Hi, time to spread the news about a bigger update of my
FDSHIELD "malware activity blocker" (I would not call it
an antivirus software, but it is definitely inspired by
VSAFE, although FDSHIELD knows no virus signatures)  :-) .

Walt Gregg has helped me a lot with this, and actually the
whole update started when he contacted me, telling that
FDSHIELD works nice for him in OS/2 DOS boxes but that he
found ways to bypass it. So I kept improving the protection
and he kept testing... Walt also wrote some nice but somehow
longish documentation. If you have suggestions about makeing
the documentation shorter, please let us know.

You can get the program from:
http://www.coli.uni-saarland.de/~eric/stuff/soft/specials/
  fdshield-26mar2005.zip

and you can view the documentation online on:
http://home.gci.net/~wmgregg/computers/fdshield.htm

Check the help screen (now with highlighting if ANSI is loaded)...:

Syntax: FDSHIELD [/?] [/v]  [/x] [/X]  [/b] [/B]  [/t] [/T]  [/w] [/W]
  /v  show verbose warnings     /?  show help, do not start shield
  /x  protect exe/sys/com       /X  protect exe/sys/com/bat more
      Warning: There is no LongFileName access file protection yet
  /b  floppy boot protect       /B  harddisk/ramdisk boot protect
      Do not try to FORMAT drives with protected boot sectors
  /t  block TSRs and devices    /T  block CWSDPMI and RTM, enable /t
      Use /T in DOS boxes or load your DOS extender as TSR first
      TSR block *halts* the PC when a TSR or device gets loaded
  /w  floppy write protect      /W  harddisk/ramdisk write protect
      Activating /w and /W together simulates all files readonly
      Writes to write-protected fixed/RAM-disks can *hang* DOS
      You cannot use '|' pipes without writeable TEMP directory
      Do not start delayed-write caches while /w or /W is on
Note: Sabotage check and raw harddisk format block are always on


The main changes are: TSR blocking got stronger, TSR blocking now has
a mode which explicitly lets through RTM and CWSDPMI (it does do some
checks to make sure that it is actually RTM and CWSDPMI), the device
driver chain is now checked for changes while TSR blocking is on, and
the executable file protection got a lot stronger and now comes in
two styles: One allowing BAT modification and definitely-non-overwriting
executable file creation, and one which even blocks creation and BATs.

The FDSHIELD COM file is now almost 4 kB big (UPXed size, otherwise it
is almost 6 kB big) and the shield takes about 4 kB RAM while resident
(you can load it to UMBs if you want, it will need 6-7 kB of UMB space
to initialize and load successfully). You definitely get more security
and more verbose and user-friendly messages for that, compared to the
04jul2004 version (which was 2.3 kB / unpacked 3.2 kB / 2.5 kB in RAM).
Make sure to check the extra in those 1.7 kB on disk and 1.2 kB in RAM  :-) .

Eric