7.5 - RHSA-2011:1241

Problem Description:

Updated ecryptfs-utils packages that fix several security issues are now available for Red Hat Enterprise Linux 5 and 6.

The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

2. Relevant releases/architectures:

RHEL Desktop Workstation (v. 5 client) - i386, x86_64 Red Hat Enterprise Linux (v. 5 server) - i386, ia64, ppc, s390x, x86_64 Red Hat Enterprise Linux Desktop (v. 5 client) - i386, x86_64 Red Hat Enterprise Linux Desktop (v. 6) - i386, x86_64 Red Hat Enterprise Linux Desktop Optional (v. 6) - i386, x86_64 Red Hat Enterprise Linux HPC Node (v. 6) - x86_64 Red Hat Enterprise Linux HPC Node Optional (v. 6) - x86_64 Red Hat Enterprise Linux Server (v. 6) - i386, ppc64, s390x, x86_64 Red Hat Enterprise Linux Server Optional (v. 6) - i386, ppc64, s390x, x86_64 Red Hat Enterprise Linux Workstation (v. 6) - i386, x86_64 Red Hat Enterprise Linux Workstation Optional (v. 6) - i386, x86_64

3. Description:

eCryptfs is a stacked, cryptographic file system. It is transparent to the underlying file system and provides per-file granularity. eCryptfs is released as a Technology Preview for Red Hat Enterprise Linux 5 and 6.

The setuid mount.ecryptfs_private utility allows users to mount an eCryptfs file system. This utility can only be run by users in the "ecryptfs" group.

A race condition flaw was found in the way mount.ecryptfs_private checked the permissions of a requested mount point when mounting an encrypted file system. A local attacker could possibly use this flaw to escalate their privileges by mounting over an arbitrary directory. (CVE-2011-1831)

A race condition flaw in umount.ecryptfs_private could allow a local attacker to unmount an arbitrary file system. (CVE-2011-1832)

It was found that mount.ecryptfs_private did not handle certain errors correctly when updating the mtab (mounted file systems table) file, allowing a local attacker to corrupt the mtab file and possibly unmount an arbitrary file system. (CVE-2011-1834)

An insecure temporary file use flaw was found in the ecryptfs-setup-private script. A local attacker could use this script to insert their own key that will subsequently be used by a new user, possibly giving the attacker access to the user's encrypted data if existing file permissions allow access. (CVE-2011-1835)

A race condition flaw in mount.ecryptfs_private could allow a local attacker to overwrite arbitrary files. (CVE-2011-1837)

A race condition flaw in the way temporary files were accessed in mount.ecryptfs_private could allow a malicious, local user to make arbitrary modifications to the mtab file. (CVE-2011-3145)

A race condition flaw was found in the way mount.ecryptfs_private checked the permissions of the directory to mount. A local attacker could use this flaw to mount (and then access) a directory they would otherwise not have access to. Note: The fix for this issue is incomplete until a kernel-space change is made. Future Red Hat Enterprise Linux 5 and 6 kernel updates will correct this issue. (CVE-2011-1833)

Red Hat would like to thank the Ubuntu Security Team for reporting these issues. The Ubuntu Security Team acknowledges Vasiliy Kulikov of Openwall and Dan Rosenberg as the original reporters of CVE-2011-1831, CVE-2011-1832, and CVE-2011-1833; Dan Rosenberg and Marc Deslauriers as the original reporters of CVE-2011-1834; Marc Deslauriers as the original reporter of CVE-2011-1835; and Vasiliy Kulikov of Openwall as the original reporter of CVE-2011-1837.

Users of ecryptfs-utils are advised to upgrade to these updated packages, which contain backported patches to correct these issues.

4. Solution:

Before applying this update, make sure all previously-released errata relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at https://access.redhat.com/kb/docs/DOC-11259

5. Bugs fixed (http://bugzilla.redhat.com/):

729465 - CVE-2011-1831 CVE-2011-1832 CVE-2011-1834 CVE-2011-1835 CVE-2011-1837 ecryptfs: multiple flaws to mount/umount arbitrary locations and possibly disclose confidential information 732607 - CVE-2011-3145 ecryptfs-utils: incorrect mtab group ownership