[comp.virus] Changed checksums on boot sector?

PJML@ibma.nerc-wallingford.ac.uk (Pete Lucas) (07/13/90)

Hi. One of my colleagues has found that the checksum of the boot sector on
his PC's hard-disk has changed...! None of the usual virus detecting
programs report anything unusual, neither does there appear to be
any change to any of the sizes of any of his other files, nor are there
bad sectors on the hard disk. He suspects a boot-sector virus even though
he has seen no symptoms of anything.
Floppy disks used with his system are likewise apparently clean with
no obvious infections/lost sectors.
I suspect that someone may have done a SYS to his disk, with a different
version of DOS. I guess there will be differences between 'Generic'
MS-DOS and 'proprietary' IBM PC-dos even though they are functionally the
same, and both DOS3.3's.
Does this make sense, or should i start crawling through his boot sector
and looking for nasties?

   Pete Lucas         PJML@UK.AC.NERC-WALLINGFORD.IBMA       0793411613