CVE-2015-8461: A race condition when handling socket errors can lead to an assertion failure in resolver.c

AA-01319


Document Version:          
2.0
Posting date: 
15 December 2015
Program Impacted: 
BIND
Versions affected: 
9.9.8 -> 9.9.8-P1, 9.9.8-S1 -> 9.9.8-S2, 9.10.3 -> 9.10.3-P1
Severity: 
Medium
Exploitable: 
Remotely

Description:

Beginning with the September 2015 maintenance releases 9.9.8 and 9.10.3, an error was introduced into BIND 9 which can cause a server to exit after encountering an INSIST assertion failure in resolver.c

Impact:

An uncommonly occurring condition can cause affected servers to exit with an INSIST failure depending on the outcome of a race condition in resolver.c  While difficult to exploit reliably, a malicious party could, through deliberate behavior, significantly increase the probability of encountering the triggering condition, resulting in denial-of-service to clients if successful.

CVSS Score:  5.4

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

Workarounds:

None.

Active exploits:

None known.

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 eligible ISC Support customers.

  • BIND 9 version 9.9.8-S3

Acknowledgements: ISC would like to thank John O'Brien of the University of Pennsylvania for discovering this issue.

Document Revision History:

1.0 Advance Notification 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.

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-officer@isc.orgTo 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/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-00861/164/ISC-Software-Defect-and-Security-Vulnerability-Disclosure-Policy.html

This Knowledge Base article https://kb.isc.org/article/AA-01319 is the complete and official security advisory document.

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