21A18.TXT - Description file for 21A18.DEF
AntiVirus Lab, SYMANTEC/Peter Norton Product Group
November 1, 1994
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[The NAV definition update installation instructions are also
available on this disk in French, German, Italian, Swedish, and
Spanish.  Please reference the appropriate file.]

		   Loading New Definitions

To update NAV 2.1 with the new virus definition you have
just received, do the following:

Note:  Each definition set completely replaces the current
       set so only the latest is required.

From DOS:
1)  At the DOS prompt, type "NAV" then <Enter>.
2)  Select the "Cancel" button (ALT-C) to bypass scanning at this time.
3)  Select the Definitions menu (ALT-D), then select the "Load from
    file" item (L).  You will now see the "Load from file" dialog box.
4)  Place the definition diskette in drive A: (Drive B: where
    applicable).
5)  In the FILE field, type "A:*.DEF " ("B:*.DEF" if applicable) then
    <Enter>.
6)  The definition file on the disk should now appear in the
    "Files" box.
7)  Select the "Files" box (ALT-L).  Note: the filename is normally
    loaded into the "File" line automatically as it is usually the
    only file available.  If this is not the case, use the TAB key
    to highlight the file then press the spacebar.
8)  Select "OK" (ALT-O) to load the new definition set.
9)  After loading, press "ESC", exit NAV, and reboot the machine.
10) NAV will now use the new definitions to scan for viruses.

From Windows:
1)  Activate NAV by double-clicking on its icon.
2)  Click on "CANCEL" in the "Scan Drives" window to bypass scanning
    at this time.
3)  From the "Definitions" menu choose "Load from file".
4)  Place the definition diskette in drive A: (Drive B: where
    applicable).
5)  Type "A:*.DEF" ("B:*.DEF" if applicable) in the "File" field, then
    press the Enter key.
6)  The latest definition file should now appear in the "Files" box.
7)  Double-Click on the filename inside the "Files" box.
8)  The file should begin to load.  If not, click the "OK" button to
    load the new definition set.
9)  After loading, exit NAV, exit Windows, then reboot the machine.
10) NAV will now use the new definitions to scan for viruses.

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Note for users who are not updated through Corporate Channels:

After updating your definitions, if every file is identified as
being infected with "MtE", don't panic.  You probably do not have
a virus.  Please download the patch file, PTCH1A.ZIP (available
through CompuServe and the Symantec BBS), unzip the file, follow
the instructions included in the readme file, and then load these
definitions again.

If you are unable to download this patch file, or are still
experiencing problems after using it, please contact Symantec
Technical Support.


Stealth Boot

It is a memory resident MBR and boot record infector.  We now also detect
Stealth.C in memory.  Both Stealth.B and Stealth.C will be detected on
media as "Stealth Boot."  Repair is now possible for hard disks.  Does
nothing more than spread.  It conceals the fact that it has taken over
the MBR (stealth).

Natas Boot

This is a highly polymorphic EXE and COM infector and an infector of
the hard disk Master Boot Record.  It is extremely prolific and is said
to be infecting perhaps one-third of all machines in Mexico.  It has also
infected some companies and government agencies in the US which have 
dealings in Mexico.

A definition to detect Natas in memory and on the MBR is provided for
NAV 2.1.  The ability to detect and/or repair files is beyond the
technology available to NAV 2.1.  If you detect this virus in memory or
on the MBR, you will need to call our Technical Support and request to
upgrade to the most current NAV 3.0.

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(Note: File size growth is given in approximate numbers.  If a number
is enclosed in parentheses, that number would be the growth of one of
the more common variants.  As it is too easy for a virus writer to alter
this number without changing the virus significantly, do not depend on
the more precise number.  It is provided for your confidence should you
encounter it, which we hope never happens.)