RHSA-2016:0010 - Security Advisory

Topic

Updated samba4 packages that fix multiple security issues are now available
for Red Hat Enterprise Linux 6.

Red Hat Product Security 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

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.

A denial of service flaw was found in the LDAP server provided by the AD DC
in the Samba process daemon. A remote attacker could exploit this flaw by
sending a specially crafted packet, which could cause the server to consume
an excessive amount of memory and crash. (CVE-2015-7540)

Multiple buffer over-read flaws were found in the way Samba handled
malformed inputs in certain encodings. An authenticated, remote attacker
could possibly use these flaws to disclose portions of the server memory.
(CVE-2015-5330)

A man-in-the-middle vulnerability was found in the way "connection signing"
was implemented by Samba. A remote attacker could use this flaw to
downgrade an existing Samba client connection and force the use of plain
text. (CVE-2015-5296)

A missing access control flaw was found in Samba. A remote, authenticated
attacker could use this flaw to view the current snapshot on a Samba share,
despite not having DIRECTORY_LIST access rights. (CVE-2015-5299)

An access flaw was found in the way Samba verified symbolic links when
creating new files on a Samba share. A remote attacker could exploit this
flaw to gain access to files outside of Samba's share path. (CVE-2015-5252)

Red Hat would like to thank the Samba project for reporting these issues.
Upstream acknowledges Stefan Metzmacher of the Samba Team and Sernet.de as
the original reporters of CVE-2015-5296, partha@exablox.com as the original
reporter of CVE-2015-5299, Jan "Yenya" Kasprzak and the Computer Systems
Unit team at Faculty of Informatics, Masaryk University as the original
reporters of CVE-2015-5252 flaws, and Douglas Bagnall as the original
reporter of CVE-2015-5330.

All samba4 users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. 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.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.7 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 Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.7 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.7 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 - Extended Update Support from RHUI 6.7 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.7 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux EUS Compute Node 6.7 x86_64
• RHEL for SAP HANA - Extended Update Support 6.7 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 1276126 - CVE-2015-5299 Samba: Missing access control check in shadow copy code
• BZ - 1281326 - CVE-2015-5330 samba, libldb: remote memory read in the Samba LDAP server
• BZ - 1288451 - CVE-2015-7540 samba: DoS to AD-DC due to insufficient checking of asn1 memory allocation
• BZ - 1290288 - CVE-2015-5252 samba: Insufficient symlink verification in smbd
• BZ - 1290292 - CVE-2015-5296 samba: client requesting encryption vulnerable to downgrade attack

CVEs

• CVE-2015-5299
• CVE-2015-7540
• CVE-2015-5296
• CVE-2015-5252
• CVE-2015-5330

References

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