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Gentoo: 202110-05 Critical: util-linux Mount Privilege Escalation

A command validation error in umount can lead to an escalation of privileges.. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Gentoo Linux Security Advisory GLSA 200509-15 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - https://security.gentoo.org/ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Severity: High Title: util-linux: umount command validation error Date: September 20, 2005 Bugs: #105805 ID: 200509-15 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Synopsis ======= A command validation error in umount can lead to an escalation of privileges. Background ========= util-linux is a suite of useful Linux programs including umount, a program used to unmount filesystems. Affected packages ================ ------------------------------------------------------------------- Package / Vulnerable / Unaffected ------------------------------------------------------------------- 1 sys-apps/util-linux < 2.12q-r3 > = 2.12q-r3 Description ========== 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. Impact ===== 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. Workaround ========= Two workarounds exist, first, the suid bit can be removed from the umount utility, or users can be restricted from mounting andunmounting filesystems in /etc/fstab. Resolution ========= All util-linux users should upgrade to the latest version: # emerge --sync # emerge --ask --oneshot --verbose "> =sys-apps/util-linux-2.12q-r3" References ========= [ 1 ] CAN-2005-2876 Availability =========== This GLSA and any updates to it are available for viewing at the Gentoo Security Website: https://security.gentoo.org/glsa/200509-15 Concerns? ======== Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users machines is of utmost importance to us. Any security concerns should be addressed to This email address is being protected from spambots. You need JavaScript enabled to view it. or alternatively, you may file a bug at https://bugs.gentoo.org/. License ====== Copyright 2005 Gentoo Foundation, Inc; referenced text belongs to its owner(s). The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license. https://creativecommons.org/licenses/by-sa/2.0/ . Investigate how validation flaws in the umount command on Gentoo systems can create vulnerabilities for privilege escalation and outline necessary remediation steps.. umount command, Gentoo advisory, Linux command error. . LinuxSecurity.com Team

Sep 20, 2005 Gentoo