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1988-11-01
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3KB
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64 lines
chkv \
rstv - protection against viruses
clrv /
---------------------------------
Copyright ©1990 by Arthur Hagen
Most viruses live in memory by attaching themselves to one of the
capture-vectors which will be called at boot-time, or by making a resident
structure which also will be run at boot-time. Most virus killers handle
these viruses nicely, and some of them even manages to find new viruses by
actively checking these few crucial places in memory. Alas, everything
hanging around at these addresses need not be viruses. E.g. if you have
more than one meg of chip-ram, and run 'setpatch r' for use with RAD:, two
of the vectors will be set just to recover this. If you use ZKick to boot
with O/S 2.0, four of the vectors will be set. Other utilities like some
resident virus killers may also use these vectors. So, if you include a
virus-killer like 'VirusX' in your startup-sequence, you may actually kill
more than you wanted! Here chkv, clrv and rstv come in handy. chkv is a
small routine that will list the boot-vectors to screen or any specified
file. When running chkv, note if you get any values shown other than
zeroes. This could mean (a) that you have some resident utility that
survives reboot or (b) that you have a virus in memory. If you are quite
certain that you don't have any viruses running, use "chkv >S:Vectors" to
save a copy of what these vectors should be on your specific system. Now
you can use rstv to actually restore these vectors to YOUR defaults after
some virus killer or virus have altered the contents! Just enter "rstv",
and the vectors will be restored, allowing you to reboot as usual. If you
accidentally have rebooted and found out that your RAD: has disappeared
(most probably because of an inferior virus killer or a virus), you might
very well recover your RAD: by running rstv and then reboot. Note that
you MUST have a file named S:Vectors that contain a list of the vectors and
their value. If you don't want to restore some of the vectors, just use
any text editor to delete the line with the vector you want to leave alone.
Sometimes you may want to kill off all boot-resident programs, and start
all over with a clean machine. clrv will do this, if you just enter "clrv"
from the CLI. If you change your mind, just use rstv to restore the
vectors as they should have been.
chkv comes in two flavours, one short and speedy, and one that should
function well even with 68020+'s with cache-ram.
For automatic check at bootup, put chkv2 into the c: directory, and the
following first in your s:startup-sequence:
chkv2 >NIL:
If WARN
Echo "POSSIBLE VIRUS IN MEMORY!"
rstv
Break 1 d
Else
Echo "Memory O.K."
EndIf
That's it!
Oh, yeah, the programs are Public Domain, so you can spread them, modify
them, eat them or do whatever you like.
If you like these programs, try out VScan by the same author.
*Art