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Bug 1351955 - (CVE-2016-2119) CVE-2016-2119 samba: Client side SMB2/3 required signing can be downgraded
CVE-2016-2119 samba: Client side SMB2/3 required signing can be downgraded
Status: CLOSED ERRATA
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
medium Severity medium
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: ---
Assigned To: Red Hat Product Security
impact=moderate,public=20160707,repor...
: Security
Depends On: 1351957 1351959 1351960 1351961 1351986 1353504
Blocks: 1351956
  Show dependency tree / graph
 
Reported: 2016-07-01 05:03 EDT by Huzaifa S. Sidhpurwala
Modified: 2016-07-27 03:14 EDT (History)
9 users (show)

See Also:
Fixed In Version: samba 4.4.5, samba 4.3.11, samba 4.2.14
Doc Type: Bug Fix
Doc Text:
A flaw was found in the way Samba initiated signed DCE/RPC connections. A man-in-the-middle attacker could use this flaw to downgrade the connection to not use signing and therefore impersonate the server.
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Clone Of:
Environment:
Last Closed: 2016-07-27 03:14:14 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
CRM:
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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External Trackers
Tracker ID Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2016:1486 normal SHIPPED_LIVE Moderate: samba security and bug fix update 2016-07-26 07:09:01 EDT
Red Hat Product Errata RHSA-2016:1487 normal SHIPPED_LIVE Moderate: samba4 security update 2016-07-26 06:49:28 EDT
Red Hat Product Errata RHSA-2016:1494 normal SHIPPED_LIVE Moderate: samba security update 2016-07-26 11:51:09 EDT

  None (edit)
Description Huzaifa S. Sidhpurwala 2016-07-01 05:03:44 EDT 
As per upstream advisory:


It's possible for an attacker to downgrade the required signing for an SMB2/3 client connection, by injecting the SMB2_SESSION_FLAG_IS_GUEST or SMB2_SESSION_FLAG_IS_NULL flags.

This applies to the combination of "client ipc signing" and "client ipc max protocol" in their effective default settings ("mandatory" and "SMB3_11").

The combination of "client signing" and "client max protocol" is also affected, but only if "client signing" is explicitly set (as the effective default is "if_required") and "client max protocol" is explicitly set to SMB2 or higher.
Comment 1 Huzaifa S. Sidhpurwala 2016-07-01 05:03:59 EDT 
Acknowledgments:

Name: the Samba project
Upstream: Stefan Metzmacher
Comment 5 Huzaifa S. Sidhpurwala 2016-07-07 06:26:45 EDT 
Public via:

https://www.samba.org/samba/security/CVE-2016-2119.html
Comment 6 Huzaifa S. Sidhpurwala 2016-07-07 06:36:34 EDT 
Created samba tracking bugs for this issue:

Affects: fedora-all [bug 1353504]
Comment 7 Fedora Update System 2016-07-12 11:03:32 EDT 
samba-4.4.5-1.fc24 has been pushed to the Fedora 24 stable repository. If problems still persist, please make note of it in this bug report.
Comment 8 Fedora Update System 2016-07-15 06:23:27 EDT 
samba-4.3.11-1.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.
Comment 11 errata-xmlrpc 2016-07-26 02:49:41 EDT 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6

Via RHSA-2016:1487 https://rhn.redhat.com/errata/RHSA-2016-1487.html
Comment 12 errata-xmlrpc 2016-07-26 03:09:36 EDT 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2016:1486 https://rhn.redhat.com/errata/RHSA-2016-1486.html
Comment 13 errata-xmlrpc 2016-07-26 07:51:49 EDT 
This issue has been addressed in the following products:

  Red Hat Gluster Storage 3.1 for RHEL 7
  Red Hat Gluster Storage 3.1 for RHEL 6

Via RHSA-2016:1494 https://rhn.redhat.com/errata/RHSA-2016-1494.html
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