Linux Today: Linux News On Internet Time.

Linux-Mandrake Security Update Advisory: modutils update

Nov 24, 2000, 09:17 (0 Talkback[s])

Date: Thu, 23 Nov 2000 13:36:06 -0700
From: Linux Mandrake Security Team security@linux-mandrake.com
To: Linux Mandrake Security Announcements
Subject: [Security Announce] MDKSA-2000:071-1 - modutils update

                Linux-Mandrake Security Update Advisory

Package name:           modutils
Date:                   November 23rd, 2000
Original Advisory Date: November 16th, 2000
Advisory ID:            MDKSA-2000:071-1

Affected versions:      7.1, 7.2

Problem Description:

All 2.3.x versions of modutils (since March 12 1999) contain a vulnerability that can lead to a local root compromise. The modprobe program uses popen() to execute the "echo" program argumented with user input. Because popen() relies on /bin/sh to parse the command string and execute "echo", un-escaped shell meta-characters can be included in user input to execute commands. Although modprobe is not installed setuid root, this vulnerability can be exploited to gain root access provided the target system is using kmod. Kmod is a kernel facility that automatically executes the program modprobe when a module is requested via request_module(). One program that can take advantage of this vulnerability is ping. When a device is specified at the command line that doesn't exist, request_module is called with the user-supplied arguments passed to the kernel. The kernel then takes the arguments and executes modprobe with them. Arbitrary commands included in the argument for module name (device name to ping) are then executed when popen() is called as root.

A new version of modutils (2.3.20) has been released that fixes this particular vulnerability. modutils still supports meta expansion, including back quoted commands, but only for data read from the configuration file. This assumes that when modutils is run as root out of the kernel, normal users cannot specify their own configuration files.


The previous version of modutils (2.3.20) contained an error in the new safe guards that caused them to not properly be enabled when run as root from the kmod process. These new safe guards check the arguments passed to modules. The 2.3.21 modutils package fixes this error and correctly checks the arguments when running from kmod, limiting kernel module arguments to those specified in /etc/conf.modules (Linux-Mandrake 7.1) or /etc/modules.conf (Linux-Mandrake 7.2).

Please verify these md5 checksums of the updates prior to upgrading to ensure the integrity of the downloaded package. You can do this by running the md5sum program on the downloaded package by using "md5sum package.rpm".

Linux-Mandrake 7.1:
75dd47e569d7ab2c92d90f5287c31701 7.1/RPMS/modutils-2.3.21-1.2mdk.i586.rpm
0c722ca0610cb30fc53c3a15052788d6 7.1/SRPMS/modutils-2.3.21-1.2mdk.src.rpm

Linux-Mandrake 7.2:
bd41dc31c12162fa35a46e72720c917b 7.2/RPMS/modutils-2.3.21-1.1mdk.i586.rpm
0f06619f247ed7616a773fffa30e707a 7.2/SRPMS/modutils-2.3.21-1.1mdk.src.rpm

To upgrade automatically, use <<MandrakeUpdate>>.

If you want to upgrade manually, download the updated package from one of our FTP server mirrors and uprade with "rpm -Uvh package_name".

You can download the updates directly from:

Or try one of the other mirrors listed at:


Updated packages are available in the "updates/[ver]/RPMS/" directory. For example, if you are looking for an updated RPM package for Linux-Mandrake 7.1, look for it in "updates/7.1/RPMS/". Updated source RPMs are available as well, but you generally do not need to download them.

Please be aware that sometimes it takes the mirrors a few hours to update, so if you want an immediate upgrade, please use one of the two above-listed mirrors.

You can view other security advisories for Linux-Mandrake at:


If you want to report vulnerabilities, please contact


Linux-Mandrake has two security-related mailing list services that anyone can subscribe to:


Linux-Mandrake's security announcements mailing list. Only announcements are sent to this list and it is read-only.


Linux-Mandrake's security discussion mailing list. This list is open to anyone to discuss Linux-Mandrake security specifically and Linux security in general.

To subscribe to either list, send a message to sympa@linux-mandrake.com with "subscribe [listname]" in the body of the message.

To remove yourself from either list, send a message to sympa@linux-mandrake.com with "unsubscribe [listname]" in the body of the message.

To get more information on either list, send a message to sympa@linux-mandrake.com with "info [listname]" in the body of the message.

Optionally, you can use the web interface to subscribe to or unsubscribe from either list: