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Bug 1101988 - (CVE-2014-0239) CVE-2014-0239 samba: potential DoS in the internal DNS server
CVE-2014-0239 samba: potential DoS in the internal DNS server
Status: CLOSED NOTABUG
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
low Severity low
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Assigned To: Red Hat Product Security
impact=low,public=20140528,reported=2...
: Security
Depends On:
Blocks: 1102108
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Reported: 2014-05-28 06:03 EDT by Vasyl Kaigorodov
Modified: 2015-07-31 03:20 EDT (History)
5 users (show)

See Also:
Fixed In Version: samba 4.0.18
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Environment:
Last Closed: 2014-05-29 02:29:50 EDT
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Vasyl Kaigorodov 2014-05-28 06:03:53 EDT 
It was reported [1] that Samba versions 4.0.0 and above have a flaw in DNS protocol handling in the internal DNS server. The server will not check the "reply" flag in the DNS packet header when processing a request. That makes it vulnerable to reply to a spoofed reply packet with another reply. Two affected servers could thus DOS each other

[1]: http://www.samba.org/samba/security/CVE-2014-0239

Patches addressing this issue have been posted to:

    http://www.samba.org/samba/security/

Samba version 4.0.18 includes a patch for this issue.

To workaround this issue, use the BIND_DLZ DNS backend.
Comment 1 Vasyl Kaigorodov 2014-05-28 06:05:38 EDT 
Additional info:

The internal DNS server in Samba 4.x before 4.0.18 does not check the
QR field in the header section of an incoming DNS message before
sending a response, which allows remote attackers to cause a denial of
service (CPU and bandwidth consumption) via a forged response packet
that triggers a communication loop, a related issue to CVE-1999-0103.
Comment 2 Alexander Bokovoy 2014-05-28 06:20:28 EDT 
Please note that there are no versions of Samba in Fedora or RHEL 6 (or RHEL 7 Release candidate) that allow to utilize internal DNS server in Samba 4. The default build is not supporting Samba AD DC functionality which is where the issue is.
Comment 4 Vasyl Kaigorodov 2014-05-28 10:01:15 EDT 
External References:

http://www.samba.org/samba/security/CVE-2014-0239
Comment 5 Huzaifa S. Sidhpurwala 2014-05-29 02:28:42 EDT 
Statement:

Not vulnerable. This issue does not affect the version of samba as shipped with Red Hat Enterprise Linux 5 and 6. This issue does not affect the version of samba3x as shipped with Red Hat Enterprise Linux 5. This issue does not affect the version of samba4 as shipped with Red Hat Enterprise Linux 6.
Comment 6 Huzaifa S. Sidhpurwala 2014-05-29 02:29:50 EDT 
This issue does not affect the version of samba as shipped with Fedora 19 and Fedora 20.
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