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SuSE Security Announcement: modules

Nov 13, 2000, 21:02 (0 Talkback[s])
(Other stories by Sebastian Krahmer)

Date: Mon, 13 Nov 2000 10:09:29 +0100 (MET)
From: Sebastian Krahmer krahmer@suse.de
To: suse-security-announce@suse.de
Subject: [suse-security-announce] SuSE Security Announcement: modules


                        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.