Author: JT Smith
SuSE: “The ‘at’ command reads commands from standard input for execution at a later time specified on the command line. If such an execution time is given in a carefully drafted (but wrong) format, the at command may crash as a result of a surplus call to free(). The cause of the crash is a heap corruption that is exploitable under certain circumstances since the /usr/bin/at command is installed setuid root.”
______________________________________________________________________________
SuSE Security Announcement
Package: at
Announcement-ID: SuSE-SA:2002:003
Date: Wednesday, Jan 16th 2001 16:00 MET
Affected SuSE versions: 6.4, 7.0, 7.1, 7.2, 7.3
Vulnerability Type: local privilege escalation
Severity (1-10): 5
SuSE default package: yes
Other affected systems: most Linux systems with the at package
installed
Content of this advisory:
1) security vulnerability resolved: at
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
The 'at' command reads commands from standard input for execution at a
later time specified on the command line. If such an execution time is
given in a carefully drafted (but wrong) format, the at command may
crash as a result of a surplus call to free(). The cause of the crash
is a heap corruption that is exploitable under certain circumstances
since the /usr/bin/at command is installed setuid root.
A temporary workaround against the bug is to disable the at command for
non-root users by removing the setuid-bit from the /usr/bin/at command.
As a permanent solution it is recommended to install the update packages
as listed for download below. In addition to the fixed heap corruption,
file handling security has been improved by adding the O_EXCL (exclusive)
option to an open(2) system call inside the at(1) code. We thank
zen-parse for reporting this vulnerability.
Please download the update package for your distribution and verify its
integrity by the methods listed in section 3) of this announcement.
Then, install the package using the command "rpm -Fhv file.rpm" to apply
the update.
i386 Intel Platform:
SuSE-7.3
ftp://ftp.suse.com/pub/suse/i386/update/7.3/ap1/at-3.1.8-459.i386.rpm
db3d2bd38f81667dcece38d1c4a86725
source rpm:
ftp://ftp.suse.com/pub/suse/i386/update/7.3/zq1/at-3.1.8-459.src.rpm
82701057fc8ea3217800b0ab1e2e544b
SuSE-7.2
ftp://ftp.suse.com/pub/suse/i386/update/7.2/ap1/at-3.1.8-458.i386.rpm
91b759e6a8d433273c5567ed26735690
source rpm:
ftp://ftp.suse.com/pub/suse/i386/update/7.2/zq1/at-3.1.8-458.src.rpm
3df6d6d708d4ef90515f6f1fbbdea5bf
SuSE-7.1
ftp://ftp.suse.com/pub/suse/i386/update/7.1/a1/at-3.1.8-458.i386.rpm
73eb22d5c958c17e264fd31ec339b763
source rpm:
ftp://ftp.suse.com/pub/suse/i386/update/7.1/zq1/at-3.1.8-458.src.rpm
1303a1328f31313a62f5645f7cb476ef
SuSE-7.0
ftp://ftp.suse.com/pub/suse/i386/update/7.0/a1/at-3.1.8-459.i386.rpm
3179e64f87371d7864d1956ceb9bd020
source rpm:
ftp://ftp.suse.com/pub/suse/i386/update/7.0/zq1/at-3.1.8-459.src.rpm
67efafe83908ac53fc54acac9a0f056b
SuSE-6.4
ftp://ftp.suse.com/pub/suse/i386/update/6.4/a1/at-3.1.8-458.i386.rpm
aaffed7c302b9ec42885087296c6f0a1
source rpm:
ftp://ftp.suse.com/pub/suse/i386/update/6.4/zq1/at-3.1.8-458.src.rpm
374cf4374fbe1e66ab2e685aa0449034
Sparc Platform:
SuSE-7.3
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/ap1/at-3.1.8-356.sparc.rpm
ec76d45245ef917e22f5f1a863a89988
source rpm:
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/zq1/at-3.1.8-356.src.rpm
40de9490a06bd294ad6a7f90e682c0cd
SuSE-7.1
ftp://ftp.suse.com/pub/suse/sparc/update/7.1/a1/at-3.1.8-356.sparc.rpm
27f575762c0b1643008968a167324347
source rpm:
ftp://ftp.suse.com/pub/suse/sparc/update/7.1/zq1/at-3.1.8-356.src.rpm
66546dc729e071039595a13d01feacfb
SuSE-7.0
ftp://ftp.suse.com/pub/suse/sparc/update/7.0/a1/at-3.1.8-357.sparc.rpm
98007292769f55e4239b6922157bfa13
source rpm:
ftp://ftp.suse.com/pub/suse/sparc/update/7.0/zq1/at-3.1.8-357.src.rpm
2d20cdbb10680282596677aac3106f30
AXP Alpha Platform:
SuSE-7.1
ftp://ftp.suse.com/pub/suse/axp/update/7.1/a1/at-3.1.8-360.alpha.rpm
df71ebf25a2252637ee1421d08779b8d
source rpm:
ftp://ftp.suse.com/pub/suse/axp/update/7.1/zq1/at-3.1.8-360.src.rpm
b8b3a4f80e0d19e0211131ca58c1e0fe
SuSE-7.0
ftp://ftp.suse.com/pub/suse/axp/update/7.0/a1/at-3.1.8-361.alpha.rpm
0bc21b9ddc12746a17592fa74473bbf6
source rpm:
ftp://ftp.suse.com/pub/suse/axp/update/7.0/zq1/at-3.1.8-361.src.rpm
4d93aa10b426224936e3de357540ea49
SuSE-6.4
ftp://ftp.suse.com/pub/suse/axp/update/6.4/a1/at-3.1.8-361.alpha.rpm
aeb76c2eb37f7e442c49c7ba3c5e44a5
source rpm:
ftp://ftp.suse.com/pub/suse/axp/update/6.4/zq1/at-3.1.8-361.src.rpm
6d783c34eb0b855a96736e58d67bc053
PPC Power PC Platform:
SuSE-7.3
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/ap1/at-3.1.8-363.ppc.rpm
111bd6e813ef33265035b21d19776b49
source rpm:
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/zq1/at-3.1.8-363.src.rpm
fa2ee9aca5b73009b1d9c90731265a19
SuSE-7.1
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/a1/at-3.1.8-362.ppc.rpm
868a1662f751823432d3d881edd371cd
source rpm:
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/zq1/at-3.1.8-362.src.rpm
d759233bfc2ce230e1c46d2ec0f15a73
SuSE-7.0
ftp://ftp.suse.com/pub/suse/ppc/update/7.0/a1/at-3.1.8-362.ppc.rpm
7b12fe4b5f31434eb7cf3c0caae75811
source rpm:
ftp://ftp.suse.com/pub/suse/ppc/update/7.0/zq1/at-3.1.8-362.src.rpm
4c6e2724bb76e08be66831ed85c60f85
SuSE-6.4
ftp://ftp.suse.com/pub/suse/ppc/update/6.4/a1/at-3.1.8-362.ppc.rpm
7ebc9a1fde97f5ac8226b9e17621a40b
source rpm:
ftp://ftp.suse.com/pub/suse/ppc/update/6.4/zq1/at-3.1.8-362.src.rpm
fa3c5e08703eb54b4f493de56ec837bb
______________________________________________________________________________
2) Pending vulnerabilities in SuSE Linux Distributions and Workarounds:
- clanlib
dotslash@snosoft.com reported an environment variable copying buffer
overflow in the clanlib package. If a program that is linked against
the clanlib shared library is installed setuid or setgid, this error
may lead to elevated privileges. In the case of SuSE Linux distributions,
this is only the case for the methane package: It comes installed with a
setgid bit to group "game", which is used to store highscores in group-
writeable files. This setgid bit will be cleared in future releases of
the SuSE Linux distribution. For already installed "methane" packages,
we recommend to remove the setgid bit with the command
chmod -s /usr/X11R6/bin/methane
The methane package is not installed on SuSE systems by default, nor is
the defective library "clanlib".
- thttpd
The thttpd daemon contained several off-by-one overflows. Due to internal
organization of the variables affected by these overflows, they seem
not exploitable. However, these bugs have been fixed. Please update to
the newest thttpd packages.
- pine
The popular mail client "pine" was found vulnerable to an attack where
shell metacharacters inside an URL could be used to execute arbitrary
commands if pine passes the URL to an external viewer on the
commandline. The pine packages on SuSE products are not vulnerable to
this weakness because they contain a patch that works around this
problem since it is not new.
- xchat
We are working on updates for the xchat packages in the SuSE Linux
7.0 and 7.1 distributions that are vulnerable to an encoding bug
while receiving and decoding ctcp datagrams. This bug can lead
an xchat IRC client to execute IRC protocol specific commands to an
IRC server such as channel mode changes.
______________________________________________________________________________
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
after you downloaded the file from a SuSE ftp server or its mirrors.
Then, compare the resulting md5sum with the one that is listed in the
announcement. Since the announcement containing the checksums is
cryptographically signed (usually using the key security@suse.de),
the checksums show proof of the authenticity of the package.
We disrecommend to subscribe to security lists which cause the
email message containing the announcement to be modified so that
the signature does not match after transport through the mailing
list software.
Downsides: You must be able to verify the authenticity of the
announcement in the first place. If RPM packages are being rebuilt
and a new version of a package is published on the ftp server, all
md5 sums for the files are useless.
2) rpm package signatures provide an easy way to verify the authenticity
of an rpm package. Use the command
rpm -v --checksig
to verify the signature of the package, where is the
filename of the rpm package that you have downloaded. Of course,
package authenticity verification can only target an uninstalled rpm
package file.
Prerequisites:
a) gpg is installed
b) The package is signed using a certain key. The public part of this
key must be installed by the gpg program in the directory
~/.gnupg/ under the user's home directory who performs the
signature verification (usually root). You can import the key
that is used by SuSE in rpm packages for SuSE Linux by saving
this announcement to a file ("announcement.txt") and
running the command (do "su -" to be root):
gpg --batch; gpg build@suse.de" upon installation or upgrade, provided that
the package gpg is installed. The file containing the public key
is placed at the toplevel directory of the first CD (pubring.gpg)
and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .
- SuSE runs two security mailing lists to which any interested party may
subscribe:
suse-security@suse.com
- general/linux/SuSE security discussion.
All SuSE security announcements are sent to this list.
To subscribe, send an email to
suse-security-subscribe@suse.com>.
suse-security-announce@suse.com
- SuSE's announce-only mailing list.
Only SuSE's security annoucements are sent to this list.
To subscribe, send an email to
suse-security-announce-subscribe@suse.com>.
For general information or the frequently asked questions (faq)
send mail to:
suse-security-info@suse.com> or
suse-security-faq@suse.com> respectively.
=====================================================================
SuSE's security contact is security@suse.com> or security@suse.de>.
The security@suse.de> public key is listed below.
=====================================================================
______________________________________________________________________________
The information in this advisory may be distributed or reproduced,
provided that the advisory is not modified in any way. In particular,
it is desired that the cleartext signature shows proof of the
authenticity of the text.
SuSE GmbH makes no warranties of any kind whatsoever with respect
to the information contained in this security advisory.
Type Bits/KeyID Date User ID
pub 2048R/3D25D3D9 1999-03-06 SuSE Security Team security@suse.de>
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key build@suse.de>
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Category:
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