Published:
11 November 2004
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2004.0721 -- UNIRAS ALERT - 40/04 Vulnerability Issues in Implementations of the DNS Protocol 11 November 2004 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Publisher: UNIRAS Impact: Denial of Service Access: Remote/Unauthenticated CVE Names: CAN-2004-0789 Original Bulletin: http://www.uniras.gov.uk/vuls/2004/758884/index.htm - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- - - ---------------------------------------------------------------------------------- UNIRAS (UK Govt CERT) ALERT - 40/04 dated 09.11.04 Time: 12:00 UNIRAS is part of NISCC (National Infrastructure Security Co-ordination Centre) - - ---------------------------------------------------------------------------------- UNIRAS material is also available from its website at www.uniras.gov.uk and Information about NISCC is available from www.niscc.gov.uk - - ---------------------------------------------------------------------------------- Title ===== Vulnerability Issues in Implementations of the DNS Protocol Detail ====== NISCC Vulnerability Advisory 758884/NISCC/DNS - - --------------------------------------------- Vulnerability Issues in Implementations of the DNS Protocol Version Information - - ------------------- Advisory Reference 758884/NISCC/DNS Release Date 9 November 2004 Last Revision 4 November 2004 Version Number 1.0 What is affected? - - ----------------- The vulnerabilities described in this advisory affect the Domain Name System (DNS) protocol. Many vendors include support for this protocol in their products and may be impacted to varying degrees, if at all. Please note that the information contained within this advisory is subject to changes. All subscribers are therefore advised to regularly check the UNIRAS website for updates to this notice. Severity - - -------- The severity of these vulnerabilities varies by vendor. Please see the vendor section below for further information. Alternatively contact your vendor for product specific information. If exploited, these vulnerabilities could allow an attacker to create a Denial of Service condition. Summary - - ------- Several vulnerabilities have been discovered within the Domain Name System (DNS) protocol by two DNS experts, Roy Arends and Jakob Schlyter. The Domain Name System (DNS) protocol is an Internet service that translates domain names into Internet Protocol (IP) addresses. Because domain names are alphabetic, they're easier to remember, however the Internet is really based on IP addresses; hence every time a domain name is requested, a DNS service must translate the name into the corresponding IP address. NISCC wishes to advise users of the availability of a test tool that is designed to confirm the existence of vulnerabilities in the DNS protocol. All users of applications that supports DNS are recommended to take note of this advisory and carry out any remedial actions suggested by their vendor(s). [Please note that revisions to this advisory will not be notified by email. All subscribers are advised to regularly check the UNIRAS website for updates to this notice.] Details - - ------- The Domain Name System (DNS) is basically a database of host information. The DNS protocol is utilised to identify servers by their IP addresses and aliases given their registered domain name. The request is usually simple, including just the name of the server. The response however can be quite complex, because it will contain all the addresses and aliases that the server might have. A DNS query is sent to a name server to provoke a response; a DNS response then either answers the query, refers the requester to another set of name servers or signals some error condition. Please refer to RFC 1034:Section 3.7, RFC 1034:Section 4.1, RFC 1034:Section 4.3.1 and RFC 1035:Section 4.1.1 for further information on the query-response relationship within the DNS protocol. The relevant vulnerabilities are a result of liberal interpretation of the DNS protocol by implementors. DNS uses a message format to provide a mechanism to resolve domain names into IP addresses; a message can either be a 'query' or a 'response'. By implementating the protocol in such a way in which a 'response' is allowed to be answered with a 'response', this will cause messages to bounce back and forth between the servers and hence cause a query-respose storm that can result in a denial-of-service attack. In addition, by sending these implementations a query that appears to originate from the localhost on UDP port 53, the server will respond to itself and will keep responding to these responses, hence entering a loop which can exhaust system resources and hence result in a denial-of-service attack. Further detail will be released as it becomes available. This vulnerability has been assigned the CVE name CAN-2004-0789. Solution - - -------- Please refer to the Vendor Information section of this advisory for platform specific remediation. Vendor Information - - ------------------ A list of vendors affected by this vulnerability is not currently available. Please visit the web site at http://www.uniras.gov.uk/vuls/2004/758884/index.htm in order to check for updates. Credits - - ------- The NISCC Vulnerability Team would like to thank Roy Arends, who discovered this issue and reported it to NISCC, and Jakob Schlyter, who helped establish the initial list of vulnerable implementations. The NISCC Vulnerability Team would also like to thank the vendors for their co-operation in handling this vulnerability. Contact Information - - ------------------- The NISCC Vulnerability Management Team can be contacted as follows: Email vulteam@niscc.gov.uk Please quote the advisory reference in the subject line Telephone +44 (0)870 487 0748 Ext 4511 Monday - Friday 08:30 - 17:00 Fax +44 (0)870 487 0749 Post Vulnerability Management Team NISCC PO Box 832 London SW1P 1BG We encourage those who wish to communicate via email to make use of our PGP key. This is available from http://www.uniras.gov.uk/UNIRAS.asc Please note that UK government protectively marked material should not be sent to the email address above. If you wish to be added to our email distribution list please email your request to uniras@niscc.gov.uk. What is NISCC? - - -------------- For further information regarding the UK National Infrastructure Security Co-ordination Centre, please visit http://www.niscc.gov.uk/aboutniscc/index.htm. Reference to any specific commercial product, process, or service by trade name, trademark manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favouring by NISCC. The views and opinions of authors expressed within this notice shall not be used for advertising or product endorsement purposes. Neither shall NISCC accept responsibility for any errors or omissions contained within this advisory. In particular, they shall not be liable for any loss or damage whatsoever, arising from or in connection with the usage of information contained within this notice. C 2004 Crown Copyright <End of NISCC Vulnerability Advisory> - - ---------------------------------------------------------------------------------- For additional information or assistance, please contact the HELP Desk by telephone or Not Protectively Marked information may be sent via EMail to: uniras@niscc.gov.uk Office Hours: Mon - Fri: 08:30 - 17:00 Hrs Tel: +44 (0) 870 487 0748 Ext 4511 Fax: +44 (0) 870 487 0749 Outside of Office Hours: On Call Duty Officer: Tel: +44 (0) 870 487 0748 and follow the prompts - - ---------------------------------------------------------------------------------- UNIRAS wishes to acknowledge the contributions of Roy Arends and Jakob Schlyter for the information contained in this Briefing. - - ---------------------------------------------------------------------------------- This Briefing contains the information released by the original author. Some of the information may have changed since it was released. If the vulnerability affects you, it may be prudent to retrieve the advisory from the canonical site to ensure that you receive the most current information concerning that problem. Reference to any specific commercial product, process, or service by trade name, trademark manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favouring by UNIRAS or NISCC. The views and opinions of authors expressed within this notice shall not be used for advertising or product endorsement purposes. Neither UNIRAS or NISCC shall also accept responsibility for any errors or omissions contained within this briefing notice. In particular, they shall not be liable for any loss or damage whatsoever, arising from or in connection with the usage of information contained within this notice. UNIRAS is a member of the Forum of Incident Response and Security Teams (FIRST) and has contacts with other international Incident Response Teams (IRTs) in order to foster cooperation and coordination in incident prevention, to prompt rapid reaction to incidents, and to promote information sharing amongst its members and the community at large. - - ---------------------------------------------------------------------------------- <End of UNIRAS Briefing> - -----BEGIN PGP SIGNATURE----- Version: PGP 8.0 iQCVAwUBQZCttIpao72zK539AQFeYwP/WT/xeGAnesMAfglL+w97gmk3h/eJgKa8 VYZjUU7/YPgpu3ZjopQbXVQnwU9/Dd+an7mMcZTi2LllnvrW22Mxg+tkjVouW83R 32bTOhGG0ejJZUHEDX7lA9plqCUeDQACb8foRPUVtFS8w5FvZXlJnr36npR5DpdD ViCfRPSgfLs= =YbP3 - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. 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It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBQZLe6ih9+71yA2DNAQKd5AP/bQsx38OqHV99QObXv2H9CoHm61m0Gm3g r9MkyxqKH1Gx845DEEqdxRmrm6LzTaypayH2LWcEZrbaSgjn8ZI1ASlH0cft4+Vd FSwJmdhKHd53UlXTr6De5gwjGBMhCUCYsit0oxPkMqWEMN2X8tbveMXqsGZJs3Jl ZtqsOM82eSU= =VOpu -----END PGP SIGNATURE-----