oss-security - Re: CVE request -- coreutils -- tty hijacking possible in "su" via TIOCSTI ioctl

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Date: Tue, 28 Jun 2011 14:21:47 +0200
From: Ludwig Nussel <ludwig.nussel@...e.de>
To: "Steven M. Christey" <coley@...us.mitre.org>
Cc: oss-security@...ts.openwall.com
Subject: Re: CVE request -- coreutils -- tty hijacking possible in "su" via TIOCSTI ioctl

Ludwig Nussel wrote:
> Josh Bressers wrote:
> >----- Original Message -----
> >> Jan Lieskovsky wrote:
> >> > Hello Josh, Steve, vendors,
> >> >
> >> >    based on Debian BTS report:
> >> >    [1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=628843
> >> >        (first CVE-2011-XXYY required for Debian case)
> >> >
> >> > looked more into original report:
> >> > [2] https://bugzilla.redhat.com/show_bug.cgi?id=173008
> >> >
> >> > and the first paragraph of [2] suggests:
> >> > "When starting a program via "su - user -c program" the user session
> >> > can escape to the parent session by using the TIOCSTI ioctl to push
> >> > characters into the input buffer. This allows for example a non-root
> >> > session to push "chmod 666 /etc/shadow" or similarly bad commands
> >> > into
> >> > the input buffer such that after the end of the session they are
> >> > executed."
> >> >
> >> > this should get a CVE-2005-YYZZ CVE id.
> >> >
> >> > Could you allocate these?
> >>
> >> ping! :-)
> >
> >I'm not sure if this should get two IDs. It's really one issue, which isn't
> >actually fixed in su.
> >
> >The fundamental issue is that tools like su and sudo keep the tty open.
> >The patch in question closes the tty for the case of su -c, but not for
> >just running su by itself. It is incomplete.
> 
> I'm not worried too much about the interactive su case really. The 
> usual direction there is user->root, not the other way around I 
> suppose. "su -c" might be used by (%post) scripts though as seen 
> with ikiwiki.

So can we have a CVE for that issue at least?

cu
Ludwig

-- 
 (o_   Ludwig Nussel
 //\
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