Bug 1711816 (CVE-2019-12435)

Summary:	CVE-2019-12435 samba: AD DC Denial of Service in DNS management server
Product:	[Other] Security Response	Reporter:	Marian Rehak <mrehak>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	abokovoy, anoopcs, asn, dblechte, dfediuck, eedri, gdeschner, jarrpa, jstephen, lmohanty, madam, mgoldboi, michal.skrivanek, rhs-smb, sankarshan, sbonazzo, sbose, security-response-team, sherold, sisharma, ssaha, ssorce, vbellur, yturgema
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	samba 4.9.9, samba 4.10.5	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-19 08:06:07 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1721872
Bug Blocks:	1711838

Description Marian Rehak 2019-05-20 07:54:22 UTC

As per upstream advisory:

The dnsserver RPC pipe provides administrative facilities to modify DNS records and zones which allows an authenticated user to crash the RPC server process via a NULL pointer de-reference. This issue affects Samba 4.0 and later.

There is no further vulnerability associated with this issue, merely a denial of service.

Comment 2 Huzaifa S. Sidhpurwala 2019-06-10 04:54:16 UTC

Acknowledgments:

Name: The samba project

Comment 3 Huzaifa S. Sidhpurwala 2019-06-10 04:54:18 UTC

Mitigation:

The dnsserver task can be stopped by setting 
 'dcerpc endpoint servers = -dnsserver'
in the smb.conf and restarting Samba.

Comment 4 Huzaifa S. Sidhpurwala 2019-06-10 06:40:28 UTC

Upstream bug: https://bugzilla.samba.org/show_bug.cgi?id=13922

Comment 7 Huzaifa S. Sidhpurwala 2019-06-19 08:00:36 UTC

External References:

https://www.samba.org/samba/security/CVE-2019-12435.html

Comment 8 Huzaifa S. Sidhpurwala 2019-06-19 08:01:16 UTC

Created samba tracking bugs for this issue:

Affects: fedora-all [bug 1721872]

Comment 9 Hardik Vyas 2019-06-19 08:09:57 UTC

Statement:

This issue did not affect the version of samba as shipped with 'Red Hat Gluster Storage 3' as they did not include support for Active Directory Domain Controller.