====================================================================

                             CERT-Renater

                 Note d'Information No. 2020/VULN351
_____________________________________________________________________

DATE                : 18/06/2020

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running ISC Bind versions prior to 9.11.20,
                                      9.16.4, 9.11.20-S1.

=====================================================================
https://kb.isc.org/docs/cve-2020-8618
https://kb.isc.org/docs/cve-2020-8619
_____________________________________________________________________

CVE-2020-8618: A buffer boundary check assertion in rdataset.c can fail
incorrectly during zone transfer

    Updated on 17 Jun 2020


CVE: CVE-2020-8618

Document version: 2.0

Posting date: 17 June 2020

Program impacted: BIND

Versions affected: BIND 9.16.0 -> 9.16.3

Severity: Medium

Exploitable: Remotely


Description:

An assertion check in BIND (that is meant to prevent going beyond the
end of a buffer when processing incoming data) can be incorrectly
triggered by a large response during zone transfer.


Impact:

An attacker who is permitted to send zone data to a server via zone
transfer can exploit this to intentionally trigger the assertion failure
with a specially constructed zone, denying service to clients.

CVSS Score: 4.3

CVSS Vector: AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

For more information on the Common Vulnerability Scoring System and to
obtain your specific environmental score please visit:
https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C&version=3.1.


Workarounds:

None


Active exploits:

We are not aware of any active exploits.


Solution:

Upgrade to the patched release most closely related to your current
version of BIND:

    BIND 9.16.4


Document revision history:

1.0 Early Notification, 10 June 2020
1.1 Simplified "Exploitable" section, 17 June 2020
2.0 Public disclosure, 17 June 2020


Related documents:

See our BIND 9 Security Vulnerability Matrix for a complete listing of
security vulnerabilities and versions affected.

Do you still have questions? Questions regarding this advisory should go
to security-officer@isc.org. To report a new issue, please encrypt your
message using security-officer@isc.org's PGP key which can be found
here: https://www.isc.org/pgpkey/. If you are unable to use encrypted
email, you may also report new issues at:
https://www.isc.org/reportbug/.


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 https://www.isc.org/download/.)


ISC Security Vulnerability Disclosure Policy:

Details of our current security advisory policy and practice can be
found in the ISC Software Defect and Security Vulnerability Disclosure
Policy at https://kb.isc.org/docs/aa-00861.

The Knowledgebase article https://kb.isc.org/docs/cve-2020-8618 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.

_____________________________________________________________________


CVE-2020-8619: An asterisk character in an empty non-terminal can cause
an assertion failure in rbtdb.c

    Updated on 17 Jun 2020


CVE: CVE-2020-8619

Document version: 2.0

Posting date: 17 June 2020

Program impacted: BIND

Versions affected: BIND 9.11.14 -> 9.11.19, BIND 9.14.9 -> 9.14.12, BIND
9.16.0 -> 9.16.3. Also, versions 9.11.14-S1 -> 9.11.19-S1 of BIND
Supported Preview Edition

Severity: Medium

Exploitable: Remotely, but only if records matching a certain pattern
are present in a zone being served.


Description:

The asterisk character ("*") is allowed in DNS zone files, where it is
most commonly present as a wildcard at a terminal node of the Domain
Name System graph. However, the RFCs do not require and BIND does not
enforce that an asterisk character be present only at a terminal node.

A problem can occur when an asterisk is present in an empty non-terminal
location within the DNS graph. If such a node exists, after a series of
queries, named can reach an inconsistent state that results in the
failure of an assertion check in rbtdb.c, followed by the program
exiting due to the assertion failure.


Impact:

Unless a nameserver is providing authoritative service for one or more
zones and at least one zone contains an empty non-terminal entry
containing an asterisk ("*") character, this defect cannot be
encountered. A would-be attacker who is allowed to change zone content
could theoretically introduce such a record in order to exploit this
condition to cause denial of service, though we consider the use of this
vector unlikely because any such attack would require a significant
privilege level and be easily traceable.

CVSS Score: 4.3

CVSS Vector: AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

For more information on the Common Vulnerability Scoring System and to
obtain your specific environmental score please visit:
https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C&version=3.1.


Workarounds:

None


Active exploits:

We are not aware of any active exploits.


Solution:

Upgrade to the patched release most closely related to your current
version of BIND:

    BIND 9.11.20
    BIND 9.16.4

BIND Supported Preview Edition is a special feature preview branch of
BIND provided to eligible ISC support customers.

    BIND 9.11.20-S1


Document revision history:

1.0 Early Notification, 10 June 2020
1.1 Corrected "Versions affected" to list Supported Preview Edition
releases, 17 June 2020
2.0 Public disclosure, 17 June 2020


Related documents:

See our BIND 9 Security Vulnerability Matrix for a complete listing of
security vulnerabilities and versions affected.

Do you still have questions? Questions regarding this advisory should go
to security-officer@isc.org. To report a new issue, please encrypt your
message using security-officer@isc.org's PGP key which can be found
here: https://www.isc.org/pgpkey/. If you are unable to use encrypted
email, you may also report new issues at:
https://www.isc.org/reportbug/.

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 https://www.isc.org/download/.)

ISC Security Vulnerability Disclosure Policy:

Details of our current security advisory policy and practice can be
found in the ISC Software Defect and Security Vulnerability Disclosure
Policy at https://kb.isc.org/docs/aa-00861.

The Knowledgebase article https://kb.isc.org/docs/cve-YYYY-NNNN 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.



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+ CERT-RENATER        | tel : 01-53-94-20-44            +
+ 23/25 Rue Daviel    | fax : 01-53-94-20-41            +
+ 75013 Paris         | email:cert@support.renater.fr   +
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