SuSE: 'openssh' Remote Vulnerability
Summary
______________________________________________________________________________
SuSE Security Announcement
Package: openssh
Announcement-ID: SuSE-SA:2002:023
Date: Tue Jun 25 2002
Affected products: 6.4, 7.0, 7.1, 7.2, 7.3, 8.0
SuSE Linux Database Server,
SuSE eMail Server III,
SuSE Linux Enterprise Server,
SuSE Linux Firewall on CD
Vulnerability Type: unknown
Severity (1-10): 9
SuSE default package: yes
Content of this advisory:
1) security vulnerability resolved: unknown vulnerability
in the OpenSSH daemon.
problem description, discussion, solution and upgrade information
2) pending vulnerabilities, solutions, workarounds
3) standard appendix (further information)
______________________________________________________________________________
1) problem description, brief discussion, solution, upgrade information
There's a new vulnerabilty in the OpenSSH daemon, of which we were
notified yesterday.
The OpenSSH/OpenBSD team has asked Linux vendors to upgrade their
platforms to OpenSSH 3.3, and change the configuration to use the
relatively new "Privilege Separation" code. According to their
information, 3.3 does not fix the vulnerability, but using privilege
separation prevents exploits.
We were not given any additional information on the nature of the
vulnerability.
Setting PrivilegeSeparation to on causes large portions of the
daemon to run in a so-called "chroot jail", i.e. in a very restricted
environment. An attacker breaking this part of the SSH daemon will
*not* obtain full root privilege (as he would if sshd ran without
this option), but will find himself in an empty directory, inside a
process running as a non privileged user (he can still do some harm
this way, but it's a far cry from full root powers).
The SuSE security team has prepared RPMs that upgrade OpenSSH to
version 3.3p1 on all SuSE Linux platforms. Based on the information
we've been given, we are unable to provide updates containing
a complete fix, nor can we guarantee that the workaround using
privilege separation is enough to protect you.
Given these imponderabilities, we suggest to you to take additional
precautions until details of the vulnerability have been published,
and we have been able to assess it:
- if you do not need external access to your SSH daemons,
turn off the SSH service on these machine completely, or block
external access at the firewall.
- if you do need external access to your SSH daemons,
make sure you restrict the hosts that it will talk to by setting
appropriate firewall rules.
If, for some reason, you cannot configure your firewall to
block external SSH access, you can also restrict access through
/etc/hosts.allow; the following will allow connections from
hosts with IP addresses 1.2.3.4, from hosts on the clas C IP
network 192.168.5.0, and from hosts in the foo.net DNS domain,
while rejecting any other connections.
sshd : 1.2.3.4 : allow
sshd : 192.168.5.0/255.255.255.0 : allow
sshd : *.foo.net : allow
sshd : ALL : deny
As soon as we are given the relevant details, the SuSE security
team will publish a follow-up advisory, and another openssh
update, as required.
Please download the update package for your distribution and
verify its integrity by the methods listed in section 3) of this
announcement.
If you are running nscd (enabled by default since SuSE Linux 7.0), the
name service caching daemon, shut down the daemon prior to upgrading
(this works around a bug in the groupadd command):
rcnscd stop
Then, install the package using the following command to apply
the update:
rpm -Fvh openssh*.rpm
After upgrading, please restart the SSH server by executing the
following command as super user:
rcsshd restart
Our maintenance customers are being notified individually. The
packages are being offered to install from the maintenance web.
Special notice concerning SuSE Linux 6.4 and 7.0:
SuSE Linux 6.4 ceased to be supported a week or two ago. However,
given the potential impact of this problem, we decided to issue update
packages for 6.4 as well. These are in the process of getting built,
and will show up on our FTP server soon.
Users of SuSE Linux 6.4 and 7.0, please also note that crypto update
packages for these platforms are always made available through
ftp.suse.de only, not ftp.suse.com, due to the crypto laws that
were in effect in the US at the time of the original release of
the product.
i386 Intel Platform
SuSE-8.0
aa29ca8bcedf674605c69d3ebb20456c
568b475b982721e62f557557c59624fb
source rpm:
5a533bd017d86346986904b0c9e6c3e5
SuSE-7.3
86b3182d742afba08a99bb04ae91f70f
source rpm:
4d017a1b4a49d0da63ca18c817961b48
SuSE-7.2
d559ad7d04162a32c58fa07b480be820
source rpm:
90a4577e90d31ab9c393269c94f4fe86
SuSE-7.1
3f5999291e0959ebbc1afbd152d3b1f0
source rpm:
73c1b72c4616253d8292fad76ef0b41b
SuSE-7.0
b670aa96ceaa97a33cd4b2009492e1ea
source rpm:
8f77876f90ef86a2e6fb8e23c34fbd6f
Sparc Platform
SuSE-7.3
d1306f869119e076bcb1693d8de837e4
source rpm:
6495e65b671b788cb62f8dcfd7f81f45
SuSE-7.1
ae8c8de1505ed2ac56fc5ec20041819c
source rpm:
16425d92da3c9fa9feeee0322a216b1b
SuSE-7.0
05a40abfdbd42b5465e367a187a3393c
source rpm:
bf000a597b2cc3b33517887fa50f0504
AXP Alpha Platform
SuSE-7.1
478503f40c0ef3ed2d5b3ea40dd74e32
source rpm:
e8b93a73622386a95497d0418d2bfa50
SuSE-7.0
3001c656fb57915c4bb5dcd5fa8de76d
source rpm:
2fd9646fa24b5298d37a79902230c826
PPC Power PC Platform
SuSE-7.3
77dd425d361dc084bad50feefdf1f94c
source rpm:
8a928dc956cd107ee91d72fe4b4a8bc6
SuSE-7.1
ddbc79c387273ddd0da636c7df951c85
source rpm:
ef9f5de04c632490fe77b96e06892f01
SuSE-7.0
67867b11cefc77dca95aaeb130012507
source rpm:
76e2f4d9fb52cc5c7220f52108614542
______________________________________________________________________________
2) Pending vulnerabilities in SuSE Distributions and Workarounds:
- mozilla
Cross-dependencies between mozilla and other packages in SuSE Linux
products keep us from providing version upgrades for the mozilla
packages. Fixing security bugs in our packages is usually done by
adding the necessary patches to the existing version to ensure the
compatibility and consistency that is expected from our products.
In some cases (as with the mozilla package) the complexity of the
issue does not allow to add patches any more. By consequence,
security related issues in mozilla cannot be addressed.
As a service to our user community, we provide packages of newer
mozilla versions at .
These packages have been verified to run fine; they are not located
in the update directory of the distribution in question because
we cannot make any claims about the compatibility with the other
packages in the product. Security-aware users are encouraged to
install the packages from the projects/ directory.
- ghostscript
Red Hat released a security announcement concerning a problem in
ghostscript, which could be exploited to gain privilege of the print
server user. We are investigating whether SuSE Linux is affected.
- kernel netfilter update
we are in the process of preparing a kernel update that will include
a security fix for a minor netfilter bug.
- fetchmail
we are in the process of releasing a security update for fetchmail
that corrects a vulnerability that could be exploited by hostile
mail servers.
______________________________________________________________________________
3) standard appendix: authenticity verification, additional information
- Package authenticity verification:
SuSE update packages are available on many mirror ftp servers all over
the world. While this service is being considered valuable and important
to the free and open source software community, many users wish to be
sure about the origin of the package and its content before installing
the package. There are two verification methods that can be used
independently from each other to prove the authenticity of a downloaded
file or rpm package:
1) md5sums as provided in the (cryptographically signed) announcement.
2) using the internal gpg signatures of the rpm package.
1) execute the command
md5sum
References
