Synopsis
The remote Samba server is affected by multiple vulnerabilities.
Description
According to its banner, the version of Samba running on the remote host is 4.2.x prior to 4.2.7 or 4.3.x prior to 4.3.3. It is, therefore, affected by the following vulnerabilities :
  - A denial of service vulnerability exists in the     ldb_wildcard_compare() function in file ldb_match.c due     to mishandling certain zero values. An unauthenticated,     remote attacker can exploit this, via crafted LDAP     requests, to exhaust CPU resources. (CVE-2015-3223)
  - A security bypass vulnerability exists in the     check_reduced_name_with_privilege() function and the     check_reduced_name() function within file smbd/vfs.c     that allows users to follow symlinks that point to     resources in another directory that shares a common path     prefix. An unauthenticated, remote attacker can exploit     this, via a symlink that points outside of a share, to     bypass file access restrictions. (CVE-2015-5252)
  - A flaw exists due to a failure to ensure that signing is     negotiated when creating encrypted connections between     the client and server. A man-in-the-middle attacker can     exploit this, by modifying the client-server data     stream, to downgrade the security of the connection,     thus allowing communications to be monitored or     manipulated. (CVE-2015-5296)
  - A security bypass vulnerability exists in the     shadow_copy2_get_shadow_copy_data() function in file     modules/vfs_shadow_copy2.c due to a failure to verify     that DIRECTORY_LIST access rights has been granted when     accessing snapshots. An unauthenticated, remote attacker     can exploit this to access snapshots by visiting a     shadow copy directory. (CVE-2015-5299)
  - A flaw exists in the LDAP server due to improper     handling of string lengths in LDAP requests. An     unauthenticated, remote attacker can exploit this to     gain sensitive information from the daemon heap memory     by sending crafted packets and then reading an error     message or a database value. (CVE-2015-5330)
  - The samldb_check_user_account_control_acl() function     in file dsdb/samdb/ldb_modules/samldb.c fails to     properly check for administrative privileges during the     creation of machine accounts. An authenticated, remote     attacker can exploit this to bypass intended access     restrictions by making use of a domain that has both     a Samba DC and Windows DC. (CVE-2015-8467)
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
Solution
Upgrade to Samba version 4.2.7 / 4.3.3 or greater.
Plugin Details
File Name: samba_4_3_3.nasl
Configuration: Enable paranoid mode
Supported Sensors: Nessus
Risk Information
Vector: CVSS2#AV:N/AC:M/Au:S/C:P/I:P/A:P
Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
CPE: cpe:/a:samba:samba
Required KB Items: Settings/ParanoidReport, SMB/samba, SMB/NativeLanManager
Exploit Ease: No known exploits are available
Patch Publication Date: 12/16/2015
Vulnerability Publication Date: 11/24/2015
Reference Information
CVE: CVE-2015-3223, CVE-2015-5252, CVE-2015-5296, CVE-2015-5299, CVE-2015-5330, CVE-2015-8467
BID: 79729, 79731, 79732, 79733, 79734, 79735