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Date: Mon, 21 Sep 2015 16:43:46 +0000
From: David Holland <dholland-oss-security@...bsd.org>
To: oss-security@...ts.openwall.com
Subject: Re: s/party/hack like it's 1999

On Sun, Sep 20, 2015 at 06:26:31AM +0300, Solar Designer wrote:
 > > Note that all that was needed for this to happen was for a stray C2
 > > byte from one writer to get injected just before the character-final
 > > 9B byte of a multibyte character from another writer. I specifically
 > > chose my example so that both writers output data which is well-formed
 > > and printable UTF-8, but that was not necessary.
 > > 
 > > Since I see no reasonable application-side mitigation for this, I
 > 
 > Yeah.  A user's mitigation may be to avoid running multiple programs at
 > a time on a UTF-8 terminal.  E.g. running "ps &" appears unsafe
 > (although is indeed unlikely to actually be used in a successful
 > attack), even if "ps" replaces control characters with question marks.

I have been arguing for years (but without success) that vt bomb
injection needs to be blocked in the tty driver. This problem
(corruption of concurrent UTF-8 streams) needs to be too, as a matter
of correctness and not even security.

You can stty +tostop, but that won't really help very much.

Sigh.

-- 
David A. Holland
dholland@...bsd.org

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