Michael McNally
2018-05-18 19:06:21 UTC
CVE: CVE-2018-5737
Document Version: 2.0
Posting date: 18 May 2018
Program Impacted: BIND
Versions affected: 9.12.0, 9.12.1
Severity: Medium
Exploitable: Remotely
Description:
A problem with the implementation of the new serve-stale feature
in BIND 9.12 can lead to an assertion failure in rbtdb.c, even
when stale-answer-enable is off. Additionally, problematic
interaction between the serve-stale feature and NSEC aggressive
negative caching can in some cases cause undesirable behavior
from named, such as a recursion loop or excessive logging.
Deliberate exploitation of this condition could cause operational
problems depending on the particular manifestation -- either
degradation or denial of service.
Impact:
Servers running a vulnerable version of BIND (9.12.0, 9.12.1)
which permit recursion to clients and which have the max-stale-ttl
parameter set to a non-zero value are at risk.
CVSS Score: 5.9
CVSS Vector: CVSS:3.0/AV:N/AC:H/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:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Workarounds:
Setting "max-stale-ttl 0;" in named.conf will prevent exploitation
of this vulnerability (but will effectively disable the serve-stale
feature.)
Setting "stale-answer enable off;" is not sufficient to prevent
exploitation, max-stale-ttl needs to be set to zero.
Active exploits:
No known active exploits.
Solution:
The error which can be exploited in this vulnerability is present
in only two public release versions of BIND, 9.12.0 and 9.12.1.
If you are running an affected version then upgrade to BIND
9.12.1-P2
Acknowledgements:
ISC would like to thank Tony Finch of the University of Cambridge
for his assistance in discovering and analyzing this vulnerability.
Document Revision History:
1.0 Advance Notification, 09 May 2018
1.1 BIND 9.12.1-P1 was recalled before public announcement
due to defect, the advisory language was re-written to be
clearer about the exploit risk, and the public disclosure
date was adjusted because of the problem with 9.12.1-P1,
17 May 2018
2.0 Public Disclosure, 18 May 2018
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
Advance Security Notifications, please visit http://www.isc.org/support/.
Do you still have questions? Questions regarding this advisory
should go to security-***@isc.org. To report a new issue,
please encrypt your message using security-***@isc.org's PGP
key which can be found here:
https://www.isc.org/downloads/software-support-policy/openpgp-key/.
If you are unable to use encrypted email, you may also report new
issues at: https://www.isc.org/community/report-bug/.
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-01606 is
the complete and official security advisory document.
Legal Disclaimer:
Internet Systems Consortium (ISC) is providing this notice on
an "AS IS" basis. No warranty or guarantee of any kind is expressed
in this notice and none should be implied. ISC expressly excludes
and disclaims any warranties regarding this notice or materials
referred to in this notice, including, without limitation, any
implied warranty of merchantability, fitness for a particular
purpose, absence of hidden defects, or of non-infringement. Your
use or reliance on this notice or materials referred to in this
notice is at your own risk. ISC may change this notice at any
time. A stand-alone copy or paraphrase of the text of this
document that omits the document URL is an uncontrolled copy.
Uncontrolled copies may lack important information, be out of
date, or contain factual errors.
(c) 2001-2018 Internet Systems Consortium
_______________________________________________
Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list
bind-users mailing list
bind-***@lists.isc.org
https://lists.isc.org/mailman/listinfo/bind-users
Document Version: 2.0
Posting date: 18 May 2018
Program Impacted: BIND
Versions affected: 9.12.0, 9.12.1
Severity: Medium
Exploitable: Remotely
Description:
A problem with the implementation of the new serve-stale feature
in BIND 9.12 can lead to an assertion failure in rbtdb.c, even
when stale-answer-enable is off. Additionally, problematic
interaction between the serve-stale feature and NSEC aggressive
negative caching can in some cases cause undesirable behavior
from named, such as a recursion loop or excessive logging.
Deliberate exploitation of this condition could cause operational
problems depending on the particular manifestation -- either
degradation or denial of service.
Impact:
Servers running a vulnerable version of BIND (9.12.0, 9.12.1)
which permit recursion to clients and which have the max-stale-ttl
parameter set to a non-zero value are at risk.
CVSS Score: 5.9
CVSS Vector: CVSS:3.0/AV:N/AC:H/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:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Workarounds:
Setting "max-stale-ttl 0;" in named.conf will prevent exploitation
of this vulnerability (but will effectively disable the serve-stale
feature.)
Setting "stale-answer enable off;" is not sufficient to prevent
exploitation, max-stale-ttl needs to be set to zero.
Active exploits:
No known active exploits.
Solution:
The error which can be exploited in this vulnerability is present
in only two public release versions of BIND, 9.12.0 and 9.12.1.
If you are running an affected version then upgrade to BIND
9.12.1-P2
Acknowledgements:
ISC would like to thank Tony Finch of the University of Cambridge
for his assistance in discovering and analyzing this vulnerability.
Document Revision History:
1.0 Advance Notification, 09 May 2018
1.1 BIND 9.12.1-P1 was recalled before public announcement
due to defect, the advisory language was re-written to be
clearer about the exploit risk, and the public disclosure
date was adjusted because of the problem with 9.12.1-P1,
17 May 2018
2.0 Public Disclosure, 18 May 2018
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
Advance Security Notifications, please visit http://www.isc.org/support/.
Do you still have questions? Questions regarding this advisory
should go to security-***@isc.org. To report a new issue,
please encrypt your message using security-***@isc.org's PGP
key which can be found here:
https://www.isc.org/downloads/software-support-policy/openpgp-key/.
If you are unable to use encrypted email, you may also report new
issues at: https://www.isc.org/community/report-bug/.
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-01606 is
the complete and official security advisory document.
Legal Disclaimer:
Internet Systems Consortium (ISC) is providing this notice on
an "AS IS" basis. No warranty or guarantee of any kind is expressed
in this notice and none should be implied. ISC expressly excludes
and disclaims any warranties regarding this notice or materials
referred to in this notice, including, without limitation, any
implied warranty of merchantability, fitness for a particular
purpose, absence of hidden defects, or of non-infringement. Your
use or reliance on this notice or materials referred to in this
notice is at your own risk. ISC may change this notice at any
time. A stand-alone copy or paraphrase of the text of this
document that omits the document URL is an uncontrolled copy.
Uncontrolled copies may lack important information, be out of
date, or contain factual errors.
(c) 2001-2018 Internet Systems Consortium
_______________________________________________
Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list
bind-users mailing list
bind-***@lists.isc.org
https://lists.isc.org/mailman/listinfo/bind-users