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From: D.Harley@icrf.icnet.uk (David Harley)
Subject: Viruses and the Mac FAQ
Date: 18 Mar 2003 10:36:49 GMT
Archive-name: computer-virus/macintosh-faq
Posting-Frequency: Fortnightly
Last-modified: Fri, 1 Jan 2000 19:14 GMT
URL: http://www.sherpasoft.org.uk/MacSupporters/macvir.faq
Copyright: Copyright 1996-2000 by David Harley and contributors
Maintainer: David Harley <D.Harley@icrf.icnet.uk>
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
5.2 EICAR
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 <D.Harley@icrf.icnet.uk>
3.0 Availability of this FAQ
=============================
++The reference site for this FAQ is now www.icsa.net. However, my own
site at <http://www.sherpasoft.org.uk/MacSupporters/> 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 <www.eicar.dk>
There are HTML versions at:
<http://www.cis.ohio-state.edu/hypertext/faq/usenet/computer-virus
/macintosh-faq/faq.html>
<http://www.faqs.org/faqs/computer-virus/macintosh-faq/>
<http://emt.doit.wisc.edu/macvir/macvir.html>
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.
<http://www.faqs.org/faqs/computer-virus/new-users/>
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:
<http://www.sherpasoft.org.uk/acvFAQ/> but the reference version will
eventually be the one at www.eicar.dk (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:
<ftp://ftp.infospace.com/pub/virus-l/comp.virus-FAQ.09-Oct-95>
<ftp://ftp.datafellows.com/pub/misc/anti-vir/vlfaq200.zip>
5.2 EICAR
----------
++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:
<http://www.eicar.org/anti_virus_test_file.htm>. [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:
<http://www.amazon.com/exec/obidos/ISBN=0387946632/> [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 (www.symantec.com), Network Associates
(www.nai.com), Sophos (www.sophos.com) and Dr. Solomon's
(www.drsolomon.com) include Macintosh virus information.
Precise URLs tend to come and go, but you might like to try the
following:
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]. ;-)
<http://www.symantec.com/avcenter/vinfodb.html>
Network Associates, formerly McAfee Associates:
Virus Information Library
<http://www.nai.com/vinfo/>
Macintosh Viruses
<http://www.nai.com/vinfo/f_13707.asp>
Sophos Plc
<http://www.sophos.com/>
About.com "Macintosh Virus Desriptions"
Part of work in progress by Ken Dunham
+ <http://antivirus.about.com/library/blenmac.htm> (new domain name)
Mac Virus
++[Site closed 5th September 1999]
<http://www.macvirus.com/reference/viruses.html>
Dr Solomon's "Mac Viral Zoo"
Starting to go out of date
<http://www.drsolomon.com/products/virex/zoo/maczoopg.html>
++Keep watching <www.icsa.org>
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
Abingdon
OX14 3YP
England
+44 1235 555139
<http://www.virusbtn.com/>
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 <http://www.sherpasoft.org.uk/MacSupporters/>
and at <http://www.icsa.net/>
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.
<ftp://agn-www.informatik.uni-hamburg.de/pub/texts/macro/>
<http://agn-www.informatik.uni-hamburg.de/vtc/eng.htm>
Other Sources:
<http://www.drsolomon.com/>
<http://www.datafellows.com/vir-info/>
<http://www.symantec.com/avcenter/>
<http://www.nai.com/>
<http://www.avpve.com/>
<http://www.sophos.com/> (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. <http://www.nai.com/> and drill down from there.]
Dr Solomon's Software Ltd.
<http://www.drsolomon.com/vircen/enc/>
Central Command
<http://www.avpve.com/viruses/macro/>
Network Associates
<http://www.nai.com/vinfo/f_3057.asp>
Data Fellows
<http://www.datafellows.com/macro/word.htm>
++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
respects.
<ftp.gate.net/pub/users/ris1/word.faq>
++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:
<http://www.sherpasoft.org.uk/anti-virus/wordvirus.FAQ>
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.
<http://www.hyperactivesw.com/Virus1.html>
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.
<http://ciac.llnl.gov/ciac/CIACVirusDatabase.html>
Virus Test Center, Hamburg: AntiVirus Catalog/CARObase early work
<ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/catalog/>
<ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/carobase/>
<ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/viruses/>
These links may be out-of-date: if they don't work, try
<ftp://agn-www.informatik.uni-hamburg.de>
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
visit.
<ftp://ftp.ucs.ubc.ca/pub/mac/info-mac/vir/>
<http://hyperarchive.lcs.mit.edu/HyperArchive/Abstracts/vir
/HyperArchive.html>
Also of interest, again sometimes outdated:
<http://wwwhost.ots.utexas.edu/mac/pub-mac-virus.html>
<http://www.unt.edu/virus/macgeneral.html>
Kevin Harris's Virus Reference was last updated 31-Aug-95. This
HyperCard stack requires HyperCard 2.1 or later.
<ftp://mirrors.aol.com/pub/info-mac/vir/virus-reference-216-hc.hqx>
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
AUFS.
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!"
Fuck: 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
incompatibilities.
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
circulation.
nCAM: nVIR variant
nVIR (nVIR A, B, C - AIDS, Fuck, 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:
<http://www.hyperactivesw.com/Virus1.html#IDay>
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
them.
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
display.
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
symantec.support.mac.sam.general 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
<http://www.macvirus.com/news/press/970903a.html>.
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
it....).
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
OLE.
++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
<http://agn-www.informatik.uni-hamburg.de/vtc/naveng.htm>
University of Tampere Virus Research Unit
<http://www.uta.fi/laitokset/virus/>
Secure Computing
<http://www.westcoast.com/>
Virus Bulletin
<http://www.virusbtn.com/>
+ About.com has an aggregation of PC anti-virus reviews links.
<http://antivirus.about.com/msub12.htm>
Robert Michael Slade's lists may also be helpful.
<http://www.freenet.victoria.bc.ca/techrev/quickref.html>
<http://www.freenet.victoria.bc.ca/techrev/rms.html>
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.
<http://www.ciac.org/>
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
Panel.
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
AutoPlay".
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 system
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:
<http://www.drsolomon.com/vircen/valerts/mac/>
<http://www.sophos.com/virusinfo/analyses/autostart9805.html>
<http://www.symantec.com/avcenter/data/autostart.9805.html>
++Dead Mac Virus link cleaned.
Detection: updates to deal with the worms are available for Virex
(http://www.drsolomon.com/products/virex/), for NAV and SAM
(http://www.symantec.com/avcenter/download.html), and for Rival
(http://www.intego.com/).
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.
<http://www.microsoft.com/office/antivirus/> (no longer accessible)
MSN: GO MACROVIRUSTOOL
AOL: the Word forum
CompuServe: the Word forum
Microsoft Product Support Services
206-462-9673 (WinWord)
206-635-7200 (Word Mac)
email: wordinfo@microsoft.com
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
detected.
* 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.
<http://www.microsoft.com/macoffice/laroux.htm>
++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.:
<ftp://ftp.acns.nwu.edu/pub/disinfectant/>
CompuServe
GEnie
America Online
Calvacom
Delphi
BIX
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.
<ftp://ftp.nwu.edu/pub/disinfectant/README-IMPORTANT>
There is a copy of the retirement announcement on the Web:
&