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Gentoo Linux Security Advisory GLSA 200509-15 |
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http://security.gentoo.org/ |
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Severity: High |
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Title: util-linux: umount command validation error |
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Date: September 20, 2005 |
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Bugs: #105805 |
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ID: 200509-15 |
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Synopsis |
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======== |
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|
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A command validation error in umount can lead to an escalation of |
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privileges. |
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Background |
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========== |
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|
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util-linux is a suite of useful Linux programs including umount, a |
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program used to unmount filesystems. |
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|
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Affected packages |
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================= |
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|
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------------------------------------------------------------------- |
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Package / Vulnerable / Unaffected |
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------------------------------------------------------------------- |
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1 sys-apps/util-linux < 2.12q-r3 >= 2.12q-r3 |
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Description |
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=========== |
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|
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When a regular user mounts a filesystem, they are subject to |
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restrictions in the /etc/fstab configuration file. David Watson |
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discovered that when unmounting a filesystem with the '-r' option, the |
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read-only bit is set, while other bits, such as nosuid or nodev, are |
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not set, even if they were previously. |
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|
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Impact |
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====== |
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|
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An unprivileged user facing nosuid or nodev restrictions can umount -r |
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a filesystem clearing those bits, allowing applications to be executed |
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suid, or have device nodes interpreted. In the case where the user can |
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freely modify the contents of the filesystem, privilege escalation may |
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occur as a custom program may execute with suid permissions. |
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|
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Workaround |
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========== |
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|
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Two workarounds exist, first, the suid bit can be removed from the |
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umount utility, or users can be restricted from mounting and unmounting |
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filesystems in /etc/fstab. |
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Resolution |
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========== |
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All util-linux users should upgrade to the latest version: |
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# emerge --sync |
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# emerge --ask --oneshot --verbose ">=sys-apps/util-linux-2.12q-r3" |
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References |
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========== |
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|
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[ 1 ] CAN-2005-2876 |
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http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=2005-2876 |
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|
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Availability |
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============ |
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This GLSA and any updates to it are available for viewing at |
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the Gentoo Security Website: |
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http://security.gentoo.org/glsa/glsa-200509-15.xml |
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Concerns? |
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========= |
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Security is a primary focus of Gentoo Linux and ensuring the |
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confidentiality and security of our users machines is of utmost |
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importance to us. Any security concerns should be addressed to |
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security@g.o or alternatively, you may file a bug at |
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http://bugs.gentoo.org. |
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|
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License |
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======= |
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Copyright 2005 Gentoo Foundation, Inc; referenced text |
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belongs to its owner(s). |
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The contents of this document are licensed under the |
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Creative Commons - Attribution / Share Alike license. |
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http://creativecommons.org/licenses/by-sa/2.0 |
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