Bug 1778586 (CVE-2019-14861) - CVE-2019-14861 samba: An authenticated user can crash the DCE/RPC DNS management server by creating records with matching the zone name
Summary: CVE-2019-14861 samba: An authenticated user can crash the DCE/RPC DNS managem...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2019-14861
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1781542
Blocks: 1778587
TreeView+ depends on / blocked
 
Reported: 2019-12-02 05:28 UTC by Huzaifa S. Sidhpurwala
Modified: 2019-12-17 02:09 UTC (History)
18 users (show)

Fixed In Version: samba 4.11.3, samba 4.10.11, samba 4.9.17
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2019-12-17 02:09:23 UTC


Attachments (Terms of Use)

Description Huzaifa S. Sidhpurwala 2019-12-02 05:28:11 UTC
As per upstream advisory:

The (poorly named) dnsserver RPC pipe provides administrative facilities to modify DNS records and zones.

Samba, when acting as an AD DC, stores DNS records in LDAP.

In AD, the default permissions on the DNS partition allow creation of new records by authenticated users.  This is used for example to allow machines to self-register in DNS.

If a DNS record was created that case-insensitively matched the name of the zone, the ldb_qsort() and dns_name_compare() routines could be confused into reading memory prior to the list of DNS entries when responding to DnssrvEnumRecords() or DnssrvEnumRecords2() and so following invalid memory as a pointer.

Comment 1 Huzaifa S. Sidhpurwala 2019-12-02 05:28:16 UTC
Acknowledgments:

Name: the Samba project
Upstream: Andreas Oster

Comment 2 Huzaifa S. Sidhpurwala 2019-12-02 05:29:22 UTC
Mitigation:

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

Comment 3 Huzaifa S. Sidhpurwala 2019-12-02 15:28:42 UTC
Statement:

This flaw does not affect the version of samba shipped with Red Hat Enterprise Linux because there is no support for samba as Active Directory Domain Controller.

Comment 4 Huzaifa S. Sidhpurwala 2019-12-10 09:02:27 UTC
External References:

https://www.samba.org/samba/security/CVE-2019-14861.html

Comment 5 Huzaifa S. Sidhpurwala 2019-12-10 09:03:01 UTC
Created samba tracking bugs for this issue:

Affects: fedora-all [bug 1781542]

Comment 6 Product Security DevOps Team 2019-12-17 02:09:23 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2019-14861


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