From: martin@cs.ualberta.ca (Tim Martin; FSO; Soil Sciences)
Newsgroups: comp.virus
Subject: Re: Need info on MONKEY virus (PC)
Date: 13 Nov 92 22:41:11 GMT

PED8C@acadvm1.uottawa.ca (Paul Deveau) writes:

>Have any of you experienced the MONKEY virus?  It has been propagating
>around here recently.  I have not been able to find much information
>about this virus: How does it manifest itself?  What damage may it
>inflict?  If any of you have details, would you be kind enough to
>share them?

This is a disturbing notice: it represents the first evidence of 
the Monkey virus getting beyond Edmonton, Alberta.  

The Monkey virus is a member of the Empire family, and a distant
cousin of Stoned.  The Empire viruses are fairly rare, worldwide,
though they are the main virus problem in the Edmonton area, next
maybe to Stoned.  

The Monkey virus has a couple curious characteristics that can
make it particularly frustrating, if people don't know how to
deal with it.  First, Monkey doesn't save the partition table 
in place in the infected MBR of a hard disk.  This means that
if the infected system is booted from a diskette, the hard disk
appears to be inaccessible.  Any attempt to use drive C: will
result in a "invalid drive specification" or some such error --
I forget the exact wording! 

Second, and more frustrating, is that the clean MBR is encoded
before it is saved to the hiding place (sector 3).  This means
the MBR must be decoded if one wishes to restore it directly.
Otherwise the MBR must be restored from a backup copy, or the
table re-entered using a partition table editor such as Norton
Utilities.  The DOS 5.0 DEBUG /MBR option simply leaves a piece
of the virus in the partition table area.  Fortunately this
piece is not virulent; unfortunately it is not a partition
table either!

Third, the Monkey virus specifically (and successfully) 
bypasses Padgett's Disk Secure program.  This virus represents
a rare case: a very specific attack against a very specific
disk security system.  Fortunately most scanners will find 
the virus in memory.  Again this stresses the importance of
having a multi-layer antivirus strategy.

Fourth, Monkey uses stealth on both the MBR and diskette boot sectors,
stopping the system from seeing or changing them.  To remove the
virus, you MUST boot the system from a clean diskette.  Or use my
KILLMONK program: it knows how to get past this stealth.

The Monkey virus has no intentional data damaging strategies.
(Some of the Empire viruses have; in particular the one 
reported wild in the USA has.)  Many of the "bugs" of most
Stoned-derivatives have been fixed in Monkey -- the only 
problem I would forsee is if Monkey infects a 2.88Mb or
other unusual format diskette.  On the 4 common formats,
Monkey successfully hides the clean boot sector (encoded
again) in the bottom of the root directory.  But if it doesn't
recognize a diskette type as being one of these four, the
boot sector is placed on side 1, sector 3.  I don't know the
2.88Mb format, but I suspect this location is in one of the
FAT tables. 

If anyone has trouble dealing with the Monkey virus, or any
other Empire viruses, send me a note.

Tim.

 -------------------------------------------------------------
  Tim Martin                   *
  Spatial Information Systems  *   These opinions are my own:
  University of Alberta        *      My employer has none!
  martin@cs.ualberta.ca        *
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