Mandrake Linux Security Advisory : kernel (MDKSA-2003:038-1)
High Nessus Plugin ID 14022
SynopsisThe remote Mandrake Linux host is missing one or more security updates.
DescriptionA bug in the kernel module loader code could allow a local user to gain root privileges. This is done by a local user using ptrace and attaching to a modprobe process that is spawned if the user triggers the loading of a kernel module.
A temporary workaround can be used to defend against this flaw. It is possible to temporarily disable the kmod kernel module loading subsystem in the kernel after all of the required kernel modules have been loaded. Be sure that you do not need to load additional kernel modules after implementing this workaround. To use it, as root execute :
echo /no/such/file >/proc/sys/kernel/modprobe
To automate this, you may wish to add it as the last line of the /etc/rc.d/rc.local file. You can revert this change by replacing the content '/sbin/modprobe' in the /proc/sys/kernel/modprobe file. The root user can still manually load kernel modules with this workaround in place.
This update applies a patch to correct the problem. All users should upgrade. Please note that the Mandrake Linux 9.1 kernel already has this patch, and an updated kernel for Mandrake Linux 8.2 will be available shortly.
For instructions on how to upgrade your kernel in Mandrake Linux, please refer to :
Kernels are now available for Mandrake Linux 8.2, 8.2/PPC, and Multi- Network Firewall 8.2.
As well, the previously noted instructions for temporarily working around the vulnerability are not completely accurate as they only defend against a certain type of attack making use of this problem.
Users should upgrade to the update kernels, however if you are unable to upgrade you may wish to look into the self-compiled no-ptrace-module.c that is loaded into a running kernel.
SolutionUpdate the affected packages.