CVE-2016-9778: An error handling certain queries using the nxdomain-redirect feature could cause a REQUIRE assertion failure in db.c
Michael McNally
mcnally at isc.org
Wed Jan 11 22:35:40 UTC 2017
CVE: CVE-2016-9778
Document Version: 2.0
Posting date: 11 Jan 2017
Program Impacted: BIND
Versions affected: 9.9.8-S1 -> 9.9.8-S3, 9.9.9-S1 -> 9.9.9-S6,
9.11.0-9.11.0 -> P1
Severity: High (for affected configurations)
Exploitable: Remotely
Description:
An error in handling certain queries can cause an assertion
failure when a server is using the nxdomain-redirect feature to
cover a zone for which it is also providing authoritative service.
A vulnerable server could be intentionally stopped by an attacker
if it was using a configuration that met the criteria for the
vulnerability and if the attacker could cause it to accept a
query that possessed the required attributes.
Please note: This vulnerability affects the "nxdomain-redirect"
feature, which is one of two methods of handling NXDOMAIN
redirection, and is only available in certain versions of BIND.
Redirection using zones of type "redirect" is not affected by
this vulnerability.
Impact:
Only servers which are performing NXDOMAIN redirection using the
"nxdomain-redirect" function are potentially vulnerable and then
only a subset of those servers. In order to be affected a server
must be using nxdomain-redirect AND must be redirecting NXDOMAIN
responses for a zone for which the server also provides authoritative
service -- therefore a purely recursive server is not at risk,
either. Successful exploitation of the vulnerability will cause
named to stop execution after encountering a REQUIRE assertion
failure in db.c, resulting in denial of service to clients.
CVSS Score: 7.5
CVSSv3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
For more information on the Common Vulnerability Scoring System and
to obtain your specific environmental score please visit:
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Workarounds:
Either provide an ordinary (that is: not redirected) NXDOMAIN
for non-existent resource records in zones for which authoritative
data is served on the same server or use redirect zones instead
of the nxdomain-redirect feature.
Active exploits:
No known active exploits.
Solution:
Upgrade to the patched release most closely related to your
current version of BIND. These can be downloaded from
http://www.isc.org/downloads.
BIND 9 version 9.11.0-P2
BIND Supported Preview Edition is a special feature preview
branch of BIND provided to eligible ISC support customers.
BIND 9.9.9-S7
Document Revision History:
1.0 Advance Notification, 03 January 2017
1.1 Updated Versions affected to include 9.11.0-P1, 04 January 2017
2.0 Public Announcement, 11 January 2017
Related Documents:
See our BIND9 Security Vulnerability Matrix at
https://kb.isc.org/article/AA-00913 for a complete listing of
Security Vulnerabilities and versions affected.
If you'd like more information on ISC Subscription Support and
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Note:
ISC patches only currently supported versions. When possible we
indicate EOL versions affected. (For current information on
which versions are actively supported, please see
http://www.isc.org/downloads/).
ISC Security Vulnerability Disclosure Policy:
Details of our current security advisory policy and practice can
be found here: https://kb.isc.org/article/AA-00861/
This Knowledge Base article https://kb.isc.org/article/AA-01442 is
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