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I N T E G R I T Y M A S T E R (tm) Version 1.13a An easy to use, data integrity and anti-virus program which also provides PC security, change control and disk error detection. Users Guide plus Data Integrity and Virus Guide ________________________________________________ Copyright 1990 - 1992 by Wolfgang Stiller All rights reserved ___________________ Written by Wolfgang Stiller Stiller Research 2625 Ridgeway St. Tallahassee, Florida 32310 U.S.A. Electronic mail to: CompuServe: 72571,3352 InterNet, Bitnet, etc.: 72571.3352@compuserve.com Uunet: uunet!compuserve.com!72571.3352 Integrity Master (tm) - 2 - Version 1.13a Second Edition (November 1991) Updated February 1992 (C) Copyright Wolfgang Stiller 1990 - 1992. All Rights reserved. The following paragraph does not apply where such provisions are inconsistent with law: Stiller Research provides this document "AS IS" without warranty of any kind, either express or implied, including, but not limited to the warranties of merchantability or fitness for a particular pur- pose. This document may include technical inaccuracies or typographical errors. We continually update and correct this document with the latest available information. Note to U.S. Government users: Use, duplication, or disclosure by the U.S. Government of the computer software and documentation in this package shall be subject to the restricted rights applicable to commercial computer software as set forth in subdivision (b)(3)(ii) of Rights in Technical Data and Computer Software clause at 252.227-7013 (DFARS 52.227-7013). The manufacturer is Stiller Research, 2625 Ridgeway St., Tallahassee, Florida 32310-5169. Integrity Master (tm) - 3 - Version 1.13a Use of Integrity Master (also known as IM) requires acceptance of the following license terms and warranty disclaimer. L I C E N S E T E R M S TO USE INTEGRITY MASTER, YOU MUST AGREE TO AND UNDERSTAND THE FOLLOWING LICENSE TERMS AND WARRANTY DISCLAIMER, OTHERWISE DO NOT USE THIS PROGRAM. Each PC must have its own licensed copy. THIS COPY MAY ONLY BE USED ON ONE PC. It may be removed from that PC and installed on another PC but IT MAY NOT BE INSTALLED ON MORE THAN ONE PC AT A TIME. To use Integrity Master on more than one PC, you must license extra copies. W A R R A N T Y D I S C L A I M E R: INTEGRITY MASTER AND ALL ASSOCIATED PROGRAMS ARE LICENSED "AS-IS". STILLER RESEARCH AND WOLFGANG STILLER MAKE NO WARRANTIES, EITHER EXPRESSED OR IMPLIED, WITH RESPECT TO THESE PROGRAMS, THEIR QUALITY, PERFORMANCE, MERCHANTABILITY, OR FITNESS FOR ANY PARTICULAR PURPOSE. IN PARTICULAR, INTEGRITY MASTER IS NOT GUARANTEED TO PREVENT OR DETECT DAMAGE TO YOUR DATA OR PROGRAMS. IN NO EVENT SHALL STILLER RESEARCH OR WOLFGANG STILLER BE LIABLE FOR ANY CLAIMS FOR LOST PROFITS OR ANY DAMAGE, INCLUDING BUT NOT LIMITED TO SPECIAL, INCIDENTAL, CONSEQUENTIAL OR OTHER DAMAGE. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THE ABOVE LIMITATION OR EXCLUSION MAY NOT APPLY TO YOU. IF YOU USE INTEGRITY MASTER (IM), YOU ASSUME EXCLUSIVE RESPONSIBILITY AND LIABILITY FOR ANY LOSS OR DAMAGE DIRECTLY OR INDIRECTLY ARISING OUT OF THE USE OF THE PROGRAM. IN NO CASE SHALL STILLER RESEARCH'S OR WOLFGANG STILLER'S LIABILITY EXCEED THE LICENSE FEES PAID FOR THE RIGHT TO USE THE LICENSED SOFTWARE. THE LICENSE AGREEMENT AND WARRANTY DISCLAIMER SHALL BE CONSTRUED, INTERPRETED AND GOVERNED BY THE LAWS OF THE STATE OF FLORIDA. Integrity Master (tm) - 4 - Version 1.13a T A B L E O F C O N T E N T S ----------------------------------- PART ONE - Integrity Master(tm) User Guide License and Warranty Terms ..................... 3 CHAPTER ONE - Why Integrity Master? Welcome! .................................... 7 Don't read this ............................. 7 Why the user guide .......................... 7 What can Integrity Master do? ............... 8 How does it do these things? ................ 8 What Makes Integrity Master Special?......... 9 Requirements and Limitations ............... 10 CHAPTER TWO - Installing Integrity Master Special Quick Install....................... 11 Full Installation........................... 11 Vital files ................................ 12 Screen Colors .............................. 13 Using Integrity Master Menus................ 14 CHAPTER THREE - Running Integrity Master Integrity Master Screen Contents ........... 15 Initializing Integrity data................. 15 What is Integrity Data? .................... 16 The Check Menu ............................. 16 The Report File ............................ 18 System Sectors ............................. 19 Reloading ............................... 19 The Commands Menu .......................... 20 Ending (Quitting) .......................... 20 Statistics Summary.......................... 20 Fighting viruses with Integrity Master ..... 21 Viruses - What Are They? ................ 21 Virus Check Procedure ................... 21 Scanning for Viruses .................... 22 Detecting Viruses ....................... 22 Detecting Unknown (new) viruses ......... 23 The Integrity Master virus report ....... 24 False Alarms ............................ 25 Destroying Viruses ...................... 26 Data Corruption ......................... 26 Integrity Master and Disk Problems ........ 27 Integrity Master for PC Security ........... 28 Integrity Master for Change Control ........ 29 Command Line (BATCH) Execution ............. 30 Syntax .................................. 30 Error Levels ........................... 31 Using IMCHECK .............................. 32 Integrity Master (tm) - 5 - Version 1.13a CHAPTER FOUR - Customizing The Parameter (Options) File ............... 33 Options Menu ............................... 34 Options in SETUPIM ......................... 37 Location of Integrity Data.................. 38 Updating your hardware configuration ....... 38 The Advanced Option Menu.................... 39 CHAPTER FIVE - Errors Error Recovery .............................. 42 Solving problems ............................ 42 Answers to Common Questions ................. 42 PART TWO - Data Integrity and Viruses CHAPTER ONE - Threats to your data Introduction - Viruses get all the glory .... 45 Hardware problems............................ 45 Finger checks ... ........................... 46 Malicious or Careless Damage................. 46 Software Problems ........................... 46 Software attacks ............................ 47 Logic Bombs ............................. 47 Trojans ................................. 47 Worms ................................... 48 Viruses ................................. 48 General Virus Behavior................ 48 System Sector Viruses................. 50 Boot Sectors ...................... 50 Partition Sectors ................. 50 File viruses ......................... 51 Miracle Infections ................ 52 How many viruses are there?.................. 52 How serious are viruses?..................... 53 CHAPTER TWO - Protection for your PC Hardware Protection ......................... 55 "Fixing" your disk .......................... 55 Goof Protection ............................ 56 Intrusion Protection......................... 56 Virus Defenses ............................. 57 Scanners ................................. 58 Disinfectors ............................. 58 Interceptors ............................. 58 Inoculators .............................. 58 ROM and Encryption ....................... 59 Integrity Checkers ....................... 59 Gadgets .................................. 60 Prevention................................ 60 Integrity Master (tm) - 6 - Version 1.13a CHAPTER THREE - Virus Myths Mythical Sources ............................ 62 Quick and Easy Cures ........................ 62 Silly Tricks ................................ 63 Certified Software? ......................... 63 Retail Software Only? ....................... 64 Write Protecting Your Hard Disk ............. 64 Safe Computing (Safe Hex?)................... 65 Software is useless against viruses.......... 65 CHAPTER FOUR - Virus Realities The ONLY Real Source of Viruses ............. 66 Shareware is as Safe or Safer ............... 66 Few Virus Free Programs ..................... 66 Write Protecting Floppies ................... 66 Beware the CE and the Demo! ................. 67 Viruses are going to get worse .............. 67 CHAPTER FIVE - What to do - Some Suggestions Action is Vital - Now! ...................... 68 Backup Policy ............................... 68 Integrity Checking Policy ................... 69 Run CHKDSK .................................. 69 Determining Causes of Corruption ............ 70 Education ................................... 71 Signs of software problems ............... 71 Signs of viruses ......................... 71 Responsibility .............................. 72 Policy and routine .......................... 72 Networks and Viruses ........................ 72 CHAPTER SIX - Handling a virus attack Don't panic and don't believe the virus ..... 73 Report the attack ........................... 73 Play Detective............................... 73 Clean House (steps to remove the virus)...... 74 Guard the house ............................. 74 INDEX .......................................... 75 Integrity Master (tm) - 7 - Version 1.13a PART ONE - INTEGRITY MASTER(tm) USERS GUIDE ------------------------------------------- ___________________________________________________________________________ C h a p t e r 1 - I n t r o d u c t i o n Welcome! -------- Welcome to the family of Integrity Master(tm) users! Integrity Master (also known as IM) is the fastest, most powerful data integrity and anti-virus software available for any price. We hope that you'll find Integrity Master an indispensable part of your PC toolkit. From now on, you'll be back in control of all the data on your PC. Don't read this! ---------------- Most people should never need to read the Integrity Master Users Guide. If you're reading this to learn how to use Integrity Master, you're here for the wrong reason. Just copy your files onto your hard disk and execute SetupIM. The tutorial should tell you all you need to know to get started. For additional help when using Integrity Master (IM), just hit F1 and select the index. The odds are what you need to know is there. While we think most people won't need to read Part One - Integrity Master Users Guide (this part), we think everyone needs to read Part 2 - Data Integrity and Viruses. This will help you understand the different threats to your PC, and what you can do about them. You'll be able to understand more clearly how viruses work, how dangerous they are, and how Integrity Master and other products can protect you. Why read the Users Guide? ------------------------- We've written this users guide for three reasons: 1) To provide more information on how to get the most benefit out of Integrity Master. You'll learn how to use it to detect totally new viruses, how to tell if damage to a file is likely due to a hardware problem or maybe a virus or a trojan, how to use it to protect your PC from unauthorized tampering, etc. 2) To explain certain aspects of Integrity Master in more detail and in different terms than available from IM's internal help screens. Integrity Master (tm) - 8 - Version 1.13a 3) To satisfy people who prefer to read things on paper. If you prefer to read things on paper, then you're here for the right reason, although we'll bet the tutorial in SetupIM will surprise you. (Give it a try!) What can Integrity Master do? ----------------------------- 1) Detect and remove viruses. IM will even detect viruses which are not known to exist at this point. For known viruses, IM will recognize them by name and describe what they do. 2) Detect possible file corruption due to hardware or software problems. This type of file damage is apparently at least 100 times more likely than virus infection, yet it usually goes undetected. 3) Supplement or replace any PC security programs you have. IM will inform you if anyone changes something on your PC's disk while you were gone. 4) You just compressed your disk or you restored your files from a backup. Are all the files really OK? IM will tell you. 5) You wanted to delete all your .BAK files, but you entered: "DEL *.BAT" by mistake. Oops! IM will tell you exactly which files you need to restore. 6) You need a change management system to keep track of growth on your hard disk. Where is all that disk space going? IM will tell you. 7) You're having problems with your disk drive. Your diagnostic programs say all is OK... now. But were some files damaged last night? IM tells you! 8) Your hard disk is having problems. DOS will not even recognize it as a disk. IM can reload your partition and boot sectors to "fix" your disk! How does Integrity Master do all these things? ---------------------------------------------- 1) It reads files as well as parts of the operating system on your disk known as system sectors. The first time you use IM, you will run an "initialize", which will read your disk and calculate cryptographic signatures for each file and system sector. While it's doing this, IM is also checking for signs of known viruses. Integrity Master (tm) - 9 - Version 1.13a 2) This signature data along with other information such as the file size is encrypted and recorded in the "integrity data" file. One such file is created for each directory on your disk. 3) On subsequent checks, the files and system sectors are read again and the computed integrity data is compared with the prior values. This allows IM to determine if anything has changed, even if the time and date stamps indicate no change. 4) IM detects changes that a virus may make to associate itself (companion and cluster viruses) with a an existing program. A virus can only infect your PC by associating itself with your programs or system sectors. Each of these actions results in changes to data on your disk. IM will detect these changes if a virus tries to infect your system. What makes Integrity Master Special? ------------------------------------ 1) Integrity Master is not just an anti-virus product but a complete data integrity system. Viruses are but one threat to the integrity of your PC. With Integrity Master you have a complete solution. 2) Unlike other integrity check programs, Integrity Master contains extensive information regarding known viruses. If a portion of a known virus is recognized, that virus will be identified and specific instructions will given to remove it and check for possible damage. If other file changes are detected which are characteristic of a virus, you will be alerted to that fact and given appropriate instructions. 3) Unlike a virus scanner, Integrity Master allows you to detect unknown as well as known viruses. 4) Unlike anti-virus products which merely find known viruses, Integrity Master detects any sectors or files damaged (not just infected!) by viruses. 5) Integrity Master is fast! It's written in 100% highly optimized assembler language. Integrity Master (tm) - 10 - Version 1.13a 6) Integrity Master checks and protects areas on your disk known as system sectors (the DOS boot and partition sectors), not just the files. If these sectors become infected or damaged, Integrity Master can quickly repair them. 7) Integrity Master utilizes easy to use menus with lots of help. You don't have to fully understand some of the more complex areas of data integrity such as system sectors, yet you can be fully protected. 8) The Integrity Advisor(tm) component of Integrity Master understands special files important to DOS and will give you special advice with step by step instructions if these files have changed. Integrity Master Requirements and Limitations: ---------------------------------------------- o IM requires a PC with 210K of available memory and DOS 2 or later. (At least 335K is needed for maximum speed.) o IM supports super large disks and files. o IM supports a maximum of 2621 files in a single directory. o Do not use the DOS APPEND, SUBST or ASSIGN commands in conjunction with IM. These can cause misleading results if not carefully considered. Integrity Master (tm) - 11 - Version 1.13a ___________________________________________________________________________ CHAPTER TWO - INSTALLING INTEGRITY MASTER Special Quick install procedure ------------------------------- Master to see how it meets your needs, we offer this short-cut install procedure. In contrast, the full install procedure is intended to guard against unknown viruses already infecting your system or an attack by a sophisticated user and is not necessary for an evaluation under normal circumstances. Quick install: -------------- Type "SETUPIM" and hit enter. Answer all the questions that SetupIM will ask. SetupIM will prepare a customized full install procedure for you and save it on a file. Rather than follow the full procedure just continue with this quick install. 2) Simply copy your IM files, IM.EXE and IM.PRM, to a convenient location. ("COPY IM.* A:" would copy them to a floppy) 3) Enter the command: "IM /IE /Dc" Substitute for "c", in the "/Dc" parameter, the disk you wish to check. That's it! To execute IM, just enter "IM". The menus will guide you from there. Full Installation ----------------- 1) Make sure your Integrity Master files are located somewhere other than drive A. If they are on drive A, simply copy them to your hard drive or a diskette which you can insert in one of the other drives. Here's an example of how to copy the IM files to your hard drive from the diskette in drive A: C: <ENTER> CD \ <ENTER> MD IMASTER <ENTER> CD IMASTER <ENTER> COPY A:*.* <ENTER> 2) Now begin the actual install process, type: SetupIM <ENTER> Or, if you have an LCD display you may want to enter: SETUPIM /L <ENTER> Integrity Master (tm) - 12 - Version 1.13a If you have a two color display on a color adapter you may wish to try: SETUPIM /M for a more readable display. SetupIM automatically senses the type of video adapter you are using but these two combinations can fool it in some cases. 3) SetupIM will guide your from there. SetupIM will provide you a full tutorial on using Integrity Master menus and give you an overview of how Integrity Master works. SetupIM will then analyze your needs and check out your hardware configuration. SetupIM's Integrity Advisor(tm) component will customize IM's options so that it will work best to meet your needs. The Integrity Advisor(tm) will also prepare a custom designed procedure to finish the install and a plan for day to day use of IM. This is written to file IMPROC.TXT as well as being displayed. You can use your favorite utility to read IMPROC.TXT or you can enter the command IMVIEW IMPROC.TXT to read it or the command IMPRINT IMPROC.TXT to print the file. Vital Files ----------- Please check file README.DOC for a full list of files that come with Integrity Master and what's important about each file. To read README.DOC, type: "IMVIEW README.DOC" and hit ENTER. If you don't have this file, then you have a bad copy of Integrity Master. After you install Integrity Master, there will be only two files you absolutely need to use Integrity Master: IM.EXE - Integrity Master itself IM.PRM - The parameter file which controls how IM works - This file is created by SETUPIM.EXE If you want to reinstall IM, or change advanced features of IM, you will need: SETUPIM.EXE The setup and install program (creates and updates IM.PRM) Integrity Master (tm) - 13 - Version 1.13a When you install IM, SetupIM will create file: IMPROC.TXT Complete instructions to finish install and run IM IM.PRM The parameter file (all option settings are stored here) SCREEN COLORS ------------- IM normally automatically detects the type of video adapter you have and uses appropriate colors for your equipment. There are two things which can confuse IM: 1) Some programs change the DOS video mode from color to monochrome or vice-versa. To correct this, just enter the appropriate mode command (eg. "MODE CO80") 2) Some equipment appears to have a different display than it actually has, such as an LCD display on a laptop. If you find your display hard to read, you may want to override IM's choice of video mode (colors). The best way to do this is to experiment by using the command line parameters to specify an alternate set of colors. Try each option and choose what looks the most pleasing. Both IM and SetupIM accept these command line parameters: /L - For liquid crystal displays (laptops) /M - Forces monochrome mode /C - Forces color mode /A - Forces automatic video detection mode (default). Example: "IM /M" will use colors appropriate for a monochrome display even if the display appears to be of a color display. Once you've found the colors that work the best, it's usually best to use SetupIM to select that video mode so that you don't have to remember to enter the command line parameter. Integrity Master (tm) - 14 - Version 1.13a Using Integrity Master Menus ---------------------------- Integrity Master (IM) and SetupIM both utilize an advanced menu system. When you first install using SetupIM, it will offer you an extensive guided tour of how these menus work. This is the best way to learn how to use the menus. Within Integrity Master, just hit F1 and select "Help using the menus" from the help menu for assistance with using the menus. On most menus you will see one option shown in a different color (or underlined) than the other options. The different color (highlight) indicates that this is the selected line. You can use the arrow (cursor) keys to select the other options on the menu. You can also type a single capitalized letter in each menu option to select that option. On many menus an extended explanation automatically appears as you select each option. (To actually take an action you must hit the enter key after selecting the option you like). Integrity Master (tm) - 15 - Version 1.13a _________________________________________________________________________ Chapter Three - Running Integrity Master(TM) Integrity Master Screen Contents -------------------------------- The top part of the Integrity Master screen tells you what options are in effect and what IM is currently doing. The menus appear below this. Be sure to go through the tutorial in SetupIM to learn how to use the menus. When IM is busy checking your files, the report screen pops up and replaces the lower half of the screen including the menu area. The best way to get familiar with the information presented to you on the IM screen is by hitting the F1 (help) key and selecting the "Explanation of the display". This will give you a step by step guided tour of IM's display. INITIALIZING INTEGRITY DATA --------------------------- Before you can check your disk, you must initialize the integrity data which describes the disk. You can use either the command line parameter (/IE) or the initialize menu within IM. _|Initialize|__________________ | Entire disk integrity | | Files on current Disk | | Current and Lower directories | | Current diRectory only | | Boot sector | | Partition sector | |_______________________________| From this menu, you create (initialize) the integrity data which describes your files and system sectors. While IM is initializing the integrity data, it will (unless you turned virus checking off) check for known viruses, and check for other indications of viruses or system problems. For the system (boot and partition) sectors, IM will save reload information. This enables you to restore your system sectors (using the reLoad menu) if anything should ever infect or damage them. This reload data is written to files BOOT.SRL and PART.SRL for the DOS boot and partition sectors respectively. Be sure to read the section in Part Two, Chapter One, which explains why system sectors are important. When you first use IM, please select "Entire disk integrity" initialize the integrity data for all files and system sectors (the boot or partition sectors) which exist on the current disk. IM will also Integrity Master (tm) - 16 - Version 1.13a create the system sector reload files (BOOT.SRL and PART.SRL). Be sure to save a copy of these files on diskette to help you recover when your hard disk fails. (Not all disks have both boot and partition sectors). The other options on this menu correspond to matching options on the check menu. What is Integrity Data? ----------------------- When IM checks a file, it uses each byte of the file in a calculation to compute cryptographic signatures for that file. A change to any part of a file will result in a different signature. These signatures along with other significant information such as file size are what we call integrity data. There is one integrity data file built for each directory on your disk. These files are named ")(.ID" and can be stored with the files that they identify or stored on separate diskettes. When you first install, SetupIM chooses, at random, one of over two billion different algorithms to compute the cryptographic signatures and also chooses a unique algorithm to encrypt your integrity data files. WHAT ARE CRYPTOGRAPHIC SIGNATURES? ---------------------------------- Just as your signature uniquely identifies you, the cryptographic signatures serve to identify the contents of each file. If a virus or a hardware problem changes a file, the signature computed for that file will be different, although the file size and time and date stamps may be the same. A change or the rearrangement of data in a file will result in a different signature. When you execute SetupIM, it will randomly select one of over 2 billion different algorithms for computing the cryptographic signatures. The Check Menu -------------- From the check menu, you can check files or system sectors for changes. Use the up and down arrow keys to select the type of checking you'd like to do. You may choose to check only specific things on your disk, such as the system sectors or individual files, or you could check everything on the entire disk. Any added, deleted or changed files will be reported, as well as any signs of viruses or other known problems. If integrity checking is on, IM will read the files and check for any changes. Use the options menu to control whether full integrity checking is on and the type of files to check. The fourth line at the top of the screen shows the Integrity Master (tm) - 17 - Version 1.13a current status of integrity checking including the type of files to be checked. If you see: "Integrity check: On", this indicates that full checking will be done on all files. The check menu looks like this: ___________|Check|_____________ | Entire disk integrity | | Files on current Disk | | Current and Lower directories | | Current diRectory only | | Specific file(s) | | Boot sector | | Partition sector | | Disk for known Viruses | |_______________________________| Entire disk integrity --------------------- Selecting this option and hitting the ENTER key will check any system sectors (the boot or partition sectors) which exist on the current disk for changes and then check all files in all directories. Files on current Disk --------------------- Selecting this option and hitting the ENTER key will check only files on the current disk. System sectors will not be checked. Current and Lower directories ----------------------------- Selecting this option and hitting the ENTER key will check files in the current directory and any files in any directories which are defined descendant from the current directory. If the current directory happens to be the root directory (eg. C:\) then all files on that disk will be checked since all other directories are descendent from the root directory. Another example: if you're in directory \DOS, directories such as \DOS\A, \DOS\UTILS or \DOS\A\B would be checked in addition to \DOS. Current diRectory only ---------------------- Selecting this option and hitting the ENTER key will check only files in the current directory. Specific file(s) ---------------- Selecting this option and hitting the ENTER key allows you to enter the name of a specific file to check. Integrity Master (tm) - 18 - Version 1.13a Boot sector ----------- Selecting this option and hitting the ENTER key will read the DOS boot sector and check it for any changes. Please see the explanation of system sectors later in this guide. Partition sector ---------------- Selecting this option and hitting the ENTER key will read the partition sector (also known as the master boot record) and check it for any changes. Please see the explanation of system sectors later in this guide. Disk for known Viruses ---------------------- The option to check "Disk for known Viruses" is intended only for one time quick scans of a disk or to do checks of all files (not just those identified as executable files) for known viruses. Checking all types of files acts as a double check if IM detects an existing virus. This is suggested since it's possible that you may have a program somewhere which uses a file with a nonstandard extension to store executable code (eg. overlays). If you are aware of a program which uses extensions which IM does not recognize as executable, then you may wish to use the advanced menu in SetupIM to add this extension to the list which IM recognizes. The virus scanning option is NOT needed other than these special cases, since IM automatically checks for viruses during its normal processing. IMPORTANT REMINDERS BEFORE CHECKING: ------------------------------------ o Before using IM, be sure you've run SetupIM (new install) and followed the directions provided for you in file IMPROC.TXT. o Before checking your files run an "Entire disk integrity" initialize. o For protection against previously unknown viruses, be sure you cold boot from a write protected floppy before checking. The Report File --------------- In addition to seeing a report of IM's findings on screen, you may wish to save a report on disk or on paper. The options menu, in both IM and SetupIM, allows you to set the type of report (if any) IM will create. We recommend you allow IM to write its findings to an "auto-named" disk file. By saving these report files, you can determine what changed last April 1st or when you last changed a particular file. Each time you use IM, IM's findings will be written to the end of the report file for that day. For example, on June 1st, 1992 the report would be on file ")(0601.REP". By saving the report files you have a complete change history for your PC. If you ever want to find out what happened to a file, the full history will be available. If you wish to keep more than one year of history on-line, try copying all the report files (COPY *.REP) to another disk or subdirectory. Integrity Master (tm) - 19 - Version 1.13a If you choose an "auto-named" report file, you can specify that the file be placed in the root directory of whatever disk is being checked or you may choose to place it on a specific disk of your choice. You can also give the report file absolutely any name you wish. If you choose a specific filename, you may include the disk and directory as part of the filename. If you do not specify a disk or directory for the filename, then this file will be created in the current directory at the time you execute IM. If you elect printed output, IM will ask you to choose LPT1, 2, or 3. If this does not work with your printer, you may also print by asking IM to write the report to a specific file name such as "PRN" (the printer). If you use "PRN", you will get less sophisticated error handling and messages since DOS drives the printer rather than IM. System Sectors -------------- System sectors are special areas on your disk containing programs that are executed when you boot your computer. These sectors are invisible to normal programs but are vital for correct operation of your PC. They are a common target for viruses. Please read the detailed description of Boot and Partition sectors in Chapter one of PART TWO Data Integrity and Viruses. Reloading --------- From the ReLoad menu, you may reload your DOS boot sector or your partition sector (master boot record), in the event that they have become damaged or infected with a virus. The "reload Missing partition" option must be used if you have a disk so badly damaged that DOS will not recognize that the disk exists. You will then be prompted to identify the disk on which to reload. You can identify it either by the logical disk letter (A-Z) or by the physical device number (0 for the first physical hard drive, 1 for the second and so on). If the disk you are about to reload is not the same disk from which the reload data was saved, you will be warned, but allowed to go ahead with the reload of the partition sector if you wish. IM will look for the sector reload files on the disk containing your integrity data, or the disk being reloaded. If it doesn't find the sector reload files (*.SRL) there, it will start looking in the root directories of your other disks and finally also look in your current directory. You can take advantage of this if you need to reload the boot sector of multiple floppy diskettes: o) Locate a clean diskette of the type which is infected o) Initialize integrity data for the boot sector of that floppy. o) Make sure that the BOOT.SRL file you just created is the only one IM can find. (Temporarily move any other .SRL files) o Turn the report file off o Change to the drive containing an infected floppy (Commands menu). o Tell IM to reload the boot sector. o Insert and another diskette and keep reloading. IM will locate the BOOT.SRL file on one of your other disks and reload the sectors on each floppy diskette. You can quickly clean numerous floppies this way. Integrity Master (tm) - 20 - Version 1.13a The Commands Menu ----------------- You can reach the "coMmands menu" by hitting "M" or ALT/M from any of the other primary IM menus. |CoMmands| _______________________| |__ | Temporarily Shell out to DOS | | Quit - exit the Integrity Master | | Disk change | | DiRectory change | |___________________________________| You'll mostly use this menu to change the current disk or directory. (You can also use the "/D" command line option to change to one or more other disks.) "Shell out to DOS" allows you to exit IM to the DOS prompt, but leaves Integrity Master loaded in memory so you can quickly return by using the Exit command. Shelling allows you to exit IM, and execute most other programs at the DOS prompt (such as copying files or formatting disks). Although you can use this menu to exit IM, it's usually easier just to hit the ESCape key or use ALT/X to quit. Ending (Quitting) ----------------- In addition to using the "Quit - exit the Integrity Master" option on the coMmands menu, you can use the ESCape and Alt/X keys to terminate IM from any point. The ESCape key allows you to terminate most IM menus without taking any action and return to the prior menu. The only exceptions to this are menus which require a response one way or the other. These are usually the result of a detected error of some type. If you hit ESCape enough times you will be asked if you really want to quit. You must select "Yes" and hit enter, to exit. The fastest way to exit IM, is by hit- ting ALT/X (hold the ALTernate key down and hit the "X" key). This allows you to quickly exit without the final "Do you really want to quit?" prompt. The Statistics Summary ---------------------- Whenever you finish checking files, IM will show you a summary of its findings. Since the summary contains a time and date stamp, you can use the report file as a chronological log of all changes on your PC even if you have it going to the printer. The summary shows statistics for all file changes as well as system sector and memory checking. IM reports the number of times it checked a file's integrity data against the DOS directory information, as "files processed". It also reports a separate count of the number of files actually read and checked. The statistics (with the exception of the memory check results) are reset every time IM displays the summary statistics. This means that on subsequent file checks, the system sectors will be indicated as "Not checked" even though they were indicated as checked on the prior display. Why is this? IM does this because some disks are removable and disk X may suddenly be a different disk. IM shows the statistics for any viruses, suspicious files, or system corruption (which in this case includes file open and read errors) in red. Integrity Master (tm) - 21 - Version 1.13a Viruses - What Are They? ------------------------ Viruses are but one of many threats to your data. You are far less likely to be hurt by a virus than the other causes of data damage such as software conflicts, and general glitches of various types. Viruses are programs which attach themselves to other programs in such a way that when the other program is executed, the virus code will also execute. The infected program usually appears to execute normally but the virus may be attaching itself to additional programs each time the infected program runs. Many viruses are triggered by some event (such as a particular time or date) into an attack phase, resulting in anything from music to serious file damage. Viruses often wait a long time before attacking; their goal is to spread as far as possible before revealing their presence. Some viruses go resident in your PC's memory, taking over your PC. This enables them to infect at will and elude detection at- tempts. A virus may attach itself to programs in two ways that many people are not aware of. The first way is to infect the programs which are in the system (boot and partition) sectors of your PC. The second way is by changing system information on your PC in such a way that the virus code is executed before the intended program. The most obvious way this is done depends on the fact that if both a .COM and .EXE file have the same name, DOS will execute the .COM file instead of the .EXE file. These viruses locate .EXE files and then plant themselves as .COM files of the same name. The virus (the .COM file) can execute, spread further, and then run the .EXE program so that everything appears normal. (Don't worry; IM detects all types of viruses!) Please read PART TWO Data Integrity and Viruses to learn more about viruses. Virus Checking Procedure ------------------------ When you install Integrity Master using SETUPIM, the Integrity Advisor will prepare a complete procedure for running IM. If you indicated that you wanted to detect viruses, then this procedure would include the steps you need to check for viruses. This step by step procedure is customized to your own preferences, so look there first (file IMPROC.TXT). To be certain of detecting even unknown viruses it is vital to cold boot from your write protected floppy containing IM, before checking for viruses. Do NOT use Ctrl/Alt/Del to boot, but turn your PC off and then on. Some PCs have a reset button which will force a cold boot. Whenever you engage in any activity which changes or rearranges a lot of files, run at least a "Quick integrity update", so that your integrity data accurately reflects the status of your PC. Use the options menu to change the type of integrity checking. o With Integrity "CHECK ON", do a full integrity check (rather than a "quick update") of all files at least once a month to detect any unexpected changes. Integrity Master (tm) - 22 - Version 1.13a o If your work exposes you to programs which may be infected with viruses, do a daily full check of your disk for any unauthorized changes. To save time, use the options menu to limit checking to executable programs. Check at least the current directory if you have executed any new or "strange" programs. o After installing any new software, IMMEDIATELY run IM to initialize the integrity data for the new files you have created. Be sure that you save a write protected disk containing a copy of the software. It is vital, that you do this before you start to use the software. o It is critical to do extra checking any time you copy programs (eg. *.EXE or *.COM files). When you copy programs, be sure to copy your integrity data also. For example, if you are doing something like a "COPY *.EXE D:\DOS", then also enter a "COPY *.ID D:\DOS" command. This copies the integrity data along with the programs. If you simply copy all files (COPY *.*), then you won't have to worry; the integrity data will automatically be copied along with the programs. Afterwards, run IM to check that the files were copied without damage or virus infection. Naturally, any files that weren't copied will be reported as deleted when you run this check. Scanning for viruses -------------------- If you wish to quickly scan a disk for known viruses: o Use the options menu and set the "Files to iNitialize" option to "Executable programs." o Use the initialize menu to initialize "Entire disk integrity". Remember that virus scanning is a limited technology and will detect only viruses known at the time this program was written. As with any scan program, you should have the latest version if you intend to rely upon scanning for serious protection. The option to check "Disk for known Viruses" on the check menu will allow you to do a one time quick scan (check) for viruses. If you intend to check this disk more than once, it's far better to do an initialize we as we just suggested above. Detecting Viruses ----------------- o Make sure that you specified that you wanted virus protection when you installed IM. If you didn't, then run SetupIM and select "Reinstall". o Make sure you carefully followed SetupIM's instructions in IMPROC.TXT. Integrity Master (tm) - 23 - Version 1.13a o If a virus is found on your PC, IM will almost always recognize it by name and explain how to remove it. IM will also advise if viral signs are present on changes that don't match known viruses. o Whenever IM reports a change to an executable program, it's important to determine the cause. Some programs modify themselves when you change their options; some programs change themselves every time they run. Changes to executable programs are indicated in red on the report screen and are bracketed by "...." to make these changes obvious. o If only a single program has changed and IM does not indicate this to be corruption, then you probably do NOT have a virus. If you have any doubt that a program change may be a virus, be very careful and run full checks with IM after executing this program. (Cold boot (power off and on) from a floppy before running IM) Any program changes detected at this point indicate a virus. Please report this (see file VIRREP.DOC for complete details). o For speed, use the options menu to limit checking to executable files. Detecting Unknown (new) viruses ------------------------------- IM has the capability to detect infection by an unknown (new) virus as well as the ability to identify known viruses and their characteristics. If IM detects an unknown virus, it clearly can't provide the detailed information that it provides when it detects a known virus. Because of some of the generic detection techniques used in IM, there's actually a good chance that it will in fact identify and describe a new virus. How is this possible? This is only possible if the virus is not totally new but a modification of an existing virus. In this case IM may identify the "new" virus as a virus it knows about because the new virus was created by someone who modified the old virus to create a new one. IM notices the code from the old virus still present in the new virus and identifies it in this way. What about totally new viruses? These are a little more work to identify. In this case, IM will inform you that it has detected a change in a file or a system sector, but won't announce that a virus is present (unless it's similar to a known virus). How do we determine whether a virus is responsible for the detected change? Consider the following factors: Integrity Master (tm) - 24 - Version 1.13a o Has IM identified virus like symptoms with this change? Such symptoms include an unusual value in the DOS time or date stamp, and file corruption detected (no change to the time and date stamp but a change to the file). o Are numerous unrelated executable files changed? If the answer to one or both of these questions is "yes" then it's time to do some more checking to see if it's really a virus. Please read the section on Virus Signs and Playing Detective in Part two Data Integrity and Viruses. Following these procedures will let you determine if you have encountered a brand new virus (lucky you!). If you have encountered a virus, or you are not sure, please contact us; see file VIRREP.DOC for details on reporting viruses. The Integrity Master Virus Report --------------------------------- When IM detects a known virus it will present at least one full screen of information. IM stops and waits for you to hit a key. We consider viruses so serious that we don't offer any way for IM to go on checking after it has detected a virus without you acknowledging that you've seen the screen. The virus report screen gives you the following information: o The name of the virus. This is usually the name that virus researchers in the United States use most often. This name corresponds to an entry in file VTEXT.DOC. Many viruses have been built as modifications to existing viruses. By identifying common (hard to change) code elements in the base virus, IM can identify multiple viruses by spotting their common characteristic. This means for example that if IM reports the Jerusalem virus, it could also be the Anarkia, Anarkia-B or the Payday virus. Since viruses go by many names, alternate names for the same virus are listed in this table too. o The type of files or system sectors infected by this virus is listed. o If the virus is known to seriously interfere with normal operation of your PC, this is mentioned. Displaying messages, bouncing balls and playing music is not considered to be serious interference. Slowing execution of your PC or halting the system ARE considered serious. o If the virus is known to either deliberately or inadvertently damage data on your disk, this is mentioned. Beware, though, harmless viruses are all too often being modified to become dangerous. An example of this is the Cascade virus (letters Integrity Master (tm) - 25 - Version 1.13a cascade down on your screen when this virus activates). The first version of this virus was harmless but someone created a variant which will format your disk. In this case, IM makes a special check for the dangerous variant of the virus and warns you if it's detected. In spite of this, please, NEVER assume that a virus is harmless. If we don't mention that a virus is known to damage files, it means only that no one has reported damage from this virus. Be careful; you may have a variant of the virus that might very well be dangerous! o Step by step removal instructions are presented for the virus. Sometimes IM presents additional screens describing necessary or suggested actions. This is true if the virus is detected in memory. When IM first starts, it checks the memory of the PC for presence of known viruses (unless you deactivate this check using SetupIM or the "/B" (bypass) command line parameter); if a virus is detected you are asked to immediately cold boot your PC. Checking further at this point could be very dangerous since it might spread the virus. Other special viruses such as companion or cluster viruses (see PART TWO for details) will generate an extra screen identifying that specific virus and mentioning alternate ways to remove the virus. False Alarms ------------ If IM announces detection of a known virus, could this be a false alarm (Not really a virus)? If IM has checked this file before or if more than one file was found infected, then it is almost certainly a REAL VIRUS! If this is the first time IM has checked this file and if only one file is found infected after checking your entire disk, then it may be a false alarm. Although it is very unlikely, it IS possible that a legitimate program could contain code that matches a virus. IF YOU THINK YOU HAVE A FALSE ALARM, PLEASE NOTIFY STILLER RESEARCH. WE WILL DETERMINE IF A VIRUS IS PRESENT; IF IT IS A FALSE ALARM, WE WILL, IF POSSIBLE, SEND A CORRECTED VERSION OF IM. Some anti-virus programs contain unencrypted virus fragments which IM may detect. It's usually safe to assume these programs are not infected. Some of these programs also leave virus fragments in memory which IM may then detect and announce as a memory resident virus. Please do not take any chances in such a case and follow IM's instructions to cold boot even though it's likely to be a false alarm. If you have just read an infected disk or a file, there is a chance that IM may detect a piece of this file in memory and announce a resident virus when one really isn't resident. In such cases it's best to play it safe and cold boot from a write-protect diskette. Integrity Master (tm) - 26 - Version 1.13a Destroying Viruses ------------------ If IM detects a known virus, it will display the steps to remove the virus. If IM detects program or system sector changes which may be due to a virus, please follow these steps: o Save at least one infected diskette or file and report this to us so that we can update IM to recognize this virus and hopefully track down its source! See file VIRREP.DOC for complete details. o Cold boot your PC (power off and on) from a write protected floppy disk. o Run an "Entire disk integrity" check, noting any changed programs or other possible damage by the virus. o Delete any infected programs. o Reload your system sectors if they were damaged. o Restore any damaged files or programs from the original diskettes if possible. o Very carefully, check any floppies you've used. o Run an "Entire disk integrity" check daily for a while. Data Corruption --------------- If a program changes a file by normal means, the file's time and date stamp will be updated to reflect this change. On the other hand, if a virus or a hardware or software problem causes a file to be changed, there is often no change to file's time and date stamps. IM calls this file corruption and raises a special alarm if it detects this. If you find, a corrupted file, the odds are it's NOT a virus. The most likely cause of corrupted files are software conflicts. The next most common cause is hardware problems. In any case, if you have a corrupted file, it's absolutely vital you determine what the likely cause is. In Part Two - Data Integrity and Viruses", we have a chapter titled Determining the Cause of Data Corruption. Please read that chapter very carefully when (not if!) you detect a corrupted file. The next section describes using IM when you are having suspected disk hardware problems. Integrity Master (tm) - 27 - Version 1.13a Integrity Master and Disk Problems ---------------------------------- It's an unfortunate fact of life that all disk drives will eventually fail; sometimes at the worst possible moment! Before disk drives totally fail, they usually start exhibiting signs of problems, such as inability to reliably read and write certain areas on the disk. Unfortunately, these failures tend to be intermittent. The result may be that you have damaged files, but when you run your disk diagnostic software, no problems are found. By using IM to do periodic full checks, you can detect these problems when they first begin and prevent more major disk problems, such as total failure, from taking you by surprise. If you have an MFM, RLL, or ESDI type of disk drive you may be able to extend it's life slightly by doing a low level format, or using a product such as Steve Gibson's SpinRite(R) which can do a non-destructive low level format. The key here is to detect disk problems early before any serious damage is done. IM replaces the DOS critical error handler with its own more advanced routine. If a disk error occurs, you will see a warning screen explaining what has happened, rather than the dreaded "Abort retry or fail" message that DOS provides. IM may also present a menu offering you additional options (depending upon the type of error and the circumstances) such as repeating (retrying) the operation. If an error occurs while IM is checking files, it will report either "Read fail" or "Open fail" in place of the normal signature data on its report: Name and Signature File Update Update Status: Type: Extension: Val1: Val2: Size: Date: Time: ------- -------- ---------- ---- ---- ---------- -------- -------- Added File NORMAL EXE 0D83 4E93 2048 11/05/91 14:00:56 Added File DISKERR EXE Read fail 140792 11/05/91 14:01:02 Added File CANTOPN FIL Open fail 123 10/05/90 10:11:20 In addition to "Read fail" or "Open fail" appearing in the IM report, additional information regarding the type of error will also appear and be recorded in the report file (or printout) as well in the on screen report. Whenever IM encounters an error reading a file, it will NOT replace the original integrity data with the current (in error) data. This means that if you have a read error on a file, and you either "fix" the file using some utility or restore the file from a backup, you can then run a check on that file and know whether or not your file is correctly restored. Integrity Master (tm) - 28 - Version 1.13a If you run IM in an environment where more than one program can have a file open, you may get an "Open fail" or I/O error due to another program having this file open. This can happen on networks, with OS/2, or with windows. Do avoid these messages try the "/NE" parameter. Integrity Master for PC Security -------------------------------- Although there are no 100 percent reliable techniques to prevent someone from making unauthorized changes to your data while you are away, IM does offer a 100 percent reliable way of detecting these changes. If you indicate security is important, when you first execute SetupIM, its Integrity Advisor will make recommendations on how to use IM to get the level of protection you need. It saves these recommendations on file IMPROC.TXT. By storing your integrity data on diskettes and keeping these diskettes in a safe location, you can detect any changes which were made on your PC. This should provide you protection even against a user who understands how IM works and is technically adept. For most situations this is probably overkill! Keeping the integrity data on diskette may provide more protection than you need. Simply keeping your parameter file (IM.PRM) on a diskette will provide a very high level of protection. Since a user breaking into your PC will not be able to tell how the integrity data is computed, this user will not be able to change a file and then adjust the integrity data to hide the changes, even if they have a copy of the IM program. This provides almost as much protection as keeping the integrity data on diskettes. If you keep the parameter file on the same disk with the files you check, it's possible that someone could modify your files and then run IM to update the integrity data, in this way covering their tracks. This person would obviously have to have enough knowledge about your PC to know that you use IM. If you'd like to keep your parameter file on the diskette with your files you can still achieve a high degree of security by renaming IM.PRM to some other name and locating it in an unlikely directory. When you invoke IM you will have to specify the name of the directory and the new name for the parameter file. For example, the command: "IM D:\DOS\UTILS\BORING.DAT" will read file BORING.DAT from directory \DOS\UTILS on disk D. Integrity Master (tm) - 29 - Version 1.13a Integrity Master for Change Control ----------------------------------- To use IM for change management, you really don't need to use integrity checking. Simply running IM, in "Quick Update" mode, (which does not actually read files unless the DOS time/date stamp or file size have changed), is adequate to provide change management. "Quick update" mode only requires about 10 seconds to check about 270 megabytes (8000 files). To keep a full record of what has changed on your PC, we recommend you use "auto-named" report files and that you keep all your report files. At the end of the year, you may wish to copy all the old report files into a directory for that year. For example, on January 1st, 1993: CD \ MD REP93 COPY *.REP \REP93 DEL *.REP This creates a directory called "\REP93", copies all report files to that directory and then deletes the old report files. By following this procedure you have a complete record of all changes on your PC. If you want to know when a particular file last changed, it's easy to search through the report files for that filename. If you want to know where all your disk space is going, you can easily see what is being added. Integrity Master (tm) - 30 - Version 1.13a C o m m a n d L i n e E x e c u t i o n ------------------------------------------- Integrity Master is really designed to work by use of its menus. However most functions can be automatically invoked from the command line to allow you to start IM from batch files. Syntax: IM [Filespec] [/A] [/B] [/C] [/Cx] [/Dxyz] [/H] [/Ix] [/L] [/N] [/M] ============================================================================= FileSpec specifies the name of the parameter file to be used. If not in the the current directory, then include the complete directory path. ----------------------------------------------------------------------------- "/Dxyz" change to disk "x", process and then change to disk "y" etc. If used with more than one disk, this should be used with one of the "/Ix" or "/Cx" parameters. "/N" Nonstop: the same as setting "Halt" to "Serious problems" on the Options menu. IM will stop only on viruses or serious problems. "/NE" Stop on Emergencies only. This almost never stops. "/B" bypass memory check ----------------------------------------------------------------------------- /Cx values: do type "x" integrity check and then quit: "/CE" Check Entire disk integrity. "/CB" Check boot sector. "/CD" Check all files on DOS disk. "/CP" Check partition sector. "/CR" Check files in this diRectory. "/CF=filespec" Check this one file. ----------------------------------------------------------------------------- /Ix values: do type "x" integrity initialize and then quit: "/IE" Init Entire disk integrity. "/IB" Init Boot sector. "/ID" Init all files on DOS Disk. "/IP" Init Partition sector. "/IR" Init files in this diRectory. ----------------------------------------------------------------------------- /Rx values will reload one of the system sectors on the current disk and quit "/RP" Reload Partition sector "/RB" Reload DOS Boot sector ----------------------------------------------------------------------------- The following may be used to override video mode selected during install: "/A" Auto adjust of video mode. "/L" Use colors for LCD displays. "/C" Force use of full color mode. "/M" Use monochrome colors. Ordinarily, you don't need ANY parameters. Just enter: "IM". IM is menu driven with lots of on-line help. The command line parameters are intended for automatic unattended integrity checking. If you don't have "HALT" set to "None" (on the options menu), use "/N" to avoid pausing for input. If you wish to have IM automatically locate your parameter file, DO NOT specify it on the command line. If you specify it on the command line,you must include the drive and directory where it is located, if it is not in the current directory. Examples: --------- "IM /L /CE" Uses colors appropriate for an LCD display and checks the system sectors as well as all files on the current disk. "IM /IR" Creates new integrity data for files in this diRectory. "IM /CF=A:\X\IO.SYS" Checks the file IO.SYS in directory \X on disk A:. "IM D:\IO\X.PRM /CD" Checks all files in the current disk using options saved in the parameter file "X.PRM" located in "D:\IO". "IM /RB /DA" Reloads the DOS boot sector on disk A. Integrity Master (tm) - 31 - Version 1.13a To execute IM automatically in unattended (batch) mode, do the following: o Use the options menu to activate the report file. Save this change by selecting the first option on the options menu, "Write option changes to disk." o Either use the "/N" (nonstop) parameter ("IM /N") or set halt options to "None" (options menu). Be aware that you can use multiple parameter files if you don't want your options always set to nonstop. o Set up the IM control card. For example: "IM /N /DG /CE" will run nonstop on disk G: and check the entire disk (/CE) including system sectors. o If you have a timed execution program such as the one available with PCtools, you may want to have it invoke IM or add IM to any batch file which you run regularly such as nightly backup batch file. Error Levels Integrity Master returns the following DOS error levels. You can check for these error levels in a batch file and execute your own special procedures depending upon IM's findings. One of our beta testers has their PCs automatically phone their help desk if an error level 24 or greater is encountered. 00 Processing complete with no changes detected 08 Checking complete with added or deleted files detected 12 Checking complete with changed files detected 16 Checking complete with changed programs detected 24 Checking complete with suspicious file changes detected 32 Checking complete but a file or system sector showed signs of corruption or an I/O error. This will be in addition to any of the lower valued indicators such as change to a program. So if a program changed, the error level would = 16 + 32 = 48. 64 One or more viruses were detected. Any of the lower status indicators will be included with this one. 128 If a vital IM file is determined to be missing or damaged 192 A fatal error occurred during execution such as not enough memory or a disk error in internal processing such as a failed drive change. 200 control card error (an error in IM's "/" parameters). Integrity Master (tm) - 32 - Version 1.13a Using IMCHECK ------------- IMCHECK.EXE is a fast stand-alone file checker. It will read whatever files you specify and compute signature data similar to what Integrity Master uses as part of its integrity data. If you print the IMPROC.TXT file created by SetupIM, you will see the check values which IMCHECK should report for IM.EXE and IMCHECK itself. The syntax is: IMCHECK [d:] [path] filename [/D] [/1] [/2] "filename" specifies the files to check. Wild card characters such as * or ? may be used. "/D" Display directory entries as well as files. "/1" Utilize an alternate check value1 algorithm. "/2" Utilize an alternate check value2 algorithm. Entering IMCHECK with no parameters will produce a explanation of how to use IMCHECK. For example: IMCHECK D:\DOS\TEST.* would check all files in the DOS directory on disk D: which begin with TEST but with any file extension. IMCHECK can be very handy when you send files to others and you want to make sure that they got a good copy of your files. Simply run IMCHECK on your files. You will see a report like: IMCHECK 1.2 - Integrity Master (TM) standalone file checker. Copyright 1990-1991 by Wolfgang Stiller - all rights reserved. Checking: MYFILE.* File Name + Check Check File Update Update Extension: Val1: Val2: Size: Date: Time: ---------- ---- ---- ------- ------ ------ MYFILE.001 AC57 C1C4 1551 11/05/91 22:38:40 MYFILE.DAT 2D53 B1D6 8666 11/07/91 18:57:30 Total======> F5AA 66A7 Simply record the check values and make sure the other person runs IMCHECK and compares the values. Note, that the "Total=====>" value will match only if the files are checked in the same order. Special license terms for IMcheck: ---------------------------------- Registered users of Integrity Master are granted permission to distribute copies of IMcheck to anyone who needs to verify the integrity of files sent by the registered user. This other user may use and keep IMcheck but may not further distribute it. ONLY registered (licensed) IM users may distribute IMcheck. ----------------------------------------------------------- Integrity Master (tm) - 33 - Version 1.13a _________________________________________________________________________ CHAPTER FOUR - Customizing Customizing Integrity Master ---------------------------- When you first install Integrity Master, SetupIM does an initial customization for you based upon how you intend to use it. There are quite a few options available to you to make it work just the way you want. From the Integrity Master options menu, you can control almost all options which determine how IM works. Your option changes may be either temporary or permanent. To make your changes perma- nent, select "Write option changes to disk" from the options menu. This will save your option changes on the parameter file. These options will be in effect the next time you execute IM. In addition to initially installing IM, SetupIM allows you to change all possible options. The more advanced options (which you may never need to change) are available only within SetupIM. These options include turning off virus checking, setting which files are considered to be programs and deciding where integrity data will be stored. SetupIM also allows you to permanently change the colors that IM uses on the display. These options are stored on the parameter file (IM.PRM). You may, if you wish, keep multiple versions of this file around to represent different sets of options. You can specify a different name for this file on IM's command line. The Parameter (options) file ---------------------------- The parameter file (IM.PRM) contains all the options which control how IM works. IM and SetupIM look for this file in either the current directory, the directory where IM.EXE is located, or the root directory on any disk. Whenever you change any options and save the changes, the parameter file is rewritten. The option "Write option changes to disk" in IM's options menu does this as well as SetupIM. Integrity Master (tm) - 34 - Version 1.13a The Options Menu ---------------- You can reach the options menu from any primary IM menu by hitting the "O" or ALT/O keys. The options menu is also avail- able from within SetupIM. From the options menu, you can con- trol almost all options which determine how IM works. These options include all normal day to day choices. _____________|Options|______________________ | Write option changes to disk | | Integrity: CHECKING ON/off=quick update | | Files to Check: Executable programs | | Files to iNitialize: Executable programs | | Halt on: ALL changes, adds or deletes | | Sound -------------------------> ON/off | | Report: (xxxxxxxxxxxxx)--------> on/OFF | | Video (screen) report ---------> ON/off | | Ignore Time/date changes ------> on/OFF | | Only changes reported ---------> on/OFF | |------------------------------------------| In addition to allowing you to set all the above options, the Options menu displays the current settings of these options. The options which have "on/off" settings, are toggled between their on and off states by hitting the ENTER key. The current setting of the option is displayed in capital letters, as well as in a distinctive color. Write option changes to disk ---------------------------- This allows you to write any option changes to the parameter file, making your option changes effective the next time you execute IM also. This option does not exist on the SetupIM version of the options menu. Integrity: CHECKING ON/off=quick update ---------------------------------------- This is the most crucial item on the Options menu. Hitting the ENTER key toggles whether integrity checking is on, or only a quick integrity data update will be done. When you hit ENTER, either "Checking ON" or "OFF=Quick update" will be in all capital letters and in a different color (on most displays). This indicates whether full integrity checking is on or off. The status of integrity checking is always visible on the fourth line at the top of the screen. Quick update mode provides a very fast way to bring all your integrity data up to date. Only files whose size, time stamp or date stamp have changed will be read and undergo a full integrity check. To detect file corruption and viruses, it's essential to regularly turn "Checking on" to do full integrity checks. Integrity Master (tm) - 35 - Version 1.13a Files to Check: --------------- You can use this option to limit IM's checking to only executable or source programs. Even if you are interested only in virus detection, we strongly recommend that you also periodically set this option to check all files, so that you can be alerted to the other (more common) causes of file damage. The advanced menu in SetupIM allows you to change which files IM considers to be executable or source programs. Files to iNitialize: -------------------- Use this option to limit IM's initializing of integrity data to only executable or source programs. Even if your primary interest is viruses only, we strongly recommend that you set this option to read all files, so that you can be alerted to the other (more common) causes of file damage. The advanced menu in SetupIM allows you to change which files IM considers to be executable or source programs. Halt on: ALL changes -------------------- When IM is checking your files for changes, it lists each new change that it detects at the top of the report screen. The other changes on the screen shift downward (scroll) as each new line is added at the top of the screen. By setting the halt options, you control when this scrolling will pause and wait for you to hit a key. This prevents a change from scrolling off the screen without you having seen it. The halt options appear on this menu: __________________________________ | Halt on: | | | | All detected differences | | Changed files only | | Changes to Executable programs | | Changes to any Program | | Signs of file corruption | | None - Pause on request only | |________________________________| If you halt scrolling on "All detected differences", anytime a line written to the report screen is about to disappear off the bottom of the screen, the display will pause and wait for you to hit a key to acknowledge that you've seen all the lines on the display. After you hit a key, the display will not pause until all the lines currently on the screen have scrolled off and a new unseen line is about to scroll off the screen. If you halt scrolling on executable or source programs, the scrolling will pause only when a program is about to disappear off the bottom of the screen. After you hit ENTER, the display will not pause scrolling until a program which was not on the previous display is about to scroll off the bottom. Integrity Master (tm) - 36 - Version 1.13a If you halt scrolling on "Signs of file corruption", only signs of viruses, corrupted files, or possible hardware errors will pause the display. If you tell IM to halt on "None", then the display will pause only on hardware errors or signs of viruses. This affects scrolling in the same way as using the "/N" parameter on the command line. If you set halt to "none", be sure that IM is writing a report to a file or to the printer, otherwise you may miss some important warnings. You can always halt scrolling by hitting the "P" key. Sound -------------------------> ON/off --------------------------------------- IM will provide beeps and tones to alert you that something important has happened (or that you've hit an unsupported key). Hitting ENTER toggles whether you will hear these sounds. Report: (xxxxxxxxxxxxx)--------> on/OFF --------------------------------------- This allows you to turn the report file off or to ask IM to write a report of its activities to either the printer or a disk file. The "xxxxxxxxx" on the option line represents the name of the current report file or printer. The disk file can be automatically named by IM or can be any file of your choice. Please see "The Report File" in Chapter three for more details on these options. This option line, as well as the third line from top of IM's screen, display the status of the report file. Video (screen) report ---------> ON/off --------------------------------------- If you have a very slow video board (such as some very old CGA adapters), IM will run a little faster if you turn the screen report off. (Be sure to turn the report file on!) Ignore Time/date changes ------> on/OFF --------------------------------------- Sometimes the DOS time or date stamp on a file will change, but the file itself won't change. If you do not want to have such files reported as changed, set this option to "ON". Only changes reported ---------> on/OFF --------------------------------------- If you do not want reports of added or deleted files, turn this option "on". If "Only changes reported" is set to "on", then you will see only reports of file changes; no added or deleted files will be reported. The integrity data will still be updated to reflect the added or deleted files, but no report of these files will appear on the screen. All other processing also continues normally including the detection of companion viruses (viruses which appear only as added files). Integrity Master (tm) - 37 - Version 1.13a O p t i o n s i n S e t u p I M ----------------------------------- When you execute SetupIM for the first time, the Integrity Advisor(tm) will set your options in a way most likely to meet your needs and interests. You can later go back and change any of the options which were set for you. If you specify that it's not your first install of IM, you will see this menu: +------------------------------------------+ | Select an option and hit ENTER: | | | | Overview of IM setup and operation | | Change how Integrity Master operates | | Repeat the install on this PC | | Install IM on an other PC | | Quit | +------------------------------------------+ From this menu, you can select "Change how Integrity Master operates" and hit ENTER. This brings you to the change menu: +---------------------------------------+ | Select an option and hit ENTER: | | | | Screen display mode | | Location of integrity data | | Primary options | | Advanced Options | | Exit - save any changes and end | +---------------------------------------+ Options available only in SetupIM --------------------------------- On this menu all options except for "Primary Options" are avail- able only in SetupIM. Selecting "Primary options" brings up a menu similar to the options menu in IM. The following options can only be changed from the change Menu in SetupIM: Screen Display Mode ------------------- This allows you to set the screen colors as explained in the Chapter Two section titled "Screen Colors". Integrity Master (tm) - 38 - Version 1.13a Location of Integrity Data -------------------------- As IM checks your files, it must store the integrity data which describes these files. Using SetupIM you can change where IM stores these files. There are two options: 1) It can store the integrity data in the same directory along with the files being checked or 2) It can store the integrity data on a separate disk (usually a floppy). Storing the integrity data on a floppy gives you total protection against a virus or a person changing a file and then modifying the integrity data to cover up the change. For viruses, this threat is fairly remote since the virus would have to be written specifically to attack files created by IM. This would be very difficult since these files are encrypted differently on each PC. Storing the integrity data with the files being checked is usually easier and more flexible since the integrity data can be copied along with the files. Any time you copy the files, it's then easy to use IM to verify that you made a good copy. If you want to restore an old copy of a file from a backup, you can restore the integrity data along with the file and then ask IM to check that the file restored correctly. If you move your files, it's easier to move the integrity data along with the files if it's stored in the same directory as the files. The Advanced Option Menu ------------------------ If you select this option on the SetupIM change menu, the advanced option menu will appear. This menu is intended only for more experienced users. The details of this menu are covered in the next section. Update hardware configuration ----------------------------- Please run this option anytime you change the configuration of disk drives on your computer, or if you use software which changes the assignment of DOS logical disk letters (A to Z) to your physical disk drives. SetupIM will check the capabilities of each of your installed disk drives. This will produce a display showing the drives that SetupIM recognizes. It will also list any drives which do not contain DOS boot sectors and any which do not have partition sectors (master boot records). Exit - save any changes and end ------------------------------- Updates the parameter file (IM.PRM) with any option changes you've selected, and exits SetupIM. Integrity Master (tm) - 39 - Version 1.13a Abort - Quit and abandon any changes ------------------------------------ Allows you to exit SetupIM without writing any of your changes. All option changes will be as they were before you entered SetupIM. The Advanced Option Menu: ------------------------- +-------------------------------------------------+ | Select an option and hit ENTER: | | (Hit ESCape when you're done) | | | | Specify Names of hidden system files | | Define which files are Executable programs | | Define which files are Source programs | | Check for virus in memory is ON; turn it off | | General virus checking is ON; turn it off | +-------------------------------------------------+ This menu is intended for more technically advanced users only. Most IM users should never need to use this menu. When you're finished making changes on this menu, just hit ESCape to go back to the previous menu. Specify Names of hidden system files ------------------------------------ Selecting this option will allow you to change the names of the files that IM recognizes as the hidden system files. This option is only needed on nonstandard PCs which don't use the standard Microsoft or the IBM names for the hidden system files. The files SetupIM recognizes by default are: IBMBIO.COM, IBMDOS.COM, IO.SYS and MSDOS.SYS. If you execute "IMCHECK *.*", in your root directory and you don't see two of the above files, but instead see two other similarly named files, you may wish to use this option so IM recognizes those files. If you don't understand what this is all about, don't worry. IM's ability to recognize your hidden system files is NOT that important. It simply allows IM to provide more specific information in two warning messages. Define which files are Executable programs ------------------------------------------ This option allows you to specify which file extensions (the letters after the "." in the file name) IM should consider to represent executable programs. This is important for three reasons: 1) Non-executable files are not normally checked for known viruses. Integrity Master (tm) - 40 - Version 1.13a 2) IM provides special warning when executable programs change. 3) If you use the options menu to limit checking to executable programs, only these files will be checked. Initially, IM will consider files ending in the following extensions to be executable programs: Numeric extensions such as .123 .OV? (where ? can be any character) .DRV .BAT .EXE .BIN .PIF .COM .SYS .DLL .SWP Note, that not all these files can actually be affected by viruses but all these files in one way or another contain instructions that are executed by your PC. Define which files are Source programs -------------------------------------- This option allows you to specify which file extensions (the letters after the "." in the file name) IM should consider to be source programs. Source programs are the programs a programmer would use to create executable programs. If you are not a programmer then you probably don't care about this option. This option is intended mostly to provide programmers with extra warning if something has changed their source code. Check for virus in Memory ------------------------- Selecting this option will toggle the checking of memory for known viruses on or off. If you toggle memory checking on, the option line will be changed to read: Check for virus in memory is ON; turn it off. This indicates that memory checking is now "ON". If you hit ENTER at this point, you will turn it "off", and the option will read: Check for virus in memory is OFF; turn it on. Integrity Master (tm) - 41 - Version 1.13a Having this option "ON" allows IM to detect known viruses which are resident in memory. If you ALWAYS, cold boot from a known good copy of DOS on a write protected diskette, you could safely turn this option off, since there would be no way for a virus to be resident in memory. Since, it's hard to guarantee that you always cold boot, please leave resident memory checking turned on. If you execute IM multiple times and you don't want to wait for the memory check to complete, you can use the"/B" (Bypass) command line parameter to bypass the resident memory check. General virus checking ---------------------- Selecting this option and hitting enter will toggle checking of files for known viruses on or off. If you have absolutely no interest in viruses, you can speed up IM's initialize processing and its check processing (only when it encounters changed files) by 10 to 20 percent. Since this option imposes so little overhead in normal file checking, we suggest everyone leave it turned on. Integrity Master (tm) - 42 - Version 1.13a _________________________________________________________________________ CHAPTER FIVE - Errors Error recovery: --------------- IM replaces the normal DOS error recovery routines with its own more sophisticated routines. If you encounter hardware errors, you'll generally see a message announcing what happened followed by a screen which will give you the option of retrying the failed operation, aborting (allowing whatever IM was trying to do, to fail) or other options depending upon the circumstances. These other options include "Shelling to DOS". Shelling allows you to temporarily exit IM and execute any DOS command (such as formatting a disk) you wish. You then return to IM by typing the EXIT command. This returns you to the same point in IM, just as if you had never left. Solving problems: ----------------- If you encounter a problem with IM, please read file QUESTION.DOC (for a list of common questions and answers) and file SUPPORT.DOC (for the complete procedure on how to quickly get technical support). File DISKHELP.TXT contains specific information on how to handle problems if IM won't recognize your disk drive. You can use IMPRINT or IMVIEW to read any of these files. Example: "IMVIEW SUPPORT.DOC" Answers to Common Questions: ---------------------------- File QUESTION.TXT contains common questions and answers regarding IM. You can read these by entering the command "IMVIEW QUESTION.TXT" at the DOS prompt or print with the command "IMPRINT QUESTION.TXT". Hopefully, any questions you may have will be answered there. Here are some examples of common questions: Q: Sometimes IM comes up with different colors on the screen than before. What's going on? A: IM checks the DOS video mode indictor on your PC to see if you are in color or monochrome mode, as well as directly checking your video adapter. This allows you to use the DOS "MODE BW80" to indicate that a two color display is present on a color adapter card. Some programs change this value to an incorrect value. If this happens to you, use the DOS mode command to set the video mode back to the correct state. For example, enter "MODE CO80" to restore normal color mode. You can also use the command line override (or SetupIM) so IM comes up using whatever colors you prefer. "IM /C" would force IM to run in color mode. Integrity Master (tm) - 43 - Version 1.13a Q: IM detected a virus on my PC. I reloaded my system sectors and either deleted or reloaded all infected files, yet the virus keeps coming back! What should I do? A: Somewhere a virus is eluding your checks. Please check the following: o Did you install IM after cold booting from a clean floppy? It's absolutely vital to do a cold boot before checking. o Are you using a task switcher (or multi-tasker) such as windows? If so, then this program may be saving some of your infected programs in its "swap" file. This file often ends in the letters ".SWP". Delete this file if it exists. o Be sure you check ALL files and floppies which come into contact with your computer. You may have missed a file or diskette somewhere. Please take the extra time and check them all. o It's possible that viral code is hidden somewhere other than an executable file. IM normally checks only executable files (programs and overlays) for known viruses. Try selecting "Disk for known Viruses" on the check menu and selecting "Check All files" on that menu. This will check all files as well as system sectors on your disk. Also, check any other disks that you've been using. Q: I was just checking a diskette for viruses and IM detected the DataCrime 2 virus in a file. When I restarted IM, it detected the DataCrime virus resident in memory! I never executed the program which was infected, so how did the virus get control of my PC? A: The virus wasn't really resident or in control of your PC. What happened was that a piece of the viral code was left somewhere in memory - probably in one of DOS's file buffers. Although IM takes great pains to clear its own buffers and areas of memory, it's not that unusual to get a false indication of the virus being active in memory after detecting a virus in a file or system sector. Integrity Master (tm) - 44 - Version 1.13a PART TWO Data Integrity and Viruses ___________________________________________ How do I make sure that my programs and files really are safe? What threats are even more likely to damage my data than viruses? What really works against viruses? What doesn't work against viruses? Why are viruses so dangerous? How do I kill a virus? ___________________________________________ Copyright 1991-1992, Wolfgang Stiller, All rights reserved. Integrity Master (tm) - 45 - Version 1.13a ___________________________________________________________________________ PART TWO Data Integrity and Viruses _______________________________________________________________________ CHAPTER ONE - Threats to Your Data Introduction - Viruses get all the Glory ---------------------------------------- In order to protect the integrity of your data, it's important to first understand the nature of the threats against it. The most publicized threats to your computer are software based attacks often lumped together as "viruses" by the media. These threats have often been sensationalized by media coverage, but can pose a serious threat to PCs anyway. See the section in this chapter titled "How serious are viruses?". Although a virus may never attack your PC, it is almost inevitable that system glitches will someday corrupt data or programs on your PC. Considering that viruses are but one threat to your data and not the most likely threat by far, it's ironic that so many people have anti-virus software and so few people take steps to protect the integrity of their programs and data from other causes. Can anyone afford NOT to know that each and every byte on their disk is intact? So what's the explanation? Why do so few people take steps to assure the integrity of the data on their PC? The main reason is that data integrity gets almost no media coverage, (even in the trade journals), while a virus story may make the local evening news. The result is that people just don't give data integrity a second thought. It's all too easy to take the reliability of our modern PCs for granted -- and, as you'll see, all too dangerous! There's a good chance that you are reading this purely because you're interested in viruses, so in your case the media attention to viruses will have had a very beneficial effect! You are about to learn how to protect your PC against much more than just viruses! Data integrity is not a very glamorous subject, yet it's both crucial and fundamental to using any computer. Without positive assur- ance of data integrity, computers can not be depended upon to process any type of important data. How would you respond if someone were going to change a byte of data somewhere at random on your disk? You'd be pretty upset; right? Well, the odds are, it's already happened but you were not aware of it. Perhaps the result was that a program quit working or CHKDSK found lost or cross linked clusters. Or perhaps (hopefully), the damage was to some inconsequential part of your disk. Integrity Master (tm) - 46 - Version 1.13a Let's take a look at the different threats to your files and programs. HARDWARE AND POWER FAULTS ------------------------- These are well known and also all too common. We all know that when your PC or disk are getting old, they might start acting errat- ically and damage some data before they totally die. But hardware problems are actually more prevalent than you may think. Your PC is busy writing data to disk and the lights go out! "Arghhhh!" Is everything OK? Maybe not, but it'd certainly be nice to know for sure if anything was changed. If your disk drive is starting to fail, you can have the same problem. Unfortunately, it's not a question of "if", but a question of "when" in regards to disk failure. There are tools (NORTON, MACE, PCtools etc) to assist in recovery from disk problems, but how do you know all the data is OK? These tools do not always recover good copies of the original files. It's vital to have some way to check that these tools really do their job correctly. You can have hardware problems on a perfectly healthy PC if you have devices installed which do not properly share interrupts. This problem is getting more and more frequent as we see multiple adapters installed in a PC which use the same interrupt (IRQ). Sometimes problems are immediately obvious, other times they are subtle, and depend upon certain events to happen at just the wrong time, then suddenly strange things happen! FINGER CHECKS (Typos and "Oops! I didn't mean to do that".) ------------- These are an all too frequent cause of data corruption. This commonly happens when you are intending to delete or replace one file but actually get another. By using wild cards, you may experi- ence a really "wild" time. "Hmmm I thought I deleted all the *.BAK files...but they're still here....something was deleted ...what was it?... or was I in the other directory?" Of course if you're a programmer or if you use sophisticated tools like Norton's sector editor (NU), then your fingers can really get you into trouble! MALICIOUS OR CARELESS DAMAGE ---------------------------- Someone may accidentally or deliberately delete or change a file on your PC when you're not around. If your PC is not kept locked in a safe, this is a risk. Who knows what was changed or deleted? Wouldn't it be nice to know if anything changed over the weekend? Integrity Master (tm) - 47 - Version 1.13a SOFTWARE PROBLEMS ----------------- This category accounts for more damage to programs and data than any other. We're talking about non-malicious software problems here, not viruses. Software conflicts by themselves are a more likely threat to your PC than virus attack. We run our PCs today in a complex environment. There are many resident programs (TSRs such as sidekick) running at the same time along with various versions of DOS, BIOS and device drivers. All these programs execute simultaneously, share data and are vulnerable to unforeseen interactions between each other. Natural- ly, this means that there may be some subtle bugs waiting to "byte" us. Anytime a program goes haywire, there's the risk it may damage information on disk. There's the further problem that not all programs do what we hope they will. If you have just undeleted a file, did you really get all the correct clusters back in the right order? When CHKDSK "fixes" your disk for you, wouldn't it be nice to know exactly what it did? This is one more reason why everyone must have the capability to verify data integrity. Software Attacks ---------------- These are programs written deliberately to cause harm to some- one's computer or to use that computer in an unauthorized way. Even though some viruses do not intentionally damage your data, we consider all viruses to be malicious software since they modify your programs without your permission with occasional disastrous results. There are many forms of malicious software; sometimes the media calls all malicious software viruses, but it's important to understand the distinction between the various types. Let's exam- ine the different types of malicious software: Logic Bombs ----------- Just like a real bomb, a logic bomb will lie dormant until triggered by some event. The trigger can be a specific date, the number of times executed, a random number, or even a specific event such as deletion of an employee's payroll record. When the logic bomb is triggered it will usually do something unpleasant. This can range from changing a random byte of data somewhere on your disk to making the entire disk unreadable. The changing of random data on disk may be the most insidious attack since it would do a lot of damage before it would be detected. It's vital to have some data integrity software in place so such changes can be detected early on. Although you can detect it after the fact there is unfortunately no way to prevent a well written logic bomb from damaging your system. On the other hand, a logic bomb which uses standard DOS or BIOS requests to do its dirty work can be caught by most inter- ceptor type programs (see Chapter two). Integrity Master (tm) - 48 - Version 1.13a Trojans ------- These are named after the Trojan horse which delivered soldiers into the city of Troy. Likewise, a trojan program is a delivery vehicle for some destructive code (such as a logic bomb or a virus) onto a computer. The trojan program appears to be a useful pro- gram of some type, but when a certain event occurs, it does some- thing nasty and often destructive to the system. Worms ----- A worm is a self-reproducing program which does not infect other programs as a virus will, but instead creates copies of itself, which create even more copies. These are usually seen on networks and on multi-processing operating systems, where the worm will create copies of itself which are also executed. Each new copy will create more copies quickly clogging the system. The so called ARPANET/INTERNET "virus" was actually a worm. It created copies of itself through the ARPA network, eventually bringing the network to its knees. It did not infect other programs as a virus would, but simply kept creating copies of itself which would then execute and try to spread to other machines. VIRUSES ------- Viruses are a cause of much confusion and a target of considerable misinformation even from some so-called virus experts. Let's define what we mean by virus: A virus is a program which reproduces its own code by attaching itself to other programs in such a way that the virus code is exe- cuted when the infected program is executed. You could probably also say that the virus must do this without the permission or knowledge of the user, but that's not a vital distinc- tion for purposes of our discussion here. Most viruses do their "job" by placing self-replicating code in other programs, so that when those other programs are executed, even more programs are "infected" with the self-replicating code. This self-replicating code, when triggered by some event, may do a potentially harmful act to your computer. Viruses are typically distributed in the form of a trojan. In other words, the virus code has been planted in some useful program. Since the virus infects other useful programs, absolutely any piece of executable code can suddenly become a trojan delivery vehicle for the virus. Integrity Master (tm) - 49 - Version 1.13a General Virus Behavior ---------------------- Viruses come in a great many different forms, but they all poten- tially have two phases to their execution, the infection phase and the attack phase: 1) When the virus executes it will infect other programs. What's often not clearly understood is precisely WHEN it will infect the other programs. Some viruses infect other programs each time they are executed, other viruses infect only upon a certain trig- ger. This trigger could by anything; it could be a day or time, an external event on your PC, a counter within the virus etc. Modern viruses have gotten very selective about when they infect programs; this is vital to the virus's survival, since if the virus infects too often, it is more likely to be discovered before it can spread far. Virus writers want their programs to spread as far as possible before anyone detects them. This brings up an impor- tant point which bears repeating: It is a serious mistake to execute a program a few times -- find nothing infected and presume there are no viruses in the program. You can never be sure that the virus simply hasn't triggered its infection phase! Many viruses go resident in the memory of your PC just as a terminate and stay resident (TSR) program such as Sidekick(R) does. This means the virus can wait for some external event such as inserting a diskette, copying a file, or executing a pro- gram to actually infect another program. This makes these viruses very dangerous since it's hard to guess what trigger condition they use for their infection. Resident viruses frequent- ly corrupt the system software on the PC to hide their existence. 2) The second phase is the attack phase. Many viruses do unpleas- ant things such as deleting files or changing random data on your disk, simulating typos or merely slowing your PC down; some viruses do less harmful things such as playing music or creating messages or animation on your screen. Just as the virus's infec- tion phase can be triggered by some event, the attack phase also has its own trigger. Viruses usually delay revealing their presence by launching their attack only after they have had ample opportunity to spread. This means that the attack may be delayed for years after the initial infection. The attack phase is optional, many viruses simply reproduce and have no trigger for an attack phase. Does this mean that these are "good" viruses? No, unfor- tunately not! Anything that writes itself to your disk without Integrity Master (tm) - 50 - Version 1.13a your permission is stealing storage and CPU cycles. This is made worse since viruses which "just infect", with no attack phase, damage the programs or disks they infect. This is not intentional on the part of the virus, but simply a result of the fact that many viruses contain extremely poor quality code. One of the most common viruses, the STONED virus is not intentionally harmful. Unfortunately the author did not anticipate other than 360K floppy disks, with the result that the virus will try to hide its own code in an area on 1.2mb diskettes which causes corrup- tion of the entire diskette. Now that we've examined general virus behavior, let's take a closer look at the two major categories of viruses and how they operate. System Sector Viruses --------------------- These are viruses which plant themselves in your system sectors. System sectors are special areas on your disk containing programs that are executed when you boot your PC. Sectors are not files but simply small areas on your disk that your hardware reads in single chunks. Under DOS, sectors are most commonly 512 bytes in length. These sectors are invisible to normal programs but are vital for correct operation of your PC. They are a common target for viruses. There are two types of system sectors found on DOS PCs: DOS BOOT SECTORS ---------------- The very first sector on disk or diskette that DOS is aware of is the boot sector. From a DOS perspective, this is the first sector on the disk. This sector can contain an executable program whether the disk is bootable or not. Since this program is exe- cuted every time you power on or boot your PC, it is very vulnerable to virus attack. Damage to this sector can make your disk appear to be unreadable. This sector is rewritten whenever you do a "SYS" or a "FORMAT /S" to a disk. Warning: EVEN A NON-BOOTABLE FLOPPY CAN CONTAIN A VIRUS IN THE BOOT SECTOR. IF YOU LEAVE THE FLOPPY IN YOUR PC WHEN YOU POWER ON OR BOOT, YOU WILL BE INFECTED EVEN THOUGH THE PC WON'T SUCCESSFULLY BOOT FROM THAT FLOPPY. PARTITION SECTOR (Master Boot Record) ------------------------------------- On hard (fixed) disk drives, the very first sector is the partition sector (also known as the master boot record or partition table). Each physical hard disk drive has one of these sectors. A single physical disk can be partitioned into one or more logical disks. For example, you may have a physical drive partitioned into C: and D: logical disks so that your single physical disk appears (to Integrity Master (tm) - 51 - Version 1.13a DOS) to be two logical disks. The single partition sector con- tains the information that describes both logical disks. If the partition sector is damaged, then DOS may not even recognize that your disk exists. The partition sector also contains a program which is executed every time you power up or boot your PC. This program exe- cutes and reads the DOS boot sector which also contains a program. Numerous viruses plant their code in the partition sector. System sector viruses modify the program in either the DOS boot sector or the partition sector. Since there isn't much room in the system sector (only 512 bytes), these viruses usually have to hide their code somewhere else on the disk. These viruses sometimes cause problems when this spot already contains data which is then overwritten. Some viruses, such as the Pakistani BRAIN virus mark the spot where they hide their code as bad sectors. This is one reason to be alarmed if CHKDSK suddenly reports additional bad sectors on your disk. These viruses usually go resident in memory on your PC, and infect any floppy disk which you access. Simply doing a DIR on a floppy disk may cause it to be infected. Some viruses will infect your diskette as soon as you close the drive door. Since they are active in memory (resident), they can hide their presence. If BRAIN is active on your PC, and you use a sector editor such as Norton's NU to look at the boot sector of an infected diskette, the virus will intercept the attempt to read the infected boot sector and return instead a saved image of the origi- nal boot sector. You will see the normal boot sector instead of the infected version. Viruses which do this are known as stealth vi- ruses. In addition to infecting diskettes some system sector viruses spread by also infecting files. File Viruses ------------ In terms of sheer number of viruses, these are the most common kind. The simplest file viruses work by locating a type of file that they know how to infect (usually a file name ending in ".COM" or ".EXE") and overwriting part of the program they are infecting. When this program is executed, the virus code executes and infects more files. These overwriting viruses do not tend to be very successful since the overwritten program rarely continues to func- tion correctly and the virus is almost immediately discovered. The more sophisticated file viruses modify the program so that the original instructions are saved and executed after the virus finishes. Just as system sector viruses can remain resident in memory and use "stealth" techniques to hide their presence, file viruses can hide this way also. If you do a directory listing, you will not see any Integrity Master (tm) - 52 - Version 1.13a increase in the length of the file and if you attempt to read the file, the virus will intercept the request and return your original unin- fected program to you. This can sometimes be used to your advan- tage. If you have a "stealth" virus (such as 4096 or Dir-2), you can copy your program files (*.EXE and *.COM files) to files with other extensions and allow the virus to automatically disinfect your files! If you "COPY *.COM *.CON", and then cold boot your PC from a known good copy of DOS and "REN *.CON *.COM", this will disinfect the renamed files. Be aware that some file viruses (such as 4096) also infect overlay files as well as the more usual *.COM and *.EXE files. Overlay files have various extensions, but ".OVR" and ".OVL" are common examples. Miracle Infections ------------------ Would you believe that viruses can infect your files without chang- ing a single byte in the file? Well, it's true! There are two types of viruses that can do this. The more common kind is what is called the companion or spawning type virus. This virus infects your files by locating a file name ending in ".EXE". The virus then creates a matching file name ending in ".COM" which con- tains the viral code. Here's what happens. Let's say a companion virus is executing (resident) on your PC and decides it's time to infect a file. It looks around and happens to find a file called "WP.EXE". It now creates a file called "WP.COM" containing the virus. If you type "WP" and hit enter, DOS will execute "WP.COM" instead of "WP.EXE". The virus executes, possibly infecting more files and then loads and executes "WP.EXE". The user probably doesn't notice anything wrong. This type of virus is fortunately easy to detect by the presence of the extra ".COM" files. There are some instances where it is normal to have both ".COM" and ".EXE" files of the same name (such as DOS 5's DOSSHELL) but this is relatively rare. It is also possible for a virus to plant either .COM or .EXE files for existing .BAT files, (IM will detect this and warn you), but this is unlikely to be an effect stategy. There is a new type of virus known as a "cluster" virus which infects your files not by changing the file or planting extra files but by changing the DOS directory information so that directory entries point to the virus code instead of the actual program. When you type the name of the program, DOS loads and executes the virus code, the virus then locates the actual program and executes it. Dir-2 is an example of this type of virus and is now spreading rapidly around the world. We are deliberately keeping our descrip- tion of this type of virus rather vague to avoid making it easier to write this type of virus. Integrity Master (tm) - 53 - Version 1.13a How many PC viruses are there? ------------------------------ There are more PC viruses than all other viruses combined, by a large margin. Estimates of exactly how many there are vary widely and are constantly growing. About a year ago, estimates ranged from 200 to 500. Now estimates range from 600 to 1300 different viruses. This confusion is partly due to the fact that it's difficult to agree on how to count viruses. New viruses frequently arise from some idiot taking an existing virus that does something like put a message out on your screen saying: "YOUR PC IS STONED" and changing it to say something like "Donald Duck is a lie". Is this a new virus? Most "experts" say "yes." This is a trivial change that probably took all of about two minutes to make and we have another virus? Another problem comes from viruses that try to conceal themselves by mutating. In other words, each copy of the virus may be different than its parent. One example, the WHALE (a huge clumsy 10,000 byte virus) creates 33 different versions of itself when it infects files. At least one researcher counts this as 33 different viruses on their list. Many of the large number of viruses known to exist have not been detected in the wild but exist (hopefully) only in someone's virus collection. Several authors of anti-virus products, including Mark Washburn and Ralph Burger, have written sophisticated viruses which are now on the loose, but other viruses that they created apparently exist only in virus collections. David M. Chess of IBM's High Integrity Computing Laboratory reports in the November Virus Bulletin that "about 30 different viruses and variants account for nearly all of the actual infections that we see in day-to-day operation." How can there be only 30 viruses active when some "experts" report such high numbers? This is probably because most viruses are poorly written and can not spread at all or spread without betraying their presence. Although the actual number of viruses will probably continue to be hotly debated, what is clear is that the overall number of viruses is increasing rapidly although perhaps not quite as rapidly as the numbers might indicate. How serious are viruses? ------------------------ It's important to keep viruses in perspective. There are many other threats to your programs and data that are MUCH more likely to harm you than viruses. A well known anti-virus researcher once said that you have more to fear from a cup of coffee than from viruses. While the growth in number of viruses now puts this statement into question, it's still clear that there are many more occurrences of data corruption from other causes than from vi- ruses. So, does this mean that viruses are nothing to worry about? Emphatically, no! It just means that it's foolish to spend a lot of Integrity Master (tm) - 54 - Version 1.13a money and time on addressing the threat of viruses if you've done nothing about the other more likely threats to your files. Because viruses have been deliberately written to invade and possibly damage your PC, they are the most difficult threat to guard against. It's pretty easy to understand the threat that disk failure represents and what to do about it (although surprisingly few people even address this threat). The threat of viruses is much more difficult to deal with. There are no "cures" for the virus problem. Why is this so? We'll explore this in the next chapter on "Protecting Your PC." Integrity Master (tm) - 55 - Version 1.13a _______________________________________________________________________ CHAPTER TWO - P r o t e c t i n g Y o u r P C Hardware Protection ------------------- Hardware is the foundation upon which your whole system is built. If you have more than one or two PC's, you probably owe it to yourself to buy some diagnostic programs. If your PC is perform- ing strangely or if a file is damaged, it's vital to be able to deter- mine whether hardware is the cause. You probably don't want to call in a repair person each time something strange happens. Even if you have just one or two PCs, there are some fairly low cost diagnostic programs which are worth having. One problem with diagnostic software (and hardware too, for that matter) is that when you run the diagnostics, everything may work perfectly, yet some time earlier there definitely was a problem. Intermittent problems like this are all too common. Disk problems can be the most insid- ious in this respect. When you run the diagnostics everything works fine. How can you find out what's happening? Run a comprehensive data integrity product (surprise)! This way you can determine if some data was damaged, but you don't have to spend days running diagnostics. This also lets you know as soon as your disk is starting to have problems rather than waiting for things to get so bad that you notice it. This almost goes without saying, but buy whatever you can to protect your hardware from failing in the first place. Buy surge protectors, keep your PC clean, and regularly clean the heads on your tape and diskette drives. Be sure to protect your PC and keyboard from spilled coffee and similar threats. Your hard disk is going to fail! It's not "if" but "when"! It's absolutely vital to be able to deal with this threat. Basic to dealing with this threat and most of the others is having backups. Please read the section in Chapter five on Backup Policy. Since your hard disk is very likely going to start performing erratically before it totally fails, it's vital to detect this as it's happening and to be able to determine what is causing the problems. It will very likely NOT be obvious to you whether a hardware problem, software problem or a virus is damaging your files. More on making this determina- tion in the section in Chapter Five titled Determining Causes of Corruption. "Fixing" Your Disk ------------------ Sometimes you will find you have damaged files, which could be caused by hardware, software or who knows what. When you are having the problem, your main concern is often not what caused it, but how to fix the damage. This is where the disk utility programs Integrity Master (tm) - 56 - Version 1.13a offered by Gibson, Norton, Mace and Central Point are often very handy. They can sometimes take unreadable data and extract some of it, or if you have logical damage to your disk such as cross linked clusters, these programs (and DOS CHKDSK) may be able to fix things for you. Unfortunately, things are not always fixed perfectly when these programs say they are. Using a data integrity product (such as Integrity Master) will allow you to determine if everything really was put back together again. More importantly than that, a data integrity product can be used to more accurately diagnose what is wrong to begin with, so you don't attempt a repair which actually makes things worse. Goof Protection --------------- Who hasn't accidentally deleted or copied onto the wrong files at some time? Very few of us! If you have a data integrity product (such as Integrity Master), a utility package (Norton, Mace, PCtools etc) and current backups, you're all set. You could proba- bly do without the utilities, but it's rather convenient to be able to unerase files after you inadvertently delete the wrong ones (this is built into DOS 5). Of course, a backup program or an undelete utility won't help you if you didn't notice the incorrect delete when it happened and you now don't know what to restore or undelete. That's why data integrity software is a vital component to handling this threat. Intrusion Protection -------------------- This may not be an issue if your PC is kept locked in a vault when you're not using it, but otherwise you can never be sure that an intruder hasn't changed something on your PC. Do you think we're exaggerating? We're not! The intruder may be your spouse or kids. They probably have no intention of changing anything but may be confused on how to use one of the programs on your PC, with the result that they inadvertently change the wrong file. On the other hand, you may work in an environment where someone may want to deliberately do you harm or perhaps just "play a little joke" on you. There are programs available which modify the partition sector on your PC so that the hard disk is unavailable unless someone pro- vides a password. There are add-in boards that provide the same function. Some PCs (eg. PS/2 PCs) come with a power-up pass- word. You can lock the case to your PC to make it more difficult to open. You may wish to consider any of these options depending upon how much risk you face, but please realize that they can all be bypassed in less than ten minutes by a knowledgeable user. Surveillance cameras are regarded as a fairly good deterrent to PC tampering. Integrity Master (tm) - 57 - Version 1.13a While you can't totally stop someone from breaking into your PC, you can detect and correct the damage. By using an integrity program which allows you to encrypt the integrity data or store the data off-line (on floppies), you can detect any illegal tampering, even from a technically advanced adversary. V I R U S D E F E N S E S --------------------------- There are numerous methods in use to protect against viruses. What follows is a quick review of the viral defense mechanisms which are widely used today. Scanners -------- Once a virus has been detected, it is possible to write programs which look for telltale code (signature strings) characteristic of the virus code. The writers of the scanner have extracted identifying strings from each virus of which they are aware. The scanner then searches memory, your files and system sectors for these signature strings. This obviously detects only known, preexisting, viruses. If a virus "mutates", in other words, changes each copy of itself somewhat, then this technique may not work. The virus V2P7 reportedly has billions of possible mutations and apparently can not be detected with assurance by normal scanning. Another, simpler, way for a virus to effectively mutate, is for a programmer to modify it after its initial release to change its behavior. It happens not too infrequently that a virus is changed just to avoid the scan- ners. A major drawback to scanners is that it's dangerous to depend upon an old scanner. With the dramatic increase in the number of viruses appearing, it's dangerous to depend upon anything other than the most current scanner. Even that scanner is necessarily a step behind the latest crop of viruses since it takes quite a bit of time before a new virus is distributed to most virus researchers, analyzed and the changes incorporated into the new program and the new program released. Commercial retail software takes so long to get to the shelves, that it is almost certainly out of date. Yet many retail products depend upon their scanner for most of their effectiveness. IF YOU DEPEND UPON A SCANNER, BE SURE TO GET THE LATEST VERSION DIRECTLY FROM THE AUTHOR. ALSO, BE SURE YOU BOOT FROM A CLEAN WRITE PROTECTED COPY OF DOS BEFORE RUNNING THE SCANNER; THERE'S A GOOD CHANCE THAT THE SCANNER CAN DETECT A RESIDENT VIRUS IN MEMORY, BUT IF IT MISSES THE VIRUS IN MEMORY, THE SCANNER WILL WIND UP SPREADING THE VIRUS RATHER THAN DETECTING IT. EACH AND EVERY SUSCEPTIBLE PROGRAM ON YOUR DISK COULD BE INFECTED IN A MATTER OF MINUTES THIS WAY! Integrity Master (tm) - 58 - Version 1.13a Disinfectors ------------ Most vendors that sell scanners also sell a disinfector (sometimes it's the same program). A disinfector has the same limitations that a scanner has, in that it must be current to be safe to use and it's always one step behind the latest crop of viruses. The disinfector, however, has an even bigger disadvantage: Many viruses simply can not be removed without damaging the infected file. There have also been numerous reports that files are still damaged even when the program claims to have disinfected the file. A disinfector like a scanner can be a very handy tool in your anti-virus arsenal, but it must be used with care. If you use a disinfector, be sure you have the latest version direct from the author and use an integrity check to verify that all files and system sectors are correctly restored. Currently, one of the oldest and most common infector of files is the Jerusalem (1813) virus. All disinfectors naturally claim to be able to remove this virus. Yet the Jerusalem virus frequently overwrites part of the original file (due mostly to its many bugs) making it impossible to restore the infected program. In spite of this, most (if not all) disinfectors claim to disinfect Jerusalem in- fected files. A very dangerous situation! It must be stressed that: IT IS TOTALLY UNSAFE AND IRRESPONSIBLE TO DEPEND UPON DISINFECTORS AS A WAY TO RECOVER FROM VIRUS INFECTIONS. Interceptors ------------ This technique is particularly useful for defusing logic bombs and trojans. With this method, the anti-viral code monitors operating system calls which write to disk or do other things that the program considers threatening (such as installing itself as a resident pro- gram). There is, however, no reliable way to intercept direct branches into low level code or to intercept direct input and output instructions done by the virus itself. Some viruses attempt to modify the interrupt 13H and 26H vectors to disable any monitor- ing code. It is important to realize that monitoring is a risky tech- nique. Some products which use this technique are so annoying to use (due to their numerous messages) that some users consider the cure worse than the disease! An interception (monitoring) product would be a useful adjunct to a data integrity program, as protection against some the more simple minded logic bombs. Integrity Master (tm) - 59 - Version 1.13a Inoculators ----------- There are two types of inoculators or so-called immunizers. One modifies your files and system sectors in an attempt to fool viruses into thinking that you are already infected so they won't infect you again. This is done by making the same changes that the viruses use to identify the file or sector as infected. This works only for a small number of viruses and in our opinion is of questionable value. The second is actually a type of integrity check technique where the check data and the checking code are planted in the program itself. When the program is executed, the check code first com- putes the check data and compares it with the stored data. This technique can be circumvented by a virus which would modify the self-checking code or the check data. Again a very questionable technique. This is the way some products claim to detect unknown viruses. ROM and Encryption ------------------ Placing executable code on a hardware write protected device, will protect all those programs on that device. DOS in ROM (Read Only Memory) is found on some PCs. This provides some degree of protection, but all the other programs are still vulnerable to infection. The more programs you can isolate on a write protected devices the more effective this technology is. Encryption is a promising technique which so far has not been successfully used to protect a system. Encrypting as many of your files as possible makes life harder for viruses, but does not stop them since there is always some unencrypted code around (boot sector, BIOS, DOS, device drivers etc). Integrity Checkers ------------------ Integrity checkers work by reading all your files and recording integrity data which acts as a signature for the file. An integrity check program is the only solution which can handle all the threats to data integrity that we've mentioned here. In theory a well writ- ten integrity checker should be able to detect any virus. So, why isn't everyone using an integrity checker? Well, until recently there hasn't been an integrity checker available without some significant drawbacks. As a matter of fact many anti-virus products now incorporate integrity checking techniques. The problem with them is that they don't use these techniques in a comprehensive way. There are still too many things not being checked. Integrity Master (tm) - 60 - Version 1.13a If you choose an integrity checker, be sure it has all these features: o It's easy to use with clear unambiguous reports and built-in help. o It hides complexity, so that complicated details of system file or system sector changes are only presented if they present informa- tion the user must act upon. o The product recognizes the various files on the PC so it can alert the user with special warnings if dangerous files have changed. o It's fast. An integrity checker is of no use if it's too slow to run. o It recognizes known viruses, so the user doesn't have to do all the work to determine if a change is due to a software conflict, or if it's due to a virus. o It's important that the integrity computation be more sophisticat- ed than a mere checksum. Two sectors may get reversed in a file or other damage may occur which otherwise rearranges data in a file. A checksum will not detect these changes. o It's comprehensive. Some integrity checkers, in order to im- prove their speed, don't read each file in its entirety. They read only portions of larger files. They just spot check. This is unacceptable - it's important to know the file hasn't changed, not just that some of the file hasn't changed. o It checks and restores both boot and partition sectors. Some programs check only files. (Naturally Integrity Master does all these things.) Gadgets ------- There are currently some gadgets (hardware devices) which are sold as virus protection. So far, we haven't seen anything which provides protection beyond what is offered by software only products. Beyond putting some of the anti-virus code in read only memory (ROM), we've seen little that can be accomplished by existing hardware. In one case, the hardware was used to store some integrity data; a floppy disk can do the same thing and it's actually more secure. Integrity Master (tm) - 61 - Version 1.13a Prevention: ----------- Hardware techniques, such as placing all your programs in read only memory (ROM), can, in theory, provide virus prevention, but nothing even comes close to doing this yet. Pure software tech- niques can probably not prevent all viruses. There are all sorts of schemes which make it more difficult for a virus to penetrate your system, but none totally eliminate the threat of a virus. For each software based technique, there is a way a virus could circumvent it. Software helps a lot but isn't absolute protection. While pre- vention of viruses may not be possible, detection is. Detection, if applied carefully, can detect all viruses, no matter how tricky. If viruses are detected before they spread, the most serious aspect of the virus threat is eliminated. If integrity checking (detection) is practiced widely, the threat of a virus spreading to millions of PCs and then years later doing a destructive act can be eliminated. Integrity Master (tm) - 62 - Version 1.13a _______________________________________________________________________ CHAPTER THREE - V i r u s M y t h s M y t h i c a l S o u r c e s ------------------------------- ATTACHMENT TO A NETWORK OR BBS ------------------------------ Simply being attached to a network (such as CompuServe, or Internet), a bulletin board system (BBS), or even a local area network will not make you susceptible to viruses. The only way you can get a virus is to execute a program on your PC which you obtained over the network. The mere act of downloading the program is harmless; it's only by downloading and then executing an infected program, that your PC can become infect- ed. Also, reading electronic mail can not infect you. There is one thing that can happen though. If you have the device driver ANSI.SYS (or an equivalent) loaded (in your CONFIG.SYS file), someone could send you an ANSI sequence which assigns a set of DOS commands to a key on your keyboard. This "prac- tical joke" could potentially cause some trouble, but it certainly can't reproduce and isn't a virus. FROM DATA --------- Since data is not executed, you can not become infected from data. If someone sent you a data file which contained a virus, you would have to rename the file and then execute it in order to become infected! You can, however, become infected from a diskette that is not bootable and contains no (apparent) programs. The explanation for this is that all diskettes have a boot sector which contains a program that can become infected by a boot sector virus. If leave such an infected diskette in your drive when you power up or boot, your PC will be infected! FROM CMOS MEMORY ---------------- PC AT (80286 and 80386 based) type computers and later models contain a small amount of battery backed CMOS memory to store the configuration and to maintain the time and date. This memory is never executed, so although it could be damaged by virus, you can never become infected from CMOS memory. Q u i c k a n d E a s y C u r e s --------------------------------------- We've discussed the various approaches to the virus problem, and you've no doubt seen that there are no instant cures for viruses, yet many products make claims which they can't live up to. Everyone would like to just buy product X, run it, and be rid of viruses forever. Unfortunately there is no such easy cure. Integrity Master (tm) - 63 - Version 1.13a S i l l y T r i c k s ----------------------- There have been many articles and books written by various virus "experts" which propose doing all kinds of things to virus proof your PC. Here are some of these suggestions which are so ineffec- tive that they are not worth the trouble it takes to do them: WRITE PROTECTING YOUR FILES --------------------------- You can use the DOS ATTRIB command to set the read only bit on files. This is so easy for a virus (or any program) to bypass, it's just not worth the trouble it causes. HIDING OR RENAMING COMMAND.COM ------------------------------ COMMAND.COM is one of the programs which executes each time you boot your PC. There was an early virus which only infected COMMAND.COM so this idea of hiding or renaming this file began. Today many viruses actually go out of their way to avoid infecting this file, since some anti-virus products single out this file and a few others for special scrutiny. CHECKING TIME AND DATE STAMPS ----------------------------- It's certainly OK, to check the time and date stamps of your executable files, but this not a reliable way to catch viruses. Many viruses are smart enough not to change the time and date stamps when they infect a file. Some viruses even hide the change to file's size when they infect a file. C e r t i f i e d S o f t w a r e ? ------------------------------------- It's the policy in many companies to have a certification desk where all software executed on PCs must be checked out. The person at the certification desk usually runs the software through an anti-virus product to check for known viruses and then sets the date ahead on the PC and checks for anything strange. If all looks OK, the software is certified clean. This is actually a reasonable idea. The myth comes from the "certified clean" label. As we've seen in our discussion of virus triggers, simply setting the date ahead is not good enough to set off most virus triggers. The danger comes from people taking the "Certified clean" label too seriously. It's just not possible to know for sure that any piece of software doesn't contain a virus. An unknown virus could be lurking which simply hasn't triggered yet. If the virus screening desk should get such a virus and the only software they used was a scanner, they could easily spread the virus to all other disks that they are certifying clean! Integrity Master (tm) - 64 - Version 1.13a R e t a i l S o f t w a r e O n l y ? ----------------------------------------- Several "virus experts" have suggested that users avoid download- ing software and avoid shareware. There are no facts to back this up. It is, of course, wise to make sure that you download your software from a source that screens each program for known vi- ruses. You are actually much more likely to be infected from software purchased at a retail outlet than from shareware. Quite a few viruses have been shipped directly from the software manufac- turer in the shrink wrapped packages. One major software compa- ny has on at least two separate occasions shipped a virus with their product. Buying shrink wrapped retail software is much more dangerous than many people think it is, since many retailers accept returned software and then simply rewrap the software and sell it again. This software could have easily been infected by the first user who tried it and then returned it. W r i t e P r o t e c t i n g Y o u r H a r d D i s k ------------------------------------------------------------- There are several programs that claim to write protect your hard disk. Since this is done in software, it can be bypassed by a virus. This technique however will stop some viruses and will protect your disk from someone inadvertently writing to it who shouldn't. These programs are generally less effective than the virus intercep- tion products. It IS possible to write protect a disk using hardware, but this does not seem to be readily available. V i r u s e s a r e t h e B i g T h r e a t ? ----------------------------------------------------- As we've seen in examining the other threats to the integrity of your data, viruses are among the less likely threats that you face. Don't protect yourself against viruses and ignore the other threats! Integrity Master (tm) - 65 - Version 1.13a S a f e C o m p u t i n g ( S a f e H e x ? ) --------------------------------------------------- You may have heard this rumor: "You don't need an anti-virus product, just backup your disk regularly and keep an eye on your programs." Yes, indeed it is vital to have good backups, but that is no longer enough. You may also have heard as long as you don't share programs or download (practice safe hex) you have nothing to worry about. Nothing could be further from the truth; each time you buy a software package you are exposing yourself to potential virus infection. It is not possible to be safe from viruses by secluding your PC! There are now some very sophisticated viruses that can do a lot of damage. Although they may not be very likely to attack your system when compared to other threats, they do represent a very real and very dangerous threat. A threat you can not ignore or combat merely with good backups, seclusion or common sense. S o f t w a r e i s u s e l e s s a g a i n s t v i r u s e s --------------------------------------------------------------------- Maybe we should just surrender to viruses and wait for a fool- proof hardware solution? Software can't defeat software -- right? Wrong! The viruses are playing on your turf, so you have an advantage. By cold booting from a good copy of DOS on diskette, you can bring up a clean operating system (DOS) and then use an integrity checker to look for any unexpected changes. A virus will betray itself in the system sectors or executable files. Integrity Master (tm) - 66 - Version 1.13a _____________________________________________________________________ CHAPTER FOUR - Virus Realities T h e O N L Y R e a l S o u r c e o f V i r u s e s ------------------------------------------------------------- You can't get a virus merely by being connected to a network or bulletin board system (BBS). There is only one way you can get a virus and that's to execute a program containing a virus. Period. End of story. Well, almost the end of the story. What some people don't know is that every disk and diskette has a program on it, even if it appears empty. This program is in the boot sector. Most people don't think of boot sectors as programs or perhaps even know that boot sectors exist. If you leave a data diskette in your A drive and boot your PC, you could be executing an infected program in the boot sector, thereby infecting your PC with a virus. Make sure you NEVER boot from a diskette unless it's a known good copy of DOS. S h a r e w a r e i s a s S a f e o r S a f e r --------------------------------------------------------- There is no reason to avoid shareware. As a matter of fact, if you want to get the very latest anti-virus software, it's easiest to get it as shareware, since you are buying directly from the author, rather than buying something that has had to go from the author to the publisher, then through the distribution chain before it even gets to sit on the shelf. Who knows how long it's been on that shelf? F e w V i r u s F r e e P r o g r a m s --------------------------------------------- Unfortunately, there is no way to look at a program (unless you wrote the program yourself in assembly language) and positively declare there's no virus in it. All you can say is that the program contains no known virus. You never know what may be lurking inside of a program waiting for just the right trigger to begin infec- tion or perhaps an attack. As we've explained, while you can't be sure of detecting a virus while it's inert inside of a program, you certainly CAN detect it as it infects or attacks your files. O t h e r C a u s e s m o r e l i k e l y ----------------------------------------------- Viruses are not the greatest threat to your data, so let's not forget about the other threats too. W r i t e P r o t e c t i n g F l o p p i e s ------------------------------------------------- While write protecting your files and your hard disk are of ques- tionable value, you definitely CAN write protect your floppy disks. Just cover the notch on the 5.25 inch diskettes or on 3.5 inch disk- ettes, slide the little tab to expose the hole. The only risk here is that some diskette drives may be defective and still allow writing on the diskette. If in doubt, do a test and check out your drive. Integrity Master (tm) - 67 - Version 1.13a B e w a r e t h e C E a n d t h e D e m o ! ----------------------------------------------------- According to our reports, one of the major sources for infections is the customer engineer (CE) or repairman. The CEs frequently carry diagnostic diskettes with them when they go from PC to PC on service calls. It's all to easy for these diskettes to become in- fected. Salesmen doing demos on various PCs are also very sus- ceptible to getting their demo diskettes infected. V i r u s e s a r e g o i n g t o g e t w o r s e ----------------------------------------------------------- Not only are we seeing the number of viruses grow at an alarming rate, but we are seeing more sophisticated and better written vi- ruses. The rate of reported infections has increased rapidly. One company (Certus International, a vendor of anti-virus software) was quoted in Information Week (a national trade journal) that based on their reports, one out of four PCs was infected every month! While one PC in four seems a bit hard to believe, it's clear that viruses are no longer something one can dismiss as very un- likely. Viruses are, in fact, a threat that we must address one way or the other. Integrity Master (tm) - 68 - Version 1.13a ____________________________________________________________________ C H A P T E R F I V E - W h a t t o d o - s o m e s u g g e s t i o n s --------------------------------------------------------- Action is Vital - Now! ---------------------- Too many people wait for a virus to attack their PC before they take any action. At this point it may be too late to recover dam- aged files. There are many viruses that can not be successfully removed due to the way the virus infects the program. It's abso- lutely vital to have protection before the virus strikes. It's also vital to protect against all threats to data integrity, not just viruses. All threats to data integrity are much easier to deal with if they are detected as early as possible. If you wait until you notice that your hard disk is losing data, you may already have hundreds of damaged files. Backup policy ------------- It's critical that each and every PC be regularly backed up and that all software be carefully protected. Do you have a single PC which you can afford NOT to regularly backup? It's rare to find any PC which does not have some type of important data stored on it. Suggested Backup Policy: ------------------------ 1) All original software (program) diskettes should immediately be write protected, copied and stored in two safe, separate, loca- tions after installation. If you are using an integrity check program, immediately record (initialize) the integrity data for the new programs after installing. 2) Considering how frequently data changes on each PC, decide on a schedule for full backups. It is an excellent idea to have at least three full sets of backup tapes or diskettes and to store one set at another location to protect against fire, theft or some other disaster. If your data is critical, you may wish to have a sepa- rate cycle of backups (eg. quarterly or yearly) which can be used to recover from in situations where someone deletes a vital file, but the deletion isn't discovered until six months later. 3) The full backups should be coordinated with daily incremental backups. The incremental backup, which copies just the files that have changed, normally runs very quickly and takes just a minute or so. 4) Make sure you use reliable backup hardware and software. Periodically test by restoring from a backup. Too many people have discovered that their backup program couldn't recover their files when it was too late. If you use an integrity check program you can verify that the restored files are correct. Integrity Master (tm) - 69 - Version 1.13a Integrity Checking Policy ------------------------- Each PC which has data that you can't afford to lose or have corrupted should have a schedule of regular integrity checking, similar to the backup schedule. By doing once a week full integrity checks, you can stay one step ahead of any trouble. By doing a quick update of your integrity data on a daily basis, you can stay aware of exactly what changes on your PC and why. This way if you start to encounter a software conflict, a failing hard disk, or a virus, you'll be able to quickly differentiate the unusual changes from the usual ones. Whenever you install new software, IMMEDIATELY record the integ- rity data for those programs, so that any future infection or damage can be detected. Whenever you copy programs, check that the new programs are exact copies of the originals. The easiest way to do this is to always copy integrity data along with the programs. You can also use any integrity checker, checksum program, CRC program, cryptographic signature program, or even the DOS COMPARE utility to verify that you made good copies. Do this check only when you know no virus is in control of your PC; therefore, it's best to cold boot from a write protected floppy to verify your program copies are good. If you have diagnostic software, plan to run it at intervals. If you leave your PCs turned on at night, why not leave them running diagnostics. Run CHKDSK ---------- Run CHKDSK (or some equivalent program such as NDD) daily on each PC, and pay attention to the results. If you are seeing problems, be sure you understand what's causing the problems. If you are experiencing cross linked or lost clusters, something is being damaged. Run an integrity checker to find out exactly what is being damaged. Also pay attention to the amount of available memory. If this suddenly changes with no new resident (TSR) software installed, you may have a virus. Integrity Master (tm) - 70 - Version 1.13a Determining Causes of Corruption -------------------------------- It's not a question of "if" but a question of "when"; all too soon you are going to encounter a damaged file (a file which has changed for unknown reasons). How can you determine what caused the damage? o First gather as much information as possible. Did you do any- thing unusual? Did you install any new software? Did you execute any programs which you don't normally? Have you seen any signs of hardware problems? (See the section following on signs of hardware problems). o Run CHKDSK to see if your directories and other areas are OK. o Run a full integrity check to see if anything else has changed. o If you suspect hardware problems as the culprit, then run any diagnostic programs you have. If the diagnostics don't turn anything up, but you still suspect a hardware problem, then run your integrity check in full check mode daily for a while. This should help track down exactly what's happening on your PC. o If you suspect software problems, run the software in question and then run your integrity check to see if anything is being corrupted. When doing this, it's very helpful to duplicate the original situation of the problem as closely as possible. Make sure the hardware is the same and that you have exactly the same resident programs and device drivers loaded as when the problem first occurred. o Could the problem be a virus? If you think so, have you seen any of the signs of virus activity listed in the next section? Are only executable files (such as files ending in .EXE, .COM, .OVR, .OVL .BIN, or .SYS) affected? If so, how many? If more than one or two unrelated program files have mysteriously changed, it could likely be a virus. Remember that some programs (such as Wordstar and SETVER) modify themselves as part of normal execution. If the programs have changed but the DOS time and date stamps haven't, this is further reason to suspect either a serious problem or a virus. If you are not using an advanced integrity checker (such as Integrity Master) which recognizes known viruses, you may wish to get a virus scanner at this point to see if you have a known virus. If this turns up nothing, then it's time to play detective - you may have discovered a brand new virus (lucky you!). Please see the section in Chapter Six on Playing Detective. Integrity Master (tm) - 71 - Version 1.13a Education --------- The single most important thing that you can do to assure the integ- rity of the data on your PCs is to educate everyone who uses a PC. It's vital that they understand how to backup their files and what files normally change on their PC and which ones don't. If you can train them to understand the output of a thorough integrity check program, you can sleep at night knowing that all is well with your PCs! Even lacking an integrity check program, it's vital that everyone be aware of what problem signs to look out for with respect to the most dangerous threats to data integrity. Signs of Hardware Problems -------------------------- Watch out for increasing error messages that the disk is not ready when you try to boot the PC. If you periodically experience any type of disk error message (even if it goes away eventually), or if disk accesses seem to be getting consistently slower, you may be experiencing the beginning of a serious disk problem. Signs of Software Problems -------------------------- These indications could indicate software conflicts or bugs: o CHKDSK reporting problems. o A file which was just processed by a program (such as a spread sheet) is damaged or unreadable by the program but you can copy the file with no error messages. Signs Of Viruses ---------------- These symptoms may betray the existence of a virus: o Disk activity when there should not be any activity. o Programs taking longer to load but the disk drive appears to be healthy. o Any unexplained behavior on the PC such as music, bouncing balls, black areas on the screen, falling letters, weird messages, or unexplained slowdown of the PC. o A decrease in the amount of available memory on your PC or unexplained bad spots on your disk or fewer total bytes (as re- ported by CHKDSK). o If you find extra ".COM" or ."EXE" files showing up you may have a companion style virus. Integrity Master (tm) - 72 - Version 1.13a Responsibility -------------- If you are in a larger organization, it's crucial that someone have the responsibility for assuring data integrity. The first task facing this person would be to assure that all important data is backed up and that all users are educated with respect to normal operation of their PC. The next step would be to start a regular program of integrity checking. Policy and routine ------------------ The procedures for backing up and checking the integrity of critical data can not be left to word of mouth, but should be set forth in a written set of procedures. Data integrity is too important to leave to chance. If this isn't done, guess what gets put on the back burner (in other words: not done), when people get busy? (Who isn't busy?). Some recommended procedures: o Never leave a floppy disk inserted in a drive longer than neces- sary. Remove all diskettes immediately. This reduces the chance inadvertently booting from the diskette and picking up a boot sector virus. o Check the integrity of all files after installing new software or copying programs. o If a stranger (such as a repair person or salesman) runs software on a PC, do a full integrity check immediately afterwards. o Immediately write protect and backup all diskettes containing software. o Schedule regular incremental and full backups. Networks and Viruses -------------------- If at all possible, do not have shared disks containing executable files which the workstations have write access to. Run regular integrity checks on the file server. This is important on the workstations too, but is critical on the file server since an infected file here could quickly infect all the workstations on the network. Never access an unchecked workstation with network administrator authority. Integrity Master (tm) - 73 - Version 1.13a _______________________________________________________________________ CHAPTER SIX - Handling a virus attack Don't panic and don't believe the virus --------------------------------------- Do not do anything rash if you suspect a virus attack. Be skeptical, there are quite a few practical joke programs that behave exactly like viruses. There's even a virus simulator which simulates the Ping Pong (bouncing ball), Jerusalem (black hole), Cascade (falling letters on the screen), Yankee doodle (music) and a few other viruses. It's perfectly harmless, but it has alarmed many people. Don't do anything drastic until you confirm that it really is a virus. If the virus is busy doing something and says not to turn off the PC, turn it off anyway and boot from a clean write protected copy of DOS. There's a good chance that the virus may be busy de- stroying your entire disk. Don't blindly do what the virus tells you to! Report the attack ----------------- Report the virus attack to the police or to a virus researcher or anti-virus developer. We need to stop sweeping this under the rug. If we can track where viruses first get started, then maybe we can apprehend the culprits that are writing and distributing these things. Play Detective -------------- It is very important that you track down how you got the virus. If you got it from someone's software, it's vital that they be notified. The sooner these viruses are detected, the less damage they can do. Suppose you have indications of a virus, but your software doesn't identify it as a known virus. What do you do? First of all cold boot (hit the red reset button or power off and back on) from a known good write protected copy of DOS on a diskette. Run a full integrity check. Run CHKDSK and print the results. Now execute any suspect programs. Execute them several times. Viruses may wait for some trigger event to begin infection. Run CHKDSK again to see if the amount of free memory has been reduced. This is a sign of a virus going resident in memory. Now cold boot again and rerun an integrity check. Repeat this cycle with the various suspect programs. This should track down the guilty program if you've got one. Keep in mind that if it's a virus, it will modify other programs and those programs should themselves further modify other programs. By executing the modified pro- grams, it's possible to tell whether you really have a virus or you just have a buggy program which is accidentally writing to other programs. Integrity Master (tm) - 74 - Version 1.13a Clean House ----------- Follow these steps when removing a virus from your PCs: o Cold boot (Power off and on or hit the reset button) from a known good write protected copy of DOS. o Delete all infected files. o Reload any infected system sectors. If you do not have a utility to reload the DOS boot sector, you can use the DOS SYS command after cold booting from a write protected diskette (eg. "SYS C:"). o Rerun a full integrity check, or at least a scan if you don't have an integrity checker. o Check any floppies which may have been infected. Remember, if you have a system sector virus such as Stoned, Joshi or Brain, even empty data diskettes can be infected. Check them all. o Notify any other PC user you have contact with to check their PCs. Guard the house --------------- Virus infections return in a very high number of cases. This is usually because somewhere there is an infected file or diskette which was missed in the first cleaning. Run your integrity checker or anti-virus program daily, for the next month, to catch a possible repeat infection. Integrity Master (tm) - 75 - Version 1.13a I N D E X Abandon changes, 39 Control card, 30, 31 Abort, 39 Copying IM files, 11 Advanced Option Menu, 18, 33, 37, 38 Copying programs, 22, 69 Algorithms, 16 Corruption, 23, 24, 26, 31, 36 Alternate colors, 13 Corruption, 45, 46, 50, 70 ALTernate key, 20 Counting viruses, 52, 67 Alt/X, 20 Critical error, 27 ANSI.SYS, 62 Cross linked clusters, 45, 56, 69 APPEND, 10 Cryptographic signatures, 8, 16 ASSIGN, 10 Current and Lower directories, 17 Attack phase, 21, 49 Current diRectory only, 17 Auto-named report file, 18, 19, 29 Current option settings, 34 Customer engineer, 67 Backups, 55, 56, 65, 68, 71, 72 Customizing, 33 Bad sectors, 51 Data integrity, 9, 26, 45, 47, 56, Badly damaged disks, 19 68 Batch file, 31 Data recovery tools, 46 Batch files, 30 Date stamp, 9, 29, 36, 56, 63, 67, BBS, 62, 66 70 BIOS, 47, 59 Descendant directories, 17 Bitnet, 1 Destroying viruses, 26 Boot sectors, 18, 19, 38, 50, 51, Device number, 19 60, 62, 66, 72 Diagnostic programs, 8, 27, 55, ,56, Brain virus, 51, 74 69, 70 Bugs, 47 Directory change, 20 Bypass memory check, 25, 30, 41 Dir-2 virus, 51 Disinfection, 25, 26, 58 Cascade virus, 24, 73 Disk change, 20 Certified software, 63 Disk drives, 8, 19, 20, 27, 38, 55 CGA, 36 Disk errors, 8, 27, 28, 31, 42, 46, Change history, 18 55, 71 Change management, 8, 29 Disk failure, 16, 19, 46, 55, 69 Change menu, 37 Disk letters, 38 Changes to executable programs, 23 Downloading, 62, 64, 65 Check disk for known viruses, 18, 22 Check menu, 43 Education, 71 Check values, 32 Electronic mail, 1, 62 Checking specific files, 17 Encryption, 9, 16, 38, 59 Checksum, 60 Ending, 20 CHKDSK, 45, 47, 51, 56, 69, 71, 73 Entire disk integrity, 17, 22, 26 Cluster viruses, 25, 52 Entire disk integrity initialize, 15 CMOS, 62 Error levels, 31 Cold booting, 21, 23, 25, 26, 41, Error recovery, 19, 42 43, 73, 74 ESCape, 20, 39 Colors, 13, 33, 42 Evaluation, 11 Command line, 13, 25, 30, 33, 36, Example report, 27 41, 42 Executable files, 18, 22, 23, 24, CoMmands menu, 20 35, 36, 39, 40, 43, 49, 51, 59, COMMAND.COM, 63 62, 63, 65, 68, 70, 72 Common Questions, 42 Exit, 38 Companion viruses, 21, 25, 37, 52, Explanation of the display, 15 71 Extend disk life, 27 CompuServe, 1 Configuration, 38 F1 (key), 14, 15 Integrity Master (tm) - 76 - Version 1.13a False alarms, 25, 43 Integrity initialize, 8 Fastest way to exit, 20 Interceptor, 47, 58 File corruption, 8, 24, 25, 26, 31, Intermittent problems, 27, 55 34, 36, 45, 47, 50, 70 InterNet, 1 Files on current Disk, 17 INTERNET "virus", 48 Files to check, 35 Introduction, 45 Files to iNitialize, 22, 35 Intrusion protection, 56 Files (vital for IM), 12 Finger checks, 8, 46 Jerusalem virus, 24, 58, 73 Fixing your disk, 10, 55 Jokes, 56, 62, 73 Full installation, 11 Full integrity checking, 34, 69, 70, Known viruses, 8, 9, 18, 24, 25, 73, 74 26, 41, 57, 60 General virus checking, 41 Laptop, 13 Glitches, 45 Large disks, 10 Guided tour, 14 LCD display, 11, 13 License terms, 3, 32 Halt menu, 35 Limitations, 10 Hardware configuration, 38 Location of integrity data, 37, 38 Hardware errors, 36, 42, 45 71 Logic bombs, 47, 58 Hardware problems, 26 Logical disk, 19, 38, 50 Hardware protection, 55 Low level format, 27 Harmless viruses, 24, 49 LPT1, 19 Help, 15 Help index, 7 Malicious damage, 46 Help menu, 14 Master boot record, 18, 38, 50 Hidden system files, 39 Maximum number of files, 10 Hiding IM.PRM, 28 Media coverage, 45 How viruses infect, 9, 21, 48 Memory check, 25, 41 Menus, 10, 14, 20 Ignore Time/date changes, 36 Minimum memory, 10 IMCHECK, 39 Miracle Infections, 52 IMcheck license, 32 Misleading results, 10 IMCHECK.EXE, 32 Monitoring, 58 IMprint, 42 Monochrome displays, 13, 42 IMPROC.TXT, 12, 13, 21, 32 Multiple parameter files, 31 IMview.exe, 42 Multiple sets of options, 33 IM.EXE, 12, 32 Music, 21, 24 IM.PRM, 12, 13, 33, 38 Music, 49, 71, 73 Infection phase, 48 Mutating virus, 53, 57 Initialize menu, 15, 22, 41 M.PRM, 28 Initializing integrity data, 15 Inoculators, 58 Networks, 28, 48, 62, 66, 72 Install, No halt mode, 36 full, 11, 16 Nonstop execution, 30, 31 on an other PC, 37 Norton utilities, 46, 51, 55, 56 quick, 11 Installing new software, 22, 69, 70, Only changes reported, 36 72 Open fail, 27, 28 Instructions, 10 Open files, 28 Integrity Advisor, 10, 12, 21, 37 Option settings, 13 Integrity checking, 21, 34, 59, 60, Options menu, 18, 21, 22, 33, 34 61, 65, 69, 72 OS/2, 28 Integrity data, 9, 15, 16, 21, 22, Overlays, 43, 52 27, 28, 38, 59, 68, 69 Overview, 37 Integrity data off-line, 38 Integrity Master (tm) - 77 - Version 1.13a Parameter file, 12, 13, 28, 30, 33, Screen report, 36 34, 38 Scrolling, 35, 36 Parameters, 30, 31 Sectors, 50 Partition sectors, 18, 19, 38, 50, Security, 8, 28, 56 51, 56, 60 Self-check 59 Partition table, 50 Self-modifying programs, 70 Pause (P) key, 36 SetupIM, 7, 11, 13, 14, 16, 18, 21, Pausing, 35 28, 33, 34, 37, 38, 39 Physical disk drive, 19, 38, 50 SETUPIM.EXE, 12 Plan for day to day use, 12 Shareware, 64, 66 Policy, 72 Shelling to DOS, 20, 42 Power faults, 45 Short-cut install, 11 Primary options, 37 Signatures, 9, 16, 27, 32, 57, 59 Printed output, 19 Silly tricks, 63 PRN, 19 Software Attacks, 47 Probability of file damage, 8 Software problems, 46, 70, 71 Procedure for running IM, 21 Solving problems, 42 Procedures, 72 Sound, 36 Program changes, 26 Source programs, 40 Programs, 21, 22, 23, 24, 35, 36, Spawning virus, 52 39, 40, 43, 49, 50, 51, 60, 62, Special characteristics, 9 66, 68, 69, 70, 73 Speed, 9, 23, 29, 41, 60 Statistics Summary, 20 QUESTION.TXT, 42 Stealth, 51 Quick evaluation, 11 Stoned, 49, 52 Quick install, 11 Stoned virus, 53, 74 Quick Update, 21, 29, 34, 69 SUBST, 10 Quit, 39 Suggestions, 68 Quitting, 20 Surge protectors, 55 Summary of statistics, 20 Read fail, 27 Syntax, 30 README.DOC, 12 SYS command, 50 Reinstall, 12 System files, 39 Reload data, 19 System sector, 51 Reload files, 16 System sector changes, 26 ReLoad menu, 19 System sector viruses, 9, 19, 23, Reload Missing partition, 19 50, 51 Reloading system sectors, 15, 74 System sectors, 8, 10, 15, 17, 19, Reminders before checking, 18 21, 50, 57 Removal instructions, 25 Repair, 10, 55 Technical support, 42 Repeat the install, 37 Threats, 9, 21, 45, 46, 53, 64, 65, Report file, 18, 19, 27, 29, 31, 36 66, 68 Report screen, 15 Trigger, 21, 47, 48, 49, 73 Reporting viruses, 24 Trojans, 47, 48, 58 Requirements, 10 TSR, 46, 49, 69, 70 Resident programs, 46, 49, 69, 70 Tutorial, 7, 15 Retail software, 57, 64, 66 Two color display, 12 ROM, 59, 60 Typos, 8, 46 Safe computing, 65 Unattended processing, 30, 31 Save changes, 38 Unauthorized changes, 22, 28 Saving option changes, 33 Unknown virus, 8, 11, 18, 21, 23, Scanning for viruses, 22, 57, 63 59, 63, 70, 73 Screen colors, 13, 33, 37 Unreadable data, 56 Screen display mode, 37 Unusual video adapters, 11 Screen layout, 15 Update hardware configuration, 38 Integrity Master (tm) - 78 - Version 1.13a V2P7 virus, 57 Video adapter, 12, 13 Video mode, 13, 42 Virus, checking, 18, 21, 33, 39, 41, 57 cluster, 52 collection, 53 companion, 21, 52, 71 damage, 15, 19, 21, 24, 26, 47, 49, 50, 53, 58, defenses, 57 definition, 48 Destroying, 26 Detection, 22, 23, 31, 34, 57, 59, 61, 66 experts, 48, 63, 64 how many, 52, 67 infection, 19, 21, 48, 51, 57, 62, 74 known, 9, 57, 60 mutating, 52, 57 myths, 62 names, 24 new, 23, 70 phases, 48, 49 prevention, 60 removal, 25, 43, 58, 68 reporting, 24, 26 resident, 21, 25, 40, 41, 43 resident, 49, 57 scanning, 18, 22, 57, 63 signs, 23, 36, 70, 71 stealth, 51 symptoms, 24 system sector, 9, 19, 23, 50, 51 trigger, 21, 48, 49, 63, 73 unknown, 21, 23, 59, 63, 70, 73 variants, 24, 25, 52, 53 what is it, 21, 48 Virus report, 24 Vital files, 12 Warranty, 3 Whale virus, 53 Why read, 7 Windows, 28, 43 Worm, 48 Write option changes to disk, 33, 34 Write protection, 59, 63, 64, 66, 68, 72