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- HOSPITAL
-
- A suite of virus prevention and detection
- programs for the Atari ST
-
- Neil Forsyth
- Department of Computer Science
- Heriot-Watt University
- 79 Grassmarket
- Edinburgh
-
- neil@uk.ac.hw.cs
-
- Introduction
-
- This suite of programs has been developed to detect and
- prevent the spread of viruses on the Atari ST computer. The
- programs apply primarily to floppy disk boot sector viruses
- but some do have a wider application.
-
- Contents
-
- The complete contents of this package is as follows:-
-
- HOSPITAL.DOC Documentation in 1st Word format
- HOSPITAL.TXT Same but in pure ASCII format
-
- STVIRUS.DOC Discussion on viruses in 1st Word format
- STVIRUS.TXT Same but in pure ASCII format
-
- BOOTCMP.PRG The programs
- DT.TTP
- GOODBOOT.TOS
- MEDICAL.TOS
- RESET2.ACC
- SKULL.PRG
- VACCINE.PRG
- VECHECK.PRG
- WATCHER.PRG
-
- Creating a 100% virus free boot disk
-
- Before using these programs you must ensure that you have a
- safe disk to boot from in the first place. The following steps
- will ensure that you have a known 'clean' disk:
-
- Switch on your computer with no floppy disk in any
- disk drive and with your hard drive switched off.
- This will take some time to boot up (about a minute )
- but it is worth it because we can be sure there is no
- virus in the computer.
-
- Next, insert a blank floppy in the floppy disk and
- format it using the normal desktop formatter. I know
- there are plenty of other formatters available, my
- own included, but if someone had modified them we'd
- be back to square one.
-
- Recommended Setup
-
- After creating your known clean disk it is recommended that
- you place the programs in an AUTO folder on this 'boot disk'
- in the following order1:
-
- VECHECK.PRG
- SKULL.PRG
-
- (other things like hard disk drivers, GDOS etc)
-
- VACCINE.PRG
- WATCHER.PRG
- BOOTCMP.PRG
-
- and on the root of the drive the following files will be
- created by two of the above programs:
-
- VECHECK.DAT
- BOOTCMP.DAT
-
- You need not use all the programs. Some may not suit your
- particular setup.
-
- Always boot up your machine with this disk, or one prepared in
- a similar way, and always keep it write protected if you
- can. This will give you the maximum amount of protection.
-
- BOOTCMP.PRG
-
- This program should be run from bootup.
-
- This program compares the floppy disk boot sector with a file.
- (BOOTCMP.DAT)
-
- When first run it will inform you that it could not find the
- file for comparison and will ask you if you would like to make
- one. Say yes to this and allow it to save to the disk.
-
- If the boot sector is ever changed then the program will stop
- and tell you. It will then ask you if you want to update the
- comparison file. Be absolutely sure that the disk does not
- have a virus before you decide to update the file.
-
- DT.TTP
-
- This is a generally useful disk toolbox.
- The full instructions for it can be obtained by double clicking
- on it and pressing return.
- The two commands relevant to this manual are:-
-
- Reversably change the executability of a boot sector
-
- -esh a:
-
- Change the order of execution of AUTO folder programs
-
- -ash a:
-
- GOODBOOT.TOS
-
- This program allows you to create custom executable boot
- sectors. What the boot sector does is up to you.
- The following options are available:
-
- ° Change to medium resolution on colour displays
-
- ° Change the colour palette to white on black until
- the desktop appears
-
- ° Run a program called COMMAND.PRG instead of the
- desktop
-
- ° Print up a message on screen
-
- If you enable one or more of these options on your boot sector
- then if it ever ceases to behave as it should then you can
- suspect foul play and examine it for a virus.
-
- You can also sterilise a boot sector. This cleans out the
- areas that can hold viruses but leaves the important parts of
- the sector alone. This can be used to kill any viruses you
- find or get rid of any custom boot sectors. Be very careful
- using this option because the code contents of the boot sector
- cannot be retrieved. If you are in any doubt use DT.TTP to
- reversably change the boot sectors executability instead.
-
- Note: If your hard drive is auto-booting then the floppy boot
- sector will not be executed after a soft reset.
-
- MEDICAL.TOS
-
- This is a program for the bulk checking of your disks for
- possible infection. It also checks the machine for possible
- infection.
-
- RESET2.ACC
-
- This desk accessory allows you to reset the computer.
- A soft reset is equivalent to pressing the reset button at the
- back and a hard reset is equivalent to switching the computer
- off then on (there is less stress on the hardware). Some
- viruses can survive a soft reset so if you think your computer
- is infected do a hard reset.
-
- If you have the TOS 1.4 ROM version in your computer then you
- can, usually, reset the machine by holding down the following
- key combinations:
-
- Soft reset: CONTROL-ALTERNATE-DELETE
-
- Hard reset: CONTROL-ALTERNATE-RIGHT SHIFT-DELETE
-
- SKULL.PRG
-
- This program should be run from bootup.
-
- This is a virus killer. If your machine is infected then a
- skull will appear at the left hand edge of the screen and the
- machine will hang up. You must then switch the computer off
- and boot with an uninfected disk.
-
- VACCINE.PRG
-
- This program should be run from bootup.
-
- When run, this program installs itself in the machine and
- attempts to prevent any active virus from infecting a disk. It
- also checks for viral code on incoming disks.
-
- Suspicious behaviour and suspect disks will cause the screen
- to pulsate for a few seconds.
-
- VECHECK.PRG
-
- This program should be run from bootup2.
-
- This program compares the vulnerable areas of memory that
- viruses usually change, with a file (VECHECK.DAT) saved when
- the machine was in a known clean state.
-
- When first run it will inform you that it could not find the
- comparison file and will ask you if you wish to make one.
- Say yes to this but no to the 'Update mask' prompt.
-
- Not all of the memory under scrutiny concerns disk access or
- viruses and some locations change constantly. For this reason
- the comparison file contains a map of the areas to be checked
- as well as what those areas of memory should contain.
-
- If the comparison goes well then an OK message will appear but
- if not the addresses of the differences will be printed with
- the option to update the file. Be sure the machine is not
- infected with a virus before you allow the program to update
- the file.
-
- RAM disks and hard disk driver programs use similar techniques
- as viruses to install their routines in the machine. If you
- have a hard disk drive and it is not auto-booting, then make
- sure this program gets run before the driver program is
- installed.
-
- Reset survivable RAM disks will probably cause the program to
- find differences since they make the system boot up again
- once they have installed themselves. Don't update the
- comparison file in this case because there are reset
- survivable viruses. Just know what to expect from your systems
- unique configuration.
-
- To understand what changes would constitute a possible viral
- threat I recommend you read a technical book about the ST.
-
- WATCHER.PRG
-
- This program should be run from bootup.
-
- When run, this program installs itself in the machine and
- checks that the boot sector has not changed during the
- most vulnerable times.
-
- If the boot sector is changed, probably by a virus, then the
- screen will pulsate for a few seconds to warn you about it.
-
- Disclaimer
-
- I make no warranty with respect to these programs, and
- disclaim any implied/explicit suggestions of usefulness for
- any purpose. Use these programs only if you are willing to
- assume all risks, and damages, if any, arising as a result,
- even if it is caused by negligence or other fault.
-
-