RHSA-2012:0313 - Security Advisory

Topic

Updated samba packages that fix one security issue, one bug, and add one
enhancement are now available for Red Hat Enterprise Linux 5.

The Red Hat Security Response Team has rated this update as having low
security impact. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available from the CVE link in
the References section.

Description

Samba is an open-source implementation of the Server Message Block (SMB) or
Common Internet File System (CIFS) protocol, which allows PC-compatible
machines to share files, printers, and other information.

The default Samba server configuration enabled both the "wide links" and
"unix extensions" options, allowing Samba clients with write access to a
share to create symbolic links that point to any location on the file
system. Clients connecting with CIFS UNIX extensions disabled could have
such links resolved on the server, allowing them to access and possibly
overwrite files outside of the share. With this update, "wide links" is
set to "no" by default. In addition, the update ensures "wide links" is
disabled for shares that have "unix extensions" enabled. (CVE-2010-0926)

Warning: This update may cause files and directories that are only linked
to Samba shares using symbolic links to become inaccessible to Samba
clients. In deployments where support for CIFS UNIX extensions is not
needed (such as when files are exported to Microsoft Windows clients),
administrators may prefer to set the "unix extensions" option to "no" to
allow the use of symbolic links to access files out of the shared
directories. All existing symbolic links in a share should be reviewed
before re-enabling "wide links".

These updated samba packages also fix the following bug:

• The smbclient tool sometimes failed to return the proper exit status

code. Consequently, using smbclient in a script caused some scripts to
fail. With this update, an upstream patch has been applied and smbclient
now returns the correct exit status. (BZ#768908)

In addition, these updated samba packages provide the following
enhancement:

• With this update, support for Windows Server 2008 R2 domains has been

added. (BZ#736124)

Users are advised to upgrade to these updated samba packages, which correct
these issues and add this enhancement. After installing this update, the
smb service will be restarted automatically.

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 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 562568 - CVE-2010-0926 samba: insecure "wide links" default

CVEs

• CVE-2010-0926

References

• https://access.redhat.com/security/updates/classification/#low