Xref: utzoo comp.sys.atari.st:14359 comp.sys.apple:10489 comp.sys.mac:27610 comp.sys.ibm.pc:25477
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!biar!trebor
From: trebor@biar.UUCP (Robert J Woodhead)
Newsgroups: comp.sys.atari.st,comp.sys.apple,comp.sys.mac,comp.sys.ibm.pc
Subject: Re: Right of reply, virus- public, private- a thin line
Message-ID: <175@biar.UUCP>
Date: 1 Mar 89 15:14:57 GMT
References: <415@odin.cs.hw.ac.uk> <14940@cup.portal.com> <3936@ttidca.TTI.COM> <1270@husc6.harvard.edu> <1154@lzfme.att.com>
Reply-To: trebor@biar.UUCP (Robert J Woodhead)
Followup-To: comp.sys.atari.st
Organization: Biar Games, Inc.
Lines: 26

In article <1154@lzfme.att.com> jwi@lzfme.att.com (Jim Winer @ AT&T, Middletown, NJ) writes:
>Most virus detecting programs work by intercepting writes to the
>hard disk and by checksumming programs before running them. A small
>change in a virus is not going to  make it invisible to this type of
>checking.

Correct (sort of) but misleading.  Virus detecting inits such as Vaccine
work by intercepting certain resource manager calls.  Unfortunately, they
can get in the way.  Checksumming programs is fine, but it involves adding
checksums to each application or storing them in a central file; each is
vulnerable to viral action.  Viruses can be reprogrammed to avoid these.

Additionally, when you talk about detect and REPAIR programs, small changes
in viruses will make them invisible and/or unrepairable until the program
is updated.  This is because none of these programs want to take a chance of
"repairing" an uninfected version of "Whiz-bang-space-aliens v1.2" just
because it looks sort of like it is infected by a virus.  We are extremely
specific in our check criteria in order to avoid this unfortunate consequence.

+---------------------------------------------------------------------------+
| Robert J Woodhead      !uunet!cornell!biar!trebor     CompuServe 72447,37 |
| Biar Games, Inc., 10 Spruce Lane, Ithaca NY 14850  607-257-1708,3864(fax) |
+---------------------------------------------------------------------------+
| Games written, Viruses killed   "I'm the head honcho of this here spread; |
| While U Wait.  Take a number.    I don't need no stinking disclaimers!!!" |
+---------------------------------------------------------------------------+