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From: ken@rochester.ARPA (Ipse dixit)
Newsgroups: net.news.adm,net.news.sa,net.sources.d,net.wanted.sources
Subject: Re: Beware of Blindly Un-SHARing a File
Message-ID: <17381@rochester.ARPA>
Date: Sun, 20-Apr-86 02:51:24 EST
Article-I.D.: rocheste.17381
Posted: Sun Apr 20 02:51:24 1986
Date-Received: Wed, 23-Apr-86 20:35:03 EST
References: <947@kitty.UUCP> <2407@prls.UUCP> <1439@garfield.columbia.edu> <850@ihlpl.UUCP>
Reply-To: ken@rochester.UUCP (Ipse dixit)
Organization: U of Rochester, CS Dept, Rochester, NY
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The only foolproof way I can see is to use a special unshar program.
Someone pointed out that this would have to be distributed. What the
heck, if you are going to do that, why not go to a format like the
afio(1) program that someone was going to post to mod.sources.

One approach would be restrict sh somehow. I experimented with putting
PATH=/u/user/mybin; readonly PATH in the front of a shar file. mybin
would contain only "safe" commands like cat. But a malicious person
could put /bin/rm -fr / in the file and this wouldn't work. Besides, if
you are going to edit the shar file, you should give it a once over
anyway.

The gist of it is, as long as sh is used to unshar, it is unsafe.

	Ken
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