[comp.virus] TSR Virus Detector

JXA5@MARISTB.BITNET (John Councill) (04/25/91)

Hi.  I'm sure that this question has been asked here before, but I'll
ask it again:

Can anyone reading this recommend a reliable program that will sit in
memory and warn against writes to .EXE and .COM files, as well as
other suspicious virus-like activity without degrading performance of
the machine too much?  Are there products like this that you've had
bad experiences with?

And while I'm posting this, I'll comment that it would be a GOOD THING
if someone from IBM who reads this, and is affiliated with VIRSCAN,
could announce new releases of this program on VIRUS-L.  Such
notification would help me out a lot, as our IBM rep is usually
ignorant about it.  AND it would help avoid the kind of rumor
flurrying that surrounded the last release.

Thanks,

John A. Councill                             Bitnet: JXA5@MARISTB
Technical Assistant                           Voice: 914-758-7494
Henderson Computer Resources Center of
Bard College in Idyllic Annandale-on-Hudson NY

<Opinions expressed are not necessarily those of my humble leaders.>

RADAI@HUJIVMS.BITNET (Y. Radai) (05/08/91)

  John Councill asks:
>Can anyone reading this recommend a reliable program that will sit in
>memory and warn against writes to .EXE and .COM files, as well as
>other suspicious virus-like activity without degrading performance of
>the machine too much?

  Several months ago, I made a quick comparison between several pro-
grams of this type which I have.  (I call them "monitoring" programs.
There are other reasonable names, and also one which I consider very
inappropriate: Robert Slade's term "vaccine" software.)
  When I saw John's question, I thought this would be a good opportu-
nity to make my comparison more complete, but I see I'm not going to
find the time, so for now I'm reporting only my previous results.
  The programs which I compared were F-LOCK, FSP, SECURE, TSAFE, and
VTAC.  I decided that the most important criterion was the ability to
prevent infection by the largest number of viruses (without giving too
many false alarms, of course), and that the type of virus which would
be most likely to separate the good programs from the mediocre would
be those viruses which avoid re-direction of interrupt vectors (by
jumping directly to the interrupt handlers or by issuing commands
directly to the controller).
  So I threw 4 viruses of this type against each of the above programs.
The number which each program stopped was as follows:
                            SECURE  4
                            F-LOCK  1
                            others  0
  On this criterion, SECURE is clearly the best monitoring program.
(Fridrik Skulason has an alternative version of F-LOCK which would do
better, but he hasn't released it because of conflicts with certain
software.)  It's conceivable that other viruses would give opposite
results, but I very much doubt it.  On the other hand, there are many
other criteria which I did not subject to a systematic comparison,
such as false alarms, slowing down of ordinary computer activity,
flexibility and convenience.
  Btw, the author of SECURE, Mark Washburn, is also the author of the
V2P* virus series, all of which are variable self-encrypting viruses
designed to demonstrate the futility of relying on programs which
attempt to detect viruses by scanning for characteristic strings.
V2P1 (better known as the 1260) was distributed publicly, and while it
is not itself destructive, someone evidently used its disassembly as
the basis for the Casper virus, which is quite destructive.
  This, of course, does not prevent SECURE from being the best moni-
toring program, at least judging by my limited comparison.  I can only
hope that others will make more thorough tests.  (All of the above
except TSAFE are available from Simtel20 in <MSDOS.TROJAN-PRO>.)

                                     Y. Radai
                                     Hebrew Univ. of Jerusalem, Israel
                                     RADAI@HUJIVMS.BITNET
                                     RADAI@VMS.HUJI.AC.IL

esaholm@utu.fi (Esa Holmberg) (05/09/91)

RADAI@HUJIVMS.BITNET (Y. Radai) writes:

>  The programs which I compared were F-LOCK, FSP, SECURE, TSAFE, and

	I'm afraid you have tested a wrong program; F-DRIVER
	would be the actual resident virus tester of the F-PROT
	package, and not F-LOCK. I wonder, what the results
	would look like with F-DRIVER instead of F-LOCK ?

- --
   __________________________________________________
   ) Esa Holmberg -- esaholm@utu.fi, ekho@ttl.fi,    )
  /                  ekho@f152.n222.z2.fidonet.org  /
 / fax : +358 21 510 017, Elisa : Holmberg Esa TTL /

frisk@rhi.hi.is (Fridrik Skulason) (05/12/91)

esaholm@utu.fi (Esa Holmberg) writes:
>RADAI@HUJIVMS.BITNET (Y. Radai) writes:
>
>>  The programs which I compared were F-LOCK, FSP, SECURE, TSAFE, and
>
>	I'm afraid you have tested a wrong program; F-DRIVER
>	would be the actual resident virus tester of the F-PROT
>	package, and not F-LOCK. I wonder, what the results
>	would look like with F-DRIVER instead of F-LOCK ?

Well, no - Y. Radai tested the correct program - the important
question was not how effective the programs were against KNOWN
viruses, but rather how effective they were against the methods used,
and how effective they would be against new viruses using those
methods.

I had a version of F-LOCK which was able to stop all the viruses from
accessing the system directly, but I removed that feature in version
1.08, (I think) as it conflicted with some programs, including my
cache program.

Besides - I don't currently put much emphasis on the F-LOCK part of my
package, for two reasons - it does not work with Windows (F-DRIVER
will), and it is being rewritten for version 2.0

Regarding version 2.0, which was originally scheduled to be released
two months ago - I have been seriously considering to change the name
of the product.  The most likely new name is taken from the Greek
mythology, 'Argus' - the name of the hundred-eye all-seeing giant.

Any suggestions ?

- -frisk

Fridrik Skulason                 Technical Editor of the Virus Bulletin (UK)
(author of F-PROT)               E-Mail: frisk@rhi.hi.is    Fax: 354-1-28801

RADAI@HUJIVMS.BITNET (Y. Radai) (05/13/91)

  In connection with my comparison of F-LOCK, FSP, SECURE, TSAFE, and
VTAC, Esa Holmberg writes:
>       I'm afraid you have tested a wrong program; F-DRIVER
>       would be the actual resident virus tester of the F-PROT
>       package, and not F-LOCK.

  No, that's incorrect.  I don't know if your mistake is in not
knowing how F-DRIVER works or in confusing two different types of
resident anti-viral programs:
(I)  Those which search for *specific strings* (or patterns), each
     characteristic of a particular *known* virus, within program
     files which are about to be executed, and (usually) also in boot
     records when the anti-viral program is loaded.  Such programs
     must be updated continually to catch new viruses.
(II) Those which warn of suspicious activity by intercepting attempts
     to modify executable files, to stay resident, to format disks,
     etc., regardless of the source of this activity.  (It might be a
     virus, a Trojan, or some perfectly innocuous program; and if a
     virus, it may be a known one or an unknown one.)  Such programs
     do not ordinarily require updating.

  Now John Councill's question certainly resembled Type II more than
Type I, so I referred to the five programs of this type which I had
compared, and that includes F-LOCK.  F-DRIVER, on the other hand, is
of Type I, and therefore was not an appropriate program for my compa-
rison.  (When I say that a program is of Type I, it may include a few
Type-II features as well, but certainly F-DRIVER and V-Shield are
basically of Type I.)

  Perhaps my posting would have been clearer if, instead of calling
Type-II programs simply "monitoring" programs, I had called them
*generic* monitoring programs.  F-LOCK is generic; F-DRIVER is not.

  (Btw, there are also generic *disinfection* programs, i.e. programs
which in the great majority of cases can restore a file to its original
state regardless of the virus which infected it.)

                                     Y. Radai
                                     Hebrew Univ. of Jerusalem, Israel
                                     RADAI@HUJIVMS.BITNET
                                     RADAI@VMS.HUJI.AC.IL