denial of service (server crash) caused by receipt of a specific remote dynamic update message.
Posting date: 28 Jul 2009
Versions affected: BIND
9 (all versions)
Urgent: this exploit is public. Please upgrade immediately.
Receipt of a specially-crafted dynamic update message to a zone for
which the server is the master may cause BIND 9 servers to exit.
Testing indicates that the attack packet has to be formulated against a
zone for which that machine is a master. Launching the attack against
slave zones does not trigger the assert.
This vulnerability affects all servers that are masters for one or
more zones – it is not limited to those that are configured to allow
dynamic updates. Access controls will not provide an effective
dns_db_findrdataset() fails when the prerequisite section of the
dynamic update message contains a record of type “ANY” and where at
least one RRset for this FQDN exists on the server:
db.c:659: REQUIRE(type != ((dns_rdatatype_t)dns_rdatatype_any)) failed
exiting (due to assertion failure).
(Some sites may have firewalls that can be configured with packet
filtering techniques to prevent nsupdate messages from reaching their
An active remote exploit is in wide circulation at this time
Upgrade BIND to one of 9.4.3-P3, 9.5.1-P3 or 9.6.1-P1. These versions can be downloaded from:
Matthias Urlichs for reporting the problem.
Tom Daly for methodical follow-on testing.
Document Revision History:
2009-07-28 Initial text
2009-07-29 Update to reflect Tom Daly's findings
See our BIND Security Matrix for a complete listing of Security Vulnerabilities and versions affected.
If you'd like more information on our Forum or product support please visit www.isc.org/support.
Do you still have questions? Questions regarding this advisory should go to email@example.com
Note: ISC patches only currently supported versions. When possible we indicate EOL versions affected.
ISC Security Vulnerability Disclosure Policy: Details of our current security advisory policy and practice can be found here: https://www.isc.org/security-vulnerability-disclosure-policy
This Knowledge Base article https://kb.isc.org/article/AA-00926 is the complete and official security advisory document.
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