Date: Wed, 26 Jun 2002 22:34:24 +0200
From: OpenPKG <[email protected]>
To: [email protected]Subject: [OpenPKG-SA-2002.005] OpenPKG Security Advisory (openssh)
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________________________________________________________________________
OpenPKG Security Advisory The OpenPKG Project
http://www.openpkg.org/security.htmlhttp://www.openpkg.org[email protected][email protected]
OpenPKG-SA-2002.005 26-Jun-2002
________________________________________________________________________
Package: openssh
Vulnerability: DoS / remote exploit
OpenPKG Specific: no
Affected Releases: OpenPKG 1.0
Affected Packages: <= openssh-3.0.2p1-1.0.2
Corrected Packages: >= openssh-3.0.2p1-1.0.3
Dependent Packages: -
Description:
According to an OpenSSH Security Advisory [5] and a corresponding
Internet Security Systems (ISS) Security Advisory [6] there is a
vulnerability within the "challenge-response" authentication mechanism
in the OpenSSH daemon (sshd). This mechanism, part of the SSH2
protocol, verifies a user's identity by generating a challenge and
forcing the user to supply a number of responses. It is possible for
a remote attacker to send a specially-crafted reply that triggers an
overflow. This can result in a remote denial of service attack on the
OpenSSH daemon or a complete remote compromise. The OpenSSH daemon
runs with superuser privilege, so remote attackers can gain superuser
access by exploiting this vulnerability.
OpenSSH supports the SKEY and BSD_AUTH authentication options. These
are compile-time options. At least one of these options must be
enabled before the OpenSSH binaries are compiled for the vulnerable
condition to be present. So OpenPKG's OpenSSH is *not* vulnerable
by default, because the S/Key authentication option is disabled
("%define with_skey no") by default. But if users enabled this
manually when building the OpenPKG "openssh" package, OpenPKG's
OpenSSH is vulnerable,too.
Please check whether you are affected by running "<prefix>/bin/rpm -qa
openssh". If you have the "openssh" package installed and its version
is affected (see above), we recommend that you immediately upgrade
it (see Solution). Additionally, we recommend that you rebuild and
reinstall all dependent OpenPKG packages, too. [2]
Solution:
Select the updated source RPM appropriate for your OpenPKG release
[4], fetch it from the OpenPKG FTP service [3] or a mirror location,
verify its integrity [1], build a corresponding binary RPM from it
and update your OpenPKG installation by applying the binary RPM [2].
For the latest OpenPKG 1.0 release, perform the following operations
to permanently fix the security problem (for other releases adjust
accordingly).
$ ftp ftp.openpkg.org
ftp> bin
ftp> cd release/1.0/UPD
ftp> get openssh-3.0.2p1-1.0.3.src.rpm
ftp> bye
$ <prefix>/bin/rpm --checksig openssh-3.0.2p1-1.0.3.src.rpm
$ <prefix>/bin/rpm --rebuild openssh-3.0.2p1-1.0.3.src.rpm
$ su -
# <prefix>/bin/rpm -Fvh <prefix>/RPM/PKG/openssh-3.0.2p1-1.0.3.*.rpm
________________________________________________________________________
References:
[1] http://www.openpkg.org/security.html#signature
[2] http://www.openpkg.org/tutorial.html#regular-source
[3] ftp://ftp.openpkg.org/release/1.0/UPD/
[4] ftp://ftp.openpkg.org/release/1.0/UPD/openssh-3.0.2p1-1.0.3.src.rpm
[5] http://www.openssh.org/txt/preauth.adv
[6] http://www.openssh.org/txt/iss.adv
________________________________________________________________________
For security reasons, this advisory was digitally signed with
the OpenPGP public key "OpenPKG <[email protected]>" (ID 63C4CB9F)
of the OpenPKG project which you can find under the official URL
http://www.openpkg.org/openpkg.pgp or on http://keyserver.pgp.com/. To
check the integrity of this advisory, verify its digital signature by
using GnuPG (http://www.gnupg.org/). For instance, pipe this message to
the command "gpg --verify --keyserver keyserver.pgp.com".
________________________________________________________________________
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