(Red Hat Issues Fix) Samba Multiple Flaws Let Remote Users Hijack Connections, Obtain Potentially Sensitive Information, and Deny Service
SecurityTracker Alert ID: 1035537|
SecurityTracker URL: http://securitytracker.com/id/1035537
CVE-2015-5370, CVE-2016-2110, CVE-2016-2111, CVE-2016-2112, CVE-2016-2115, CVE-2016-2118
(Links to External Site)
Date: Apr 13 2016
Denial of service via network, Disclosure of system information, Disclosure of user information, Modification of user information, User access via network|
Fix Available: Yes Vendor Confirmed: Yes |
Version(s): 3.0.0 to 4.4.0|
Multiple vulnerabilities were reported in Samba. A remote user can cause denial of service conditions on the target system. A remote user can hijack connection. A remote user can obtain potentially sensitive information on the target system.|
A remote authenticated user can exploit a missing error check in dcesrv_auth_bind_ack() in the DCE/RPC protocol implementation to cause excessive CPU consumption on the target system or cause the target service to crash or execute arbitrary code [CVE-2015-5370]. Versions 3.6.0 to 4.4.0 are affected.
The NTLMSSP implementation is not protected against downgrading. A remote user that can conduct a man-in-the-middle attack can hijack the target connection [CVE-2016-2110].
The NTLMSSP implementation is not protected against downgrading. A remote user that can conduct a man-in-the-middle attack can spoof a system name to a Domain Controller and obtain session-related information about the spoofed system [CVE-2016-2111].
The LDAP implementation does not enforce integrity protection for LDAP connections. A remote user that can conduct a man-in-the-middle attack can downgrade the target LDAP connection to use no integrity protection and gain access to the connection [CVE-2016-2112].
A remote user that can conduct a man-in-the-middle attack can gain access to LDAP connection [CVE-2016-2113]. Versions 4.0.0 to 4.4.0 are affected.
The system does not enforce the mandatory server signing configuration setting. As a result, a remote user can conduct a man-in-the-middle attack to hijack SMB1 connections [CVE-2016-2114]. Versions 4.0.0 to 4.4.0 are affected.
The IPC implementation does not enforce integrity protection by default. A remote user that can conduct a man-in-the-middle attacker can view and modify data sent via the IPC connection [CVE-2016-2115].
A remote user that can conduct a man-in-the-middle attack against DCE/RPE connections can impersonate the target user against the Security Account Manager Remote Protocol (MS-SAMR) and the Local Security Authority (Domain Policy) Remote Protocol (MS-LSAD) implementations to obtain read/write access to the target Security Account Manager database [CVE-2016-2118]. This can be exploited to obtain passwords in the database. Versions 3.6.0 to 4.4.0 are affected.
[Editor's note: Microsoft Windows is also affected by this vulnerability, as described in CVE-2016-0128 (Alert ID 1035534). This vulnerability is known as "Badlock".]
Jouni Knuutinen of Synopsys reported the dcesrv_auth_bind_ack() vulnerability. Stefan Metzmacher of SerNet (https://samba.plus) reported the other vulnerabilities.
A remote user can cause denial of service conditions.|
A remote user can obtain potentially sensitive information on the target system.
A remote user can hijack connections.
Red Hat has issued a fix for CVE-2015-5370, CVE-2016-2110, CVE-2016-2111, CVE-2016-2112, CVE-2016-2115, and CVE-2016-2118.|
The Red Hat advisory is available at:
Vendor URL: rhn.redhat.com/errata/RHSA-2016-0623.html (Links to External Site)
Access control error, Authentication error|
|Underlying OS: Linux (Red Hat Enterprise)|
|Underlying OS Comments: 5.6, 5.9|
This archive entry is a follow-up to the message listed below.|
Source Message Contents
Subject: [RHSA-2016:0623-01] Important: samba security update|
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Red Hat Security Advisory
Synopsis: Important: samba security update
Advisory ID: RHSA-2016:0623-01
Product: Red Hat Enterprise Linux
Advisory URL: https://rhn.redhat.com/errata/RHSA-2016-0623.html
Issue date: 2016-04-12
CVE Names: CVE-2015-5370 CVE-2016-2110 CVE-2016-2111
CVE-2016-2112 CVE-2016-2115 CVE-2016-2118
An update for samba is now available for Red Hat Enterprise Linux 5.6 Long
Life and Red Hat Enterprise Linux 5.9 Long Life.
Red Hat Product Security has rated this update as having a security impact
of Important. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available for each vulnerability
from the CVE link(s) in the References section.
2. Relevant releases/architectures:
Red Hat Enterprise Linux Long Life (v. 5.6 server) - i386, ia64, x86_64
Red Hat Enterprise Linux Long Life (v. 5.9 server) - i386, ia64, ppc, s390x, x86_64
Samba is an open-source implementation of the Server Message Block (SMB)
protocol and the related Common Internet File System (CIFS) protocol, which
allow PC-compatible machines to share files, printers, and various
* Multiple flaws were found in Samba's DCE/RPC protocol implementation. A
remote, authenticated attacker could use these flaws to cause a denial of
service against the Samba server (high CPU load or a crash) or, possibly,
execute arbitrary code with the permissions of the user running Samba
(root). This flaw could also be used to downgrade a secure DCE/RPC
connection by a man-in-the-middle attacker taking control of an Active
Directory (AD) object and compromising the security of a Samba Active
Directory Domain Controller (DC). (CVE-2015-5370)
Note: While Samba packages as shipped in Red Hat Enterprise Linux do not
support running Samba as an AD DC, this flaw applies to all roles Samba
* A protocol flaw, publicly referred to as Badlock, was found in the
Security Account Manager Remote Protocol (MS-SAMR) and the Local Security
Authority (Domain Policy) Remote Protocol (MS-LSAD). Any authenticated
DCE/RPC connection that a client initiates against a server could be used
by a man-in-the-middle attacker to impersonate the authenticated user
against the SAMR or LSA service on the server. As a result, the attacker
would be able to get read/write access to the Security Account Manager
database, and use this to reveal all passwords or any other potentially
sensitive information in that database. (CVE-2016-2118)
* Several flaws were found in Samba's implementation of NTLMSSP
authentication. An unauthenticated, man-in-the-middle attacker could use
this flaw to clear the encryption and integrity flags of a connection,
causing data to be transmitted in plain text. The attacker could also force
the client or server into sending data in plain text even if encryption was
explicitly requested for that connection. (CVE-2016-2110)
* It was discovered that Samba configured as a Domain Controller would
establish a secure communication channel with a machine using a spoofed
computer name. A remote attacker able to observe network traffic could use
this flaw to obtain session-related information about the spoofed machine.
* It was found that Samba's LDAP implementation did not enforce integrity
protection for LDAP connections. A man-in-the-middle attacker could use
this flaw to downgrade LDAP connections to use no integrity protection,
allowing them to hijack such connections. (CVE-2016-2112)
* It was found that Samba did not enable integrity protection for IPC
traffic by default. A man-in-the-middle attacker could use this flaw to
view and modify the data sent between a Samba server and a client.
Red Hat would like to thank the Samba project for reporting these issues.
Upstream acknowledges Jouni Knuutinen (Synopsis) as the original reporter
of CVE-2015-5370; and Stefan Metzmacher (SerNet) as the original reporter
of CVE-2016-2118, CVE-2016-2110, CVE-2016-2112, and CVE-2016-2115.
For details on how to apply this update, which includes the changes
described in this advisory, refer to:
After installing this update, the smb service will be restarted
5. Bugs fixed (https://bugzilla.redhat.com/):
1309987 - CVE-2015-5370 samba: crash in dcesrv_auth_bind_ack due to missing error check
1311893 - CVE-2016-2110 samba: Man-in-the-middle attacks possible with NTLMSSP authentication
1311902 - CVE-2016-2111 samba: Spoofing vulnerability when domain controller is configured
1311903 - CVE-2016-2112 samba: Missing downgrade detection
1312084 - CVE-2016-2115 samba: Smb signing not required by default when smb client connection is used for ipc usage
1317990 - CVE-2016-2118 samba: SAMR and LSA man in the middle attacks
6. Package List:
Red Hat Enterprise Linux Long Life (v. 5.6 server):
Red Hat Enterprise Linux Long Life (v. 5.9 server):
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
The Red Hat security contact is <firstname.lastname@example.org>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2016 Red Hat, Inc.
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