Re: Invalid Boot Sectors (PC)

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Article #4781

#4781

From: Fridrik Skulason
Date: Wed, 06 Jan 1993 09:06

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riordan@tmxmelb.mhs.oz.au (Roger Riordan) writes:

>It appears the original message got lost, but the gist was that, 
>IN THEORY, it is possible to write a BS virus which is invisible 
>on an infected PC, but impossible to detect on an uninfected PC 
>with any existing scanner because DOS will crash if any attempt is 
>made to access an infected disk. 

well, only if the scanner uses int 21H/25H/26H to access the disk.  If it uses
int 13H to access the disk the disk can be read no matter what data is in the
boot sector.

- -frisk

- -- 
- --
Fridrik Skulason      Frisk Software International     phone: +354-1-694749
Author of F-PROT      E-mail: frisk@complex.is         fax:   +354-1-28801

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Path: arc1-ca.pugleaf.net!sparky!uunet!think.com!yale.edu!jvnc.net!netnews.upenn.edu!netnews.cc.lehigh.edu!news
From: frisk@complex.is (Fridrik Skulason)
Newsgroups: comp.virus
Subject: Re: Invalid Boot Sectors (PC)
Message-ID: <0008.9301071651.AA16031@barnabas.cert.org>
Date: 6 Jan 93 09:06:21 GMT
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