Bug 841940 - (CVE-2012-3409) CVE-2012-3409 ecryptfs-utils: suid helper does not restrict mounting filesystems with nosuid,nodev leading to possible privilege escalation
CVE-2012-3409 ecryptfs-utils: suid helper does not restrict mounting filesyst...
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
All Linux
medium Severity medium
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Assigned To: Red Hat Product Security
: Security
Depends On: 842512
Blocks: 841942
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Reported: 2012-07-20 11:25 EDT by Vincent Danen
Modified: 2012-08-03 07:28 EDT (History)
2 users (show)

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Doc Type: Bug Fix
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Last Closed: 2012-07-24 00:54:33 EDT
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Description Vincent Danen 2012-07-20 11:25:56 EDT
It was reported [1] that the private ecryptfs mount helper (/sbin/mount.ecryptfs_private), which is setuid-root, could allow an unprivileged local user to mount user-controlled ecryptfs shares on the local system.  Because the ecryptfs helper does not mount filesystems with the "nosuid" and "nodev" flags, it would be possible for a user to mount a filesystem containing setuid-root binaries and/or device files that could lead to the escalation of their privileges.  This could be done via a USB device, if the user had physical access to the system.

It was however also noted [2] that this may only affect version 86 and later, as the encrypted home source and destination mount points were hard-coded up until that version.

Forcing MS_NOSUID and MS_NODEV mount flags was added to version 99 (commits [3],[4])

[1] http://www.openwall.com/lists/oss-security/2012/07/10/19
[2] http://www.openwall.com/lists/oss-security/2012/07/11/2
[3] http://bazaar.launchpad.net/~ecryptfs/ecryptfs/trunk/revision/705
[4] http://bazaar.launchpad.net/~ecryptfs/ecryptfs/trunk/revision/708
Comment 1 Vincent Danen 2012-07-20 11:30:39 EDT
I also forgot to note that on Fedora and RHEL, you need to be part of the ecryptfs group to even use the ecryptfs filesystems/utilities, which lowers the attack surface considerably.
Comment 3 Huzaifa S. Sidhpurwala 2012-07-24 00:53:07 EDT

Not Vulnerable. This issue does not affect the version of ecryptfs-utils as shipped with Red Hat Enterprise Linux 5 and 6.
Comment 4 Huzaifa S. Sidhpurwala 2012-07-24 00:53:57 EDT
Created ecryptfs-utils tracking bugs for this issue

Affects: fedora-all [bug 842512]
Comment 5 Fedora Update System 2012-08-03 07:27:42 EDT
ecryptfs-utils-99-1.fc17 has been pushed to the Fedora 17 stable repository.  If problems still persist, please make note of it in this bug report.
Comment 6 Fedora Update System 2012-08-03 07:28:20 EDT
ecryptfs-utils-99-1.fc16 has been pushed to the Fedora 16 stable repository.  If problems still persist, please make note of it in this bug report.

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