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The modules package is responsible for on-demand loading of kernel modules/drivers. The /sbin/modprobe command, when executed as a new task by the kernel-internal function request_module(), runs with the priviledges of the init process, usually root. Newer versions of the modprobe program contain a bug which allows local users to gain root priviledges. modprobe expands given arguments via /bin/echo and can easily be tricked into executing commands. In order for this bug to be exploitable, a setuid root program must be installed that can trigger the loading of modules (such as ping6).
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-----BEGIN PGP SIGNED MESSAGE-----
______________________________________________________________________________
SuSE Security Announcement
Package: modules
Announcement-ID: SuSE-SA:2000:44
Date: Monday, November 13th, 2000 10:00 MEST
Affected SuSE versions: 6.4, 7.0
Vulnerability Type: local root compromise
Severity (1-10): 8
SuSE default package: yes
Other affected systems: many newer Linux distributions
Content of this advisory:
1) security vulnerability resolved: modprobe shell metacharacter
expansion
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 modules package is responsible for on-demand loading of kernel
modules/drivers. The /sbin/modprobe command, when executed as a new
task by the kernel-internal function request_module(), runs with the
priviledges of the init process, usually root.
Newer versions of the modprobe program contain a bug
which allows local users to gain root priviledges. modprobe expands
given arguments via /bin/echo and can easily be tricked into executing
commands. In order for this bug to be exploitable, a setuid root program
must be installed that can trigger the loading of modules (such as ping6).
The fix for this bug consists of a change to modprobe which disables
the expansion of arguments to modprobe via /bin/echo.
A temporary workaround for this bug is to disable the automatic loading
of modules in the running kernel by running the command (as root)
/sbin/sysctl -w kernel.modprobe=/
or
echo "/" > /proc/sys/kernel/modprobe
Please note that this temporary workaround will have to be repeated
after the next reboot to become effective again.
Download the update package from locations desribed below and install
the package with the command `rpm -Uhv file.rpm'. The md5sum for each
file is in the line below. You can verify the integrity of the rpm
files using the command
`rpm --checksig --nogpg file.rpm',
independently from the md5 signatures below.
i386 Intel Platform:
SuSE-7.0
ftp://ftp.suse.com/pub/suse/i386/update/7.0/a1/modules-2.3.11-73.i386.rpm
9643216a1e0c147635ef62d894a9d7ad
source rpm:
ftp://ftp.suse.com/pub/suse/i386/update/7.0/zq1/modules.spm
Due to a packaging error, the modules package source rpm is not
available on our ftp servers yet. It will appear at the location above
in very few hours.
SuSE-6.4
ftp://ftp.suse.com/pub/suse/i386/update/6.4/a1/modules-2.3.9-63.i386.rpm
d3a95b93e549aae9a462e84d179efe45
source rpm:
ftp://ftp.suse.com/pub/suse/i386/update/6.4/zq1/modules.spm
Due to a packaging error, the modules package source rpm is not
available on our ftp servers yet. It will appear at the location above
in very few hours.
Sparc Platform:
SuSE-7.0
ftp://ftp.suse.com/pub/suse/sparc/update/7.0/a1/modules-2.3.11-73.sparc.rpm
c0ab9aab7a61cefdb2cade98c663d4e3
source rpm:
ftp://ftp.suse.com/pub/suse/sparc/update/7.0/zq1/modules.spm
Due to a packaging error, the modules package source rpm is not
available on our ftp servers yet. It will appear at the location above
in very few hours.
AXP Alpha Platform:
SuSE-6.4
ftp://ftp.suse.com/pub/suse/axp/update/6.4/a1/modules-2.3.9-63.alpha.rpm
a88b84d7f3d79f2a47ff9e78681a0390
source rpm:
ftp://ftp.suse.com/pub/suse/axp/update/6.4/zq1/modules.spm
Due to a packaging error, the modules package source rpm is not
available on our ftp servers yet. It will appear at the location above
in very few hours.
PPC Power PC Platform:
SuSE-7.0:
ftp://ftp.suse.com/pub/suse/ppc/update/7.0/a1/modules-2.3.11-73.ppc.rpm
ef09b5c6438a0de8e18653e0a60d9c4c
source rpm:
ftp://ftp.suse.com/pub/suse/ppc/update/7.0/zq1/modules.spm
Due to a packaging error, the modules package source rpm is not
available on our ftp servers yet. It will appear at the location above
in very few hours.
SuSE-6.4
ftp://ftp.suse.com/pub/suse/ppc/update/6.4/a1/modules-2.3.9-63.ppc.rpm
27ba13500292c44969dd865f0c543c19
source rpm:
ftp://ftp.suse.com/pub/suse/ppc/update/6.4/zq1/modules.spm
Due to a packaging error, the modules package source rpm is not
available on our ftp servers yet. It will appear at the location above
in very few hours.
______________________________________________________________________________
2) Pending vulnerabilities in SuSE Distributions and Workarounds:
A seperate message is being prepared to address the currently ongoing
security vulnerabilites.
______________________________________________________________________________
3) standard appendix:
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>.
===============================================
Regards,
Sebastian Krahmer
______________________________________________________________________________
The information in this advisory may be distributed or reproduced,
provided that the advisory is not modified in any way.
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 2048/3D25D3D9 1999/03/06 SuSE Security Team <security@suse.de>
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This archive was generated by hypermail 2.1.0
: Mon Jun 04 2001 - 18:25:15 PDT
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