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
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".
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