
randomly chosen stacks on the startup disk. On triggering, displays
visual effects or hangs the system. Overwrites stack resources, so
a repaired stack may not run properly.

HC 9603 - infects the Home stack, then other running stacks. No
intended effects, but may damage the Home stack.

HC "Two Tunes" (referred to by some sources as "Three Tunes") -
infects stack scripts. Visual/Audio effects: 'Hey, what are you
doing?' message; plays the tune "Muss I denn"; plays the tune
"Behind the Blue Mountains"; displays HyperCard toolbox and pattern
menus; displays 'Don't panic!' fifteen minutes after activation.
Even sources which describe this virus as "Three Tunes" seem to
describe the symptoms consistently with the description here, but
we will, for completeness, attempt to resolve any possible
confusion when time allows. This virus has no known with the PC
file infector sometimes known as Three Tunes.

MerryXmas - appends to stack script. On execution, attempts to
infect the Home stack, which then infects other stacks on access.
There are several strains, most of which cause system crashes and
other anomalies. At least one strain replaces the Home stack script
and deletes stacks run subsequently. Variants include Merry2Xmas,
Lopez, and the rather destructive Crudshot. [Ken Dunham discovered
the merryXmas virus. His program merryxmasWatcher 2.0 was very
popular and still can eradicate the most common two strains,
merryXmas and merry2Xmas. merryxmasWatcher 2.0 is outdated for the
rest this family.]

Antibody is a recent virus-hunting virus which propagates between
stacks checking for and removing MerryXmas, and inserting an
inoculation script.

Independance (sic) Day - reported in July, 1997. It attempts to
to be destructive, but fortunately is not well enough written to be
more than a nuisance. More information at:

Blink - reported in August, 1998. Nondestructive but spreads;
infected stacks blink once per second starting in January, 1999.

7.3 Mac Trojan Horses
These are often unsubtle and immediate in their effects: while
these effects may be devastating, Trojans are usually very
traceable to their point of entry. The few Mac-specific Trojans are
rarely seen, but of course the commercial scanners generally detect

ChinaTalk - system extension - supposed to be sound driver, but
actually deletes folders.

CPro - supposed to be an update to Compact Pro, but attempts to
format currently mounted disks.

+ ExtensionConflict - supposed to identify Extensions conflicts, but
installs one of the six SevenDust a.k.a. 666 viruses.

FontFinder - supposed to lists fonts used in a document, but
actually deletes folders.

MacMag - HyperCard stack (New Apple Products) that was the origin
of the MacMag virus. When run, infected the System file, which then
infected System files on floppies. Set to trigger and self-destruct
on March 2nd, 1988, so rarely found.

Mosaic - supposed to display graphics, but actually mangles
directory structures.

NVP - modifies the System file so that no vowels can be typed.
Originally found masquerading as 'New Look', which redesigns the

Steroid - Control Panel - claims to improve QuickDraw speed, but
actually mangles the directory structure.

Tetracycle - implicated in the original spread of MBDF

Virus Info - purported to contain virus information but actually
trashed disks. Not to be confused with Virus Reference.

Virus Reference 2.1.6 mentions an 'Unnamed PostScript hack' which
disables PostScript printers and requires replacement of a chip on
the printer logic board to repair. A Mac virus guru says:

"The PostScript 'Trojan' was basically a PostScript job that
toggled the printer password to some random string a number of
times. Some Apple laser printers have a firmware counter that
allows the password to only be changed a set number of times
(because of PRAM behavior or licensing -- I don't remember which),
so eventually the password would get "stuck" at some random string
that the user would not know. I have not heard any reports of
anyone suffering from this in many years."

AppleScript Trojans - A demonstration destructive compiled
AppleScript was posted to the newsgroups alt.comp.virus,
comp.sys.mac.misc, comp.sys.mac.system, it.comp.macintosh,
microsoft.public.word.mac, nl.comp.sys.mac, no.mac, and on 16-Aug-97, apparently in
response to a call for help originally posted to alt.comp.virus on
14-Aug-97 and followup on 15-Aug-97. On 03-Sep-97, MacInTouch
published Xavier Bury's finding of a second AppleScript trojan
horse, which, like the call for help followup, mentioned Hotline
servers. It reportedly sends out private information while running
in the background. A note to users from Hotline Communications CEO
Adam Hinkley is posted at
AppleScripts should be downloaded only from known trusted sources.
It is nigh impossible for an average person to know what any given
compiled script will do.

7.4 Macro viruses, trojans, variants
At the time of the longstanding second-to-last upgrade of
Disinfectant (version 3.6 in early 1995), there were no known macro
viruses in the wild, apart from HyperCard infectors. In any case,
Disinfectant was always intended to deal with system viruses, not
trojans or macro/script viruses. However, many users are unaware of
these distinctions and still assume that Disinfectant is a complete
solution, even after its effective demise (in fact, there were
people still relying on Gatekeeper long after its author disowned

Unfortunately, the number of known macro viruses runs into several
thousand, though the number in the wild is far fewer.

Most macro viruses (if they have a warhead at all) target Intel
platforms and assume FAT-based directory structures, so they
usually have no discernible effect on Macs when they trigger.
Viruses that manipulate text strings within a document may work
just as well on a Macintosh as on a PC.

In any case, the main costs of virus control are not recovery from
virus payloads, but the costs of establishing detection and
protection (or of not establishing them). The costs of not
establishing these measures can be considerable, irrespective of
damage caused on infected machines, especially in corporate
environments. Secondary distribution of infected documents may
result in:

* civil action - for instance, inadvertent distribution of an
infected document to external organisations may be in breach of
contractual obligations

* legal action in terms of breach of data-protection legislation
such as the UK Data Protection Act or the European Data Protection
directive. The eighth principle of the Data Protection Act, for
instance, requires that security measures are taken to protect
against unauthorised access to, and alteration, disclosure and
destruction of personal data, or its accidental loss.

* damage to reputation - no legitimate organisation wants to be
seen as being riddled with viruses.

Since Word 6.x for Macintosh supports WordBasic macros, it is as
vulnerable as Word 6.x and 7.x on Intel platforms to being infected
by macro viruses, and therefore to generating other infected
documents (or, strictly speaking, templates). Working Excel viruses
are now beginning to appear also, and any future Macintosh
application that supports Visual Basic for Applications will also
be vulnerable. Note also that the possibility of virus-infected
files embedded as objects in files associated with other
applications: this possibility exists on any platform that supports

++Office 98 is in general vulnerable to infection by most viruses which
affect corresponding applications in Office 97.

Macro viruses are therefore highly transmissible via
Macintoshes, even if they don't have a destructive effect on
Motorola platforms, if there is an equivalent application
available on the Macintosh. For instance, although Word for
Windows versions before vs. 6 support WordBasic, Word
versions for the Mac up to and including version 5.1 do not.
[Thus Word 5.1 users can not be directly infected, but may,
like anyone, pass on infected documents to vulnerable systems.]]

Network Associates, Symantec, and Intego all make known-virus
scanners that detect a range of macro viruses. Microsoft make
available a free 'protection tool' whose effectiveness is often
overestimated. (See below.)

++[I'm no longer able to find any reference on Intego's site to Rival:
their efforts seems to be focused on their personal firewall for Macintosh.]

For further information on specific macro viruses, try one of the
information resources given earlier.

7.5 Other Operating Systems, emulation on a Mac
Any Mac running any sort of DOS or Windows emulation such as
Virtual PC, SoftPC, SoftWindows, RealPC, or a DOS compatibility
card is a potential target for any PC virus, including Boot Sector
Infectors/Multipartites; (effects will vary). It is highly
recommended that anyone with such a system should run a reputable,
up-to-date PC antivirus program under emulation, as well as a good
Mac antivirus program. [Dr. Solomon's for the Mac detected PC boot
sector infectors as well as Mac viruses, but didn't detect PC file
viruses (apart from macro viruses), and so was not sufficient
protection for a Mac with DOS emulation.]

Recommendations for defending PC systems or PC emulation on Macs
are slightly out-of-scope for this FAQ. In fact, I don't know of
any formal testing for PC antivirus software in the context of PC
emulation on Macs. I've done some informal testing (referred to in
another paper), but am not prepared to make vendor-specific
recommendations on the basis of such testing. F-Prot, AVP, and Dr
Solomon's are particularly well-regarded PC antivirus packages, of
which some components on some platforms are available as freeware
or for evaluation, but their efficacy in the context of PC
emulation is not well tested or documented.

To find a commercial or shareware package relevant to PCs, check
through the independent comparative reviews sites:
University of Hamburg Virus Test Center
University of Tampere Virus Research Unit
Secure Computing
Virus Bulletin

+ has an aggregation of PC anti-virus reviews links.

Robert Michael Slade's lists may also be helpful.

7.6 AutoStart 9805 Worms
AutoStart 9805 is not a virus, but a worm: that is, it replicates
by copying itself, but doesn't attach itself parasitically to a
host program. The original took hold rapidly in Hong Kong and
Taiwan in April 1998, and has been reported on at least four
continents. In addition to the original worm, there are five
variants. Virus Bulletin, July, 1998, includes a comprehensive
analysis of AutoStart and some of its variants.

CIAC Bulletin I-067 is based on Eugene Spafford's information
release on the original AutoStart worm. Unfortunately,this is now a
little out-of-date, particularly as regards the update status of
the antivirus software it mentions. Nor does it mention any of the
subsequently discovered variants.

Symptoms: Perhaps the most noticeable symptom of the worms is that
an infected system will _lock up and churn with unexplained disk
activity_ every 6, 10, or 30 minutes.[SL]

Affected platforms: any PowerMac. Macintoshes and clones driven by
Motorola 680x0 series CPUs can't run the replicative code. It works
under any version of Mac OS, if QuickTime 2.0 or later is installed
and CD-ROM AutoPlay is enabled in the "QuickTime Settings" Control

Transmission media: HFS or HFS+ volumes (hard disks, diskettes,
most types of removable media, even disk images). Audio CDs can't
transmit the virus, and it isn't necessary to disable "Audio CD

Transmission method: infected media contain an invisible
application file named "DB" or "BD" or "DELDB" in the root
directory (type APPL, creator ????). This is an AutoStart file:
i.e. it will run automatically if CD-ROM autoplay is enabled. If
the host Mac isn't already infected, it copies itself to the
Extensions folder. The new copy is renamed "Desktop Print Spooler"
or "Desktop Printr Spooler", or "DELDesktop Print Spooler"
respectively (type appe, creator ????). Unlike the legitimate
Desktop Printer Spooler extension, the worm file has the invisible
attribute set, and isn't listed as a running process by the sstem
software, though it can be seen with Process Watcher or Macsbug.
After copying itself, it reboots the system and is now launched
every time the system restarts. At approximately 6, 10, or 30
minute intervals, it examines mounted volumes to see if they're
infected: if not, it writes itself to the root directory and sets
up AutoStart (however, AutoStart won't work on a server volume).

Damage: files with names ending "data", "cod" or "csa" are targeted
if the data fork is larger than 100 bytes. Files with names ending
"dat" are targeted if the whole file is c. 2Mb or larger. Targeted
files are attacked by overwriting the data fork (up to the 1st Mb)
with garbage.

Besides the original, there are five variants: AutoStart 9805-B,
which is less noticeable but can cause irreparable damage to files
of type 'JPEG', 'TIFF', and 'EPSF'; AutoStart 9805-C and AutoStart
9805-D which do not intentionally damage data; AutoStart 9805-E
which spreads like B and is most similar to the original; and
AutoStart 9805-F which is most similar to A and E.
Dr Solomon's, Sophos, and Symantec had descriptions on the Web:
++Dead Mac Virus link cleaned.

Detection: updates to deal with the worms are available for Virex
(, for NAV and SAM
(, and for Rival

The last versions of VirusScan for Mac and Disinfectant did not detect
AutoStart. [Reference to Dr Solomon's for Mac removed, as the product is
no longer supported.]

Prevention: uninfected systems can be protected by disabling the
AutoStart option in QuickTime settings (QuickTime 2.5 or later only
- earlier versions don't have a disable option). This should also
prevent infection by future malware exploiting the same loophole,
but will fail if a setup is booted from a volume with an infected
Extensions Folder [SL].

Removal: the easiest and safest method for most people will be to
use the updated version of their favoured anti-virus software, as
it becomes available.

The worms can be also be removed manually.
* Reboot with extensions disabled (hold down the shift key till an
alert box tells you that extensions are off).
* Use Find File to search all volumes for all instances of a file
called "DB" or "BD" or "DELDB" with the invisibility attribute set
(hold down Option key when clicking on "Name" pop-up menu to select
for visibility). Trash 'em.
* Use Find File to find and trash an invisible "Desktop Print
Spooler", "Desktop Printr Spooler", or "DELDesktop Print Spooler"
file (-not- Desktop Printer Spooler, which is a legitimate and
usually necessary system file).
* Empty the trash.
* Disable AutoStart in QuickTime Settings Control Panel.
* Restart.

7.7 Esperanto.4733
This probably doesn't belong here. It's a PC file infector which
works with a number of PC executable file formats. When it was
first seen, it was reported to be a multiplatform virus capable of
executing under some circumstances on Macintoshes. Subsequent
reports indicate that this belief results from misinformation on
the part of the author. However, at least two reputable PC
anti-virus vendors still list it as capable of activating on a
Macintosh. No Mac scanner is known to attempt to detect it.

8.0 What's the best antivirus package for the Macintosh?
================================================== =======

As ever, we can't give a definitive answer to this. The best choice
depends on subjective criteria and individal needs. Nonetheless,
Here are some thoughts on the main contenders.

8.1 Microsoft's Protection Tools
Microsoft's Macro Virus Protection Tools originally detected
Concept (Nuclear and DMV were also mentioned in the documentation,
but were not identified specifically by the tools). Principally,
they merely warned users that the document they are about to open
contained macros and offered the choice of opening the file without
macros, opening it with macros, or cancelling the File Open. Later
implementations built into the application are better on
identifying a few specific viruses and on integration into Word
itself, but should not be relied on for 100% effective detection,
blocking and disinfection of macro viruses. More information from
Microsoft may be available at the addresses below.
<> (no longer accessible)
AOL: the Word forum
CompuServe: the Word forum
Microsoft Product Support Services
206-462-9673 (WinWord)
206-635-7200 (Word Mac)
email: (E-Mail Removed)

NB The Protection Tool traps some File Open operations, but not
all. There are a number of ways of opening a document which bypass
it, some of which are rather commonly used (e.g. double-clicking or
using the Recent Documents list).

The Protection Tool can be used to scan for Concept-infected files,
but there are a number of possible problems with it.

* Earlier versions could only handle a limited size of directory
tree, and ran very slowly if a large number of files required
scanning. Speed is certainly still a problem: I can't say about the
overflow problem.
* Files created in Word for Windows won't be scanned until they've
been opened in Word 6 for Mac (this is a system issue, not a bug in
the code). However, Microsoft suggest that you open the file in
Word for the Macintosh and save it before scanning. This will do
the job, but will also infect your system, if the file is infected.
If it's infected with a virus -other- than Concept, this could
create problems if the Protection Tool is bypassed on a subsequent
file open.
* Infected files embedded in OLE2 files or e-mail files will not be
* The Microsoft tools are not useful on non-English Windows systems
(which may be run under Virtual PC or Real PC). SCANPROT cannot
handle non-English documents, and will hang during the scanning
process if it encounters a document created with a non-English
version of Word. Microsoft's Excel add-in for the Laroux macro
virus causes multiple file open buttons to appear in non-English
versions of Excel, and so it has worse effects than the macro virus
itself. Again this applies to Windows emulation; however, most
virus protection and detection products are only tested in an
English language environment, and may cause problems on non-English
systems. [Thanks to Eric Hildum for this information.]

Windows 95 users should be aware that SCANPROT is not recommended
for use with MS Word 7.0a for Windows with internal detection
enabled, as these two tools will cancel each other out.

The Excel add-in for Macs removes only Laroux A and B.

++Office 98 moves the goalposts again. This issue will probably be
addressed again here in more depth. In brief, Office 98 does a
better job of implementing a primarily generic approach [i.e. "If
it contains macros, it's suspicious: sort it out yourself...."],
but whether this is enough is a question demanding more space and
time than I have to spare right now. Office 97/98 include limited
detection of a handful of known viruses during upconversion of
macros. This is poorly implemented and in any case is only triggered
when macros are converted to VBA from WordBasic. Vesselin Bontchev
has considered macro upconversion at some length in papers for
Virus Bulletin and EICAR conferences.

++Microsoft's home page has recommended using an ICSA-certified
antivirus utility and sidesteps any hint of responsibility for any
macro virus or SCANPROT related problems. However, ICSA does not
currently certify Mac products, though this is being looked at.

8.2 Disinfectant
[On May 6th 1998, John Norstad, author of this widely-used freeware
package announced that it was to be retired. 3.7.1 is the latest
and last version, and it won't be updated to detect AutoStart 9805
or any subsequent Macintosh malware. The main reason for this is
that he doesn't have the resources to extend its capabilities to
detect macro viruses, which have become by far the most significant
virus problem for most Macintosh users.

This is probably a wise decision, given the number of people who
still overestimate the effectiveness of the package in the face of
the macro virus threat. However, the entire Macintosh community
owes John Norstad a debt of gratitude for making it freely
available for so long, an act of altruism which has probably
contributed very significantly to the comparative rarity of native
Macintosh viruses.]

Disinfectant was an excellent anti-virus package with exemplary
documentation, and didn't cost a penny: however, it didn't detect
all the forms of malware that a commercial package usually does,
including HyperCard infectors, most Trojans, jokes or macro
viruses. Unlike some commercial packages, it didn't scan compressed
files, either: compressed files had to be expanded before scanning.
Self-extracting archives were probably best scanned before
unpacking, then again when unpacked.

Disinfectant has been available up to now from the following
sources, but this may not continue to be the case.:
America Online
Info-Mac mirrors in the ../vir/ directory

The Disinfectant README was updated to README-IMPORTANT on 6 May
1998, with the message, "because of the widespread and dangerous
Microsoft macro virus problem," "...All Disinfectant users should
switch..." to another program. README-IMPORTANT was updated again
on 11 October 1998, adding, "In addition to the Autostart worm and
the Microsoft macro viruses, several other new Mac viruses have
appeared since Disinfectant's retirement in May. This makes it even
more important that Disinfectant users switch..." to one of the
commercial products.
There is a copy of the retirement announcement on the Web:

8.3 Demo Software
Symantec has a 30-day fully-functioning trialware NAV (Norton
AntiVirus for Macintosh). Update it with current definitions.

Network Associates has a 30-day fully-functioning evaluation
version of Virex 5.9.1. The Virex trial includes the application,
not the control panel.
Update the demo with current definitions:

Sophos also has a 30-day evaluation, also fully-functioning,
which includes the SWEEP application. The demo supports both
English and Japanese.

++Intego has a limited-function French demo of Rival, "miniRival."
<> [This seems to have disappeared,
along with Rival itself - 11-12-99]

Disinfector 1.0 is described by its author as shareware. However,
it's strictly speaking a limited-runtime demo -- it stops
functioning after 20 trial runs on one system. It's described as a
beta release, but the author expects users to register it at a
charge of $30 [subsequently reduced to $15]: in return, they get a
version which can be used an unlimited number of times. It only
detects a handful of Mac system viruses which the author claims
that commercial vendors have not detected, and have not been
reported in the wild. In the early days of virus/antivirus
technology, a number of utilities were made available which
addressed only one or a few viruses, and a proliferation of free
AutoStart worm detectors continues that honourable tradition.
However, charging for this particular utility puts it into the same
arena as the commercial scanners which detect a far wider range of
threats and for which full support is available, an area in which
it cannot at present compete. Disinfector was briefly available at
Info-Mac, but has since been removed.
++[I suspect that this product has been removed from circulation, but
haven't checked with the author. This section will probably be amended
or removed in the next version of the FAQ, when I've checked.]

There have also been a number of proposals since John Norstad
announced the retirement of Disinfectant, suggesting that if the
code was made public, it would be possible to maintain and further
develop Disinfectant, possibly still as a freeware product. This is
misguided, for a number of reasons.

* It misses one of the main points of Norstad's announcement, which
is to acknowledge the dangers of continuing to develop a scanner
which detects only one class of virus, when so many people have
laboured so long under the misapprehension that it was a complete
* Disinfectant -has- been developed further. VirusScan is based on
Disinfectant technology (under licence), and NAI are in a much
better position to develop it as commercial-grade software than a
group of well-meaning individuals without the specialised skills
and resources of a mainstream anti-virus development team. Indeed,
it may be that the terms of that agreement would prevent Norstad
from making the code public even if he wanted to (I doubt that he
* Making the code public, even to a limited circle, would increase
the chances of its falling into irresponsible hands. In fact, the
online documentation has long stated that the code for the
detection engine is not available, though some of the interface
code was. (I'm paraphrasing from memory: I may well check out
exactly what it says for the next update of the FAQ.)
* To think that a committee of well-intentioned amateurs (or a
single ambitious amateur can develop Disinfectant to the same high
standard that it achieved through its lifetime demonstrates a
profound underestimation of the difficulties of maintaining (let
alone creating) a first-class known-virus scanner. [DH] Curiously,
the same fallacies have recently been been aired on a Unix virus
discussion list.

8.4 Other freeware/shareware packages
For other freeware\shareware Mac packages, try Info-Mac mirrors

The University of Texas holds some older documentation on Mac

Tracker INIT and DelProtect INIT, both by Ioannis Galidakis, were
first released on 19-Nov-98. Tracker is a behavior blocker something
like the retired program GateKeeper. DelProtect protects against
malicious file deletion. Tracker is now at version 1.1. Scanner 1.1x
also by Ioannis Galidakis was released 15-Jan-99, and is a free,
generic, heuristic 68k virus scanner for advanced Macintosh users.

John Dalgliesh has created Agax, an extensible, free anti-virus
program which replaces his program AntiGax, and uses plug-ins called
"Additives." At this time, Agax will detect and try to clean only
SevenDust, CODE 9811, and the AutoStart worms (the worm additive was
in beta testing at the time of this writing). The author's Web page
and documentation invite Mac programmers to contribute additives.

The Exorcist, free from Laffey Computer Imaging, may give some (by
one description, about 90%) protection from the SevenDust family.

Gatekeeper was not a scanner, but a generic tool. It is no longer
supported by its author, but is still available on some sites. It
is probably not safe to use or rely on on modern systems, and I
believe the author recommends that people don't attempt to use it,
though I've been unable to contact him to get confirmation.

In January 1997 Padgett Peterson, author of the PC utility
DiskSecure, released the first version of his MacroList macro
detection tool, which has been tested by the author on Macs (System
7.5 on SE/30, IIci and PowerMac) as well as Windows PCs, using
considerably more macro viruses than Microsoft seem to have heard
of..... The MacroList template is accessed by a button in the
standard toolbar. This is not a virus scanner, but allows disabling
of automacros, listing of any macros found in the current document
etc. Version 1.10 was due for release by the time of writing
(February 1997), and an adaptation for Office97 is in progress.
Watch the Web page for further details. [v1.1 and the Office 97
"late beta" were available as at 18th March 1997.] MacroList is
freeware, but please be sure to read the TRIALS link.
(under Anti-Virus Hobby) - NB change of URL.

WormGuard by Clarence Locke is a free on-access extension that
affords AutoStart worm protection:

The following free scanners may remove AutoStart 9805 and its B, C,
D, E, and F variants and may be useful in the absence of a
commercial application. There are a few reported instances of
failures by some of these programs to identify or remove the
AutoStart worms, and it is likely that D might be mis-identified as
C, and E may be mis-identified as the original worm. [SL]

WormScanner by James Walker
Autostart Hunter by Akira Nagata
<> (English)
<> (Japanese)
BugScan by Mountain Ridge Dataworks (also detects SevenDust E)
Worm Gobbler by Jim Kreinbrink
Innoculator by MacOffice
WormFood by Doug Baer
Eradicator with update, by Uptown Solutions Ltd.

As stated above, one-shot solutions to a very small subset of a
particular class of threat have a long and honourable history, and
are very welcome when a new threat catches the antivirus developers
on the hop (it can take some time to incorporate detection of new
threats into the product update cycle). NB The maintainer does not
currently have the time or resources to do full detection testing of
these products (or any other). [DH]

8.5 Commercial Packages
Commercial packages include NAV (Norton AntiVirus for Macintosh)
[NAV supersedes SAM (Symantec Antivirus for Macintosh)], Virex for
Macintosh, Rival, and Sophos Anti-Virus for Macintosh (SAV).

Virex, NAV, and SAM [obsolete] all address a full range of threats,
including Trojans and macro viruses, and can do scheduled scanning
as well as on-access (memory-resident) scanning.

++Sophos Anti-Virus for Macintosh (SAV) was upgraded in January 1999
to include the SWEEP on-demand scanner. The shipping version can be
downloaded for free evaluation. English and Japanese are supported.
<> Stand-alone on-access scanning
is now available in the release version. Server-based on-access scanning
has long been available for Mac clients on NT or NetWare networks.
The program offers customizable reporting and notification from an
attractive interface. So far, compressed archives must be
decompressed before scanning; I am assured that archive scanning
will be in future versions. Complete documentation is in PDF format.
+ Sophos combines an intercept driver (InterCheck) and a scanner
application (SWEEP). Sales are not retail, but direct or through
the Sophos Distributor network. Free technical support is all-year
round, any time of day. Virus identity updates are available from
the Web between monthly CD-ROMs. Major developments in the Sophos
product are expected, including smooth large-scale deployment and
ease of updating over networks.[SL]
[This section is overdue for serious refurbishment. Next FAQ release, maybe. There
may be an issue with the Sophos control panel and some USB drives - not formally
tested to date.]

Norton AntiVirus for Macintosh (NAV) launched May 18, 1998. New
features included LiveUpdate virus definition updates over the
Internet, enhanced macro virus protection, automatic file repair, a
bootable CD-ROM for emergencies, faster scanning for PPC, and a
universal SafeZone.

NAV, SAM, and Virex offer checksumming/integrity checking
(detecting possible infection by unknown viruses, by monitoring
changes in infectable files) - the correct checksums or
fingerprints for individual files are kept in a database file. All
three applications check files compressed with StuffIt.

NAV, formerly SAM, is particularly oriented towards behaviour
blocking: the Intercept tool can be configured to raise an alert at
the slightest whiff of a 'suspicious' operation. Unfortunately,
this can be counterproductive in real life, since an over-stringent
alert policy is apt to result in the facility being turned off
altogether. However, configuration is very flexible.

SAM (Symantec AntiVirus for Macintosh) support was discontinued
May 1; the last update is for July '99. From Symantec's advice:
"In order to maintain the safety and security of your data
from viruses without interruption, we recommend that you
upgrade to NAVM 5.0.3 before May 1st. For presales and
upgrade questions, please contact customer service. They
can be reached at 800-441-7234 or online at:"

[SAM 4.5.x needs the 4.5->4.5.1 application patch to run current
definitions, and the 4.5.3 Intercept patch to resolve a compatibility
issue with Microsoft Office 98, and Segment Loader errors when
Intercept loads.
SAM application Minimum and Preferred memory allocations must be
increased from their shipping defaults to 5000K or greater. The
(May 1998) SAM definitions files included a Read Me with
instructions. More information may be available from Symantec SAM
support on the Web.]

Symantec issued a Norton AntiVirus 5.x->5.0.3 patch for Mac OS 8.5,
fixing the problem with copying files on AppleShare networks.

Virex offers very fast scanning is easy to update, and includes
checksumming for the detection of unknown viruses. It's also
possible to buy an administration package. The basic package
includes a control panel for scanning on file or diskette access
which can be locked independently of the administration package.
Installation and interface are easy and efficient. Virex 5.8 scans
ZIP archives, has a contextual menu plug-in module, and interface

Virex 5.9.1 was released on 18-Jan-99, for compatibility with
Mac OS 8.5 and Virex Administrator 1.4, and can be downloaded.
<>. Registered users who
bought McAfee VirusScan during the past six months or so, and
registered users of Virex 5.8 and 5.9 could still upgrade:
Virex Administrator version 1.4 was released by NAI on 23-Dec-98.
Virex and Virex Administrator had these home pages:
++Current Virex release is 6.0. Licensed 5.9x users can obtain an
upgrade. OS 9 users will need the beta control panel available from, to overcome compatibility problems.

Dr Solomon's Software acquired Virex and netOctopus from Datawatch
Corp. on 10-Oct-97. Network Associates (NAI) acquired Dr Solomon's
on 13-Aug-98. Netopia, Inc., acquired what is now named Timbuktu
netOctopus in late '98 or early '99.

++VirusScan 3.0.1 is the final version for Macintosh, and may be
updated for macro viruses into 1999, but will never have AutoStart
worm definitions or definitions for the new System viruses like
SevenDust E. VirusScan customers need to take advantage of a free
upgrade to Virex as soon as possible.

Dr. Solomon's for Macintosh went through various stages of neglect
through late 1998 and support appears to have vanished altogether in
1999, when customers started to receive Virex disks instead of Dr.
Solly's updates.

++Rival 3.0.4 is available from Intego. [Probably obsolete info.]

++F-Secure for Macintosh is one of the best-kept secrets in anti-virus.
The last time I saw it, it detected macro viruses only. You might be
lucky and find some reference to it at:
It features on datafellows evaluation CDs.

8.6 Contact Details
Network Associates
(for Virex, Dr Solomon's Anti-Virus Toolkit, and VirusScan)

Network Associates Corporate Headquarters
3965 Freedom Circle
McCandless Towers
Santa Clara, CA 95054
United States
Customer Care:
Voice +1 408 988 3832
Fax +1 408 970 9727
Fax-back automated response system
+1 408 988 3034
BBS +1 408 988 4004
America Online keyword: MCAFEE
CompuServe: GO NAI
(E-Mail Removed)

Dr. Solomon's Software Ltd.
(for Dr. Solomon's Anti-Virus Toolkit)

Alton House
Gatehouse Way
Buckinghamshire HP19 3XU
United Kingdom
UK Support: (E-Mail Removed)
US Support: (E-Mail Removed)
UK Tel: +44 (0)1296 318700
USA Tel: +1 781-273-7400, 1-888-DRSOLOMON

Symantec Corporation (for NAV and SAM)

10201 Torre Avenue
Cupertino CA 95014
United States
+1 408 725 2762
Fax: +1 408 253 4992
US Support: 541-465-8420
European Support: 31-71-353-111
Australian Support: 61-2-879-6577

Intego (for Rival)

10, rue Say
75009 Paris
+33 1 49 95 07 80
Fax: +33 1 49 95 07 83
Email: (E-Mail Removed)

Sophos Plc (for Sophos Anti-Virus)

The Pentagon
England OX14 3YP
US Support: +1-888-SOPHOS-9
UK Support: +44-1235-559933

++Details on DataFellows will be included when I've determined the current
status of F-Secure for Macintosh. [Sorry: next time round, guys....]

9.0 Welcome Datacomp

From time to time there are reports from Mac users that the message
'Welcome Datacomp' appears in their documents without having been
typed. This is the result of using a Trojanised 3rd-party
Mac-compatible keyboard with this 'joke' hard-coded into the
keyboard ROM. It's not a virus - it cannot infect anything. The
only cure is to replace the keyboard (be polite but firm with the
dealer if you were sold this as a new keyboard!).

10.0 Hoaxes and myths

Some of these are PC-specific, rather than Mac-specific, while some
have no basis in reality on any system. [I look forward to hearing
about the first Turing machine infector....] They are included here
(a) because Mac support staff are accustomed to being asked about
them (b) because anything that -might- work on a real PC -might-
also work with DOS emulation, in principle.
++This section may vanish in the near future, or at least contract.
The hoax business has changed a lot since this FAQ began.

10.1 Good Times virus
There is *no* Good Times virus that trashes your hard disk and
launches your CPU into an nth-complexity binary loop when you read
mail with "Good Times" in the Subject: field.

You can get a copy of the latest version of Les Jones' FAQ on the
Good Times Hoax on the World Wide Web:

There's a Mini-FAQ available as:

10.2 Modems and Hardware viruses
There is no modem virus that spreads via an undocumented subcarrier
- whatever that means.... There is no virus that causes damage to

10.3 Email viruses
Any file virus can be transmitted as an E-mail attachment. However,
the virus code has to be executed before it actually infects.
Sensibly configured mailers and browsers don't allow this: check
yours. In particular, check that your Web browser doesn't
automatically pass Word documents to Word 6 to open, since this may
result in embedded macros being launched.

10.4 JPEG/GIF viruses
There is no known way in which a virus could sensibly be spread by
a graphics file such as a JPEG or .GIF file, which does not contain
executable code. Macro viruses work because the files to which they
are attached are not 'pure' data files.

10.5 Hoaxes Help
If you should receive a virus warning, look at these sites before
forwarding it along (in fact, it's probably never justified to pass
on a virus alert indiscriminately, and reputable antivirus
companies don't do this. In fact, the information that such and
such a virus exists is not, in itself, useful to the average
computer user, even if it does. A statement like, "Please forward
to everyone!" is one mark of a hoax.

Computer Virus Myths home page


Data Fellows

Scams and Hoaxes FAQ: Messages you DON'T want to post

Corporates who haven't sorted out their hoax management strategy
might get some mileage out of my mini-paper on "Dealing with
Internet Hoaxes", though it's getting a bit long in the tooth. It
is, however, one of the few papers on the subject which deals with
it from an adminstrator's/manager's point of view as well as from
an everyday user/victim's. [DH]
I'm slightly surprised to find that I'm managing an EICAR project
in this area: watch this space.

11.0 Glossary

* Change Detectors/Checksummers/Integrity Checkers - programs that
keep a database of the characteristics of all executable files on a
system and check for changes which might signify an attack by an
unknown virus.
* Cryptographic Checksummers use an encryption algorithm to lessen
the risk of being fooled by a virus that targets that particular
* Dropper - a program that installs a virus or Trojan, often
* Generic - catch-all name for antivirus software that doesn't know
about individual viruses, but attempts to detect viruses by
detecting virus-like code, behaviour, or changes in files
containing executable code.
* Heuristic scanners - scanners that inspect executable files for
code using operations that might denote an unknown virus.
* Monitor/Behaviour Blocker - a TSR that monitors programs while
they are running for behaviour which might denote a virus.
* Scanner (conventional scanner, command-line scanner, on-demand
scanner) - a program that looks for known viruses by checking for
recognisable patterns ('scan strings', 'search strings',
'signatures') or using a more flexible algorithmic approach for
detection of polymorphic viruses, which can't be found by a search
for a simple scan string. These are not usually associated with the
Macintosh platform, but there are Word Macro viruses which exhibit
* Trojan (Trojan Horse) - a program intended to perform some covert
and usually malicious act that the victim did not expect or want.
It differs from a destructive virus in that it doesn't reproduce,
(though this distinction is by no means universally accepted).
* Virus - a program (a block of executable code) that attaches
itself to, overwrites or otherwise replaces another program in
order to reproduce itself without the knowledge of the computer
user. Most viruses are comparatively harmless, and may be present
for years with no noticeable effect: some, however, may cause
random damage to data files (sometimes insidiously, over a long
period) or attempt to destroy files and disks. Others cause
unintended damage. Even benign viruses (apparently non-destructive
viruses) cause significant damage by occupying disk space and/or
main memory, by using up CPU processing time, by introducing the
risk of incompatibilities and conflicts, and by the time and
expense wasted in detecting and removing them.

12.0 General Reference Section

12.1 Mac Newsgroups


The focus on these two groups tends to be IBM-compatible, but Mac
issues are certainly aired. Alt.comp.virus is unmoderated, and the
quality of the advice and opinions aired there is very variable -
there are many reputable and expert posters, and many mischievous
and misleading contributions. Caveat lector.... comp.virus lies
dormant for years at a time, but is well worth watching when there's
anything there.

12.2 References and Publications
Sensei Consulting Macintosh WAIS Archives

"Inside the Apple Macintosh" - Peter Norton & Jim Heid (Brady) (The
2nd Edition is pre-PowerMac, and I haven't seen a later one, but
there's some surprisingly useful stuff in there).

"Inside Macintosh" (Addison Wesley). Essential reading for Mac
programmers. (Umpteen volumes of fairly low-level info. Expensive
(in the UK, at any rate), and whenever you get near some useful
info, it refers you to one of the volumes you haven't got. However,
the series has been re-vamped since I acquired my copies, and this
may be less than just. It's possible to download them in Acrobat
and in some cases other formats from:
where you can also order hardcopy and CD versions. Lots of other
useful files.

"Power Macintosh Emergency Handbook" (Apple Computer)

MacFixIt "Troubleshooting for the Macintosh"

"Sad Macs, Bombs and other Disasters"
Ted Landau (Addison Wesley)

MacInTouch home page (info and services)
<> (Have run MacInTouch columns about the AutoStart worms.)
Macworld magazine
TidBITS (Have done many good articles on Mac/macro virus issues.)

13.0 Mac troubleshooting

Since the initial release of this document, a number of people have
E-mailed me asking for help with a possibly virus-related problem.
While I'll always help if I can, I should point out (1) I'm an
experienced Mac user and an IT support professional, but I don't
claim to be a Mac expert (2) pressure of work and other commitments
and a huge E-mail turnover means that I can't promise a quick or
in-depth response [DH]. Whether you mail direct or post to a
relevant newsgroup, it's helpful if you can supply a few details,
such as:

* Which model of Macintosh you're using. It may be useful to know
how much RAM it has, the size of the hard disk, and any peripherals
you're using.
* Which version of MacOS you're using.
* Which applications you're using, and which version. If you're
using Word, it may be critical to know whether you're using version
6 or later, or an earlier version.
* Which, if any, antivirus packages you use, and what version
number. If you're using NAV, for instance, what version?
* List any error messages or alerts that have appeared.
* List any recent changes in configuration, additional hardware
* List any diagnostic/repair packages you've tried, and the
* List any other steps you've taken towards determining the cause
of the problem and/or trying to fix it, e.g. rebuilding the
desktop, booting without extensions, zapping PRAM etc.

Here are a few steps that it might be appropriate to try if virus
scanning with an up-to-date scanner finds nothing. This section
will be improved when and if I have time.

Rebuilding the desktop is by no means a cure-all, but rarely does
any harm. It may be worth disabling extensions when you do this,
especially if the operation doesn't seem to be completed

To disable extensions, restart the machine with the shift key held
down until you see an Extensions Off message. If you're rebuilding
the desktop, release the shift key and hold down Command (the key
with the Apple outline icon) & Options (alt) until requested to
confirm that you want to rebuild.

Disabling extensions is also a good starting point for tracking
down an extensions conflict. If booting without extensions appears
to bypass the problem, try removing extensions with Extensions
Manager (System 7.5) - remove one at a time, and replace it before
removing the next one and booting with that one removed. Remember
that if removing one stops the problem, it's still worth putting it
back and trying all the others to see if you can find one it's
conflicting with. Extensions Manager also lets you disable control
panels. If you don't have Extensions Manager, try Now Utilities or
Conflict Catcher.

Parameter RAM (PRAM) contains system information, notably the
settings for a number of system control panels. 'Zapping' PRAM
returns possibly corrupt PRAM data to default values. A likely
symptom of corrupted PRAM is a problem with date and time (but
could be a symptom of a corrupted system file). With system 7, hold
down Command-Option-P-R at bootup until the Mac beeps and restarts.
You may have restore changes to some control panels before your
system works properly. If the reset values aren't retained, the
battery may need replacing.

End "Viruses and the Macintosh" version 1.6a by David Harley

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