Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!gem.mps.ohio-state.edu!ginosko!uunet!mcsun!ukc!warwick!ecctp
From: ecctp@warwick.ac.uk (Dr J A K Cave)
Newsgroups: comp.binaries.ibm.pc.d
Subject: Bombs in non-executable files: BEWARE!
Message-ID: <233@orchid.warwick.ac.uk>
Date: 12 Sep 89 10:04:45 GMT
Organization: Computing Services, Warwick University, UK
Lines: 23

Summary:
Expires:
References:
Sender:
Reply-To: ecctp@warwick.ac.uk (Dr J A K Cave)
Followup-To:
Distribution:
Organization: Computing Services, Warwick University, UK
Keywords:

Recently, reports have surfaced about destructive "bombs" appearing in
text files.  The way they work is by appealing to ANSI.SYS or NANSI.SYS
(ZANSI.SYS is OK, for reasons that will become obvious) and reprogramming
keyboard definitions.  For example, the "d" key may be reassigned to
"del *.* y" so the next time you ask for "dir" you will get a nasty
shock.  This can happen whenever a file is sent to the screen by any of
a wide (and as yet undetermined) range of commands, including "type."

Use of ZANSI.SYS or avoiding any screen enhancer will obviate the problem,
since the keyboard reassignment feature is disabled. Alternatives for
key definition include various TSR programs.  Another approach is to use the
"browse" utility that PC magazine put out a little while back.  Copies of
ZANSI.SYS and BROWSE.COM  can be obtained on request.