[comp.virus] Boot Sectors and Viruses

padgett%tccslr.dnet@uvs1.orl.mmc.com (A. Padgett Peterson) (02/27/91)

	More and more we are seeing reports of institutions being hit
by the STONED and other BSI viruses. Unless there is a trojan
involved, the only way for a machine to become infected by one of
these is by booting from a floppy.

	What amazes me is that boot records contain no integrity
checking whatsoever (this includes the DOS 5.00 beta we are testing)
particularly since the code would take only a few bytes.

	Following with the DISKSECURE experiment, I wrote a Boot
Record program that just replaces the executable on a non-booting disk
with such a check procedure. If all goes well, it tells you. If the
disk has become infected, it also tells you, not what has infected the
disk, but that something has.

	In the future, I expect large organizations to remove FORMAT
and SYS from most machines and either use a central formatting
facility or purchase preformatted disks. Putting a new boot record on
a disk takes 2-3 seconds.

	Since the difficulty of putting such checks into disk
approaches zero. My feeling is that use of such disks should be one of
the layers of protection for the "safe" PC model.

					Padgett

Would you trust ANY computer in Kuwait today ?