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Vulnerability of Samba: use after free via NetLogon

Synthesis of the vulnerability 

An unauthenticated attacker can force the usage of a freed memory area in NetLogon of Samba, in order to trigger a denial of service, and possibly to execute code with root privileges.
Vulnerable products: Debian, Fedora, HP-UX, OES, openSUSE, Solaris, RHEL, Samba, Slackware, SUSE Linux Enterprise Desktop, SLES, Synology DSM, Ubuntu.
Severity of this weakness: 3/4.
Creation date: 23/02/2015.
Revision date: 15/04/2015.
Références of this bulletin: 7014420, bulletinjan2015, c04636672, CERTFR-2015-AVI-078, CVE-2015-0240, DSA-3171-1, FEDORA-2015-2519, FEDORA-2015-2538, HPSBUX03320, MDVSA-2015:081, MDVSA-2015:082, MDVSA-2015:083, openSUSE-SU-2015:0375-1, openSUSE-SU-2016:1064-1, openSUSE-SU-2016:1106-1, openSUSE-SU-2016:1107-1, openSUSE-SU-2016:1108-1, openSUSE-SU-2016:1440-1, RHSA-2015:0249-01, RHSA-2015:0250-01, RHSA-2015:0251-01, RHSA-2015:0252-01, RHSA-2015:0253-01, RHSA-2015:0254-01, RHSA-2015:0255-01, RHSA-2015:0256-01, RHSA-2015:0257-01, SSA:2015-064-01, SSRT101952, SUSE-SU-2015:0353-1, SUSE-SU-2015:0371-1, SUSE-SU-2015:0386-1, USN-2508-1, VIGILANCE-VUL-16242.

Description of the vulnerability 

The Samba product implements the NetLogon service.

An unauthenticated attacker (NULL session over IPC) can use the RPC ServerPasswordSet() of NetLogon. However, the _netr_ServerPasswordSet() function frees a memory area before reusing it.

An unauthenticated attacker can therefore force the usage of a freed memory area in NetLogon of Samba, in order to trigger a denial of service, and possibly to execute code with root privileges.
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This weakness note impacts software or systems such as Debian, Fedora, HP-UX, OES, openSUSE, Solaris, RHEL, Samba, Slackware, SUSE Linux Enterprise Desktop, SLES, Synology DSM, Ubuntu.

Our Vigil@nce team determined that the severity of this threat note is important.

The trust level is of type confirmed by the editor, with an origin of intranet client.

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a specialist ability can exploit this computer weakness.

Solutions for this threat 

Samba: version 4.1.17.
The version 4.1.17 is fixed:
  https://www.samba.org/samba/download/

Samba: version 4.0.25.
The version 4.0.25 is fixed:
  https://www.samba.org/samba/download/

Samba: version 3.6.25.
The version 3.6.25 is fixed:
  https://www.samba.org/samba/download/

Samba: patch for NetLogon.
A patch is available in information sources.

Samba: workaround for NetLogon.
A workaround is to add in the [global] section of smb.conf:
  rpc_server:netlogon=disabled

Debian: new samba packages.
New packages are available:
  Debian 7: samba 2:3.6.6-6+deb7u5

Fedora: new samba packages.
New packages are available:
  Fedora 20: samba 4.1.17-1.fc20
  Fedora 21: samba 4.1.17-1.fc21

HP-UX: fixed versions for CIFS-Server.
Fixed versions are indicated in information sources.

Mandriva BS1: new samba packages.
New packages are available:
  Mandriva BS1: samba 3.6.25-1.mbs1

Mandriva BS2: new samba4 packages.
New packages are available:
  Mandriva BS2: samba4 4.1.17-1.mbs2

Mandriva BS2: new samba packages.
New packages are available:
  Mandriva BS2: samba 3.6.25-1.mbs2

Novell OES 11 SP2: patch 10853.
A patch is available:
  https://www.novell.com/support/kb/doc.php?id=7014420

openSUSE 11.4/13.1: new samba packages.
New packages are available:
  openSUSE 13.1: samba 4.2.4-3.54.2, apparmor 2.8.4-4.20.1
  openSUSE 11.4: samba 3.6.3-141.1

openSUSE 13.2: new samba packages.
New packages are available:
  openSUSE 13.2: samba 4.2.4-37.1

openSUSE: new samba packages.
New packages are available:
  openSUSE 13.1: samba 4.1.17-3.30.1
  openSUSE 13.2: samba 4.1.17-5.1

RHEL: new samba packages.
New packages are available:
  RHEL 5: samba3x 3.6.23-9.el5_11, samba3x 3.5.4-0.70.el5_6.4
  RHEL 6: samba 3.6.23-14.el6_6, samba 3.6.9-151.el6_4.3, samba 3.6.9-167.10.3.el6rhs, samba 3.6.509-169.6.el6rhs, samba4 4.0.0-66.el6_6.rc4, samba4 4.0.0-57.el6_4.rc4
  RHEL 7: samba 4.1.1-38.el7_0

Slackware: new samba packages.
New packages are available:
  Slackware 14.1: samba 4.1.17-*-1_slack14.1

Solaris: patch for Third Party (24/03/2015).
A patch is available:
  https://support.oracle.com/rs?type=doc&id=1448883.1

SUSE LE: new samba packages.
New packages are available:
  SUSE LE 11: samba 3.6.3-0.56.1
  SUSE LE 12: samba 4.1.12-16.1

Synology DiskStation Manager: solution for Samba.
The solution is indicated in information sources.

Ubuntu: new samba packages.
New packages are available:
  Ubuntu 14.10: samba 2:4.1.11+dfsg-1ubuntu2.2
  Ubuntu 14.04 LTS: samba 2:4.1.6+dfsg-1ubuntu2.14.04.7
  Ubuntu 12.04 LTS: samba 2:3.6.3-2ubuntu2.12
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