Invalid Disk Boot Sectors. (PC)

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1 total messages Started by Roger Riordan Thu, 17 Dec 1992 22:29

#4167

Author: Roger Riordan
Date: Thu, 17 Dec 1992 22:29

21 lines
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In a recent comment on a query by MOPURC01@ULKYVM.LOUISVILLE.EDU 
(Michael Purcell) about a virus which allegedly made disks 
unreadable I wrote.

> If you put the wrong byte in the wrong place you can get the 
> symptoms described.  ...

We have since established that if you set the sectors per cluster 
field (offset 0dh) in the BIOS Parameter Block to zero in the boot 
sector of an otherwise normal disk all versions of DOS will crash 
immediately you try to access the disk.  All utilities we have 
tested also crash.  You can format the disk with DOS 3 & 4 but 
Format will crash under DOS 5 unless you use the /u option.

F-Prot, Dr. Solomon's Toolkit, & McAfee Scan all crash.  VET crashes 
too, but we are working on it!

Roger Riordan                     riordan.cybec@tmxmelb.mhs.oz.au

CYBEC Pty Ltd.                                 Tel: +613 521 0655
PO Box 205, Hampton Vic 3188   AUSTRALIA       Fax: +613 521 0727

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