CVE-2007-2930: cryptographically weak DNS query IDs (BIND 8)


BIND 8 generates cryptographically weak DNS query IDs which could allow a remote attacker to poison DNS caches.

Posting date: 
29 Aug 2007
Program Impacted: 
Versions affected: 
All versions of BIND8


ISC BIND 8 generates cryptographically weak DNS query IDs which could allow a remote attacker to poison DNS caches.

This bug only affects outgoing queries, generated by BIND 8 to answer questions as a resolver, or when it is looking up data for internal uses, such as when sending NOTIFYs to slave name servers.

The DNS query id generation is vulnerable to analysis which provides a high chance of guessing the next query id. This can be used to perform cache poisoning by an attacker.

All users are encouraged to upgrade.


A remote attacker could predict DNS query IDs and respond with arbitrary answers, thus poisoning DNS caches.



Active exploits:

None known at this time.


Upgrade or Patch

This issue is addressed in ISC BIND 8.4.7-P1, available as patch that can be applied to BIND 8.4.7.

The more definitive solution is to upgrade to BIND 9. BIND 8 is being declared "end of life" by ISC due to multiple architectural issues. Please see ISC's website at for additional information and tools.

Note that BIND 8.x.x is End of Life as of August 2007.

Users who obtain BIND 8 from their operating system vendor should see the systems affected portion of this document for a partial list of affected vendors.

Acknowledgements: Thanks to Amit Klein from Trusteer ( for reporting this.

Related Documents:

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

Do you still have questions?  Questions regarding this advisory should go to

Note: ISC patches only currently supported versions. When possible we indicate EOL versions affected. 

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This Knowledge Base article is the complete and official security advisory document.

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