[13698] in bugtraq
Re: Tempfile vulnerabilities
daemon@ATHENA.MIT.EDU (Theo de Raadt)
Thu Feb 3 17:06:16 2000
Message-Id: <200002022136.OAA09251@cvs.openbsd.org>
Date: Wed, 2 Feb 2000 14:36:20 -0700
Reply-To: Theo de Raadt <deraadt@CVS.OPENBSD.ORG>
From: Theo de Raadt <deraadt@CVS.OPENBSD.ORG>
X-To: Werner Koch <wk@GNUPG.ORG>
To: BUGTRAQ@SECURITYFOCUS.COM
In-Reply-To: Your message of "Wed, 02 Feb 2000 09:27:32 +0100."
<20000202092732.A2096@frodo.gnupg.de>
The terrible /tmp race handling aside...
I suppose then that anyone who attacks a machine which relies on
/dev/random -- a world readable device -- should do the following:
cat /dev/random > /dev/null &
Crypto software which uses those devices should be doing some kind of
checking to make sure that they are getting at least good entropy. I
suppose I could even argue that the random devices should make it easy
for customer software to determine that entropy is low.
> On Mon, 31 Jan 2000, Grant Taylor wrote:
>
> > open RAN, "/dev/random" || die;
> > read(RAN,$foo,16);
> > close RAN;
> > $file = '/tmp/autobuse' . unpack('H16',$foo);
>
> Please, never use /dev/random or /dev/urandom for such purposes.
>
> Aside the fact, that it does not help much in what you want to achieve
> it is a desaster to system performance because it empties the system's
> entropy pool and wastes precious entropy for unneeded things.
>
> Crypto software _really_ needs these random numbers.
>
>
> --
> Werner Koch at guug.de www.gnupg.org keyid 621CC013
>
> Boycott Amazon! - http://www.gnu.org/philosophy/amazon.html
