SuSE Security Announcement: modulesNov 13, 2000, 21:02 (0 Talkback[s])
(Other stories by Sebastian Krahmer)
Date: Mon, 13 Nov 2000 10:09:29 +0100 (MET)
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=/
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
i386 Intel Platform:
AXP Alpha Platform:
PPC Power PC Platform:
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's security contact is email@example.com.
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.