ÖÄÄÄ· · Ò ÖÄÄÒÄÄ· · º Ð º º Ö º º º ×ÄÄ º ÇÄÄÄ· ÖÄÄÄ· ÇÄÄз º º º ÖÄÄÄÒ º ÖÄÄÄ· º · º º ÇÄÄĽ º º º Ð º º º º ÇÄÄĽ ÓÄÄĽ Ó ½ ÓÄÄĽ Ð Ó ½ Ð ÓÄÄÄÐÄ ÓÄÄÙÓÄÄĽ 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 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 This will create your CHEKMATE.INI file. 2) Enter CHEKMATE /CREATE This will create the fingerprints of those portions of the system that ChekMate monitors. 3) Enter CHEKRESQ /GETINT (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 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.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:\ where 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. ___________________________________________________________________________ ÛÛÛÛÛÛÛÛÛÛÛÛ ChekMate û 2.1 UNREGISTERED [20th April 1996] ÛÛÛÛÛÛÛÛÛÛÛÛÛ ÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ *1 Ý Checking ChekMate Files & The Command Processor ... ßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßß Current Task Progress ÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ ÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ *2 Ý ChekMate.EXE OK Þ Ý Interrupts OK Þ *3 Ý MD5.EXE OK Þ Ý 640Kb (DOS BASE) Memory Detected Þ Ý Command Processor OK Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ Ý Þ ßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßß ßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßß ÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ *4 Ý Þ Ý Þ ßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßßß _____________________________________________________________________________ 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 ***