

              ķ                 ķ        
                                             
                   ķ ķ з           ķ
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              Ľ     Ľ            Ľ


                            Known\Unknown Virus
                             Detection Utility



                 Copyright (c) 1994,1995,1996 Martin Overton
                                  (ChekWARE)
                             All rights reserved.


              Written by:                     Internet:

              Martin Overton,(ChekWARE)       ChekMate@salig.demon.co.uk
              51 Cook Road,
              Horsham,
              West Sussex,
              RH12 5GJ,
              UNITED KINGDOM

_________________________________________________________________________

 THE INFORMATION AND CODE PROVIDED IS PROVIDED AS IS WITHOUT WARRANTY OF
 ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

 IN NO EVENT SHALL MARTIN OVERTON OR HIS AGENT(S) BE LIABLE FOR ANY DAMAGES
 WHATSOEVER INCLUDING GENERAL, DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL,
 LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES. EVEN IF THE AUTHOR HAS BEEN
 ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
_________________________________________________________________________

 The UNREGISTERED version of this program, its executables, bait  files
 and related files may be distributed freely as long as no money is charged
 for the program itself or any of its components.

 This program MUST be distributed as a whole with its associated files
 and this document.

 This version of ChekMate may not be distributed as a part of any commercial
 package without prior written agreement of the author.

 It has been tested on many different PCs and Operating System versions
 with no major problems encountered.

 This program was developed entirely using personal time and personal
 resources.  This program has no connection with, or is in any way
 endorsed by my employers.


License:
_______

This version of ChekMate is hereby released under the Shareware concept.

ChekMate can be evaluated for up to 30 days without having to register.
After that period of time, please either register ChekMate or remove it
from your system.

Registration will entitle you to the registered version which is free of
the 'nag-screen' and has additional features, such as a repair facility.
See REGISTER.TXT for full details.

The author retains the copyright of ChekMate and all of its components
(except MD5 which is copyright RSA Data Security, Inc.)

ChekMate or any of its components may not be used as part of any other
package unless written agreement is obtained from the author.

ChekMate must not be modified in any way.

MD5 is the RSA Data Security, Inc. MD5 Message-Digest Algorithm,
Copyright 1991 RSA Data Security, Inc.


Requirements:
____________

ChekMate requires you to have an IBM PC Compatible running DOS 3.3 or later
or one of the other supported operating systems and at least 384Kb of memory
and a Hard Disk.

To use ChekWord, you will need a copy of Microsoft Word 6.0 or later.


What is ChekMate:
________________

ChekMate was written to detect new and known file, Word macro, boot and
partition sector viruses.

It should be used alongside a good quality, up-to-date virus scanner.

       !!! ChekMate is NOT a substitute for a virus scanner. !!!

ChekMate can be integrated with your current DOS based virus scanner.
It will detect most file infector, boot or partition sector viruses,
the ChekWord module will also detect macros in any Word document.

ChekMate makes no wild claims about 'Providing 100% protection against all
current and future viruses!' (I'll leave that to other products.)

ChekMate is simply an extra layer for a virus to try to defeat. When
combined with 'frequent' backups and a good up-to-date virus scanner,
ChekMate WILL help to protect your data from many known and unknown viruses.

One of ChekMate's users said: "ChekMate has been a real security blanket"
Another ChekMate user wrote:  "I wouldn't boot up without it."

ChekMate will NOT bombard you with lots of false alarms (unless your
system is always in a state of flux!). It just monitors the areas/files
that a virus will frequently target.

             !!! Think of ChekMate as a viral smoke alarm. !!!



Before Installation:
___________________

Before installation, scan the target PC with a good quality up-to-date
virus scanner.

    ***    Only once the PC is found to be free of viruses    ***
    *** should you proceed with the installation of ChekMate. ***

Copy all the files to a floppy disk and write protect it.  In the event
of a virus outbreak, this disk can then be used to replace infected
ChekMate files.

Also, after ChekMate is run for the first time, copy the .CHK files to
the floppy disk you've just created (above).

Below are the MD5 hash values for key ChekMate files.  Please check
these values before you run ChekMate to ensure the files have not been
tampered with by a third party.  If they do not match, then do NOT run
them.  Please contact me if the files have been changed.

MD5 Validation Information:
__________________________

        MD5 (chekmate.exe) = 2fd92293d39fa6b7ecc727c8e7369846
        MD5 (chekmate.chk) = 1bb8c9e8ee668d111fddace2e0915a9e
        MD5 (setup.exe)    = de9ec68d36c9db9e426e06acb083974b
        MD5 (md5.exe)      = 7881d18adf5f4406984cd863beaecda7
        MD5 (filechk1.chk) = 2f7ef57505f1eaf11bce7a33459c97d1
        MD5 (filechk2.chk) = c3d93fa3a6cf5f137f7217051ed7f6c5
        MD5 (four.com)     = ae199cf3e7cdb865d363ae0565968313
        MD5 (four.exe)     = c48dc146c0013ce9d2dcc5b56e7d1a35
        MD5 (ten.com)      = 82e08f193cefa2fc67b5b23f7e341640
        MD5 (ten.exe)      = d70dd3547b8d8160003e2d05cb1c48ae
        MD5 (thirtytw.com) = f3845983f560a6b20d29ebf622b7c6fd
        MD5 (thirtytw.exe) = 3770b6bc9a2bf8ab59331dc6068a999f
        MD5 (chekword.doc) = 7895f5a2d85c3fe54ca73a430421ae4a

To validate the files, run MD5.EXE as below for each file listed above:

        MD5 <FileName>

        e.g MD5 CHEKMATE.EXE




Install (ALL Operating Systems):
_______________________________

Create a directory (e.g., C:\CHEKMATE) and copy the files listed below
to that directory:

        CHEKMATE.EXE    ->       The Main Program File
        CHEKMATE.ICO    ->       Windows Icon File for ChekMate
        CHEKMATE.PIF    ->       Windows PIF File for ChekMate
        CHEKMATE.CHK    ->       ChekMate Finger-Print file
        CHEKWORD.DOC    ->       Word Macro detection document
        SETUP.EXE       ->       Setup program for modifying CHEKMATE.INI
        CHEKMATE.INI    ->       Program INI File (See Later)
        MD5.EXE         ->       RSA's MD5 hash generator (PUBLIC DOMAIN)
        FILECHK1.CHK    ->       Bait files Finger-Print file (Start of Files)
        FILECHK2.CHK    ->       Bait files Finger-Print file (End of Files)
        FOUR.COM        \
        FOUR.EXE         \
        TEN.COM           \
        TEN.EXE           /  Bait files
        THIRTYTW.COM     /
        THIRTYTW.EXE   /

(Bait files are simple files that display a message and return to the OS,
they act as a decoy to tempt a virus into infecting it. They have no other
purpose and DO NOT execute any other code or files.)

The BAIT files MUST not be replaced with your own versions of BAIT or any
other executable files as MD5 hash values for the files are stored within
the main CHEKMATE.EXE file.

They must also be left in the same order in the CHEKMATE.INI provided,
you can though, rename them if you so wish. Renaming them can help to
stop a targeted virus attack.



Install (DOS):
_____________

From the directory where you copied ChekMate.

1) Enter SETUP /AUTO <return>
   This will create your CHEKMATE.INI file.

2) Enter CHEKMATE /CREATE <return>
   This will create the fingerprints of those portions of the system
   that ChekMate monitors.

3) Enter CHEKRESQ /GETINT <return>    (Applies to the Registered
   Version).

   This will create a file INT.SET in the ChekMate directory.  The file
   holds information about key interrupts.  It is used by ChekResQ (a
   utility that can remove boot sector and partition table viruses both
   from memory and your hard disk.

4) Enter CHEKMATE /SPARSE /SYSTEM <return>
         Note: the /SPARSE parameter is not required but is worth using
               as it is designed to detect sparse infecting viruses.
         Note: the /SYSTEM parameter is not required but is worth using.
               It checks to see that your AUTOEXEC.BAT and
               CONFIG.SYS files remain unchanged.  Although the /SYSTEM
               parameter applies to the Registered Version, including
               it on the command line will have no effect on the Share-
               ware version.

5) Invoke ChekMate at boot-up and whenever there has been any signifi-
   cant activity.  For boot-up, you might add the following to your
   AUTOEXEC.BAT file:

        CD \CHEKMATE (or whatever directory name you're using)
        CHEKMATE /SPARSE /SYSTEM
        CD \

   If you modify your AUTOEXEC.BAT file, erase the file SYSTEM.CHK
   (created in Step 2) since that SYSTEM.CHK carries the fingerprint of
   your _original_ AUTOEXEC.BAT.  The next time you run CHEKMATE, it
   will create a _new_ SYSTEM.CHK fingerprint corresponding to your
   _new_ AUTOEXEC.BAT.

6) If you have Microsoft's Word For Windows Version 6.0 (or later),
   a) Run Windows
   b) Under File | Run, enter C:\CHEKMATE\CHEKWORD.DOC
      (Note, if you have installed ChekMate in a directory other than
       C:\CHEKMATE, substitute that directory's name for C:\CHEKMATE.)

   c) Follow the instructions in the CHEKWORD.DOC file to install ChekWord.


Install (Windows 3.x and '95):
______________________________

To run ChekMate from Windows, then:

        Use the 'File' 'New' 'Program Item' menu option in Program Manager
        to create an entry for this program. (PIF file supplied.)

        Edit the .PIF file to reflect the correct 'working directory'.

        The ICON can be set to CHEKMATE.ICO  in the directory where
        ChekMate was installed.

If you wish to run ChekMate from NT, you must run it with the /NOBP and
/NOCMOS switches, otherwise ChekMate will return an error.


Install (OS/2 2.x & Warp):
_________________________

To set up ChekMate under OS/2, follow the instructions below:

        For both HPFS and FAT file systems:

        From  the OS/2 desktop, drag a new 'PROGRAM' icon from the
        'Templates' folder and enter the following details:

        Path and file name:

        C:\<ChekMate Dir>\CHEKMATE.BAT

        The batch file should contain the following commands:
        (.... = any other batch file command)

        @ECHO OFF
        CHEKMATE.EXE
        .....
        .....
        PAUSE

        This will make sure that ChekMate doesn't just exit back to the
        OS/2 Desktop when it's finished.  (Optionally, just check the
        'do not close on exit' box in the setting folder)

        Working directory:

        C:\<ChekMate Dir>

        where <ChekMate Dir> is the directory that you installed ChekMate.

        eg. CHEKMATE

        Click on the General tab of the program notebook and change
        the title to:

        ChekMate

        Now drag this icon to the Startup folder.



Upgrading From Version 2.0:
____________________________

To upgrade ChekMate from version 2.0, proceed as follows:

1.      Read this manual BEFORE proceeding.

2.      Copy CHEKMATE.EXE, CHEKMATE.CHK, CHEKMATE.INI, SETUP.EXE, FOUR.COM,
        FOUR.EXE, TEN.COM, TEN.EXE, THIRTYTW.COM, THIRTYTW.EXE, FILECHK1.CHK
        and FILECHK2.CHK to your ChekMate directory. Now run SETUP /AUTO.

4.      Now run CHEKMATE.EXE, if ChekMate informs you that a FingerPrint
        file is missing, Press any key to continue. You will then be told
        that the missing .CHK file is being created.

5.      ChekMate should now work fine with the updated files.

6.      If the above does not work correctly, then run CHEKMATE.EXE /CREATE
        as this will re-generate all the .CHK files.



How ChekMate Works:
__________________

ChekMate, when run for the first time, will create a series of Finger-Print
(.CHK) files of the following:

        COMMAND.COM or an alternate command processor,
        THE BOOT SECTOR(s) and THE PARTITION TABLE.

Each time ChekMate is run, it will first test key Interrupts and base
memory for modifications (unless you disable this test, see below).

Any other time that ChekMate is run it will match the Finger-Print files
with the actual files or image files taken at runtime.

These Finger-Print (.CHK) files are not CRC's (Checksums), as these are
easily fooled by some viruses; they are actual code fragments of the
start and, in some cases, the end of the file or area.

All the BAIT files, ChekMate.EXE, MD5.EXE and the Command Processor are
also protected with MD5 hash values.

MD5 hash values are 128 bit cryptographic signatures of the files, which
are VERY secure; far more secure than other similar techniques.

If these Finger-Print files and/or hash values do NOT match the runtime
images, you will be warned that one or more of the files/areas have

been changed. The actual area/file name will be displayed.

The information will also be written to the error log (ERROR.LOG) in the
ChekMate directory.

If a change is detected then ChekMate will return to the OS without checking
any other files/areas for modifications.

Most viruses change executable code at the beginning and/or end of a file
or area. ChekMate checks for this sort of modification.

MD5 hash values are computed from the contents of the whole file and
therefore will detect ANY change to the file(s).



A Guided Tour of ChekMate:
_________________________

Below is an example of the output that ChekMate produces when run.

Explanations are given at each stage of the process.

___________________________________________________________________________
    ChekMate  2.1 UNREGISTERED [20th April 1996]  
   
*1          Checking ChekMate Files & The Command Processor ...
   
     Current Task                       Progress
     
*2  ChekMate.EXE               OK    Interrupts OK                      *3
    MD5.EXE                    OK    640Kb (DOS BASE) Memory Detected  
    Command Processor          OK                                      
                                                                       
                                                                       
                                                                       
                                                                       
                                                                       
                                                                       
                                                                       
     
   
*4                                                                        
                                                                          
   
_____________________________________________________________________________

Fig 1.

*1      Header, Shows current task identity.
*2      Current Task Window, Shows detail of current task.
*3      Progress, Shows completed task identities.
*4      Message Window, Shows error messages etc.

The main screen (Fig 1.) shows ChekMate reporting the checked interrupts,
the DOS base memory detected at execution. This is compared with a stored
value in the CHEKMATE.INI. If these values are different, then a warning
message is shown, ChekMate returns an errorlevel and returns control to
the operating system.


Many boot sector or partition table viruses lower the base memory value by
1Kb or more.

ChekMate detects many of those viruses by this method alone.

The next step, assuming no change is detected in the DOS base memory is for
ChekMate to check itself (it also checks itself BEFORE it gets this far!).
It checks its fingerprint file against its own code and then checks its MD5
cryptographic fingerprint against a stored value.

If either of these do not match, a warning message appears, ChekMate returns
an errorlevel and returns control to the operating system.

More detailed information is written out to the error log file (ERROR.LOG).

This is repeated for MD5.EXE and the Command Processor.

(The error/change reporting is the same at each stage of ChekMate's
examination of your system files/areas.)

A similar routine is used for the boot sector(s) and the partition table.

The main difference is that the whole 512 bytes are compared with the
values/images stored the first time that ChekMate was run.

If either of these do not match, a warning message appears, ChekMate
returns an errorlevel and returns control to the operating system.

The next phase of ChekMate is to check the decoy/bait files used to trap
file infecting viruses before they are executed.

These files are first checked in the same way as CHEKMATE.EXE etc., except
that the cryptographic fingerprints are stored inside CHEKMATE.EXE, and
the filesize is also checked.

This is done to minimize the chance of modifications to these files by an
unknown party. That is to say, this is an anti-hacker ploy.

If these files are found to be unchanged, they are then executed. This
is to purposely expose them to any viruses that are capable of infecting
files.

This is like a lamb walking up to wolf and saying "my you have big teeth!"

This has proved to be very effective in trapping unknown file infecting
viruses.

Yet again, if ANY changes are detected, you will see an error message.

The decoy/bait files are then checked AGAIN after they have been executed
to determine whether a file infecting virus has modified them.

If you got this far without any warning messages, then your system is
deemed to be clean (assuming it was clean BEFORE ChekMate was installed,
and that an up to date, good quality virus scanner is used at reasonable
intervals, say weekly!)



ERRORLEVEL Returns:
______________________

The following errorlevel values are returned when ChekMate exits back to the
operating system.

 0  = No modifications detected
 1  = COMMAND.COM (or other COMMAND processor) appears to have been changed
 2  = ChekMate.EXE appears to have been changed
 3  = The BOOT SECTOR(s) appears to have been changed
 4  = The PARTITION TABLE appears to have been changed
 5  = One or more of the BAIT files appear to have been changed
 6  = The DOS base memory amount appear to have been changed
 7  = MD5.EXE appears to have been changed
 8  = The memory hole contains code
 9  = A change has been detected in the CMOS *REGISTERED version only!
 10 = One or more of the interrupts are outside the normal boundries
 98 = Dir2.Byway appears to be active on this system
 99 = A companion virus appears to be active on this system

 Q.     What can you do with this information?

 A.     You can use the errorlevels returned in a batch file to automatically
        run your favourite virus scanner when ChekMate detects a modification
        to your system.

In this example, the virus scanner is McAfee Scan

        e.g. CHECK.BAT
        @ECHO OFF
        CLS
        CD C:\CHEKMATE
        CHEKMATE.EXE
        IF NOT ERRORLEVEL 1 GOTO :End
        :Change!
        C:\SCANNER\SCAN.EXE /ADL
        CD C:\
        :End

The batch file above will only run your virus scanner if the errorlevel
does not equal zero (0).



Help/Command Line Switches:
__________________________

To get help, run:


CHEKMATE.EXE /? or /H


Other command line switches:


/CREATE         Creates a 'new' set of Finger-Print files.
                Usually only used after DOS upgrade or after cleaning up
                after a virus attack.

/NOEXPOSE       Used to only check Finger-Print files against original
                files/area. Does NOT execute BAIT files.

/QUIET          Force ChekMate to run in QUIET mode.
                (ChekMate will only display warnings no other information
                is shown. REGISTERED version only!)

/NOBP           Disable the boot and partition checking. This is only
                recommended for use with Windows NT.

/NOCMOS         Disable the CMOS checking. This is only
                recommended for use with Windows NT.

/NODRIVES       This is only for use with /AUTO on NT systems. This is
                required on NT systems; otherwise an error #71 is
                generated.


Known problems/limitations:
__________________________

1)      May not detect direct action non-TSR viruses very quickly.
        Most new viruses are TSR (memory resident) variants.

        The best way to test 'suspect' files is to place them in the same
        directory as ChekMate, Virus Scan them and if they are not reported
        as infected, then run them from there. Then run ChekMate.

                   **** REMEMBER TO BACKUP YOUR SYSTEM FIRST ****

2)      Link viruses, such as DIR II may not be detected, as no
        executable code is changed.

        A special routine has been added for the Dir2.Byway Link virus.



Common Questions & Answers:
__________________________

If ChekMate detects a change in your system then proceed as follows:

        To confirm this run your favourite virus scanner, after booting from
        the original write-protected bootable system disk.

        If the scanner finds nothing then send the following files to me
        (you will find them in the directory where ChekMate was installed):

For the correct files to send see the relevant question.


Q1.     ChekMate informed me that the 'DOS Base Memory' value has changed.
        What should I do?

A1.     If ChekMate has been working fine before, then you have probably
        been infected by a Boot or Partition Sector virus. Most of
        these types of viruses 'steal' 1Kb or more from DOS.

        Please send me the following files for inspection:

        ?BOOT.SEC files  (Where ? is C, D, E or F)
        ?BOOT.CHK files  (Where ? is C, D, E or F)
        PART.CHK
        PART.SEC
        ERROR.LOG


Q2.     ChekMate informed me that ChekMate.EXE has changed. What should I do?

A2.     ChekMate.EXE should NEVER change, apart from being upgraded to the
        latest version.

        Please send me the CHEKMATE.EXE & CHEKMATE.CHK files to inspect.


Q3.     ChekMate informed me that MD5.EXE has changed. What should I do?

A3.     MD5.EXE should NEVER change, apart from being upgraded to the
        latest version.

        Please send me the MD5.EXE file to inspect.



Q4.     ChekMate informed me that 'The Command Processor' has changed.
        What should I do?

A4.     Your Command Processor should NEVER change, apart from DOS being
        upgraded to another version.

        Please send me a copy of your Command Processor file to inspect.
        (Usually COMMAND.COM, could be NDOS.COM or 4DOS.COM)


Q5.     ChekMate informed me that 'The Boot Sector' has changed. What should
        I do?

A5.     If ChekMate has been working fine before, & you have NOT upgraded
        your version of DOS or changed the 'Volume Label' then you have
        probably been infected by a Boot Sector virus.

        Please send me the following files:

        ?BOOT.SEC files  (Where ? is C, D, E &/or F)
        ?BOOT.CHK files  (Where ? is C, D, E &/or F)
        ERROR.LOG


Q6.     ChekMate informed me that 'The Partition Sector' has changed. What
        should I do?

A6.     If ChekMate has been working fine before, & you have NOT upgraded
        your version of DOS or changed the Partition Table by running FDISK
        then you have probably been infected by a Partition Table virus.

        Please send me the following files:

        PART.SEC
        PART.CHK
        ERROR.LOG


Q7.     ChekMate informed me that '1 or More of The BAIT File(s)' have
        changed. What should I do?

A7.     The BAIT files should NEVER change. (except from version 1.05d to
        1.06a and 2.0 to 2.1)

        Please send me the following files to inspect.

        FOUR.COM
        FOUR.EXE
        TEN.COM
        TEN.EXE
        THIRTYTW.COM
        THIRTYTW.EXE


Q8.     ChekMate informed me that 'Interrupt xx has changed'. What should
        I do?

A8.     These are the main possibilities:

        1. You are running a TSR that has modified an interrupt address that
           is frequently used by memory resident and /or stealth virus.

           Remove all TSR programs and try ChekMate again to see if the
           problem stops.

           If it does, re-load the TSR's one at a time (running ChekMate
           after each one) until the problem re-occurs.

           Please inform me of the problem and send me a copy of the
           ERROR.LOG file for me to inspect. I will then try to fix the
           problem.

        2. A memory resident and/or stealth virus is active in your system.

           Please manually run the bait files, FOUR.COM, etc. and then
           send them to me to inspect for signs of infection.

           Please send me a copy of the ERROR.LOG file for me to inspect.

        3. You are running EZDRIVE or DISK MANAGER drivers for your
           Enhanced IDE hard disk.

           Note: if you have been running ChekMate without problem and
                 ChekMate now reports an interrupt changed, a virus is
                 probably active in your system.  Please return to #2,
                 immediately above.

           If, however, you are just setting up ChekMate, please read on:

           EZDRIVE or DISK MANAGER may set an interrupt in a virus-like
           way as they use interrupt addressing techniques similar to
           those of some computer viruses.  Assuming you have scanned
           your system with a good and up-to-date virus scanner (such as
           F-Prot, ThunderBYTE etc...) ChekMate permits you to tell it
           to ignore that/those interrupts.  This is the only way to
           resolve a wrongly-reported interrupt.

           Look at the file ERROR.LOG, it will show an Interrupt Number
           (say, 13) and an address (say, 9E70:0A3D).  With any ASCII
           editor (such as EDIT or NOTEPAD), create a file called
           EXCLUDE.INT and, as the first line, starting in column 1, put
           the number of the interrupt and the address.  Thus, as above:
           "13=9E70:0A3D" (the quotation marks are not used).

           The maximum number of entries in EXCLUDE.INT is 5.  Each must
           be on a separate line and have (as above) 12 characters only.

           If EXCLUDE.INT does not solve the problem, please inform me
           of the problem and send me a copy of the ERROR.LOG file for
           me to inspect.  I will then try to fix the problem.

In all cases ensure that you have scanned your system with a good and
up-to-date virus scanner (such as F-Prot, ThunderBYTE etc...).

Please remember to inform me which scanner and version was used. Also
please ensure that you send the ERROR.LOG file.



Latest Version:
______________

The latest version of this application should always be available from the
internet site or bulletin board that you originally obtained it from.

The main site is the SimTel archives (ftp.simtel.net) or one of the mirror
sites, in the pub/simtelnet/msdos/virus directory.

Other sites include:

 ftp.demon.co.uk in /pub/antivirus/ibmpc/av-progs
 http://www.valleynet.com/~joe/avdos.htm
 garbo.uwasa.fi in /pc/virus


You will also find it on many BBS's throughout the world.

Please E-Mail me if you want to know when a new version is released,
I will add you to the mailing list for new version announcements.

Registered users will informed automatically.


Bug reports, suggestions, etc...
________________________________

If you catch a virus with ChekMate in one of the Bait files, then please
send me a copy for analysis. I will send a reply to anyone who sends me
such a file. If possible I will send a search string to correctly identify
the new virus to aid removal.

To date ChekMate has trapped numerous unknown viruses ("in the wild"). The
latest was even undetected by heuristic based scanners.

Mail files to the E-Mail or Postal address at the top of this document.
(If you e-mail the file(s) then please use UUENCODE or MIME. Also for
greater security please use PGP (my public key is supplied with this
version as well as older versions beginning with 1.06b)).

Please send all bug reports, suggestions, etc to the E-Mail or Postal
address at the top of this document.

If you like this program, let other people know about it!

If you have tested ChekMate against any viruses then please let me know
the outcome of these tests, whether the results are good or bad.

For details of viruses that ChekMate has been tested against, please see
the file enclosed in this ZIP file, TESTS.TXT.

Thanks:
______

Thanks to Philip Tong for early Beta testing and a copy of the then unknown
'Dalian' virus which ChekMate captured. Thanks also go to Ed Fenton, Hugh
Brecher, Jon Dron, Flint Howard and many others for their suggestions for
improvements, Beta testing of new versions and constructive feedback.
A very BIG thank you goes to Christy Gemmell and Glen Blankenship who helped
with some of the low-level routines used in this program.



Why was ChekMate Written?:
_________________________

I frequently receive suspect files from people throughout the world that
believe, either rightly or wrongly, they are infected with a new/unknown or
known virus.

I needed a way to confirm that the file/disk was indeed infected.

My first step was to scan it for known viruses, if that did not detect a
known virus then the infected file/disk was run on a 'sheep-dip' PC and
ChekMate was then used to tempt the virus into infecting one or more of the
bait files or the Boot sector or Partition Table.

In all cases the virus was caught by ChekMate. Either by infecting one or
more of the BAIT files or the Boot Sector or Partition Table.

Many people do not perform a daily scan of their PC, because they feel it
takes too long (3-20 Minutes). ChekMate takes under 20 seconds to  run,
even on 80286 based systems.


And finally .........
_____________________

Thank you for trying ChekMate.



-----------------  APPENDIX A: --- "Using SETUP.EXE"--------------------

CHEKMATE.INI:
____________

You can use the SETUP.EXE file supplied to change the CHEKMATE.INI.
(Strongly Recommended)

SETUP will in many cases tell you what the settings should be for a
particular line.

If you use the /AUTO switch for SETUP.EXE it will build a INI file
automatically, without your intervention. You must use the /NODRIVES
switch with /AUTO on Windows NT systems or an error #71 will be generated.

If the /AUTO switch fails, then please try the /ALTAUTO switch instead
as you may have a BIOS that is not supported by /AUTO.

(See SETUP later in this document)

Otherwise, manually edit the CHEKMATE.INI file (Shown Below) if
required:

Notes   Example File            What each line is/means

        [System]                Section Label
        CMDir=C:\CHEKMATE       The Directory That ChekMate is Installed in.
*1      Shell=C:\COMMAND.COM    Path & Name of Command Processor in use.
*2      Drives=1                Number of drives (Physical or Logical).
*3      BaseMem=640             The BASE DOS Memory as reported by MEM /C.

        [BaitFiles]             Section Label
        1=FOUR.COM              Small  .COM Bait file.
        2=TEN.COM               Medium .COM Bait file.
        3=THIRTYTW.COM          Large  .COM Bait file.
        4=FOUR.EXE              Small  .EXE Bait file.
        5=TEN.EXE               Medium .EXE Bait file.
        6=THIRTYTW.EXE          Large  .EXE Bait file.


This file MUST exist and the contents MUST be correct or ChekMate will NOT
work correctly.

*1      The command processor can be COMMAND.COM. 4DOS & NDOS.COM are also
        supported as common replacements for COMMAND.COM.

        Use SETUP.EXE if you are unsure about this.

*2      ChekMate will handle up to drive F:
        (The CHEKMATE.INI entry would then need to be 4)

*3      This is usually 640Kb (655,360 Bytes), Some systems may report 639Kb
        due to HD controllers and some extended BIOSes 'borrowing' 1Kb for
        their own purposes.

        ChekMate displays the DOS base memory detected at run time.



Using SETUP:
___________

SETUP.EXE allows you to change/set the contents of CHEKMATE.INI without the
use of an editor or require you to have any specialist knowledge of your
system setup (apart from the number of LOCAL drive letters!).

To run SETUP, simply ensure that you are in the directory that CHEKMATE.INI
(default is the ChekMate directory) was placed into, now type the line below
at your DOS or OS/2 prompt:

        SETUP

Or to run SETUP on a mono screen type:

        SETUP /MONO

Either way, you will see the screen below:

__________________________________________________________________________


               +----- ChekMate  Version 2.1 [20th April 1996] -----+
               |          Configuration / Setup Program            |
               +---------------------------------------------------+

                      The CHEKMATE.INI Currently Looks Like This
                      ChekMate Directory      :=     C:\CHEKMATE
                      Command Processor       :=     C:\COMMAND.COM
                      No. of Drive Letters    :=     3
                      (C:,D:,E:)
                      DOS (BASE) Memory       :=     640

                  Please Note: Not showing BAIT file information

                            Are These Values Correct (Y/N)

            Choose 'N' To Edit CHEKMATE.INI or 'Y' Will Exit Back To Dos

__________________________________________________________________________


As you can see above, the CURRENT settings are shown.  You are asked if
the values are correct.

 - If you answer 'Y', SETUP simply exits back to the operating system
   without making any modifications.

 - If you answer 'N' then you will be asked questions.  An example is
   shown below:


__________________________________________________________________________

               +----- ChekMate  Version 2.1 [20th April 1996] -----+
               |          Configuration / Setup Program            |
               +---------------------------------------------------+


Enter Directory Where ChekMate is Installed Currently (C:\CHEKMATE)
Path=: c:\AV\CHEKMATE
Set To: C:\AV\CHEKMATE

Enter The Path & Name of Your Command Processor, Currently (C:\COMMAND.COM)
I Detect The Following (C:\OS2\MDOS\COMMAND.COM)
Shall I Set It To That (Y/N) ?
Set  To: D:\OS2\MDOS\COMMAND.COM

Enter The Number of Drive Letters (Up to F: Only), Currently ( 3)
Number =: 2
Set  To:  2

Enter The Amount of DOS BASE Memory (Up to 640Kb Only),Currently ( 640 )
I Detect( 640 ) Set It to That Value (Y/N) ?
Set  To:  640

                          Is This Correct (Y/N) ?

      Choose 'N' To Try Again or 'Y' Will Write Changes And Exit To Dos

__________________________________________________________________________

As you can see, SETUP will tell you what the settings SHOULD be set to.

It will automatically work out what command processor is running from
the environment variable COMSPEC.

The DOS base memory is also detected automatically. Common values are 640
or 639, the latter is mainly found in systems with extended BIOSes.

                  ANY other value should be questioned!

Once all the questions are answered, you are then asked to confirm whether
the settings are correct.

Answering 'N' will restart the questions.

Answering 'Y' will write out the changes to CHEKMATE.INI and exit to
DOS.



---------  APPENDIX B: --- "Information about MD5 (Quoted from RFC1321)

1. Executive Summary

This document describes the MD5 message-digest algorithm.  The algorithm
takes as input a message of arbitrary length and produces as output a
128-bit "fingerprint" or "message digest" of the input.

It is conjectured that it is computationally infeasible to produce two
messages having the same message digest, or to produce any message
having a given prespecified target message digest.

The MD5 algorithm is intended for digital signature applications, where
a large file must be "compressed" in a secure manner before being
encrypted with a private (secret) key under a public-key cryptosystem
such as RSA.

The MD5 algorithm is designed to be quite fast on 32-bit machines.  In
addition, the MD5 algorithm does not require any large substitution
tables; the algorithm can be coded quite compactly.

The MD5 algorithm is an extension of the MD4 message-digest algorithm
1,2].  MD5 is slightly slower than MD4, but is more "conservative" in
design.  MD5 was designed because it was felt that MD4 was perhaps being
adopted for use more quickly than justified by the existing critical
review; because MD4 was designed to be exceptionally fast, it is "at the
edge" in terms of risking successful cryptanalytic attack.  MD5 backs
off a bit, giving up a little in speed for a much greater likelihood of
ultimate security.  It incorporates some suggestions made by various
reviewers, and contains additional optimizations.  The MD5 algorithm is
being placed in the public domain for review and possible adoption as a
standard.
** END OF DOCUMENT ***
