RHSA-2011:1241 - Security Advisory

Topic

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.

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.

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

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.1 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.1 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.1 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.1 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.1 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.1 i386
• Red Hat Virtual Storage Appliance (from RHUI) 6.1 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 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
• BZ - 732607 - CVE-2011-3145 ecryptfs-utils: incorrect mtab group ownership

CVEs

• CVE-2011-1831
• CVE-2011-3145
• CVE-2011-1832
• CVE-2011-1835
• CVE-2011-1834
• CVE-2011-1837

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/support/offerings/techpreview/