Security Advisory: CVE-2011-2464 - ISC BIND 9 Remote packet Denial of Service against Authoritative and Recursive Servers

Barry Greene bgreene at
Tue Jul 5 13:42:32 UTC 2011

Hash: SHA512

ISC BIND 9 Remote packet Denial of Service against Authoritative and
Recursive Servers

A specially constructed packet will cause BIND 9 ("named") to exit,
affecting DNS service.

CVE: CVE-2011-2464

Document Version:  2.0

Posting date: 05 Jul 2011

Program Impacted: BIND

Versions affected:  9.6.3, 9.6-ESV-R4, 9.6-ESV-R4-P1, 9.6-ESV-R5b1 9.7.0,
9.7.0-P1, 9.7.0-P2, 9.7.1, 9.7.1-P1, 9.7.1-P2, 9.7.2, 9.7.2-P1, 9.7.2-P2,
9.7.2-P3, 9.7.3, 9.7.3-P1, 9.7.3-P2, 9.7.4b1 9.8.0, 9.8.0-P1, 9.8.0-P2,
9.8.0-P3, 9.8.1b1

Severity:  High

Exploitable:  Remotely


A defect in the affected BIND 9 versions allows an attacker to remotely
cause the "named" process to exit using a specially crafted packet. This
defect affects both recursive and authoritative servers. The code location
of the defect makes it impossible to protect BIND using ACLs configured
within named.conf or by disabling any features at compile-time or run-time.

A remote attacker would need to be able to send a specially crafted packet
directly to a server running a vulnerable version of BIND. There is also
the potential for an indirect attack via malware that is inadvertently
installed and run, where infected machines have direct access to an
organization's nameservers.

CVSS Score: 7.8


For more information on the Common Vulnerability Scoring System and to
obtain your specific environmental score please visit:


There are no known workarounds for publicly available servers.
Administrators of servers that are not publicly available may be able to
limit exposure via firewalls and packet filters.

Active exploits: 

ISC knows of no public tools to exploit this defect at the time of this


Upgrade to: 9.6-ESV-R4-P3, 9.7.3-P3 or 9.8.0-P4.

Download these versions from the following locations:

ISC releases of BIND 9 software may be downloaded from

If you do not obtain your BIND software directly from ISC, contact your
operating system or software vendor for an update.

If you are participating in ISC's beta or release candidate (RC) programs,
please upgrade. ISC Beta/RC testers are expected to remove vulnerable
versions and upgrade. No security advisories are issued for beta / release
candidates once the corresponding final release is made.

In addition, 9.5.3b1 and 9.5.3rc1 are affected although ISC has not
released a final production version of 9.5.3. Note that BIND 9.5 is
End-of-Life, therefore if you are running a pre-release version of 9.5.3 we
recommend upgrading to a supported production version of BIND.

9.6-ESV-R4-P2 is not affected by any known attack vectors, but has been
replaced by 9.6-ESV-R4-P3 which carries a more complete fix

Other versions of BIND 9 not listed in this advisory are not vulnerable to
this problem.


ISC thanks Roy Arends from Nominet for pin-pointing the exact nature of the
vulnerability. We also thank Ramesh Damodaran of Infoblox for finding a
variation of the attack vector and Mats Dufberg of TeliaSonera Sweden for
confirming additional variants.

Document Revision History:

Version 1.0 - 14 June 2011:  Phase One Disclosure Date
Version 1.1 - 20 June 2011:  Phase Two Disclosure Date with updates.
Version 1.2 - 21 June 2011:  Updates on beta, RC, and clarity editing
Verison 1.3 - 21 June 2011:  Sent Hold Notices to Phase I constituents,
extended Acknowledgments
Version 1.4 - 23 June 2011:  Updated -P versions to include Advanced
Security Patches release to Phase I, and "Upgrade to:" versions
Version 1.5 - 24 June 2011:  Added document URL, sent schedule update to
Phase I constituents.
Version 1.6 - 28 June 2011:  Updated Versions Affected, extended
Acknowledgments, sent Phase I updates
Version 1.7 - 30 June 2011:  Updated attribution text.
Version 1.8 - 4 July 2011: Phase Three and Four Disclosure Date
version 2.0 - 5 July 2011:  Public Disclosure

Do you have Questions? Questions regarding this advisory should go to
security-officer at

Do you need Software Support? Questions on ISC's Support services or other
offerings should be sent to sales at More information on ISC's
support and other offerings are available at:

ISC Security Vulnerability Disclosure Policy: Details of our current
security advisory policy and practice can be found here:

Legal Disclaimer:: 

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