GLSA-200509-15 : util-linux: umount command validation error
High Nessus Plugin ID 19814
SynopsisThe remote Gentoo host is missing one or more security-related patches.
DescriptionThe remote host is affected by the vulnerability described in GLSA-200509-15 (util-linux: umount command validation error)
When a regular user mounts a filesystem, they are subject to restrictions in the /etc/fstab configuration file. David Watson discovered that when unmounting a filesystem with the '-r' option, the read-only bit is set, while other bits, such as nosuid or nodev, are not set, even if they were previously.
An unprivileged user facing nosuid or nodev restrictions can umount -r a filesystem clearing those bits, allowing applications to be executed suid, or have device nodes interpreted. In the case where the user can freely modify the contents of the filesystem, privilege escalation may occur as a custom program may execute with suid permissions.
Two workarounds exist, first, the suid bit can be removed from the umount utility, or users can be restricted from mounting and unmounting filesystems in /etc/fstab.
SolutionAll util-linux users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose '>=sys-apps/util-linux-2.12q-r3'