CVE-2015-8000: Responses with a malformed class attribute can trigger an assertion failure in db.c

Michael McNally mcnally at isc.org
Tue Dec 15 21:16:47 UTC 2015


CVE:                CVE-2015-8000
Document Version:   2.0
Posting date:       15 December 2015
Program Impacted:   BIND
Versions affected:  9.0.x -> 9.9.8, 9.10.0 -> 9.10.3
Severity:           Critical
Exploitable:        Remotely

Description:

   An error in the parsing of incoming responses allows some records
   with an incorrect class to be be accepted by BIND instead of
   being rejected as malformed.  This can trigger a REQUIRE assertion
   failure when those records are subsequently cached. Intentional
   exploitation of this condition is possible and could be used as
   a denial-of-service vector against servers performing recursive
   queries.

Impact:

   An attacker who can cause a server to request a record with a
   malformed class attribute can use this bug to trigger a REQUIRE
   assertion in db.c, causing named to exit and denying service to
   clients.  The risk to recursive servers is high. Authoritative
   servers are at limited risk if they perform authentication when
   making recursive queries to resolve addresses for servers listed
   in NS RRSETs.

CVSS Score:         7.1

CVSS Vector:        (AV:N/AC:M/Au:N/C:N/I:N/A:C)

For more information on the Common Vulnerability Scoring System and
to obtain your specific environmental score please visit:
https://nvd.nist.gov/cvss.cfm?calculator&version=2&vector=(AV:N/AC:M/Au:N/C:N/I:N/A:C)

Workarounds:        None.
Active exploits:    No known active exploits.

Solution:

   Upgrade to the patched release most closely related to your
   current version of BIND. Public open-source branches can be
   downloaded from http://www.isc.org/downloads.

     BIND 9 version 9.9.8-P2
     BIND 9 version 9.10.3-P2

   BIND 9 Supported Preview edition is a feature preview version
   of BIND provided exclusively to ISC Support customers.

     BIND 9 version 9.9.8-S3

Document Revision History:

   1.0  Advance Notification, 24 November, 2015
   1.1  Software releases 9.9.8-P1 and 9.10.3-P1 replaced with
        9.9.8-P2 and 9.10.3-P2 to address CVE-2015-8461, advisory
        text and schedule updated, 8 December 2015
   2.0  Public Disclosure, 15 December 2015

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.

Do you still have questions?

Questions regarding this advisory should go to security-officer at isc.org.
To report a new issue, please encrypt your message using
security-officer at 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-01317 is
the complete and official security advisory document.

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