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VirusScan Version 2.00
Copyright 1994 by McAfee, Inc.
All Rights Reserved.
Brought to you by:
Igor Grebert Project Leader
Jivko Koltchev Lead Programmer
David Mai TSR Programmer
Vadim Ivanov Algorithms/Emulation Programmer
Tatyana Shishkina Virus Librarian, Programmer
Bruce de Graaf GUI Programmer
Dmitri Orlov DOS UI Programmer
Geoff Brandenburg GUI Artist
Spencer Clark SQA Manager
David Pierce Lead SQA Engineer
Sean Birch SQA Engineer
John Zussman Documentation Project Leader
Eric Ivory Technical Writer
Aryeh Goretsky Manager Technical Support
With special thanks to Bob Chappelear, Rudite Emir, and Bill Larson
McAfee, Inc. (408) 988-3832 office
2710 Walsh Avenue (408) 970-9727 fax
Santa Clara, CA 95051-0963 (408) 988-4004 BBS (25 lines)
U.S.A. USR HST/v.32/v.42bis/MNP1-5
CompuServe GO MCAFEE
InterNet support@mcafee.COM
America Online MCAFEE
Using VirusScan (Version 2.0) 1
CHAPTER 1: WELCOME TO VIRUSSCAN
Thank you for evaluating McAfee, Inc.'s, VirusScan(TM)
software Version 2.0, a powerful and advanced system
designed to detect, eradicate, and prevent computer viruses.
VirusScan will help you protect one of your most important
assets--the information on your computer or local area network.
VirusScan includes two main programs:
o The Scan program detects known viruses in your
computer's memory or on disks. See the README.1ST file
for the number of viruses that Scan detects. It can
also detect new and unknown viruses. Once viruses are
detected, it can remove them and restore your system to
normal operation.
o The VShield(TM) program continuously monitors and
protects your system from viruses that might be
introduced.
The VirusScan programs run on IBM-PC or 100% compatible
personal computers (PCs) that use DOS 3.0 and above, Windows
3.1, or OS/2 2.0 and above.
VirusScan is an important element of a comprehensive
security program that includes a variety of safety measures,
such as regular backups, meaningful password protection,
training, and awareness. We urge you to set up and comply
with such a security program in your organization. For tips
on how to do this, see "Other Sources of Information" in
this chapter.
HOW TO USE THIS MANUAL
This manual will help you get VirusScan running quickly and
properly on DOS, Windows, and OS/2 systems.
o All the key information is in Chapter 2, "Don't Skip
this Chapter." Please don't install VirusScan before
reading it, even if you are already familiar with
Scan. Installing and using VirusScan is not like using
other software.
The rest of Chapter 1, "Welcome to VirusScan," describes the
programs and files on your VirusScan disk, system
requirements, how to register, and how to get help.
Chapter 3, "Scan Reference," in this document and Chapter 3,
"VShield Reference," in the VShield documentation contain
reference information for Scan and VShield, respectively.
Using VirusScan (Version 2.0) 2
Many users will not need to read these chapters, because basic
operation of VirusScan, as described in Chapter 2, will detect
and remove most viruses from your system. The options described
in Chapter 3 in this document and Chapter 3 in the VShield
documentation offer additional power and control, and are most
useful in vulnerable environments and to network administrators
and information services staff.
Chapter 4, "Tips & Troubleshooting," explains how to get the
most out of VirusScan, and how to cope with some common
problems.
Appendix A, "Retrieving VirusScan Updates via the McAfee BBS,"
provides instructions for using the McAfee Bulletin Board (BBS).
Appendix B, "Options Comparison Between VirusScan Versions
1.5 and 2.0," shows the differences between command line options
in Scan 1.5 and 2.0.
Using VirusScan (Version 2.0) 3
NOTATION
In this manual, we use several conventions to distinguish
particular kinds of text.
CONVENTION │ EXAMPLE │ REPRESENTS
═══════════════╪══════════════╪══════════════════════════
Upper-case │ C:\> │ What your
│ │ computer displays
│ │ on your screen.
───────────────┼──────────────┼──────────────────────────
Lower-case │ scan c: │ What you
│ │ type, verbatim.
───────────────┼──────────────┼──────────────────────────
Curly braces │ {filename} │ Required
│ │ element; do not
│ │ type braces { }.
───────────────┼──────────────┼──────────────────────────
Square braces │ [filename] │ Optional
│ │ element; do not
│ │ type braces [ ].
───────────────┼──────────────┼──────────────────────────
Upper-case in │ <ENTER> │ Key to press
brackets │ │ on the
│ │ keyboard.
WHAT VIRUSSCAN INCLUDES
In addition to Scan or VShield, the Validate program
ensures that new versions of VirusScan software
you've obtained are authentic.
Finally, the VirusScan archive contains several useful text
files, which you can view and print with a text editor, word
processor, or DOS PRINT command. You'll find version-
specific information in the README.1ST text file.
Using VirusScan (Version 2.0) 4
VIRUSSCAN FILES AFTER UNPACKING
After unpacking VirusScan you should have appropriate
program files on your system for the version you have
obtained (DOS, Windows, or OS/2). Several useful text
files are also included.
VirusScan for DOS.
AGENTS.TXT - list of McAfee authorized agents.
CLEAN.DAT - virus removal data file required by SCAN.EXE
COMPUSER.NOT - explains how to obtain CompuServe membership
FILE_ID.DIZ - description of VirusScan used by some BBS
software
FILENAME.TXT - explains new McAfee BBS file name conventions
LICENSE.TXT - explains how to license VirusScan
NAMES.DAT - virus name data file required by SCAN.EXE
PACKING.LST - contains a list of all files, including
validation information
README.1ST - late-breaking information and new
instructions not contained in this manual
REGISTER.TXT - explains how to register VirusScan for
your use
SCAN.DAT - virus string data file required by SCAN.EXE
SCAN.EXE - the VirusScan program
SCAN.TXT - on-line manual for Scan
VALIDATE.EXE - used to check VirusScan programs for
authenticity
VALIDATE.TXT - explains how to run VALIDATE.EXE
VShield
AGENTS.TXT - list of McAfee authorized agents.
CHKVSHLD.EXE - checks for presence of VShield and VShieldCRC
in memory
COMPUSER.NOT - explains how to obtain CompuServe membership
FILE_ID.DIZ - description of VShield used by some BBS
software
FILENAME.TXT - explains new McAfee BBS file name conventions
LICENSE.TXT - explains how to license VShield
PACKING.LST - contains a list of all files, including
validation information
REGISTER.TXT - explains how to register VirusScan for
your use
VALIDATE.EXE - used to check VirusScan programs for
authenticity
VALIDATE.TXT - explains how to run VALIDATE.EXE
VSHIELD.DAT - virus string data file required by
VSHIELD.EXE
VSHIELD.EXE - the VShield program
VSHIELD.TXT - on-line manual for VShield
VSHLDCRC.EXE - the VShieldCRC program
VSHLDWIN.EXE - used by VShield and VShieldCRC to display
messages within Windows
Using VirusScan (Version 2.0) 5
VirusScan for OS/2
AGENTS.TXT - list of McAfee authorized agents.
CLEAN.DAT - virus removal data file required by
OS2SCAN.EXE
COMPUSER.NOT - explains how to obtain CompuServe membership
FILE_ID.ZIP - description of VirusScan used by some BBS
software
FILENAME.TXT - explains new McAfee BBS file name conventions
LICENSE.TXT - explains how to license VirusScan
NAMES.DAT - virus name data file required by OS2SCAN.EXE
PACKING.LST - contains a list of all files, including
validation information
README.1ST - late-breaking information and new
instructions not contained in this manual
REGISTER.DOC - explains how to register VirusScan for your
use
OS2SCAN.EXE - the VirusScan program
SCAN.DAT - virus string data file required by
OS2SCAN.EXE
SCAN.TXT - on-line manual for Scan
VALIDATE.EXE - used to check VirusScan programs for
authenticity
VALIDATE.TXT - explains how to run VALIDATE.EXE
Using VirusScan (Version 2.0) 6
SYSTEM AND MEMORY REQUIREMENTS
The VirusScan programs require an IBM-compatible personal
computer and any of the following operating systems:
o DOS 3.0 or later and at least 340Kb of free RAM for the
command line programs.
o Windows 3.1 or later and at least 4Mb of RAM.
o IBM OS/2 2.00(GA) or later and at least 8Mb of RAM.
VirusScan for DOS requires 340Kb of available free memory in
order to scan a system for viruses.
VShield is a terminate-and-stay-resident (TSR) program that
requires 67Kb of free memory. VShield will minimize the use
of conventional memory by loading into expanded, extended,
or upper memory, when available. For more information, see
"System Requirements and Performance" in Chapter 3.
LICENSING VIRUSSCAN
The VirusScan software is provided under license from
McAfee, Inc., a copy of which is included in the file
LICENSE.TXT. Please read it and comply with it.
If you want to use VirusScan after the evaluation period,
please register your copy of the software by filling out and
returning the enclosed registration form, REGISTER.TXT.
Registration entitles you to upgrades at no charge from
McAfee's bulletin board system and other sources, as well as
technical support, for one year from your date of purchase.
Using VirusScan (Version 2.0) 7
TECHNICAL SUPPORT
For help in using this product, we invite you to contact
McAfee technical support. You can contact us:
o On-line 24 hours a day, through our bulletin board
system, CompuServe, fax, or Internet (see "Online
Access to Updates and Technical Support" below); or
o By telephone at (408) 988-3832, Monday through Friday,
7:00 am to 5:30 pm Pacific Time.
For fast and accurate help, please have the following
information ready when you contact McAfee:
o Program name and version number.
o Type and brand of computer, hard disk, and any
peripherals.
o Version of DOS, along with any TSR's or device drivers
in use.
o Printouts of your AUTOEXEC.BAT and CONFIG.SYS files.
o A printout of the contents of memory, from the MEM
command (provided in DOS 4.0 and later) or a similar
utility.
o A description of the exact problem you are having.
Please be as specific as possible. If you can't be at
your computer when you call, a printout of the screen
will be helpful.
If you are overseas, you can contact a McAfee authorized
agent for support. Agents are located in more than 50
countries around the world and provide local sales and
support for our software. Please refer to the AGENTS.TXT
file for a complete list of McAfee agents.
ONLINE ACCESS TO UPDATES AND TECHNICAL SUPPORT
McAfee updates VirusScan monthly to add new virus detectors,
new options, and fix reported bugs. To distribute these new
versions, we run a multi-line bulletin board system, a forum
on CompuServe, and an Internet node.
Using VirusScan (Version 2.0) 8
Bulletin board system (BBS) access
Our multiline BBS is accessible 24 hours a day, 365 days a
year, except for scheduled downtime and maintenance. All
lines run high-performance modems operating from 1,200 bps
to 14,400 bps with line settings of 8 data bits, no parity,
and 1 stop bit. The McAfee BBS phone number is (408) 988-4004.
CompuServe Access
We sponsor the McAfee Virus Help Forum on CompuServe. To
reach it, type GO MCAFEE at any CompuServe prompt. A free
introductory membership is available. For more information,
please read the enclosed COMPUSER.TXT file.
Internet Access
The latest versions of McAfee's anti-virus software are
available by anonymous ftp (file transfer protocol) over the
Internet from the site mcafee.com. If your domain resolver
does not support names, use the IP# 192.187.128.1. Enter
"anonymous" or "ftp" as your user ID (do not type the
quotation marks) and your own e-mail address as the
password. Programs are located in the pub/antivirus
directory. If you have questions, please send e-mail to
support@mcafee.com.
You can also find McAfee's anti-virus software at the SimTel
Software Repository at Oak.Oakland.EDU in the
pub/msdos/virus directory and its associated mirror sites:
o WUARCHIVE.WUSTL.EDU (US).
o FTP.SWITCH.CH (Switzerland).
o FTP.FUNET.FI (Finland).
o SRC.DOC.IC.AC (UK).
o ARCHIE.AU (Australia).
Using VirusScan (Version 2.0) 9
OTHER SOURCES OF INFORMATION
The McAfee BBS and CompuServe Virus Help Forum are excellent
sources of information on virus protection. Batch files and
utilities to help you use VirusScan software are often
available, along with helpful advice.
Independent publishers, colleges, training centers, and
vendors also offer information and training about virus
protection and computer security.
We especially recommend the following books:
o Ferbrache, David. A Pathology of Computer Viruses.
London: Springer-Verlag, 1992. (ISBN 0-387-19610-2)
o Hoffman, Lance J. Rogue Programs: Viruses, Worms, and
Trojan Horses. Van Nostrand Reinhold, 1990.
(ISBN 0-442-00454-0)
o Jacobson, Robert V. The PC Virus Control Handbook,
2nd Ed. San Francisco: Miller Freeman Publications, 1990.
(ISBN 0-87930-194-0)
o Jacobson, Robert V. Using McAfee, Inc. Software
for Safe Computing. New York: International Security
Technology, 1992. (ISBN 0-9627374-1-0)
In addition, the following sources can provide useful
information about viruses:
o National Computer Security Association (NCSA)
10 South Courthouse Avenue
Carlisle, PA 17013
o CompuServe McAfee Computer Virus Help Forum (GO
VIRUSFORUM)
o Internet comp.virus newsgroup
Using VirusScan (Version 2.0) 10
CHAPTER 2: DON'T SKIP THIS CHAPTER
(or, What you really need to know about VirusScan)
We're serious about this. Installing and running the
VirusScan(TM) programs is not like using other software.
Even if you are a long-time user of McAfee's software,
please take the time to read through and follow the tasks in
this chapter.
The reason is to avoid spreading a computer virus infection.
Viruses spread when you start your computer (sometimes
called booting) from an infected disk, or when you run an
infected program. If your computer is infected, installing
and running VirusScan on your hard disk may spread the
infection, even to the VirusScan programs themselves. The
tasks in this chapter will ensure that you have a clean
environment to detect, eradicate, and prevent viruses.
This is like a surgical team establishing a "sterile field"
before performing surgery. Once it is established, they make
sure that everything brought into the field has already been
sterilized. In this procedure, you will create a clean anti-
viral start-up diskette with which you can always re-
establish the sterile field.
Your VirusScan archive (.ZIP) file is created with
authenticity checks and a serial number embedded in it to
ensure that it has not been tampered with or modified.
Additionally, VirusScan comes with Validate, a Cyclic
Redundancy Check (CRC) program that computes a check-sum for
VirusScan's files. Once you have unpacked the VirusScan
archive, you should copy all the files to a diskette in
drive A: and write-protect it to ensure that no virus can
alter the programs and information stored there. Under no
circumstances should you remove the write protection. Label
this diskette as your 'VirusScan Program Diskette.'
Here's a summary of the tasks you'll follow in this chapter:
o Installing VirusScan.
o Scanning your system.
o If you detect a virus.
o Activating VShield(TM).
o Making a clean start-up (boot) diskette.
o Running the VirusScan programs.
o When to scan for viruses.
o Updating VirusScan regularly.
NOTE: Because OS/2 programs run in a protected mode, OS/2
systems are not vulnerable to viruses as DOS and Windows
Using VirusScan (Version 2.0) 11
systems are. Many OS/2 users run DOS and Win-OS/2 sessions,
however, and they are still vulnerable. By using the
VirusScan programs as described in this manual, you can
protect the DOS and Win-OS/2 portions of your OS/2 system
from infection.
Using VirusScan (Version 2.0) 12
INSTALLING VIRUSSCAN
This task explains how to check your system and install the
VirusScan software under DOS, Windows, or OS/2. Don't use
any other method to install VirusScan, or you risk spreading
a virus.
INSTALLATION STEPS
Start from the system prompt (C:\> or [C:\]). If you are
running Windows or an application program, exit from it to
display the prompt. If you are running OS/2, close all DOS
and Win-OS/2 sessions open the Command Prompts folder in the
OS/2 System folder, and click on either the OS/2 Full Screen
or OS/2 Window icons.
After typing each entry on the command line, press <ENTER>.
1. Create a directory to contain the VirusScan files, as
in the following example:
C:\> mkdir c:\mcafee
and press <ENTER>.
If you have an earlier version of VirusScan already
installed, create a separate directory (such as
c:\newvscan) for the new version. (You should test
the new version before removing the earlier version.)
2. Copy the VirusScan archived (.ZIP) file to this
directory, as in the following example:
C:\> copy c:\download\*.zip c:\mcafee
and press <ENTER>.
3. Change to the VirusScan directory you just created,
as in the following example:
C:\> cd c:\mcafee
and press <ENTER>.
4. Unzip the file using PKUNZIP.EXE, as in the following
example:
C:\mcafee> PKUNZIP *.ZIP
and press <ENTER>.
Using VirusScan (Version 2.0) 13
5. Run VirusScan to check your local hard disk(s) by
typing:
c:\mcafee> scan /adl
and pressing <ENTER>. It may take several minutes
for the Scan program to check for viruses in memory,
then on the system and user portions of your drives.
Scan keeps you informed of its progress. Read the
information carefully, and write down the name of any
viruses Scan reports.
6. If Scan does not report any viruses, congratulations
--most likely your system is currently virus-free.
Continue with "Making a Clean Start-Up Diskette" in
this chapter.
If Scan finds one or more viruses you'll see a
message like:
Found the Jerusalem Virus
Stop the installation. Don't panic, even if the virus
has infected many files. At the same time, don't run
any other programs, especially if the virus is found
in memory. Go directly to "If You Detect a Virus"
later in this chapter for further instructions.
7. Create a directory on your hard disk to store the
VirusScan files in by typing:
C:\> mkdir mcafee
and pressing <ENTER>.
8. Copy the VirusScan files from the 'VirusScan Program
Diskette' in drive A: to your hard disk by typing:
C:\> copy a:\*.* c:\mcafee
and pressing <ENTER>. VirusScan has now been installed
onto your hard disk. Now your system's startup files
must be modified to find VirusScan on your system.
9. DOS and Windows users: Using a text editor program,
load your AUTOEXEC.BAT file. Locate the path statement,
which typically begins with a 'PATH' or 'SET PATH ='
statement. Place your cursor at the end of this line
and type:
;C:\MCAFEE
Using VirusScan (Version 2.0) 14
and press <ENTER>. Now save your AUTOEXEC.BAT file and
exit the editor.
NOTE: If a semi-colon ";" is already present at the end
of the line, do not add one to the path statement.
OS/2 users: Make the same change listed above to the
'SET PATH=' statements in your CONFIG.SYS
file. Now save your CONFIG.SYS file and
exit the editor.
Congratulations! You've successfully installed VirusScan.
Restart your computer now and continue with this chapter to
see how you can use VirusScan to keep your computer virus-
free. We recommend looking over the following sections in
this chapter:
"Scanning Your System"
"If You Detect A Virus"
"Activating VShield"
"Making A Clean Start-Up Diskette"
so you'll know what took place during installation. Then
continue with the remaining tasks in this chapter, beginning
with "Running the VirusScan Programs" to find out how and
when to run and update the VirusScan programs.
Using VirusScan (Version 2.0) 15
SCANNING YOUR SYSTEM
VirusScan's Scan program examines your PC and disks to
detect viruses there. The first time you run Scan, do so
from the original, write-protected diskette so that the
programs themselves cannot be infected.
Start from the system prompt (C:\> or [C:\]). If you are
running Windows or an application program, exit from it to
display the prompt. If you are running OS/2, close all DOS
and Win-OS/2 sessions. Next, open the Command Prompts folder
in the OS/2 system folder, then click the OS/2 Full Screen or
OS/2 Window icon.
After typing each entry on the command line, press <ENTER>.
If you include the /REPORT option, Scan saves a report of
infected files and any system errors to a log file that you
specify.
o Insert the 'VirusScan Program Diskette' in drive A:
o Scan your C: drive for known viruses by typing:
C:\> a:scan c: /report c:\virus.log
OS/2 Users: Be sure to replace "a:scan" with
"a:os2scan" in the above example.
Or, if you have more than one hard drive, scan them in
the same fashion. For example, if you have C and D
drives:
C:\> a:scan c: d: /report c:\virus.log
You can also scan all local drives using the /ADL
option. For example:
C:\> a:scan /adl /report c:\virus.log
Using VirusScan (Version 2.0) 16
It may take several minutes for the Scan program to
check for viruses in memory, then on the system and
user portions of your drives. Scan keeps you informed
of its progress. Read the information on the screen
carefully. Below is a sample of what Scan reports
when checking a drive for viruses:
┌─────────────────────────────────────────────────────┐
│ Database file V1.00 created Fri Apr 1 12:01:00 1994 │
│ Finished scanning memory for viruses. │
│ Scanning C: │
│ │
│ Summary report on C: │
│ │
│ File(s) │
│ Analyzed: .............. 1500 │
│ Scanned: ............... 750 │
│ Possibly Infected: ..... 0 │
│ Master Boot Record(s):.. 1 │
│ Possibly Infected:...... 0 │
│ Boot Sector(s):......... 1 │
│ Possibly Infected:...... 0 │
│ │
│ Time: 60.00 sec. │
└─────────────────────────────────────────────────────┘
o If Scan reports 0 viruses found, congratulations--most
likely your system is currently virus-free. Skip to
"Activating VShield" later in this chapter to continue.
If Scan finds one or more viruses, you'll see a message
like:
┌─────────────────────────────────────────────────────┐
│ Scanning C: │
│ Scanning file C:\DOS\ATTRIB.EXE │
│ Found the Jerusalem virus │
└─────────────────────────────────────────────────────┘
Don't panic, even if the virus has infected many files.
At the same time, don't run any other programs,
especially if the virus is found in memory. Turn to "If
You Detect a Virus" later in this chapter, where
VirusScan will help you eradicate it.
o Scan has many options to control and fine-tune the
scope, validation, and operation of its scan. For
details, see Chapter 3 and "Detecting new
and unknown viruses" in Chapter 4.
Using VirusScan (Version 2.0) 17
IF YOU DETECT A VIRUS
In this task, you will run Scan with the /CLEAN option to
eradicate most known viruses from your disks.
o If you are at all unsure about how to proceed once
you've found a virus, contact McAfee for assistance
(see "Technical Support" in Chapter 1).
We strongly recommend that you get experienced help in
dealing with viruses if you are unfamiliar with anti-virus
software and methods. This is especially true for "critical"
viruses and master boot record (MBR or so-called "partition
table")/boot sector infections, because improper removal of
these viruses can result in the loss of all data and use of
the infected disks.
RESTART FROM A CLEAN ENVIRONMENT
You must run Scan from a clean, virus-free environment. With
DOS or Windows, restart from a clean diskette. With OS/2,
simply close all DOS and Win-OS/2 sessions.
DOS or Windows
With DOS or Windows, the only way to ensure a clean
environment is to turn your computer off to eliminate any
viruses in memory, then restart from a virus-free floppy
diskette in drive A:, preferably the original, write-
protected DOS installation diskette that came with your
computer. If you don't have one, borrow or buy one; don't
use a diskette that might be infected. (You will create a
new anti-viral diskette in "Making a Clean Start-Up
Diskette" later in this chapter to use in the future,
but you need a clean environment before you create one.)
1. Turn off your computer. (Don't just reset or reboot,
which may leave some viruses intact in the computer's
memory.)
2. Make sure your clean boot (start-up) diskette is write-
protected.
o For a 3.5" diskette, slide its corner tab so that
the square hole is open.
o For a 5.25" diskette, cover its corner notch with
a write-protect tab. Be sure to use the black or
silver write-protect stickers provided with your
diskettes, not transparent tape, which is ignored
by the floppy drive's infrared write-protection
mechanism.
Using VirusScan (Version 2.0) 18
3. Insert your start-up diskette in drive A:.
4. Turn on your computer and wait until you see the system
prompt (probably A>). Don't run any programs on your
hard disk, or you may reactivate the virus.
OS/2
With OS/2, you can eliminate most viruses from memory by
closing all DOS, Win-OS/2, and virtual DOS machine (VDM)
sessions. Because OS/2 programs run in protected mode,
viruses cannot spread between them.
BACK UP YOUR HARD DISK
Some viruses may leave certain disks or files unusable when
cleaned up. To increase your chance of recovery, copy all
the files on all of your hard disks onto fresh diskettes or
a backup tape after booting from a clean copy of the
operating system. You can use a commercial backup program,
or the one included with DOS or OS/2. Scan the program disk
first to make sure that the backup program itself is not
infected. Do not run the backup program if it is infected.
Instead, reload it from your original installation
diskettes.
Although some of the backed-up files may be infected, it is
better to have current copies than not. However, don't
overwrite previous backup disks or tapes, which may or may
not be infected.
RUN SCAN WITH THE /CLEAN OPTION
Start from the system prompt (probably A> or [A:\]). If you
are running OS/2, open the Command Prompts folder in the
OS/2 system folder, and click on the OS/2 Full Screen or
OS/2 Window icons.
After typing each entry on the command line, press [Enter].
1. Insert the 'VirusScan Program Diskette' in drive A:.
2. Eliminate the first known virus on your hard drive(s)
by typing:
DOS or Windows
A> a:scan /adl /clean
OS/2
[A:\] a:os2scan /adl /clean
Using VirusScan (Version 2.0) 19
Scan keeps you informed of its progress and generally
reports that a virus was removed successfully. If Scan
reports that the virus could not safely be removed,
see the next section, "If Viruses Were Not Removed,
Contact Technical Support."
3. Repeat step 2 for other viruses found by Scan, and for
other infected hard drives. For example:
DOS or Windows
A> a:scan /clean d:
OS/2
[A:\] a:os2scan /clean d:
o Scan has options to control and fine-tune the
scope, validation, and operation of its
disinfection. For details, see Chapter 3.
If Viruses were NOT removed, contact Technical Support
If Scan can't remove a virus, it will tell you:
Virus cannot be safely removed from this file.
Make sure to take note of the filename, because you will
need to restore it from backups. Run Scan again, this time
using the /CLEAN and /DEL options to delete the remaining
infected files, as described in Chapter 3. If you have
any questions, contact McAfee (see "Technical Support"
in Chapter 1).
If viruses were safely removed, rescan and check diskettes
If Scan has successfully removed all the viruses, restart
your computer.
Restart installation as described in "Installing VirusScan"
earlier in this chapter. Assuming that your system is now
virus-free, installation will scan your system, activate
VShield, and make a clean start-up diskette as part of the
installation procedure. Thereafter, you can proceed to
"Running the VirusScan programs" later in this chapter.
One common source of virus infection is floppy diskettes.
Once you've finished installing VirusScan on your hard disk,
use Scan again to examine and disinfect the diskettes you
use, as described in "When to Rescan," in this chapter.
Using VirusScan (Version 2.0) 20
FALSE ALARMS
Due to the nature of anti-virus software, there is a small
possibility that Scan may report a virus in a file that is
not infected. This can be more likely if you are using more
than one brand of virus protection software, especially if
the virus is only reported in memory and not anywhere on the
disk when you boot.
If Scan reports a virus infection that you suspect may be in
error, contact McAfee (see "Technical Support" in Chapter 1).
You can upload the file to our bulletin board system at
(408) 988-4004, along with your name, address, daytime
telephone number, and electronic mail address (if any).
ACTIVATING VSHIELD
VirusScan's VShield program can help prevent viruses from
infecting your system. It runs as a "terminate-and-stay-
resident" (TSR) program, remaining in memory and scanning
and intercepting programs as they are executed.
To install VShield, use your editor to load your
AUTOEXEC.BAT file. Insert the following as the first line:
C:\MCAFEE\VSHIELD
If you load network drivers, disk-caching software, or
other memory-resident programs that changes the way
in which you access disks, insert a second VShield line
after the last invocation of such software:
C:\MCAFEE\VSHIELD /RECONNECT
and press <ENTER>. This reactivates VShield if it has been
deactivated by another memory-resident program. Now save
your AUTOEXEC.BAT file.
Using VirusScan (Version 2.0) 21
Windows
VShield can display messages from within Windows in a
message dialog. This is done through VShield's
Windows Messager. If you choose not to install the
Messager, VShield will still detect viruses, but will
not be able to report them to you.
1. To activate the Messager, you must copy the
VSHLDWIN.EXE file from your VirusScan directory
(typically C:\MCAFEE) to your Windows directory
(typically C:\WINDOWS). You can do this by typing:
C:\> copy c:\mcafee\vshldwin.exe c:\windows
and pressing <ENTER>.
2. Go to your Windows directory, and using a text editor
program, load your WIN.INI file. Go to the [Windows]
settings and insert the following line:
load=vshldwin.exe
NOTE: If you already have a "load=" line in your WIN.INI
file, go to the end of it and type:
; vshldwin.exe
and press <ENTER>. Now save your WIN.INI file and
exit the editor.
VShield will now run whenever you start or restart your
computer. To activate VShield at any time:
DOS or Windows - Restart your computer by pressing the
<CTRL>, <ALT>, and <DEL> keys simultaneously, or by turning
it off and then on again (if Windows is running, exit out
of it before doing restarting your computer).
OS/2 - Restart all DOS and Win-OS/2 windows.
o If you have difficulties running VShield, it may be due
to conflicts with other TSR programs in your system, or
with other programs that monitor disk access. See
Chapter 3 in the VShield documentation for details, and
Chapter 4, "Tips and Troubleshooting," in this document
for more information. Contact McAfee technical support
if you need help (see "Technical Support" in Chapter 1).
Using VirusScan (Version 2.0) 22
o VShield normally occupies up to 67Kb of conventional
(base 640Kb) memory. VShield minimizes the use of
conventional memory by attempting to load into extended
(XMS) memory, expanded (EMS) memory, upper memory, or a
combination of them before using conventional memory.
For computers with extreme available memory
limitations, you can use VShield's /SWAP option to
reduce its memory requirements to 7Kb, although this
will decrease VShield's speed. For details, see
Chapter 3 in the VShield documentation.
o VShield has options to control and fine-tune the scope,
validation, and operation of its virus prevention. For
details, see Chapter 3 in the VShield documentation.
o When used in conjunction with some of Scan's options,
VShield can help protect your system from new and
unknown viruses. For details, see "Detecting New and
Unknown Viruses" in Chapter 4.
o Under OS/2, VShield runs in DOS and Win-OS/2 sessions
only, because current viruses can operate only in those
sessions.
o In Windows, you can use the VShield icon to turn
messages from VShield on and off (VShield itself,
however, remains active). For details, see Chapter 3
in the VShield documentation.
Using VirusScan (Version 2.0) 23
MAKING A CLEAN START-UP DISKETTE
In DOS or Windows, create a clean anti-viral start-up (boot)
diskette that you can use to regain your "sterile field" if
your system becomes infected. This is not necessary in OS/2,
although it will be helpful to make backup copies of your
OS/2 installation diskettes.
DOS or Windows
In DOS, start from the system prompt (C:\>). In Windows, you
may open a DOS window, or duplicate these steps using
Windows' File Manager.
1. Insert a blank or dispensable diskette into drive A.
Make sure the diskette contains no important
information, as this procedure will erase it.
2. Format the disk as a DOS-bootable diskette with the
system files on it by typing:
C:\> format a: /s /v /u
and pressing <ENTER>. If you are using a version of
DOS before DOS 5.0, do not type the "/u" option. The
/U option is used in recent versions of DOS to insure
that the floppy diskette is erased completely (earlier
versions of DOS automatically do this).
When prompted for a volume label, type:
virusfree01
and press <ENTER>, or use another name of up to 11
characters.
3. Copy the VirusScan program files onto the diskette.
Here's one way to do this, assuming that your VirusScan
files are stored in C:\MCAFEE:
C:\> copy c:\mcafee\scan.exe a:
C:\> copy c:\mcafee\scan.dat a:
C:\> copy c:\mcafee\clean.dat a:
C:\> copy c:\mcafee\names.dat a:
4. Copy useful DOS programs to the diskette. Here's one
way to do this, assuming that your DOS files are stored
in C:\DOS:
C:\> copy c:\dos\format.* a:
C:\> copy c:\dos\xcopy.* a:
C:\> copy c:\dos\diskcopy.* a:
C:\> copy c:\dos\sys.* a:
Using VirusScan (Version 2.0) 24
C:\> copy c:\dos\fdisk.* a:
C:\> copy c:\dos\debug.* a:
C:\> copy c:\dos\unerase.* a:
C:\> copy c:\dos\mem.* a:
C:\> copy c:\dos\chkdsk.* a:
In the same way, copy other DOS programs that you think
might be useful.
5. Remove the diskette from the drive and write-protect it
so that it cannot become infected.
o For a 3.5" diskette, slide its corner tab so that
the square hole is open.
o For a 5.25" diskette, cover its corner notch with
a write-protect tab. Be sure to use the opaque
write-protect stickers provided with your
diskettes, not transparent tape.
6. Label the diskette "Virus-Free Boot Disk" and put it
away in a secure place in case you need to reestablish
a virus-free environment in the future. You may want
to include supplemental information on the disk label,
such as the date and versions of DOS and VirusScan.
OS/2
With OS/2, you don't need a virus-free start-up disk.
However, it will be helpful to keep a clean copy of
important files, such as your system configuration files.
Copy your CONFIG.SYS, STARTUP.CMD, and AUTOEXEC.BAT files
onto an empty, formatted diskette. Write-protect the
diskette, label it, and put it away in a secure place.
Using VirusScan (Version 2.0) 25
RUNNING THE VIRUSSCAN PROGRAMS
VIRUSSCAN FOR DOS
To run the VirusScan programs from the DOS command prompt,
type the program name (SCAN) on the command line. Follow the
program name with the drive, directory, or file(s) you want
to scan for viruses and the options you want to use.
Note: If you have not changed the path statement in your
AUTOEXEC.BAT file, you will need to include its
location (usually C:\MCAFEE) in the command, or
change to that directory.
For example, to examine a diskette in drive A: type:
C:\> c:\mcafee\scan a:
and press <ENTER>.
EXCEPTION:
If Scan detects a virus in memory or on your hard
disk, don't run Scan with the /CLEAN option from
C:\MCAFEE. Instead, restart your computer and run
Scan from your clean start-up diskette as described
in "If you detect a virus" in this chapter.
VirusScan can list the viruses it detects. To view this list,
run Scan with the /VIRLIST option, described in Chapter 3.
VSHIELD
VShield loads automatically upon startup for DOS and Windows
computers, or when a DOS or Win-OS/2 session is started
within OS/2.
o You can change VShield options from the DOS command
line by removing VShield from memory and re-running it,
or by editing the VShield command line in your
AUTOEXEC.BAT file. See Chapter 3 in the VShield
documentation for details.
Using VirusScan (Version 2.0) 26
VIRUSSCAN FOR OS/2
To run Scan from OS/2, open the Command Prompts folder in
the OS/2 System folder and click on the OS/2 Full Screen or
OS/2 Window icons. Next, type the program name (OS2SCAN) on
the command line. Follow the program name with the drive,
directory, or file(s) you want to scan for viruses and
the options you want to use.
Note: If you have not changed the PATH and LIBPATH
statements in your CONFIG.SYS file, you will need to
include its location (usually C:\MCAFEE) on the command
line, or change to that directory.
For example, to examine a diskette in drive A: type:
[C:\] c:\mcafee\os2scan a:
and press <ENTER>.
o VShield does not run in native OS/2 sessions, only
under DOS and Win-OS/2 sessions inside of OS/2. If you
have placed the VShield command in your AUTOEXEC.BAT
file, it will run automatically when you start a DOS or
Win-OS/2 session. You can also run it from the DOS
command line, as described earlier in this section.
Using VirusScan (Version 2.0) 27
WHEN TO RESCAN
Although VShield will monitor your software for viruses,
it's wise to scan your disks when you introduce new programs
or disks that may be infected. New programs and files are
generally introduced in two ways: by inserting a diskette,
and by installing new programs. It is also possible to
download a computer virus using a modem, however, this is
extremely rare.
o You can use VShield with the /ANYACCESS option to scan
diskettes automatically. For more information, see
the discussion of /ANYACCESS in Chapter 3 in the VShield
documentation.
o For instructions on running VirusScan, see "Running the
VirusScan programs" earlier in this chapter.
WHEN YOU INSERT AN UNCHECKED DISKETTE
Every time you insert a new diskette in your drive, run Scan
on it before executing, installing, or copying its files. If
you have several diskettes to scan, you can scan them
consecutively. In fact, we recommend doing this now with all
the diskettes you normally use, as well as diskettes
received from friends, co-workers, salespeople, and even
your own diskettes if they have been in another PC.
WHEN YOU INSTALL OR DOWNLOAD NEW FILES
Every time you install new software on your hard drive, or
download executable files from a network server, bulletin
board, or on-line service, run Scan on the directory the
files were placed in before executing the files.
Using VirusScan (Version 2.0) 28
UPDATING VIRUSSCAN REGULARLY
Unfortunately, new viruses (and variants of old ones) appear
and circulate often in the personal computer community.
Fortunately, McAfee updates the VirusScan programs
regularly--usually every month, but sooner if many new
viruses have appeared. Each new version may detect and
eradicate as many as 60-100 new viruses or more, and may add
new features. To find out what's new, review the README.1ST
text file.
DOWNLOADING NEW VERSIONS
You may use your own communications software to download new
versions from the McAfee bulletin board, CompuServe, or the
Internet. See Chapter 1, "Welcome to VirusScan" for more
information.
Always download and decompress the files in a separate
directory from your current files. That way, if you
discover a problem with the new files, you'll still
have the old ones intact.
VALIDATING VIRUSSCAN
When you download a program file from any source other than
the McAfee bulletin board system or other direct-from-McAfee
service, it's important to verify that it is authentic,
unaltered, and uninfected.
McAfee anti-virus software includes a program called
Validate that helps you do this. When you receive a new
version of VirusScan, run Validate on all of the program
files.
To do this for Scan, start from the system prompt (C:\> or
[C:\]):
1. Change to the directory to which you've downloaded the
files. For example, if you've stored the files in
C:\DOWNLOAD, type:
C:\> cd \download
and press <ENTER>.
2. Type the command:
C:\DOWNLOAD> c:\mcafee\validate scan.exe
and press <ENTER>.
Using VirusScan (Version 2.0) 29
OS/2 Users: Be sure to replace SCAN.EXE with
OS2SCAN.EXE as the file to be validated.
3. Compare the results with the information in the
README.1ST file or other text file for the program you
have just validated. If the validation results match
what's in the file, it is highly unlikely that the
program has been modified.
4. Once you have validated the new version, copy it into
your C:\MCAFEE directory. In addition, create a new
"VirusScan Start-Up Diskette" containing the new
version.
UPDATE YOUR CLEAN START-UP DISKETTE
Once you have validated the new version, copy it into
your C:\MCAFEE directory. In addition, copy the Scan
program onto your clean start-up diskette. Below is one
way to do this; you may also use the Windows File Manager
or the OS/2 environment.
Note any changes you've made to default options, because
you may want to select and save them again. Start from
the system prompt (C> or [C:\]).
1. Navigate to the directory to which you've
retrieved the files, such as C:\MCAFEE:
cd c:\mcafee
2. Temporarily remove write-protection from your clean
start-up diskette and insert it in drive A.
o For a 3.5" diskette, slide its corner tab so that
the square hole is closed.
o For a 5.25" diskette, remove the tab or tape from
its corner notch.
3. Copy the Scan program, and its data files to the diskette.
DOS or Windows C> copy SCAN.EXE a:
C> copy *.DAT a:
OS/2 [C:\] copy OS2SCAN.EXE a:
[C:\] copy *.DAT a:
4. Remove the diskette from the drive and write-protect
it again.
Using VirusScan (Version 2.0) 30
Chapter 3: VIRUSSCAN REFERENCE
VirusScan(TM)'s Scan program detects, identifies, and
disinfects known DOS computer. Scan checks memory and both
the system and data areas of disks for virus infections. If
Scan finds a known virus, in most cases it will eliminate
the virus and fully restore infected programs or system
areas to normal operation. To obtain a list of all the
viruses that Scan detects, run SCAN with the /VIRLIST
option.
In addition, Scan can also assign validation and recovery
codes to files, and then use those codes to detect and treat
infection by new and unknown viruses. If Scan has stored
validation or recovery data for files, it may detect file
changes and warn that infection by an unknown virus may have
occurred. Scan can also use the recovery codes to remove new
or unknown viruses and restore infected files, master boot
record (MBRs), and boot sectors.
This chapter describes how to use Scan from the DOS or OS/2
command prompt.
The command-line versions of VirusScan run under DOS and
OS/2. The program files are SCAN.EXE and OS2SCAN.EXE,
respectively. This chapter describes them both.
Note: Because OS/2 operates in a protected mode
environment, Scan for OS/2 does not check memory. To
protect against viruses in OS/2 DOS and Win-OS/2
sessions, use the VShield(TM) virus prevention program.
DO YOU NEED TO READ THIS CHAPTER?
Many users will not need the Scan command line options
described in this chapter. We have designed Scan so that
basic operation, as described in "Scanning Your System" and
"When to Rescan" in Chapter 2, will detect most viruses in
your system. The command line options described here offer
additional power and control over virus detection. They
enable you to run Scan from batch or script files, and are
most useful in vulnerable environments and to network
administrators and information services staff.
Using VirusScan (Version 2.0) 31
SYSTEM REQUIREMENTS AND SUPPORT
Scan requires DOS 3.0 or later, Windows 3.1 or later, or IBM
OS/2 Version 2.0 or later. Running Scan for DOS requires
340Kb of free RAM.
Scan works with 3Com 3/Share and 3/Open, Artisoft LanTastic,
AT&T StarLAN, Banyan VINES, DEC Pathworks, IBM LAN Server,
Microsoft LAN Manager, Novell NetWare, and any other IBMNET-
or NETBIOS-compatible network operating systems. Contact
McAfee or your local authorized agent if you do not see your
network listed (see "Technical Support" in Chapter 1).
Scan is designed to check for pre-existing infections of
known and unknown viruses on floppy, hard, CD-ROM, and
compressed (SuperStor, Stacker, DoubleSpace, and so on)
disks on both stand-alone and networked personal computers,
as well as network file servers. If you have a Novell
NetWare/386 V3.1X or 4.01 file server, you may want to use
the NETShield(TM) virus prevention NetWare Loadable Module
in conjunction with Scan.
o To use Scan to clean up (disinfect) virus-infected
files, the CLEAN.DAT file must be present in the same
subdirectory as Scan. If you don't have the CLEAN.DAT
file, first verify whether you should contact your
system administrator or information systems staff
directly for virus clean-up. Otherwise, you can contact
McAfee (see "Technical Support" in Chapter 1).
TECHNICAL OVERVIEW
KNOWN VIRUS DETECTION
Scan detects known viruses by searching the system for known
characteristics (sequences of code) unique to each computer
virus and reporting their presence if found. For viruses
that encrypt or cipher their code so that every infection is
different, Scan uses detection algorithms that work by
statistical analysis, heuristic analysis, and code
disassembly.
NEW AND UNKNOWN VIRUS DETECTION
Scan can also check for new or unknown viruses by comparing
files against previously recorded validation data. If a file
has been modified, it will no longer match the validation
data, and Scan will report that the file may have become
infected. With certain options, Scan /CLEAN can use the
validation and recovery data to restore infected files,
master boot records (MBRs), or boot sectors.
Using VirusScan (Version 2.0) 32
NOTE TO NETWORK USERS
To use Scan on a network drive (or directory), you must be
connected to that drive and have read access to it. Some
command line options described in this chapter attempt to
create, change, and delete files. To use these options, you
must have sufficient access rights. If you have questions
about access rights, contact your network administrator.
Using VirusScan (Version 2.0) 33
VALIDATING SCAN
The VirusScan program has several safeguards to ensure that
it remains free of viruses. See "Validating VirusScan" in
Chapter 2 for more information.
We recommend that you update your copy of the VirusScan
programs regularly. You can obtain an upgrade from several
sources, as described in "Updating VirusScan Regularly" in
Chapter 2.
Before using a new version of Scan for the first time,
verify that it has not been tampered with or infected by
using the Validate program, as described in "Validating
VirusScan" in Chapter 2. If your new copy of Scan differs
from the validation data in the on-line documentation file,
it may have been damaged. Don't use it, and obtain a clean
copy of Scan from a known source.
Scan performs an integrity test when run. This self-check
allows Scan to determine if it has been modified. If Scan
fails its integrity test, a warning message will appear, and
Scan will refuse to run and return to the command line
prompt. If Scan reports that it failed its integrity check,
you must then obtain an undamaged copy before continuing.
RUNNING SCAN FROM THE COMMAND LINE
Scan checks files and other areas of the system that can
contain computer viruses. When a virus is found, Scan
identifies it and the system area or file where it was found.
By default, Scan examines all files on a system. Once you've
installed VirusScan and have established a "sterile field"
(as described in Chapter 2), you might not need to scan
every file on your system again, just the executable files
(.EXE, .COM, .SYS, .BIN, .OVL, and .DLL files). Use the /STD
option to scan executable files only. (Note that the list of
extensions for standard executables has changed from
previous versions of Scan.)
Using VirusScan (Version 2.0) 34
From DOS or OS/2, you can run Scan from the command line
prompt. (From OS/2, open the Command Prompts folder in the
OS/2 system folder, then choose the OS/2 Full Screen or OS/2
Window icons to see the command line prompt.) The syntax is:
DOS C:\> scan {drives} [options]
OS/2 [C:\] os2scan {drives} [options]
{drives} indicates one or more drives to be scanned. You
must specify one or more drives to scan. If you list a drive
like C:, all of its subdirectories will be scanned. If you
list \, only the root directory and boot area of the current
disk will be scanned. If you list a directory or \, its
subdirectories will not be scanned unless you use the /SUB
option.
[options] indicates one or more of the Scan options listed
in the "Scan Command Line Option Summary" on the following
page.
Using VirusScan (Version 2.0) 35
SCAN COMMAND LINE OPTION SUMMARY
/? or /HELP
Display help screen.
/ADL
Scan all local drives (except floppy drives).
/ADN
Scan all network drives.
/AF {filename}
Store validation/recovery codes in filename.
/APPEND
Append to rather than overwrite, the report file
(/REPORT).
/AV
Add validation/recovery data to program files.
/BOOT
Scan master boot record and boot sector only.
/CF {filename}
Check validation/recovery codes in filename.
/CLEAN
Clean up infections in master boot records, boot
sectors, and files when possible.
/CV
Check validation/recovery data in files.
/DEL
Overwrite and delete infected files.
/EXCLUDE {filename}
Exclude from scan any files listed in filename.
Typically used in conjunction with the /AV option.
/FAST
Speed up VirusScan's scanning; may detect fewer
viruses.
/LOAD {filename}
Use Scan settings stored in filename.
/LOG
Save date and time VirusScan was last run in SCAN.LOG.
Using VirusScan (Version 2.0) 36
/MOVE {directory}
Move infected files to directory.
/NOMEM
Skip memory checking (not applicable to OS/2).
/PAUSE
Enable screen pause at end of display page.
/PLAD
Preserve Last-Access date of scanned files on Novell
drives.
/REPORT {filename}
Create report of infected files found during scan in
filename.
/RF {filename}
Remove validation/recovery codes in filename.
/RPTCOR
Add list of corrupted files to the report file
(/REPORT).
/RPTERR
Add list of system errors to the report file (/REPORT).
/RPTMOD
Add list of modified files to the report file
(/REPORT).
/RV
Remove validation/recovery data from files.
/SHOWLOG
Display information in SCAN.LOG.
/STD
Scan executable files only (.COM, .EXE, .SYS, .BIN,
.OVL, and .DLL)
/SUB
Scan subdirectories inside a directory.
/VIRLIST
Display list of viruses detected by VirusScan.
Using VirusScan (Version 2.0) 37
SCAN OPTION DESCRIPTIONS
Here is a detailed description of Scan's options.
/? or /HELP
Display list of Scan options
Displays a list of Scan command line options with a brief
description of each. No virus scanning will be performed
when these options are specified. Use either of these
options alone on the command line.
/ADL
Scan all local drives (except floppy drives)
Scans all local drives for viruses, in addition to those
specified on the command line. In DOS, use /ADL to check all
local drives, including compressed drives and CD-ROMs. To
scan both local and network drives, use /ADL and /ADN
together in the same command line.
/ADN
Scan all network drives
Scans all network drives for viruses, in addition to those
specified on the command line. To scan both local and
network drives, use /ADL and /ADN together in the same
command line.
/AF {filename}
Store validation/recovery codes in file
Helps you detect and recover from new or unknown viruses.
/AF logs validation and recovery data for the executable
files, boot sector, and master boot record (MBR) of a disk
in the file you specify. The log file is about 95 bytes per
file validated. You must specify a filename, which can
include the target drive and directory (such as
D:\VAL\DRIVES.VAL). If the target path is a network drive,
you must be able to create and delete files in that drive.
If filename exists, Scan updates it. The /AF option adds
about 300% more time to scanning.
To exclude self-modifying or self-checking files that might
cause false alarms, use the /EXCLUDE option. To recover from
a virus using the /AF information, use the /CF and /CLEAN
options together in the same command line. Using any of the
/AF, /CF, or /RF options together in the same command line
returns an error.
o /AF performs the same function as /AV, but stores its
data in a separate file rather than changing the
executable files themselves. For more information, see
"Detecting new and unknown viruses" in Chapter 4.
Using VirusScan (Version 2.0) 38
/APPEND
Append to the report file.
Used in conjunction with /REPORT, appends the report message
text to the specified report file, if it exists. Otherwise,
the /REPORT option overwrites the specified report file, if
it exists.
/AV
Add validation/recovery data to files
Helps you detect and recover from new or unknown viruses.
/AV adds recovery and validation data to each standard
executable file (.EXE, .COM, .SYS, .BIN, .OVL. and .DLL),
increasing the size of each file by 98 bytes. To update
files on a shared network drive, you must have update access
rights. The /AV option adds about 100% more time to
scanning.
To exclude self-modifying or self-checking files that might
cause false alarms, use the /EXCLUDE option. To recover from
a virus using the /AF information, use the /CV and /CLEAN
options together in the same command line. Using any of the
/AV, /CV, or /RV options together in the same command line
returns an error.
o The /AV option does not store any information about the
master boot record (MBR) or boot sector of the drive
being scanned.
/BOOT
Scan boot sector and master boot record only
Scans the boot sector and master boot record on the
specified drive(s), but not the files or directories on
those drives.
/CF {filename}
Check validation/recovery codes in file
Helps you detect new or unknown viruses. Checks validation
data stored by the /AF option in filename. If a file or
system area has changed, Scan reports that a viral infection
may have occurred. The /CF option adds about 250% more time
to scanning. For more information, see "Detecting New And
Unknown Viruses" in Chapter 4. You can use /CF and /CLEAN in
the same command line to check validation/recovery codes and
remove any viruses found. Using any of the /AF, /CF, or /RF
options together in a command line returns an error.
o Some older Hewlett-Packard and Zenith PCs modify the
boot sector each time the system is booted. If you use
/CF or /CV, Scan will continuously report that the boot
sector has been modified even though no virus may be
present. Check your system's technical reference manual
to determine whether your PC has self-modifying boot
code, or contact McAfee for help (see "Technical
Using VirusScan (Version 2.0) 39
Support" in Chapter 1).
o OS/2 dual boot systems change the boot sector between
DOS and OS/2 depending on which operating system is
active. This causes Scan to report that the boot sector
has been modified.
/CLEAN
Remove viruses from boot sector, master boot record (MBR),
and infected files
Attempts to restore the boot sector, if infected, and any
infected files. Usually, between 10% and 20% of all viruses
are not removable; they damage the file they infect beyond
repair. If the infected file resides on a network drive, you
must be able to modify files on that drive to clean it. If
it cannot restore a file, you'll see a message that
identifies the name of the unrecoverable file. To use
/CLEAN, the CLEAN.DAT file must reside in the Scan
directory.
Use /CLEAN instead of /DEL when you want to restore infected
files, not just delete or overwrite them. The /CLEAN option
can remove master boot record and boot sector viruses,
but the /DEL option cannot. If you use /CLEAN and /DEL in
the same command line, Scan first attempts to disinfect an
infected file, then deletes it only if it cannot be
repaired. Similarly, if you use /CLEAN and /MOVE in the same
command line, Scan attempts first to clean an infected file,
then moves it automatically if the file is unrecoverable.
You can use /CLEAN and /CF or /CV in the same command line
to check validation/recovery codes and remove any viruses
found. We strongly recommend that you get experienced help
in dealing with viruses if you are unfamiliar with anti-
virus software and methods. This is especially true for
"critical" viruses and master boot record/boot sector
infections, because improper removal of these viruses can
result in the loss of all data on the infected disks.
o When scanning a network drive using /CLEAN, you must
have sufficient rights to update files on that drive.
/CV
Check validation/recovery data in files
Helps you detect new or unknown viruses. Checks validation
data added by the /AV option. If a file is modified, Scan
reports that a viral infection may have occurred. The /CV
option adds about 50% more time to scanning. You can use
/CLEAN and /CF or /CV in the same command line to check
validation/recovery codes and restore infected files. Using
any of the /AV, /CV, or /RV options together in the same
command line returns an error.
Using VirusScan (Version 2.0) 40
/DEL
Overwrite and delete infected files
Deletes and overwrites each infected file. Files erased by
the /DEL option cannot be recovered (generate a report so
that you can restore them from backups). Instead of /DEL
alone, we recommend using it in combination with the /CLEAN
option to attempt to disinfect an infected file first, then
delete it only if the file is unrecoverable. The /CLEAN
option can remove master boot record and boot sector
viruses, but the /DEL option cannot.
o When scanning a network drive using /DEL, you must have
sufficient access rights to delete files on that drive.
/EXCLUDE {filename}
Scan using exception list file
Allows you to exclude files from /AF or /AV validation.
Self-modifying or self-checking files can cause a false
alarm during a scan. To create filename, see "Technical Note
1: Creating an Exception List File for the /EXCLUDE Option"
in this chapter.
/FAST
Speed up VirusScan's scanning
Reduces Scan time by about 15%. Using the /FAST option, Scan
examines a smaller portion of each file for viruses,
although it examines more files overall. Using /FAST might
miss some infections found in a more comprehensive (but
slower) scan. Do not use this option if you have found a
virus or suspect one.
/LOAD {filename}
Use Scan settings stored in {filename}.
By default, Scan loads its internal default settings plus
any options specified on the command line. You can store all
custom settings in a separate ASCII text file, then use
/LOAD to load those settings from that file.
Use a text editor to create the file. You can put all
options on the same line separated by a space or put each
option (with its parameter) on its own line, separated by a
hard carriage return and line feed, as shown in the
following examples:
Using VirusScan (Version 2.0) 41
Sample load file with all options on the same command line:
m: /report a:infectn.rpt /rptcor /rpterr
Sample load file with each option on a separate command
line:
m:
/report a:infectn.rpt
/rptcor
/rpterr
/LOG
Save date and time of last scan
Stores the time and date Scan is being run by updating or
creating a file called SCAN.LOG in the current directory.
/MOVE {directory}
Move infected files to directory
Moves all infected files found during a scan to the
specified directory. If you use /MOVE in conjunction with
/CLEAN, Scan attempts to restore an infected file first,
then moves it to the specified directory only if the file
cannot be restored. Using /MOVE and /DEL in the same command
line returns an error message.
/NOMEM
Skip memory checking
Reduces scan time by omitting all memory checks for viruses.
Use /NOMEM only when you are absolutely certain that your
system is virus-free.
By default, Scan checks system memory for all for critical
known computer viruses that can inhabit memory. In addition
to main memory from 0Kb to 640Kb, Scan checks upper memory
from 640Kb to 1,024Kb and the high memory area from 1,024Kb
to 1,088Kb that can be used by computer viruses on 286 and
later systems. Memory above 1,088Kb is not addressed
directly by the processor and is not presently susceptible
to viruses.
o /NOMEM is not applicable to OS/2.
Using VirusScan (Version 2.0) 42
/PAUSE
Enable screen pausing.
If you specify /PAUSE, a "More? (H = Help)" prompt will
appear when Scan fills up a screen with messages, such as
when using the /SHOWLOG or /VIRLIST options. Otherwise,
Scan will, by default, fill the screen with messages and
scroll the screen continuously without stopping. This
allows Scan to be run against PCs with many drives or on
PCs with severe infections without requiring user
intervention. We recommend that you omit /PAUSE when
keeping a record of Scan's messages using the report options
(/REPORT, /RPTCOR, /RPTMOD, and /RPTERR).
/PLAD
Preserve Last-Access date on NetWare drives.
Prevents changing the Last-Access date attribute for files
stored on a network drive of a Novell network. Normally,
NetWare updates the Last-Access date when files are
accessed on network drives. However, some tape backup
systems use the Last-Access date to decide whether to back
up the file. Use /PLAD to ensure that the last access date
does not change as the result of scanning.
/REPORT {filename}
Create report of infected files and system errors
Saves the output of Scan to filename in ASCII text file
format. If filename exists, /REPORT erases and replaces it.
You can include the destination drive and directory (such as
D:\VSREPRT\ALL.TXT), but if the destination is a network
drive, you must be able to create and delete files on that
drive. You can also use /RPTCOR, /RPTMOD, and /RPTERR to add
corrupted files, modified files, and system errors to the
report.
/RF {filename}
Remove validation/recovery codes in file
Removes validation and recovery data from filename created
by the /AF option. If filename resides on a shared network
drive, you must be able to delete files on that drive. Using
any of the /AF, /CF, or /RF options together in the same
command line returns an error.
/RPTCOR
Add corrupted files to Scan report
Used in conjunction with /REPORT, adds the names of
corrupted files to the report file. A corrupted file is a
file that a virus has damaged beyond repair, which typically
occurs in 10% to 20% of all viral infections. You can use
/RPTCOR with /RPTMOD and /RPTERR on the same command line.
Using VirusScan (Version 2.0) 43
/RPTERR
Add errors to Scan report
Used in conjunction with /REPORT, adds system errors to the
report file.
System errors include problems reading or writing to a
diskette or hard disk, file system or network problems,
problems creating reports, and other system-related
problems. You can use /RPTERR with /RPTCOR and /RPTMOD on
the same command line.
/RPTMOD
Add modified files to the Scan report
Used in conjunction with /REPORT, adds the names of modified
files to the report file. Scan identifies modified files
when the validation/recovery codes do not match (using the
/CF or /CV options). You can use /RPTMOD with /RPTCOR and
/RPTERR on the same command line.
/RV
Remove validation/recovery from files
Removes validation and recovery data from files validated
with the /AV option, along with the SCAN.LOG file on the
specified drive. To update files on a shared network drive,
you must have access rights to update them. Using any of the
/AV, /CV, or /RV options together in the same command line
returns an error.
/SHOWLOG
Update and display the contents of SCAN.LOG
Stores the time and date Scan is being run by updating or
creating a file called SCAN.LOG in the current directory,
and shows you the date and time of previous scans that have
been recorded in the SCAN.LOG file using the /LOG switch.
The SCAN.LOG file contains text and some special formatting.
To pause when the screen fills with messages, specify the
/PAUSE option.
/STD
Scan executable files only (.COM, .EXE, .SYS, .BIN, .OVL, .DLL)
Reduces scan time when a full scan is not needed. Otherwise,
Scan checks all files on the drive scanned and examines
files in greater detail, which increases Scan's ability to
detect viruses in overlay files but substantially increases
the scanning time required. Do not use this option if you
have found a virus or suspect one. (The list of extensions
for standard executables has changed from previous releases
of VirusScan.)
Using VirusScan (Version 2.0) 44
/SUB
Scan subdirectories
By default, when you specify a directory to scan rather than
a drive, Scan will examine only the files it contains, not
its subdirectories. Use /SUB to scan all subdirectories
inside any directories you've specified. Do not use /SUB if
you are scanning an entire drive.
/VIRLIST
Display list of viruses detected by VirusScan
Shows the name of the viruses that VirusScan detects. To
pause when the screen fills with messages, specify the
/PAUSE option. Use /VIRLIST alone on the command line.
Using VirusScan (Version 2.0) 45
CLEANING VIRUSES
Although /CLEAN removes many viruses and restores normal
operation, viruses can be harmful and insidious, and no
anti-virus program can undo all their damage. Usually,
between 10% and 20% of all viruses corrupt the files they
infect, making them unrecoverable. If the file is infected
with an uncommon virus that /CLEAN can't remove, Scan
notifies you and identifies the filename. Write down this
filename so that you can restore it from a backup diskette
or tape. If you use both the /CLEAN and the /DEL options,
Scan will first attempt to repair an infected file and, if
the file is damaged beyond repair, Scan will delete it.
Deleted files are not recoverable except from backups.
Some viruses damage or overwrite program (.EXE) files or
overlay files. Removing the virus can truncate the file or
otherwise render it inoperable. Others, like the common
virus Stoned, infect the master boot record (MBR). On
systems partitioned with programs other than DOS (such as
Disk Manager and SpeedStor), removing the virus can cause
loss of the master boot record (MBR) and all data on the
disk if done improperly.
BASIC PRINCIPLES TO MINIMIZE DAMAGE
These considerations lead to the three important principles:
1. Before running Scan with the /CLEAN option, back up all
of your programs and data.
Of course, this works best if you backup your files
regularly, so that you can restore your files from a
backup made before your system was infected. But even a
backup from an infected system can be useful for
restoring data, because most viruses do not corrupt
data. If a program no longer runs after being cleaned,
replace it from the original disk or from a virus-free
backup.
When disinfecting an infected system, it is important
to start from a "sterile field," as described in
Chapter 2.
2. Before running Scan with the /CLEAN option for DOS,
restart your computer from a clean, write-protected
diskette; before running it for OS/2, close all DOS and
Win-OS/2 sessions.
Preferably, use the clean anti-virus start-up diskette
you created in "Making a clean start-up diskette" in
Chapter 2. And, because running any program can spread
the infection:
Using VirusScan (Version 2.0) 46
3. Do not run any programs, including Windows, before
running Scan /CLEAN.
Run Scan /CLEAN from DOS instead of from Windows.
Exit completely from Windows. Do not run Scan /CLEAN
from within a DOS window.
IMPORTANT: If you are at all unsure about how to
proceed once you've found a virus, contact
McAfee technical support, or your local
authorized agent, for assistance (see
"Technical support" in Chapter 1).
Using VirusScan (Version 2.0) 47
RUNNING SCAN TO CLEAN UP INFECTIONS
Preparation
1. Before running Scan to clean up infections, clear the
virus from system memory and prevent reinfection:
o With DOS, turn off your PC, then restart from a
clean start-up diskette, preferably the anti-virus
diskette you prepared in "Making a clean start-up
diskette" in Chapter 2.
o With OS/2, close all DOS and Win-OS/2 sessions.
o With an OS/2 dual-boot system infected by a boot
sector virus (like FORM, Disk Killer, or others
identified by Scan), boot (start up) OS/2 first,
delete the BOOT.DOS file from the \OS2 directory,
and then boot DOS to create a new, virus-free DOS
boot sector file.
2. Run the Scan program to locate and identify the
infections.
3. Back up the files on the infected disks (be sure not to
overwrite any previous backups).
4. Repeat Step 1.
5. Don't run any programs, including Windows, before
running Scan /CLEAN. If you have Windows, run Scan
/CLEAN from DOS.
6. When disinfecting a hard disk, always run Scan /CLEAN
from your write-protected VirusScan diskette to prevent
infection of the Scan program. When disinfecting
diskettes, make sure there is no active virus in memory
before running Scan from your hard disk.
Using VirusScan (Version 2.0) 48
SUCCESSFUL AND UNSUCCESSFUL RESULTS
Scan /CLEAN reports the results of its attempt to remove the
virus from each infected file. If a file has several
infections, it will report on each. If viruses were not
removed, contact technical support.
If Scan can't remove a virus, you'll see a message like:
Virus cannot be safely removed from this file.
Make sure to take note of the file name, because you will
need to restore it from backups. If you have any questions
about how to proceed, contact McAfee technical support or
your local authorized agent (see "Technical Support" in
Chapter 1).
IF VIRUSES WERE SAFELY REMOVED, RESCAN AND CHECK DISKETTES
If Scan /CLEAN has successfully removed all the viruses,
turn your computer off again and restart from the system
disk. Scan your hard disks again to make sure they are
virus-free. If you suspect that your system was infected
from a diskette, run Scan from your hard disk to examine
and disinfect the diskettes you use.
Using VirusScan (Version 2.0) 49
EXAMPLES
These examples show different option settings. In OS/2,
remember to use OS2SCAN instead of SCAN.
scan c:
Scan all executable files on drive C.
scan f:
Scan drive F:, a network drive.
scan c: /adl /adn
Scan all local and network drives (except floppy drives).
scan f: g: h: /del
Scan all files on drives F:, G:, and H:, and delete any
infected files found.
scan c: d: e: /av
Scan for viruses in all files and add validation codes
to executable files on drives C:, D:, and E:.
scan m: /report a:infectn.rpt /rptcor /rpterr
Scan for viruses on network drive M: and create a log
file of infections, corruptions, and errors in the file
INFECTN.RPT on drive A:.
scan e:\user\mike e:\user\chris e:\user\cindy /sub
Scan all subdirectories inside the directories
USER\MIKE, USER\CHRIS, and USER\CINDY on drive E:.
scan c: d: e: /fast /cv
Quickly scan drives C:, D:, and E:, and also report any
executable files that do not have validation codes.
scan c:\command.com
Scan a single file.
Using VirusScan (Version 2.0) 50
ERROR LEVELS
o This section is primarily for network administrators,
information systems staff, and other people who may
want to run VirusScan from DOS batch files, network
login scripts, or OS/2 REXX scripts.
After Scan has finished running, it sets the ERRORLEVEL. You
can use the ERRORLEVEL in batch or script files to take
different actions based on the results of the scan. See your
operating system documentation for information on creating
these types of files.
Scan returns the following ERRORLEVELs:
ERRORLEVEL DESCRIPTION
0 No errors occurred and no viruses were found.
1 An error occurred while accessing a file
(either reading or writing).
2 A VirusScan database (*.DAT) file is
corrupted.
3 An error occurred while accessing a disk
(either reading or writing).
4 An error occurred with the file created with
the /AF option; the file has been damaged.
5 Insufficient memory to load program or
complete an operation.
6 An internal program error occurred.
7 An error occurred while accessing or
processing an international message file
(MCAFEE.MSG).
8 A file required to run VirusScan, such as
SCAN.DAT or NAMES.DAT, is missing.
9 Incompatible or unrecognized option(s) or
argument(s) for an option were specified on
the command line.
10 A computer virus was found in memory.
11 An internal program error occurred.
Using VirusScan (Version 2.0) 51
12 An error occurred while attempting to remove
a virus, such as no CLEAN.DAT file found
or VirusScan was unable to remove the virus.
13 One or more viruses was found in the master
boot record, boot sector, or file(s).
14 The SCAN.DAT file is out-of-date; please
upgrade VirusScan data files.
15 VirusScan failed its self-check. It may be
infected with a virus, tampered with, or
damaged.
16 An error occurred while accessing or
attempting to access a specified drive,
directory, or file.
17 No drive, directory or file was specified for
scanning.
18 A validated file has been modified and no
longer matches its CRC check-sum (/CF or /CV
options).
19 - 99 Reserved.
100+ An error within the operating system.
VirusScan adds 100 to original error number.
Using VirusScan (Version 2.0) 52
APPLICATION NOTE 1: UPDATING VALIDATION CODES
If you install any new software or programs on your system,
including a new version of DOS, and are running Scan or
VShield with the /CF (preferred) or /CV validation options,
you need to install validation codes for the new files with
Scan's /AF (preferred) or /AV options.
The quickest way to update the validation codes is to remove
all validation codes from the hard disk and then add them
back. To do this, first run Scan with the /RF or /RV option,
then run it again with the /AF or /AV option.
Using VirusScan (Version 2.0) 53
APPLICATION NOTE 2: REFORMATTING INFECTED DISKETTES WITH DOS
5.0 AND LATER
When reformatting infected diskettes using DOS 5.0 and later
versions, be sure to add the /U switch to the FORMAT
command. This tells DOS to do an unconditional format of the
diskette, without saving the original infected boot sector.
This is necessary to erase certain infections, and will
prevent reinfection by unformatting the diskette.
Using VirusScan (Version 2.0) 54
TECHNICAL NOTE 1: CREATING AN EXCEPTION LIST FILE
FOR THE /EXCLUDE OPTION
If you set up validation codes using Scan's /AF or /AV
options, subsequent scans using the /CF or /CV options will
detect changes in executable files. This can generate false
alarms if the executable files are self-modifying or self-
checking (most programs that do this will tell you to turn
off your anti-virus software before running them; some of
these files are listed below). Therefore, use the /EXCLUDE
option in conjunction with /AF or /AV to identify such files
and exclude them from the validation.
The exception list is an ASCII (or DOS) text file. If you
use a word processor to create it, be sure to save the file
as ASCII or DOS Text. Each line in the file contains the path
and file name of one file that should not be validated.
Here is an example:
C:\CLIPPER\BIN\CLIPPER.EXE
C:\123\123.COM
C:\FOX\FOXPROLX.EXE
C:\DOS\SETVER.EXE
C:\PKWARE\PKLITE.EXE
C:\PKWARE\PKZIP.EXE
C:\PKWARE\PKUNZIP.EXE
C:\SEMWARE\Q.EXE
C:\SWAPVOL.COM
C:\WORDSTAR\WS.EXE
Using VirusScan (Version 2.0) 55
Chapter 4: TIPS & TROUBLESHOOTING
The other chapters in this manual are meant to tell you
clearly and concisely how to use the VirusScan(TM) software.
Still, you may have questions or encounter confusing
situations. This chapter contains two kinds of advice:
o Tips for getting the most out of VirusScan.
o Common problems and how to solve or avoid them.
If this information doesn't help resolve your question or
problem, contact McAfee (see "Technical Support" in
Chapter 1).
DETECTING NEW AND UNKNOWN VIRUSES
There are two ways of dealing with new and unknown viruses
that may infect your system:
o Update VirusScan regularly.
o Store and check validation and recovery information
about your files.
UPDATE VIRUSSCAN REGULARLY
Most likely, McAfee will see new viruses long before you do.
We update the VirusScan programs often--usually montly, but
more often if many new viruses have appeared. Each new
version may detect and eradicate as many as 60 to 100 new
viruses or more, and may fix bugs that have been reported.
Updating VirusScan regularly is probably all you need to do
to protect against new viruses. See the instructions for
obtaining new versions in "Updating VirusScan Regularly" in
Chapter 2.
USE THE VALIDATION AND RECOVERY OPTIONS
If your environment is highly vulnerable to viruses, or you
require unusual security against them, you can use
VirusScan's validation and recovery options. Scan checks for
new or unknown viruses by comparing files against previously
recorded validation data. If a file has been modified, it no
longer matches the validation data, and Scan reports that
the file may have become infected. Scan has two levels of
validation, which are stored in two separate ways:
Using VirusScan (Version 2.0) 56
o It can store the enhanced code in a separate recovery
file, which can be stored off-line (for example, on a
diskette) for recovery purposes (/AF, /CF, and /RF
switches). This is the preferred method because it
stores the data for files, the boot sector, and the
master boot record (MBR) of a disk in the recovery
file.
o It can append a 98-byte validation code to .COM and
.EXE files (/AV, /CV, and /RV switches). This method
applies to the files you specified only. It does not
store data for the boot sector and master boot record
(MBR).
Once the validation codes are stored, both Scan and VShield
can use the /CV and /CF options to detect changes to the
files. More importantly, if you have stored the recovery
information with /AF, Scan can use it to restore infected
files, master boot record (MBRs), and boot sectors.
All of these options require continuing effort to store and
maintain the codes. For example, if you install new programs
or upgrade old ones, you should use the /RV or /RF options
to remove all codes, then /AV or /AF to restore them.
If you want to use one of these methods, which should you
use? We recommend the "F" options--/AF, /CF, and /RF--over
the "V" options. /AF stores the validation and recovery
information in a separate file, instead of modifying the
program files themselves. This has three advantages:
o You can store the recovery file off-line (on your clean
anti-viral startup diskette, for example, or on a
network drive or tape drive) and access it on demand to
check for, and recover from, infection by unknown
viruses. Use the procedure below to create a recovery
diskette.
o This method keeps self-checking files (usually copy-
protected programs) from reporting that they have been
tampered with.
o If you use this method, you don't need an exception
list. However, it's important that you run Scan with
the /RF option on individual self-modifying files, such
as Lotus 1-2-3, to remove the validation codes for
those programs from the validation file.
The "V" options are primarily useful for companies that
distribute software to their customers or employees, and
want to incorporate an additional level of virus protection.
Using VirusScan (Version 2.0) 57
CREATING A RECOVERY DISKETTE
To store the recovery file, create a new "VirusScan Startup
Diskette" and then run Scan to create a validation code and
recovery data file by typing:
scan /adl /af a:\scancrc.crc
and pressing <ENTER>. The above command scans the local
hard disk drive(s) for known viruses and creates
"SCANCRC.CRC," a file containing validation codes and
recovery data, on the diskette. After Scan finishes,
write-protect the diskette, label it as your "VirusScan
Recovery Diskette," and store in a safe location.
To check for virus infection, turn your computer off, insert
your "VirusScan Recovery Diskette" in drive A:, and turn
the power back on. The PC will now start from the diskette.
At the DOS prompt, type:
scan /adl /cf a:\scancrc.crc
and press <ENTER>. This will compare the local hard disk
drive(s) against the recovery data stored on the diskette
in the SCANCRC.CRC file.
If you detect an unknown virus, to disinfect your system,
turn your PC off, insert the recovery diskette, and turn the
power back on. The PC will start from the floppy disk. At
the DOS prompt, type:
scan /adl /cf a:\scancrc.crc /clean
to restore drives C and D with the recovery data stored in
SCANCRC.CRC on the diskette.
If you install new software, or upgrade your DOS version,
remember to update your recovery file. See Application
note 1, "Updating Validation Codes," in Chapter 3.
Using VirusScan (Version 2.0) 58
INTERACTING WITH YOUR NETWORK
Many personal computers are interconnected through a local
area network (LAN). VirusScan is highly compatible with most
networks. Here are some ways of using the VirusScan software
with your network:
Run Scan on network drives
Run from a workstation (PC) on the network, Scan checks
network drives for viruses just as it does local drives. For
convenience, the /ADN option scans all network drives to
which the workstation is connected.
Use VShield and CheckVShield
By activating VShield as part of every workstation's
AUTOEXEC.BAT file, you can prevent the workstations from
introducing viruses into the network. Network administrators
can ensure that VShield is active on each workstation by
running CheckVShield as part of the network login script,
before actual login.
Use NETShield
NETShield provides continuous virus protection on a NetWare
server. NetWare network administrators can use it to check
for both known and unknown viruses and to monitor all
network activities. On other kinds of networks, you can use
Scan to check network servers.
Develop a network security program, as described in the next
tip.
Develop a security program
VirusScan has been shown to be an effective virus-preventive
measure when used in a conscientiously applied program of
network security and regular professional care.
VirusScan is one important element of a comprehensive
computing security program that includes a variety of safety
measures, such as regular backups, meaningful password
protection, user training, and awareness. Even with
VirusScan, some viruses--not to mention theft or fire--an
render a disk unrecoverable without a recent backup to
reload information. Although outlining such a security
program is beyond the scope of this manual, see "Other
Sources of Information" in Chapter 1 for suggestions.
If you are a network administrator, we urge you to implement
a security program to safeguard your organization's data and
productivity. If you are a network user, please support and
comply with such a program.
Using VirusScan (Version 2.0) 59
TROUBLESHOOTING
Using VirusScan with other anti-virus software
When you run more than one anti-virus program from different
vendors, you risk strange results and false alarms. For
example, some anti-virus programs store their "virus
signature strings" unprotected in memory. Running VirusScan
may "detect" them falsely as a virus.
False alarms
Scan may incorrectly report a virus in the boot sector or
master boot record (MBR) of a disk if the diskette using a
special copy-protection or encryption mechanism. Contact
technical support if you're unsure (see "Technical Support"
in Chapter 1).
TSR conflicts
Some "terminate-and-stay-resident" (TSR) software may
conflict with VirusScan programs, especially VShield (which
is itself a TSR). To check whether this is the problem,
"comment out" the other TSR files in your AUTOEXEC.BAT file
and restart your system. If the errors disappear, the TSR
conflict caused them.
Slow disk access, program locks
Running VShield will slow your system slightly as described
in Chapter 3 in the VShield documentation, especially if you
use either the /ANYACCESS or /SWAP options. If you experience
very slow disk access, or if programs lock or freeze while
using Windows 3.1, you may be using a disk cache program that
interferes with program operation, or you may need to increase
the number of BUFFERS in your CONFIG.SYS file.
Program locks with VShield's /SWAP option
When VShield is running with the /SWAP option, certain
programs may lock up the computer. These programs may use
memory without allocating it first, including older versions
of Lotus 1-2-3, pfs:Write and Professional Write,
OfficeWrite, and DisplayWrite4. To correct, restart your
computer and run VShield without the /SWAP option.
Unable to remove VShield
If the /REMOVE option doesn't successfully remove VShield
from memory, you have probably loaded other terminate-and-
stay-resident (TSR) programs after VShield. VShield can't be
removed until the other TSRs are removed. If you need to
unload VShield often, load it last.
Using VirusScan (Version 2.0) 60
APPENDIX A: RETRIEVING VIRUSSCAN UPDATES VIA THE McAFEE BBS
McAfee runs a multiple line bulletin board system (BBS) for
you to download program updates, receive technical support,
and interact with other McAfee users.
DIAL UP
o The McAfee BBS phone number is (408) 988-4004.
o The BBS operates at up to 14,400 bps (baud). Set your
communications parameters to 8 data bits, 1 stop bit,
no parity, and your terminal emulation to ANSI or TTY.
o The BBS is Bell- and ITU- (formerly CCITT) compatible.
LOG ON
After receiving the CONNECT message from your communications
package:
o Enter your name, geographic location, and password.
To retrieve the VirusScan programs, type "GUEST" for
first name, and "USER" for last name.
Or, if you want personal answers or feedback, create
your own account by entering your first and last name
and a password. Passwords should be 3-8 characters long
and are case-sensitive.
THE MAIN MENU
Here are some of the important functions on the main menu:
F File transfer area (download McAfee updates)
M Message area (read and write messages in all sections
and e-mail)
G Goodbye (hang up and leave the BBS)
Downloading McAfee programs
1. Select <F> from the Main Menu to go to the File
transfer area. This is the area from which you can
download McAfee programs.
2. Select <1> for the McAfee Antivirus Files. A sorted
directory listing of files available for download will
be displayed.
Using VirusScan (Version 2.0) 61
3. Type <D> for download, then type in the filename as
found in the directory.
4. The BBS will prompt you to select a protocol. We
recommend error-correcting protocol such as ZMODEM,
YMODEM or XMODEM.
5. You'll see the message Awaiting start signal. Tell your
software to receive files. With PROCOMM for DOS or
TELIX, press the <PAGE DOWN> key, with BITCOM, press
the <F2> key. For other communications programs, check
your manual.
7. Your software will prompt you to select a protocol and
file name to receive the file. Select the same protocol
and name.
Using VirusScan (Version 2.0) 62
APPENDIX B: OPTIONS COMPARISON BETWEEN
VIRUSCAN VERSIONS 1.5 AND 2.0
VERSION COMPARISON OF SCAN OPTIONS
Scan │ Scan │
Version 1.5 │ Version 2.0 │ Option Description
═══════════════╪══════════════╪══════════════════════════
/? /H or │ /? or /HELP │ Display help screen.
/HELP │ │
───────────────┼──────────────┼──────────────────────────
/A │ │ Scan all files,
│ │ including data files.
───────────────┼──────────────┼──────────────────────────
/AD{x} │ /AD{x} │ Scan all drives
│ │ {L=Local, N=Network}.
│ │ Leave blank for both
│ │ (version 1.5 only).
───────────────┼──────────────┼──────────────────────────
/AF │ /AF │ Store
{filename} │ {filename} │ validation/recovery
│ │ codes in filename.
───────────────┼──────────────┼──────────────────────────
/AG │ │ Add recovery/validation
{filename} │ │ data to files except
│ │ those listed in {filename}.
───────────────┼──────────────┼──────────────────────────
/AV │ /AV │ Add validation/recovery
{filename} │ │ data to program files.
│ │ Exclude those listed in
│ │ {filename} (version 1.5
│ │ only); exclude those
│ │ listed in /EXCLUDE
│ │ option (version 2.0 only).
───────────────┼──────────────┼──────────────────────────
/BELL │ │ Beep whenever a virus
│ │ is found.
───────────────┼──────────────┼──────────────────────────
/BMP │ │ Scan OS/2 Boot Manager
│ │ partition only.
───────────────┼──────────────┼──────────────────────────
│ /BOOT │ Scan master boot record
│ │ and boot sector only.
───────────────┼──────────────┼──────────────────────────
/CERTIFY │ │ List files not having a
│ │ validation code.
───────────────┼──────────────┼──────────────────────────
/CF │ /CF │ Check
{filename} │ {filename} │ validation/recovery
│ │ codes in filename.
───────────────┼──────────────┼──────────────────────────
Using VirusScan (Version 2.0) 63
VERSION COMPARISON OF SCAN OPTIONS (continued)
Scan │ Scan │
Version 1.5 │ Version 2.0 │ Option Description
═══════════════╪══════════════╪══════════════════════════
/CG │ │ Check
│ │ recovery/validation
│ │ data in files.
───────────────┼──────────────┼──────────────────────────
/CHKHI │ │ Check memory from 0Kb
│ │ to 1,088Kb (not
│ │ applicable to OS/2).
───────────────┼──────────────┼──────────────────────────
(CLEAN.EXE) │ /CLEAN │ Clean up infections in
│ │ master boot records,
│ │ boot sectors, and files
│ │ when possible.
───────────────┼──────────────┼──────────────────────────
/CV │ /CV │ Check
│ │ validation/recovery
│ │ data in files.
───────────────┼──────────────┼──────────────────────────
/D │ /DEL │ Overwrite and delete
│ │ infected files.
│ │ Save date and time
│ │ VirusScan was last run
│ │ in SCAN.LOG.
───────────────┼──────────────┼──────────────────────────
/DATE │ /LOG │ Save date and time
│ │ VirusScan was last run.
│ │ Save in SCAN.LOG file
│ │ (version 2.0 only).
───────────────┼──────────────┼──────────────────────────
│ /EXCLUDE │ Exclude from scan any
│ {filename} │ files listed in
│ │ filename. Typically
│ │ used in conjunction
│ │ with the /AV option.
───────────────┼──────────────┼──────────────────────────
EXT │ │ Scan using external
{filename} │ │ virus information from
│ │ filename.
───────────────┼──────────────┼──────────────────────────
/FAST │ /FAST │ Speed up VirusScan's
│ │ scanning; may detect
│ │ fewer viruses.
───────────────┼──────────────┼──────────────────────────
/HISTORY │ /APPEND │ Append Scan report to
filename │ │ filename (version 1.5).
│ │ Append to, rather than
│ │ overwrite, the report
│ │ file (/REPORT, version 2.0)
Using VirusScan (Version 2.0) 64
VERSION COMPARISON OF SCAN OPTIONS (continued)
Scan │ Scan │
Version 1.5 │ Version 2.0 │ Option Description
═══════════════╪══════════════╪══════════════════════════
/M │ │ Scan memory for all
│ │ viruses (not applicable
│ │ to OS/2).
───────────────┼──────────────┼──────────────────────────
/MANY │ │ Scan multiple floppy
│ │ disks (diskettes).
───────────────┼──────────────┼──────────────────────────
│ /MOVE │ Move infected files to
│ {directory} │ directory.
───────────────┼──────────────┼──────────────────────────
/NLZ │ │ Skip internal scan of
│ │ LZEXE compressed files.
───────────────┼──────────────┼──────────────────────────
/NOBREAK │ │ Disable Ctrl-C and Ctrl-
│ │ Brk during scan.
───────────────┼──────────────┼──────────────────────────
/NOEXPIRE │ │ Do not display
│ │ expiration notice.
───────────────┼──────────────┼──────────────────────────
/NOMEM │ /NOMEM │ Skip memory checking
│ │ (not applicable to OS/2).
───────────────┼──────────────┼──────────────────────────
/NOPAUSE │ /PAUSE │ Disable screen pause
│ │ (version 1.5 only).
│ │ Enable screen pause
│ │ (version 2.0 only).
───────────────┼──────────────┼──────────────────────────
/NPKL │ │ Skip internal scan of
│ │ PKLITE compressed files.
───────────────┼──────────────┼──────────────────────────
│ /PLAD │ Preserve Last-Access
│ │ date of scanned files
│ │ on Novell drives.
───────────────┼──────────────┼──────────────────────────
/REPORT │ /REPORT │ Create report of
{filename} │ {filename} │ infected files found
│ │ during scan in filename.
───────────────┼──────────────┼──────────────────────────
/RF │ /RF │ Remove
{filename} │ {filename} │ validation/recovery
│ │ codes in filename.
───────────────┼──────────────┼──────────────────────────
/RG │ /RG │ Remove
│ │ recovery/validation
│ │ data from files.
Using VirusScan (Version 2.0) 65
VERSION COMPARISON OF SCAN OPTIONS (continued)
Scan │ Scan │
Version 1.5 │ Version 2.0 │ Option Description
═══════════════╪══════════════╪══════════════════════════
│ /RPTCOR │ Add list of corrupted
│ │ files to the report
│ │ file (/REPORT).
───────────────┼──────────────┼──────────────────────────
│ /RPTERR │ Add list of system
│ │ errors to the report
│ │ file (/REPORT).
───────────────┼──────────────┼──────────────────────────
│ /RPTMOD │ Add list of modified
│ │ files to the report
│ │ file (/REPORT).
───────────────┼──────────────┼──────────────────────────
/RV │ /RV │ Remove
│ │ validation/recovery
│ │ data from files.
───────────────┼──────────────┼──────────────────────────
/SAVE │ /SAVE │ Save specified options
│ │ as new defaults (not
│ │ available in Windows).
───────────────┼──────────────┼──────────────────────────
/SHOWDATE │ /SHOWLOG │ Show date and time of
│ │ last scan (version 1.5
│ │ only). Display
│ │ information in SCAN.LOG
│ │ (version 2.0 only)
───────────────┼──────────────┼──────────────────────────
│ /STD │ Scan executable files
│ │ only (.COM, .EXE, .SYS,
│ │ .BIN, .OVL, and .DLL)
───────────────┼──────────────┼──────────────────────────
/SUB │ /SUB │ Scan subdirectories
│ │ inside a directory.
───────────────┼──────────────┼──────────────────────────
│ /VIRLIST │ Display list of viruses
│ │ detected by VirusScan.
───────────────┼──────────────┼──────────────────────────
@filename │ /LOAD │ Use Scan settings
│ {filename} │ stored in filename.
│ │