6 - USN-2855-2

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 15.10 - Ubuntu 14.04 LTS - Ubuntu 12.04 LTS

Summary:

USN-2855-1 introduced a regression in Samba.

Software Description: - samba: SMB/CIFS file, print, and login server for Unix

Details:

USN-2855-1 fixed vulnerabilities in Samba. The upstream fix for CVE-2015-5252 introduced a regression in certain specific environments. This update fixes the problem.

Original advisory details:

Thilo Uttendorfer discovered that the Samba LDAP server incorrectly handled
certain packets. A remote attacker could use this issue to cause the LDAP
server to stop responding, resulting in a denial of service. This issue
only affected Ubuntu 14.04 LTS, Ubuntu 15.04 and Ubuntu 15.10.
(CVE-2015-3223)
Jan Kasprzak discovered that Samba incorrectly handled certain symlinks. A
remote attacker could use this issue to access files outside the exported
share path. (CVE-2015-5252)
Stefan Metzmacher discovered that Samba did not enforce signing when
creating encrypted connections. If a remote attacker were able to perform a
man-in-the-middle attack, this flaw could be exploited to view sensitive
information. (CVE-2015-5296)
It was discovered that Samba incorrectly performed access control when
using the VFS shadow_copy2 module. A remote attacker could use this issue
to access snapshots, contrary to intended permissions. (CVE-2015-5299)
Douglas Bagnall discovered that Samba incorrectly handled certain string
lengths. A remote attacker could use this issue to possibly access
sensitive information. (CVE-2015-5330)
It was discovered that the Samba LDAP server incorrectly handled certain
packets. A remote attacker could use this issue to cause the LDAP server to
stop responding, resulting in a denial of service. This issue only affected
Ubuntu 14.04 LTS, Ubuntu 15.04 and Ubuntu 15.10. (CVE-2015-7540)
Andrew Bartlett discovered that Samba incorrectly checked administrative
privileges during creation of machine accounts. A remote attacker could
possibly use this issue to bypass intended access restrictions in certain
environments. This issue only affected Ubuntu 14.04 LTS, Ubuntu 15.04 and
Ubuntu 15.10. (CVE-2015-8467)

Update instructions:

The problem can be corrected by updating your system to the following package versions:

Ubuntu 15.10:
samba 2:4.1.17+dfsg-4ubuntu3.2

Ubuntu 14.04 LTS:
samba 2:4.1.6+dfsg-1ubuntu2.14.04.12

Ubuntu 12.04 LTS:
samba 2:3.6.3-2ubuntu2.14

In general, a standard system update will make all the necessary changes.

References:
http://www.ubuntu.com/usn/usn-2855-2
http://www.ubuntu.com/usn/usn-2855-1
https://launchpad.net/bugs/1545750

Package Information:
https://launchpad.net/ubuntu/+source/samba/2:4.1.17+dfsg-4ubuntu3.2
https://launchpad.net/ubuntu/+source/samba/2:4.1.6+dfsg-1ubuntu2.14.04.12
https://launchpad.net/ubuntu/+source/samba/2:3.6.3-2ubuntu2.14