home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Magnum One
/
Magnum One (Mid-American Digital) (Disc Manufacturing).iso
/
d23
/
scanv85.arc
/
SCANB85.DOC
< prev
next >
Wrap
Text File
|
1991-12-07
|
33KB
|
745 lines
VIRUSCAN Version BETA85
Copyright (C) 1989, 1990, 1991 by McAfee Associates
All rights reserved.
Documentation by Aryeh Goretsky.
McAfee Associates (408) 988-3832 office
4423 Cheeney Street (408) 970-9727 fax
Santa Clara, CA 95054-0253 (408) 988-4004 BBS 2400 bps
U.S.A. (408) 988-5138 BBS HST 9600
(408) 988-5190 BBS v32 9600
CompuServe GO VIRUSFORUM
InterNet mcafee@netcom.com
TABLE OF CONTENTS:
SYNOPSIS . . . . . . . . . . . . . . . . . . . . . . . . . . .2
- What VIRUSCAN is, system requirements
AUTHENTICITY . . . . . . . . . . . . . . . . . . . . . . . . .2
- Verifying the integrity of VIRUSCAN
WHAT'S NEW . . . . . . . . . . . . . . . . . . . . . . . . . .3
- Features, new viruses added in this release
OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . .4
- Detailed description of VIRUSCAN
OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . .5
- How to use VIRUSCAN
EXAMPLES . . . . . . . . . . . . . . . . . . . . . . . . . . .9
- Samples of frequently-used options
EXIT CODES . . . . . . . . . . . . . . . . . . . . . . . . . .10
- For running VIRUSCAN from batch files
VIRUS REMOVAL. . . . . . . . . . . . . . . . . . . . . . . . .10
- How to manually remove a virus
REGISTRATION . . . . . . . . . . . . . . . . . . . . . . . . .11
- How to register VIRUSCAN
TECH SUPPORT . . . . . . . . . . . . . . . . . . . . . . . . .11
- Information you should have ready when calling
APPENDIX A . . . . . . . . . . . . . . . . . . . . . . . . . .12
- Creating a virus string file with the /EXT option
APPENDIX B . . . . . . . . . . . . . . . . . . . . . . . . . .13
- Miscelleaneous Application Notes
Page 1
VIRUSCAN Version BETA85 Page 2
SYNOPSIS
VIRUSCAN (SCAN) is a virus detection and identification
program for the IBM PC and compatible computers. VIRUSCAN will
search a PC for known computer viruses in memory, the boot sector,
the partition table, and the files of a PC and its disks. VIRUSCAN
can also detect the presence of unknown viruses.
SCAN works by searching the system for instruction sequences
or patterns that are unique to each computer virus, and then
reporting their presence if found. This method works for viruses
that VIRUSCAN recognizes. SCAN can detect unknown viruses in
files and boot sector by appending validation (CRC) codes to .COM
and .EXE files and then checking the files against their codes for
changes, warning that an infection may have occurred if the file
has been modified in any way, and by checking boot sectors for
generic routines that a boot sector virus must have. SCAN can check
for new viruses from a user-supplied list of virus search
strings.
VIRUSCAN runs on any PC with 256Kb and DOS version 2.00 or
greater.
AUTHENTICITY
VIRUSCAN runs a self-test when executed. If SCAN has been
modified in any way, a warning will be displayed. The program will
still continue to check for viruses, though. If SCAN reports that it
has been damaged, it is recommended that a clean copy be obtained.
VIRUSCAN versions 46 and above are packaged with the VALIDATE
program to ensure the integrity of the SCAN.EXE file. The
VALIDATE.DOC instructions tell how to use the VALIDATE program.
The VALIDATE program distributed with VIRUSCAN may be used to check
all further versions of SCAN.
The validation results for Version BETA85 should be:
FILE NAME: SCAN.EXE
SIZE: 60,495
DATE: 12-03-91
FILE AUTHENTICATION
Check Method 1: D76E
Check Method 2: 193C
If your copy of SCAN.EXE differs, it may have been modified.
Always obtain your copy of VIRUSCAN from a known source. The
latest version of VIRUSCAN and validation data for SCAN.EXE can be
obtained off of McAfee Associates' bulletin board system at (408)
988-4004 or from the Computer Virus Help Forum on CompuServe.
Beginning with Version 72, all McAfee Associates programs for
download are archived with PKWare's PKZIP Authentic File Verification.
If you do not see the "-AV" message after every file is unzipped and
receive the message "Authentic Files Verified! # NWN405 Zip Source:
McAFEE ASSOCIATES" when you unzip the files then do not run them. If
your version of PKUNZIP does not have verification ability, then this
message may not be displayed. Please contact McAfee Associates if
your .ZIP file has been tampered with.
VIRUSCAN Version BETA85 Page 3
WHAT'S NEW
Version 85 of VIRUSCAN adds several new options as well as
enhancing existing ones: The ability to NOT add validation codes to
files with the /AV option by creating an exception list of files to
ignore, the option of beeping whenever a virus is found with the /BEEP
switch, the option of displaying messages in Spanish with the /SP switch,
the ability to search a system for files that do not have validation codes
with the /CERTIFY switch, the option to speed up VIRUSCAN's output with the
/FAST switch, the option to skip scanning inside of PKLITE-compressed files
with the /NPKL switch, the abilty to display a help screen by typing /?, /H,
or /HELP, and the ability of storing the options to run VIRUSCAN in a
configuration file.
Additionally, 76 viruses have been added. Viruses that have
been reported at multiple sites include the Barcelona virus in Spain,
the Haifa virus in Israel, the Hary and Irish viruses in the U.K., the
New 1701 virus in Finland and Norway, the SBC, Stoned III, and SVC 5.0
viruses in North America. Other viruses added in this release are the
123, 233, 370-B, 408, 487, 621, 640, 658, 709, 712, 737, 7th Son, 802,
812, 1193, 1241, 1463, 1530, Ada, Argentina, ASC, Brothers, Cara, Caz,
Color, COP, CRF, CSL, Day10, DM400, Dutch, Einstein, Error, Got-You,
Grape, H-2, Hero-b, Invol, Joke, Karin, Kiev-1, KU-448, LC, Mono, MPS-11,
MSTU, Parasite, PathHunt, Pirate, Plov, Poem, Pregnant, QML, Reset, SCT,
Sentex, Socha, Suriv 4.02, Squeeker, Stink, Sys, SX, Tony, Travel, V82,
V-5, VTS, and Word-1 viruses.
For a listing of the viruses that were added, please refer to
the enclosed VIRLIST.TXT file for a short description. For a more
complete description, please refer to Patricia Hoffman's VSUM listing.
THE COMPUSERVE COMPUTER VIRUS HELP FORUM
We are now sponsoring the Computer Virus Help Forum on CompuServe.
Updates to VIRUSCAN, information about computer viruses, and
technical support may be obtained by typing GO VIRUSFORUM at any
CompuServe prompt. A free introductory membership to CompuServe
is also available. Please read the COMPUSER.NOT file for details.
VIRUSCAN Version BETA85 Page 4
OVERVIEW
VIRUSCAN scans diskettes or entire systems for pre-existing
computer virus infections. It will identify the virus infecting
the system, and tell what area of the system (memory, boot sector,
file) the virus occupies. Infected files can be removed with
the overwrite-and-delete option, /D, which will erase the file.
The CLEAN-UP program is also available to disinfect the system and
repair damaged areas whenever possible.
VIRUSCAN Version 85 identifies all 377 known computer viruses
along with their variants. Some viruses have been modified so that
more than one "strain" exists. Counting such modifications, there
are 973 virus variants. This includes the twenty most common viruses
which account for over 98% of all reported PC infections. The
accompanying VIRLIST.TXT file lists describes all viruses identified
by SCAN. The number of variants of each virus is listed in parentheses
after the virus name.
All known computer viruses infect one or more of the following
areas: the hard or fixed disk partition table (also known as the master
boot record); the boot sector of hard disks and floppy disks; or one or
more executable files within the system. Executable files include
operating system files, .COM files, .EXE files, overlay files, or any
other files containing program code. A virus that infects more than one
area, such as a boot sector and an executable file is called a multipartite
virus.
VIRUSCAN identifies every system area or file infected, and
indicates both the virus name and CLEAN-UP I.D. code used to remove it.
SCAN will check the entire system, an individual diskette, subdirectory,
subdirectory tree or individual files for pre-existing virus infection.
VIRUSCAN can also check files for unknown viruses with the Add
Validation and Check Validation options. This is done by calculating a
checksum for files, appending it to the end of the file, and then
comparing the file against it. If the file has been modified, the check
will no longer match, indicating that viral infection may have occurred.
VIRUSCAN calculates checksums using two independently-generated CRC (Cyclic
Redundancy Check). Files which are self-checking or self-modifying should
not be validated since this will set off their own internal checks. VIRUSCAN
adds validation codes to .COM and .EXE files only. The validation codes for
the partition table, boot sector, and system files, are kept in a hidden file
called SCANVAL.VAL in the root directory. To detect boot sector and
partition table (MBR) viruses, SCAN checks the boot sector and MBR for signs
of viral code. If suspicious code is found, SCAN will report it has found a
Generic Boot Sector or MBR Virus.
VIRUSCAN can also be updated to search for new viruses via
an External Virus Data File option, which allows the user to
provide the VIRUSCAN program with new search strings for viruses.
VIRUSCAN can display messages in English, French, or Spanish.
VIRUSCAN works on stand-alone and networked PC's, but not on
a file server. For networks, use the NETSCAN file server scanner
instead.
VIRUSCAN Version BETA85 Page 5
OPERATION
IMPORTANT NOTE: WRITE PROTECT YOUR FLOPPY DISK BEFORE SCANNING
YOUR SYSTEM TO PREVENT INFECTION OF THE VIRUSCAN PROGRAM.
VIRUSCAN will check each area or file on the designated
drive(s) that could be host to a virus. If a virus is found, a
message is displayed telling the name of the infected file or
system area and the name of the identified virus. SCAN will
examine files for viruses based on their extensions. The default
file extensions supported by SCAN are .APP, .BIN, .COM, .EXE, .OV?,
.PGM, .PIF, .PRG, .SWP, .SYS, and .XTP. Additional extensions can
be added to SCAN or all files on disk can be selected for scanning.
To run VIRUSCAN type:
SCAN d1: ... d26: /? /A /AV filename BELL /CERTIFY /CHKHI /CV /D /DATE
/E .xxx .yyy .zzz /EXT filename /FAST /FR /H /HELP
/MAINT /MANY /NLZ /NOBREAK /NOMEM /NOPAUSE /NPKL
/REPORT filename /RV /SHOWDATE /SP /SUB @filename
Options are:
\ - Scan root directory and boot area only
/? /H /HELP - Display help screen
/A - Scan all files, including data, for viruses
/AV filename - Add validation codes to specified files
(the file contains a list of files
NOT to add validation codes to)
NOT to add validation codes to)
/BELL - Beep whenever a virus is found
/CERTIFY - List files that do not have a validation code
/CHKHI - Check memory from 0Kb to 1088Kb
/CV - Check validation codes on files
/D - Overwrite and delete infected file
/DATE - Save the date and time VIRUSCAN was last run
/E .xxx .yyy .zzz - Scan overlay extensions .xxx .yyy .zzz
/EXT filename - Scan using external virus data file
/FAST - Speed up VIRUSCAN's output
/FR - Display messages in French
/M - Scan memory for all viruses
(see below for specifics)
/MAINT - Scan MS-DOS 4.0+ boot sector damaged disk
/MANY - Scan multiple floppies
/NLZ - Skip internal scan of LZEXE compressed files
/NOBREAK - Disable Ctrl-C / Ctrl-Brk during scanning
/NOMEM - Skip memory checking
/NOPAUSE - Disable screen pause when scanning
/NPKL - Skip internal scan of PKLITE compressed files
/REPORT filename - Create report of infected files
/RV - Remove validation codes from specified files
/SHOWDATE - Display date and time VIRUSCAN was last run
/SP - Display messages in Spanish
/SUB - Scan subdirectories
@filename - Scan using options from configuration file
(d1: ... d26: indicate drives to be scanned)
VIRUSCAN Version BETA85 Page 6
The /A option will cause SCAN to check all files on the
referenced drive. This should only be used if a file-infecting
virus has already been detected. Otherwise the /A option should
only be used when checking a new program. The /A option will add
a substantial time to scanning. This option takes priority over
the /E option.
The /AV option allows the user to add validation codes to the
files being scanned. If a full drive is specified, SCAN will
create validation data for the partition table, boot sector, and
system files of the disk as well. Validation adds ten (10) bytes
to files; the validation data for the partition table, boot sector,
and system files is stored separately in a hidden file in the root
directory of the scanned drive. Files which are already immunized
against computer viruses or contain self-modifying code should not
have validation codes added to them. To prevent VIRUSCAN from adding
validation codes to these files, a validation exception list can
be created with the complete path and filename of the each file NOT
to be validated listed on each line. Only one file should be on a line.
To put a comment in, start a line with the asterisk "*" character. A
sample file might look like this:
*This is MS-DOS 5.00's self-modifying program, SETVER
C:\DOS\SETVER.EXE
*PKWare's PKZIP programs already perform a self-check for viruses
C:\PKWARE\PKZIP.EXE
C:\PKWARE\PKUNZIP.EXE
*WordStar
C:\WORDSTAR\WS.EXE
*Stac Technologies hard disk swapping program
C:\SWAPVOL.COM
The validation exception list should be an ASCII text file. If a word
processor is used to create the list, be sure to save the file as ASCII.
Specify the filename after the /AV switch. Be sure to include a space
between the /AV and the filename.
The /BELL option will cause VIRUSCAN to beep each time a computer
virus is found.
The /CERTIFY option will audit a system for files that have
validation codes added to them with the /AV switch. Files that have
no validation code will be reported as being uncertified by VIRUSCAN.
The /CHKHI option checks the memory above 640Kb that can be
used on AT (286) and 386 systems for computer viruses. This
includes the 384Kb Upper Memory Area from 640Kb to 1024Kb, and
the 64Kb High Memory Area from 1024Kb to 1088Kb. On XT systems with
extended memory cards installed, this will cause the first 64K of
RAM to be scanned again. This option can not be used with the
/NOMEM option.
VIRUSCAN Version BETA85 Page 7
The /CV option checks validation codes inserted by the /AV
option. If the file has been changed, SCAN will report that the
file has been modified, and that viral infection may have occurred.
Using the /CV option adds about 25% more time to scanning.
NOTE: Some older Hewlett Packard and Zenith PC's modify the boot
sector or partition table each time the system is booted. This
will cause SCAN to continually notify the user of boot sector or
partition table modifications if the /CV switch is selected. Check
your system's manual to determine if your system contains
self-modifying boot code.
The /D option tells VIRUSCAN to prompt the user to overwrite
and delete an infected file when one is found. A file erased by the
/D option can not be recovered. If the McAfee Associates' CLEAN-
UP program is available, it can be used to disinfect the file.
Boot sector and partition table infectors can not be removed by the /D
option and require the CLEAN-UP virus disinfection program.
The /DATE option will save the date and time that VIRUSCAN was
last run by updating the date of the SCANVAL.VAL file. If no
SCANVAL.VAL file exists, VIRUSCAN will create one.
The /FAST option will speed VIRUSCAN up by displaying less
information on the screen during scanning and by not scanning inside
of LZEXE- and PKLITE-compressed files. This may cause some viruses to
be missed.
The /E option allows the user to specify an extension or set
of extensions to scan. Extensions should include the period
character "." and be separated by a space after the /E and between
each other. Up to three extensions may be added with the /E. For
more extensions, use the /A option.
The /EXT option allows VIRUSCAN to search for viruses from a
text file containing user-defined search strings in addition to the
viruses that already SCAN checks for. The syntax for using the
external virus data file is /EXT d:filename, where d: is the drive
name and filename is the name of the external virus data file. For
instructions on how to create an external virus data file, refer
to Appendix A.
NOTE: The /EXT option is intended for users to add strings for
detection of computer viruses on an interim or emergency
basis. When used with the /D option, it will delete
infected files. This option is not recommended for general
use and should be used with caution.
The /FR option tells VIRUSCAN to output all messages in French
instead of English.
The /M option tells VIRUSCAN to check system memory for all
known computer viruses that can inhabit memory. SCAN by default
only checks memory for critical and "stealth" viruses, which are
viruses which can cause catastrophic damage or spread the infection
during the scanning process. SCAN will check memory for the
following viruses in any case:
VIRUSCAN Version BETA85 Page 8
1024 1253 1554 1963
1971 2100 2560 337
3445-Stealth 4096 512 Anthrax
Anti-Tel Brain Dark Avenger Darth Vader
DIR-2/FAT Disk Killer Doom2 EDV
Empire Fish6 Form Greemlin
Invader Joshi Microbes Mirror
Murphy Nomenclature Phantom Plastique
Polish-2 P1R (Phoenix) Sentinel Stoned
Tequila Taiwan-3 Whale Zero-Hunt
If one of these viruses is found in memory, SCAN will stop and
advise the user to power down, and reboot the system from a
virus-free system disk. The /M option will add 6 to 20 seconds
to the scanning time.
The /MAINT option is used to scan hard disks partitioned with
DOS 4.0 or above that have been damaged by a boot sector or partition
table infecting virus. Attempts to access disks damaged in such a
manner result in an "invalid media" message being displayed. The
/MAINT option will only scan the partition table and boot sector,
not the files.
The /MANY option is used to scan multiple diskettes placed in
a given drive. If the user has more than one floppy disk to
check for viruses, the /MANY option will allows the user to check
them without having to run SCAN multiple times. If a system has
been disinfected, the /MANY and /NOMEM options can be used to speed
up scanning of disks.
The /NLZ option tells VIRUSCAN not to look inside files
compressed with the LZEXE file compression program. SCAN will
still check the programs for external infections.
The /NOBREAK option disables Control-C or Control-Break from
stopping VIRUSCAN while running.
The /NOMEM option is used to turn off all memory checking for
viruses. It should only be used when a system is known to be free
of viruses. The /NOMEM option can not be used with the /CHKHI or /M
options.
The /NOPAUSE option disables the "More..." prompt that appears
when SCAN fills up a screen with data. This allows VIRUSCAN to run
on a machine with multiple infections without requiring operator
intervention when the screen fills up with messages from the SCAN
program.
The /NPKL option tells VIRUSCAN not to look inside files
compressed with the PKLITE file compression program. SCAN will
still check the programs for external infections.
The /REPORT option is used to generate a listing of infected
files. The resulting list is saved to disk as an ASCII text file.
To use the report option, specify /REPORT on the command line,
followed by the device and filename [See EXAMPLES below for
samples].
The /RV option is used to remove validation codes from a file
or files. It can be used to remove the validation code from a
diskette, subdirectory, or file(s). Using /RV on a disk will
remove the partition table, boot sector, and system file
validation. This option can not be used with the /AV option.
VIRUSCAN Version BETA85 Page 9
The /SHOWDATE option will display the time and date VIRUSCAN was
last run using the /DATE option.
The /SP option tells VIRUSCAN to output all messages in Spanish
instead of English.
The /SUB option allows SCAN to scan subdirectories under a
a subdirectory when scanned. Previously, SCAN would only
recursively check subdirectories if a logical device (e.g., C:)
was scanned.
The @filename option allows the user to store a list of preferred
options and/or areas of the system to be scanned in a configuration file
and then have SCAN read the options in and execute them. Options need
to be separated by a space, while system areas (a disk or subdirectory
or file) need to be on a separate line for each entry. A sample file
might look like this:
/A /BELL /CV /NOMEM /REPORT C:\VIRUSCAN\SCAN.LOG
C:
D:\BBS
E:\MCAFEE\CLEAN-UP\CLEAN.EXE
The first line contains the VIRUSCAN options while the other lines
contain the name of files, subdirectories, or disks to be scanned
The configuration file should be an ASCII text file. If a word
processor is used to create the list, be sure to save the file as ASCII.
EXAMPLES
The following examples are shown as they would be typed in.
SCAN C:
To scan drive C:
SCAN A:R-HOOPER.EXE
To scan file "R-HOOPER.EXE" on drive A:
SCAN A: /A /CV
To scan all files and check validation codes for unknown
viruses on drive A:.
SCAN B: /D /A
To scan all files on drive B:, and prompt for erasure of
infected files.
SCAN C: D: E: /AV /NOMEM
To add validation codes to files on drives C:, D:, and
E:, and skip memory checking.
SCAN C: D: /M /A /FR
To scan memory for all known and extinct viruses, as well
as all files on drives C: and D:, and output all messages
in French.
SCAN C: D: /E .WPM .COD
To scan drives C: and D:, and include files with the
extensions .WPM and .COD
VIRUSCAN Version BETA85 Page 10
SCAN C: /EXT A:SAMPLE.ASC /BELL
To scan drive C: for known computer viruses and also for
viruses added by the user via the external virus data
file option, and beep whenever a virus is found.
SCAN C: /M /NOPAUSE /REPORT A:INFECTN.RPT
To scan for all viruses in memory and drive C: without
stopping, and create a log on drive A: called INFECTN.RPT
SCAN C: D: /NOPAUSE /REPORT B:VIRUS.RPT
To scan drives C: and D: for viruses without stopping,
and create a log on drive B: called VIRUS.RPT
SCAN E:\DOWNLOADS /SUB
To scan all subdirectories under DOWNLOADS on drive E:
SCAN C: D: E: /FAST /CERTIFY
To perform a fast scan of drives C:, D:, and E: and
check for any files that do not have validation codes.
SCAN @C:\SCANOPTN.LST
To run VIRUSCAN using configuration file SCANOPTN.LST
in the root directory of drive C:.
EXIT CODES
VIRUSCAN will set the DOS ERRORLEVEL upon program termination to:
ERRORLEVEL | DESCRIPTION
-----------+--------------------------
0 | No viruses found
1 | One or more viruses found
2 | Abnormal termination (program error)
If a user stops the scanning process, SCAN will set the ERRORLEVEL
to 0 or 1 depending on whether or not a virus was discovered prior
to termination of the SCAN. The /NOBREAK option can be used to
prevent scanning from being stopped.
VIRUS REMOVAL
What do you do if a virus is found? You can contact McAfee
Associates for help with removing viruses by BBS, FAX, telephone,
or Internet. There is no charge for support calls to McAfee
Associates.
The CLEAN-UP universal virus disinfection program is available
and will disinfect the majority of reported computer viruses. It
is updated with each release of the SCAN program to remove new
viruses. The CLEAN-UP program can be downloaded from McAfee
Associates BBS, the SIMTEL20 archives on the InterNet, the McAfee
Associates' sponsored Computer Virus Help Forum on CompuServe, or
from the agents listed in the enclosed text file.
VIRUSCAN Version BETA85 Page 11
It is strongly recommended that you get experienced help in
dealing with viruses, especially critical viruses that can damage
or destroy data [for a listing of critical viruses, see the /M
option under OPTIONS, above] and partition table or boot sector
infecting viruses, as improper removal of these viruses could
result in the loss of all data and use of the disk(s).
For qualified assistance in removing a virus, please contact
McAfee Associates directly or check the enclosed AGENTS.TXT file
for an Authorized McAfee Associates Agent in your area. Agents may
charge McAfee Associates normal support rates for their services.
REGISTRATION
A registration fee of $25.00US is required for the use of
VIRUSCAN by individual home users. Registration is for one year
and entitles the holder to unlimited free upgrades off of McAfee
Associates BBS or CompuServe Computer Virus Help Forum. When
registering, a diskette containing the latest version may be
requested. Add $9.00US for diskette mailings. Only one diskette
mailing will be made.
Registration is for home users only and does not apply to
businesses, corporations, organizations, government agencies, or
schools, who must obtain a license for use. Contact McAfee
Associates for more information.
Outside of the United States, registration and support may be
obtained from the Agents listed in the accompanying AGENTS.TXT
file.
TECH SUPPORT
For fast and accurate help, please have the following information
ready when you contact the technical support staff:
- Program name and version number.
- Type and brand of computer, hard disk, plus any
peripherals.
- Version of DOS you are running, plus any TSRs or device
drivers in use.
- Printouts of your AUTOEXEC.BAT and CONFIG.SYS files.
- The exact problem you are having. Please be as specific
as possible. Having a printout of the screen and/or
being at your computer will help also.
McAfee Associates can be contacted by CompuServe Forum, BBS, fax, or
InterNet 24 hours a day, or call our business office at (408) 988-3832,
Monday through Friday, 7:00AM to 5:30PM Pacific Standard Time.
McAfee Associates (408) 988-3832 office
4423 Cheeney Street (408) 970-9727 fax
Santa Clara, CA 95054-0253 (408) 988-4004 BBS 2400 bps
U.S.A (408) 988-5138 BBS HST 9600
(408) 988-5190 BBS v32 9600
CompuServe GO VIRUSFORUM Internet mcafee@netcom.com
VIRUSCAN Version BETA85 Page 12
If you are overseas, please refer to the AGENTS.TXT file for
a listing of McAfee Associates Agents for support or sales.
APPENDIX A: Creating a Virus String File with the /EXT Option
The External Virus Data file should be created with an editor
or a word processor and saved as an ASCII text file. Be sure each
line ends with a CR/LF pair.
NOTE: The /EXT option is intended for emergency and research use
only. It is an temporary method for identifying new viruses prior
to the subsequent release of SCAN. A sound understanding of
viruses and string-search techniques is advised as a prerequisite
for using this option.
The virus string file uses the following format:
#Comment about Virus_1
"aabbccddeeff..." Virus_1_Name
#Comment about Virus_2
"gghhiijjkkll..." Virus_2_Name
.
.
"uuvvwwxxyyzz..." Virus_n_Name
Where aa, bb, cc, etc. are the hexadecimal bytes that you wish to
scan for. Each line in the file represents one virus. The Virus
Name for each virus is mandatory, and may be up to 25 characters
in length. The double quotes (") are required at the beginning and
end of each hexadecimal string.
SCAN will use the string file to search memory, the Partition
Table, Boot Sector, System files, all .COM and .EXE files, and
Overlay files with the extension .BIN, .OV?, .PGM, .PIF, .PRG, .SYS
and .XTP.
Virus strings may contain wild cards. The two wildcard
options are:
FIXED POSITION WILDCARD
The question mark "?" may be used to represent a wildcard in
a fixed position within the string. For example, the string:
"E9 7C 00 10 ? 37 CB"
would match "E9 7C 00 10 27 37 CB", "E9 7C 00 10 9C 37 CB", or any
other similar string, no matter what byte was in the fifth place.
RANGE WILDCARD
The asterisk "*", followed by range number in parentheses "("
and ")" is used to represent a variable number of adjoining random
bytes. For example, the string:
"E9 7C *(4) 37 CB"
would match "E9 7C 00 37 CB", "E9 7C 00 11 37 CB", and
"E9 7C 00 11 22 37 CB". The string "E9 7C 00 11 22 33 44 37 CB"
VIRUSCAN Version BETA85 Page 13
would not match since the distance between 7C and 37 is greater
than four bytes. You may specify a range of up to 99 bytes.
Up to 10 different wildcards of either kind may be used in one
virus string.
COMMENTS
A pound sign "#" at the begining of a line will denote that
it is a comment. Use this for adding notes to the external virus
data file. For example:
#New .COM virus found in file FRITZ.EXE from
#Schneiderland on 01-22-91
"53 48 45 45 50" Fritz-1 [F-1]
Could be used to store a description of the virus, name of the
original infected file, where and when it was received, and so
forth.
APPENDIX B: Miscellaneous Application Notes
CHECKING MEMORY FOR VIRUS ONLY
VIRUSCAN can perform a quick check of for viruses in memory only.
In this mode, the SCAN program will not check the disk for computer
viruses. This option is useful for network administrators who need
to check workstations for viruses before allowing them to log on to a
LAN but can not run the VSHIELD program due to memory constraints.
The command to enter is:
SCAN NUL /M /CHKHI
By designating NUL as the drive to be scanned, the SCAN program will
check system memory for viruses (up to 1088Kb if the /CHKHI option
is used) and then return to DOS without scanning any disks. SCAN
will set the DOS ERRORLEVEL as it normally does.
VIRUSCAN VALIDATION CODES
If you have installed any new software or programs on your system,
and are running VIRUSCAN or VSHIELD with the check validation codes
/CV option, you will need to reinstall validation codes to the new
files with the add validation codes /AV option of VIRUSCAN.
Additionally, the SCANVAL.VAL hidden file containing validation codes
for the partition table, boot sector, COMMAND.COM, and system files
may have to be replaced. The MS-DOS 5.00 SETVER.EXE file contains
self-modifying code and can not have a validation code added to it.
The quickest way to update the validation codes is to remove all
validation codes from the hard disk and then add them back on by
running VIRUSCAN with the /RV and then the /AV options, and then
removing the validation code from SETVER.EXE by typing "
SCAN C:\DOS\SETVER.EXE /RV" and pressing enter.
VIRUSCAN Version BETA85 Page 14
NOTE: This applies to any new version of DOS, as well as any
programs which you install on your system.
DOS 5 AND REFORMATTING INFECTING FLOPPIES
If you are reformatting infected floppy disks under DOS 5.0,
be sure to add the /U switch to the FORMAT command. This tells DOS
to do an Unconditional format of the disk, and not to save the original
(infected) boot sector of the disk. This should be done to prevent the
virus from reappearing by unformatting the disk.