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Date:      Wed, 1 Mar 2000 21:07:21 -0500 (EST)
From:      Robert Watson <robert@cyrus.watson.org>
To:        Warner Losh <imp@village.org>
Cc:        Andrey Novikov <scriber@webclub.ru>, freebsd-security@FreeBSD.ORG
Subject:   Re: schg flag 
Message-ID:  <Pine.NEB.3.96L.1000301210317.53787D-100000@fledge.watson.org>
In-Reply-To: <200003012001.NAA96951@harmony.village.org>

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On Wed, 1 Mar 2000, Warner Losh wrote:

> In message <00022921443000.05868@novikov.web2000.ru> Andrey Novikov writes:
> : Hello,
> : 
> : It seems to me that it will be more secure for my
> : public server to say at least:
> : 
> : chflags schg /bin/*
> : chflags schg /sbin/*
> : chflags schg /usr/bin/*
> : chflags schg /usr/sbin/*
> : chflags schg /usr/local/bin/*
> : chflags schg /usr/local/sbin/*
> : 
> : to prevent any troyans in my system binaries, am I wrong?
> 
> It will make the much less likely to happen, but you've forgotten all
> the /etc/rc* scripts, which can be used to drive a torjan truck
> through the secure level stuff.

As well as /boot, /modules, etc.  Today's system is really not intended to
survive root compromise.  The best bet is to use 4.0, and stuff all your
nasty-users in jail().  Optionally with all but a writable component of
the jail mounted from a read-only file system.  Ideally, once we have
mandatory access control, integrity-based MAC could be used to protect
in the event of compromise.

(I'm just waiting for us to allow multiple mounts of a read-only file
system in multiple places, currently unsupported...)

  Robert N M Watson 

robert@fledge.watson.org              http://www.watson.org/~robert/
PGP key fingerprint: AF B5 5F FF A6 4A 79 37  ED 5F 55 E9 58 04 6A B1
TIS Labs at Network Associates, Safeport Network Services



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