Summary

• Multiple Cisco products are vulnerable to DNS cache poisoning attacks due to their use of insufficiently randomized DNS transaction IDs and UDP source ports in the DNS queries that they produce, which may allow an attacker to more easily forge DNS answers that can poison DNS caches.

  To exploit this vulnerability an attacker must be able to cause a vulnerable DNS server to perform recursive DNS queries. Therefore, DNS servers that are only authoritative, or servers where recursion is not allowed, are not affected.

  Cisco has released software updates that address these vulnerabilities.

  This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080708-dns.

  This security advisory is being published simultaneously with announcements from other affected organizations.

Affected Products

• Products that cache DNS responses and process DNS messages with the recursion desired (RD) flag set may be vulnerable to a DNS cache poisoning attack depending on implementation of the DNS protocol. Products that process DNS messages with the RD flag set will attempt to answer the question asked on behalf of the client. A product is only affected if using a vulnerable implementation of the DNS protocol, the DNS server functionality for the product is enabled, and the DNS feature for the product is configured to process recursive DNS query messages.

  Vulnerable Products

  The following Cisco products are capable of acting as DNS servers and have been found to have the DNS implementation weakness that makes some types of DNS cache poisoning attacks more likely to succeed:

  • Cisco IOS Software
    
    A device that is running Cisco IOS Software will be affected if it is running a vulnerable version and if it is acting as a DNS server.
    
    All Cisco IOS Software releases that support the DNS server functionality and that have not had their DNS implementation improved are affected. For information about specific fixed versions, please refer to the Software Versions and Fixes section.
    
    A device that is running Cisco IOS Software is configured to act as a DNS server if the command ip dns server is present in the configuration. This command is not enabled by default.
    
    
  • Cisco Network Registrar
    
    All Cisco Network Registrar versions are affected, and DNS services are enabled by default.
    
    The DNS server on CNR is enabled via the command-line interface (CLI) commands server dns enable start-on-reboot or dns enable start-on-reboot or via the web management interface in the Servers page by selecting the appropriate "Start," "Stop," or "Reload" button.
    
    
  • Cisco Application and Content Networking System
    
    All Cisco Application and Content Networking System (ACNS) versions are affected; DNS services are disabled by default.
    
    ACNS is configured to act as a DNS server if the command dns enable is present in the configuration.
    
    
  • Cisco Global Site Selector Used in Combination with Cisco Network Registrar
    
    The Cisco Global Site Selector (GSS) is affected when it is used in combination with Cisco Network Registrar software to provide a more complete DNS solution. Fixed software would come in the form of an update of the Cisco Network Registrar software rather than an update of the GSS software.
    

  Products Confirmed Not Vulnerable

  Products that do not offer DNS server capabilities are not affected by this vulnerability.

  The Cisco GSS by itself is not affected by this vulnerability. However, it is affected when it is used with Cisco Network Registrar software.

  No other Cisco products are currently known to be affected by these vulnerabilities.

Details

• The Domain Name System is an integral part of networks that are based on TCP/IP such as the Internet. Simply stated, the Domain Name System is a hierarchical database that contains mappings of hostnames and IP addresses. The DNS protocol is part of the TCP/IP protocol suite and allows DNS clients to query the DNS database to resolve hostnames to IP addresses.

  A DNS server is an application that implements the DNS protocol and that has the ability to respond to queries made by DNS clients. When handling a query from a DNS client, a DNS server can look into its portion of the global DNS database (if the query is for a portion of the DNS database for which the DNS server is authoritative), or it can relay the query to other DNS servers (if it is configured to do so and if the query is for a portion of the DNS database for which the DNS server is not authoritative.)

  Because of the processing time and bandwidth that is associated with handling a DNS query, most DNS servers locally store responses that are received from other DNS servers. The area where these responses are stored locally is called a "cache." Once a response is stored in a cache, the DNS server can use the locally stored response for a certain time (called the "time to live") before having to query DNS servers again to refresh the local (cached) copy of the response.

  A DNS cache poisoning attack is an attack in which an entry in the DNS cache of a DNS server is changed so the IP address associated with a hostname in the cache does not point to the correct place. For example, if www.example.com is mapped to the IP address 192.168.0.1 and this mapping is present in the cache of a DNS server, an attacker who succeeds in poisoning the DNS cache of this server may be able to map www.example.com to 10.0.0.1 instead. If this happens, a user who is trying to visit www.example.com may end up contacting the wrong web server.

  Although DNS cache poisoning attacks are not new, a security researcher recently presented a technique that allows an attacker to mount successful DNS cache poisoning attacks with low complexity tools and low traffic requirements. This technique exploits a weakness in most implementations of the DNS protocol. The fundamental implementation weakness is that the DNS transaction ID and source port number used to validate DNS responses are not sufficiently randomized and can easily be predicted, which allows an attacker to create forged responses to DNS queries that will match the expected values. The DNS server will consider such responses to be valid.

  The following Cisco products that offer DNS server functionality have been found to be susceptible to DNS cache poisoning attacks:

  • Cisco IOS Software: The vulnerability documented in Cisco bug ID CSCso81854 ( registered customers only) .
    
  • Cisco Network Registrar: The vulnerability documented in Cisco bug ID CSCsq01298 ( registered customers only) .
    
  • Cisco Application and Content Networking System (ACNS): The vulnerability documented in Cisco bug ID CSCsq21930 ( registered customers only) .
    

  This vulnerability has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2008-1447.

  Port Address Translation Considerations

  Port Address Translation (PAT) is a form of Network Address Translation (NAT) that allows multiple hosts in a private network to access a public network using a single, public IP address. This is accomplished by rewriting layer 4 information, specifically TCP and UDP source port numbers and checksums, as packets from the private network traverse a network device that is performing PAT. PAT is configured by network administrators and performed by network devices such as firewalls and routers in situations where public IP addresses are limited.

  After the initial multi-vendor DNS advisory was published on July 8th, 2008 it was discovered that in some cases the fixes to DNS implementations to use random source ports when sending DNS queries could be negated when such queries traverse PAT devices. The reason for this is that in these cases the network device performing PAT uses a predictable source port allocation policy, such as incremental allocation, when performing the layer 4 rewrite operation that is necessary for PAT. Under this scenario, the fixes made by DNS vendors can be greatly diminished because, while DNS queries seen on the inside network have random source port numbers, the same queries have potentially predictable source port numbers when they leave the private network, depending on the type of traffic that transits through the device.

  Several Cisco products are affected by this issue, and if DNS servers are deployed behind one of these affected products operating in PAT mode then the DNS infrastructure may still be at risk even if source port randomization updates have been applied to the DNS servers.

  The affected Cisco products, and the respective Cisco bugs that have been created to track the issue, are the following:

  Product	Cisco Bug ID
  Cisco PIX (6.3.x and earlier)	CSCsr28354 ( registered customers only)
  Cisco ASA and Cisco PIX (7.0.x and later)	CSCsr28008 ( registered customers only)
  Firewall Services Module (FWSM)	CSCsr29124 ( registered customers only)
  Cisco IOS	CSCsr29691 ( registered customers only)
  Cisco Content Switching Module (CSM)	CSCsr61220 ( registered customers only)
  Cisco Application Control Engine (ACE) Module	CSCsr98689 ( registered customers only)
  Cisco Application Control Engine (ACE) Appliance	CSCsu10546 ( registered customers only)

  Fixed software information for these bugs will not be added to this document. Instead, customers should use their regular support channels or the bug tracking features of the Bug Toolkit application on cisco.com to obtain fixed software information.

  With the exception of the ACE module and the ACE appliance, the above products use an incremental source port allocation policy when performing the source port rewrite operation that is needed for PAT. In the case of Cisco IOS, the original source port will be tried first, but if that port is already allocated and in use for an existing PAT translation then a new port will be incrementally assigned.

  The ACE module and the ACE appliance do not use an incremental source port allocation. However, they use a hash algorithm that may make predictable the chosen source port number during PAT operation.

  Note that traditional NAT, i.e. allocating one public IP address for each private IP address, is not affected by this problem because, unlike PAT, NAT only rewrites layer 3 information and does not modify layer 4 header information of packets traversing the NAT device.

Workarounds

• There are no workarounds.

  Additional information about identification and mitigation of attacks against DNS is in the Cisco Applied Intelligence white paper "DNS Best Practices, Network Protections, and Attack Identification," available at http://www.cisco.com/web/about/security/intelligence/dns-bcp.html.

Fixed Software

• When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

  In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center (TAC) or your contracted maintenance provider for assistance.

  Cisco IOS Software

  Each row of the Cisco IOS Software table (below) names a Cisco IOS Software release train. If a given release train is vulnerable, then the earliest possible releases that contain the fix (along with the anticipated date of availability for each, if applicable) are listed in the "First Fixed Release" column of the table. The "Recommended Release" column indicates the releases which have fixes for all the published vulnerabilities at the time of this Advisory. A device running a release in the given train that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. Cisco recommends upgrading to a release equal to or later than the release in the "Recommended Releases" column of the table.

  Major Release	Availability of Repaired Releases
  Affected 12.0-Based Releases	First Fixed Release	Recommended Release
  12.0	Not Vulnerable
  12.0DA	Not Vulnerable
  12.0DB	Releases prior to 12.0(7)DB are vulnerable, release 12.0(7)DB and later are not vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.0DC	Releases prior to 12.0(7)DC are vulnerable, release 12.0(7)DC and later are not vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.0S	Not Vulnerable
  12.0SC	Not Vulnerable
  12.0SL	Not Vulnerable
  12.0SP	Not Vulnerable
  12.0ST	Not Vulnerable
  12.0SX	Not Vulnerable
  12.0SY	Not Vulnerable
  12.0SZ	Not Vulnerable
  12.0T	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.0W	Not Vulnerable
  12.0WC	Vulnerable; contact TAC
  12.0WT	Not Vulnerable
  12.0XA	Not Vulnerable
  12.0XB	Not Vulnerable
  12.0XC	Not Vulnerable
  12.0XD	Not Vulnerable
  12.0XE	Note: Releases prior to 12.0(7)XE1 are vulnerable, release 12.0(7)XE1 and later are not vulnerable;
  12.0XF	Not Vulnerable
  12.0XG	Not Vulnerable
  12.0XH	Not Vulnerable
  12.0XI	Not Vulnerable
  12.0XJ	Not Vulnerable
  12.0XK	Releases prior to 12.0(7)XK2 are vulnerable, release 12.0(7)XK2 and later are not vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.0XL	Not Vulnerable
  12.0XM	Not Vulnerable
  12.0XN	Not Vulnerable
  12.0XQ	Not Vulnerable
  12.0XR	Releases prior to 12.0(7)XR1 are vulnerable, release 12.0(7)XR1 and later are not vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.0XS	Not Vulnerable
  12.0XV	Not Vulnerable
  12.0XW	Not Vulnerable
  Affected 12.1-Based Releases	First Fixed Release	Recommended Release
  12.1	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.1AA	Not Vulnerable
  12.1AX	Not Vulnerable
  12.1AY	Releases prior to 12.1(22)AY1 are vulnerable, release 12.1(22)AY1 and later are not vulnerable;	12.1(22)EA11
  12.1AZ	Not Vulnerable
  12.1CX	Not Vulnerable
  12.1DA	Not Vulnerable
  12.1DB	Releases prior to 12.1(4)DB1 are vulnerable, release 12.1(4)DB1 and later are not vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.1DC	Releases prior to 12.1(4)DC2 are vulnerable, release 12.1(4)DC2 and later are not vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.1E	Not Vulnerable
  12.1EA	Releases prior to 12.1(11)EA1 are vulnerable, release 12.1(11)EA1 and later are not vulnerable;	12.1(22)EA11
  12.1EB	Not Vulnerable
  12.1EC	Not Vulnerable
  12.1EO	Not Vulnerable
  12.1EU	Not Vulnerable
  12.1EV	Not Vulnerable
  12.1EW	Not Vulnerable
  12.1EX	Note: Releases prior to 12.1(8a)EX are vulnerable, release 12.1(8a)EX and later are not vulnerable;
  12.1EY	Not Vulnerable
  12.1EZ	Not Vulnerable
  12.1GA	Not Vulnerable
  12.1GB	Not Vulnerable
  12.1T	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.1XA	Not Vulnerable
  12.1XB	Not Vulnerable
  12.1XC	Releases prior to 12.1(1)XC1 are vulnerable, release 12.1(1)XC1 and later are not vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.1XD	Not Vulnerable
  12.1XE	Not Vulnerable
  12.1XF	Not Vulnerable
  12.1XG	Not Vulnerable
  12.1XH	Not Vulnerable
  12.1XI	Not Vulnerable
  12.1XJ	Not Vulnerable
  12.1XK	Not Vulnerable
  12.1XL	Not Vulnerable
  12.1XM	Not Vulnerable
  12.1XN	Not Vulnerable
  12.1XO	Not Vulnerable
  12.1XP	Not Vulnerable
  12.1XQ	Not Vulnerable
  12.1XR	Not Vulnerable
  12.1XS	Not Vulnerable
  12.1XT	Not Vulnerable
  12.1XU	Not Vulnerable
  12.1XV	Not Vulnerable
  12.1XW	Not Vulnerable
  12.1XX	Not Vulnerable
  12.1XY	Not Vulnerable
  12.1XZ	Not Vulnerable
  12.1YA	Not Vulnerable
  12.1YB	Not Vulnerable
  12.1YC	Not Vulnerable
  12.1YD	Not Vulnerable
  12.1YE	Note: Releases prior to 12.1(5)YE1 are vulnerable, release 12.1(5)YE1 and later are not vulnerable;	12.4(19a) 12.4(19b)
  12.1YF	Not Vulnerable
  12.1YG	Not Vulnerable
  12.1YH	Not Vulnerable
  12.1YI	Not Vulnerable
  12.1YJ	Not Vulnerable
  Affected 12.2-Based Releases	First Fixed Release	Recommended Release
  12.2	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2B	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2BC	Not Vulnerable
  12.2BW	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2BY	Releases prior to 12.2(8)BY are vulnerable, release 12.2(8)BY and later are not vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2BZ	Not Vulnerable
  12.2CX	Not Vulnerable
  12.2CY	Not Vulnerable
  12.2CZ	Vulnerable; contact TAC
  12.2DA	Not Vulnerable
  12.2DD	Not Vulnerable
  12.2DX	Not Vulnerable
  12.2EU	Not Vulnerable
  12.2EW	Not Vulnerable
  12.2EWA	Not Vulnerable
  12.2EX	Not Vulnerable
  12.2EY	Not Vulnerable
  12.2EZ	Not Vulnerable
  12.2FX	Not Vulnerable
  12.2FY	Not Vulnerable
  12.2FZ	Not Vulnerable
  12.2IXA	Not Vulnerable
  12.2IXB	Not Vulnerable
  12.2IXC	Not Vulnerable
  12.2IXD	Not Vulnerable
  12.2IXE	Not Vulnerable
  12.2IXF	Not Vulnerable
  12.2JA	Not Vulnerable
  12.2JK	Not Vulnerable
  12.2MB	Not Vulnerable
  12.2MC	Not Vulnerable
  12.2S	Not Vulnerable
  12.2SB	Not Vulnerable
  12.2SBC	Not Vulnerable
  12.2SCA	Not Vulnerable
  12.2SE	Not Vulnerable
  12.2SEA	Not Vulnerable
  12.2SEB	Not Vulnerable
  12.2SEC	Not Vulnerable
  12.2SED	Not Vulnerable
  12.2SEE	Not Vulnerable
  12.2SEF	Not Vulnerable
  12.2SEG	Not Vulnerable
  12.2SG	Not Vulnerable
  12.2SGA	Not Vulnerable
  12.2SL	Not Vulnerable
  12.2SM	Not Vulnerable
  12.2SO	Not Vulnerable
  12.2SRA	Not Vulnerable
  12.2SRB	Not Vulnerable
  12.2SRC	Not Vulnerable
  12.2SU	Not Vulnerable
  12.2SV	Not Vulnerable
  12.2SVA	Not Vulnerable
  12.2SVC	Not Vulnerable
  12.2SVD	Not Vulnerable
  12.2SW	Not Vulnerable
  12.2SX	Not Vulnerable
  12.2SXA	Not Vulnerable
  12.2SXB	Not Vulnerable
  12.2SXD	Not Vulnerable
  12.2SXE	Not Vulnerable
  12.2SXF	Not Vulnerable
  12.2SXH	Not Vulnerable
  12.2SXI	Not Vulnerable
  12.2SY	Not Vulnerable
  12.2SZ	Not Vulnerable
  12.2T	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2TPC	Releases prior to 12.2(8)TPC10d are vulnerable, release 12.2(8)TPC10d and later are not vulnerable;
  12.2UZ	Not Vulnerable
  12.2XA	Not Vulnerable
  12.2XB	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2XC	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2XD	Not Vulnerable
  12.2XE	Not Vulnerable
  12.2XF	Not Vulnerable
  12.2XG	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2XH	Not Vulnerable
  12.2XI	Not Vulnerable
  12.2XJ	Not Vulnerable
  12.2XK	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2XL	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2XM	Not Vulnerable
  12.2XN	Not Vulnerable
  12.2XNA	Not Vulnerable
  12.2XO	Not Vulnerable
  12.2XQ	Not Vulnerable
  12.2XR	Not Vulnerable
  12.2XS	Not Vulnerable
  12.2XT	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2XU	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2XV	Not Vulnerable
  12.2XW	Not Vulnerable
  12.2YA	Not Vulnerable
  12.2YB	Not Vulnerable
  12.2YC	Not Vulnerable
  12.2YD	Not Vulnerable
  12.2YE	Not Vulnerable
  12.2YF	Not Vulnerable
  12.2YG	Not Vulnerable
  12.2YH	Not Vulnerable
  12.2YJ	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2YK	Not Vulnerable
  12.2YL	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2YM	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2YN	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2YO	Vulnerable; migrate to any release in 12.2SY	12.2(18)SXF15; Available on 08-AUG-08
  12.2YP	Not Vulnerable
  12.2YQ	Not Vulnerable
  12.2YR	Not Vulnerable
  12.2YS	Not Vulnerable
  12.2YT	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2YU	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2YV	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2YW	Not Vulnerable
  12.2YX	Not Vulnerable
  12.2YY	Not Vulnerable
  12.2YZ	Not Vulnerable
  12.2ZA	Not Vulnerable
  12.2ZB	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2ZC	Not Vulnerable
  12.2ZD	Vulnerable; contact TAC
  12.2ZE	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2ZF	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2ZG	Vulnerable; first fixed in 12.4T	12.4(19a) 12.4(19b) 12.4(20)T; Available on 11-JUL-08
  12.2ZH	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b) 12.4(20)T; Available on 11-JUL-08
  12.2ZJ	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.2ZL	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b) 12.4(20)T; Available on 11-JUL-08
  12.2ZP	Not Vulnerable
  12.2ZU	Not Vulnerable
  12.2ZY	Not Vulnerable
  12.2ZYA	Not Vulnerable
  Affected 12.3-Based Releases	First Fixed Release	Recommended Release
  12.3	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3B	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3BC	Not Vulnerable
  12.3BW	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3EU	Not Vulnerable
  12.3JA	Not Vulnerable
  12.3JEA	Not Vulnerable
  12.3JEB	Not Vulnerable
  12.3JEC	Not Vulnerable
  12.3JK	Not Vulnerable
  12.3JL	Not Vulnerable
  12.3JX	Not Vulnerable
  12.3T	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3TPC	Vulnerable; contact TAC
  12.3VA	Vulnerable; contact TAC
  12.3XA	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b) 12.4(20)T; Available on 11-JUL-08
  12.3XB	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3XC	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b) 12.4(20)T; Available on 11-JUL-08
  12.3XD	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3XE	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b) 12.4(20)T; Available on 11-JUL-08
  12.3XF	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3XG	Vulnerable; first fixed in 12.4T	12.4(19a) 12.4(19b) 12.4(20)T; Available on 11-JUL-08
  12.3XH	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3XI	Vulnerable; contact TAC
  12.3XJ	Vulnerable; first fixed in 12.3YX	12.3(14)YX12 12.4(20)T; Available on 11-JUL-08
  12.3XK	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3XQ	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3XR	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b) 12.4(20)T; Available on 11-JUL-08
  12.3XS	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b)
  12.3XU	Not Vulnerable
  12.3XW	Vulnerable; first fixed in 12.3YX	12.3(14)YX12 12.4(20)T; Available on 11-JUL-08
  12.3XY	Not Vulnerable
  12.3YA	Vulnerable; first fixed in 12.4	12.4(19a) 12.4(19b) 12.4(20)T; Available on 11-JUL-08
  12.3YD	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.3YF	Vulnerable; first fixed in 12.3YX	12.3(14)YX12 12.4(20)T; Available on 11-JUL-08
  12.3YG	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.3YH	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.3YI	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.3YJ	Not Vulnerable
  12.3YK	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.3YM	Releases prior to 12.3(14)YM12 are vulnerable, release 12.3(14)YM12 and later are not vulnerable;	12.3(14)YM12
  12.3YQ	Not Vulnerable
  12.3YS	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.3YT	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.3YU	Vulnerable; first fixed in 12.4XB
  12.3YX	12.3(14)YX12	12.3(14)YX12
  12.3YZ	Vulnerable; contact TAC
  Affected 12.4-Based Releases	First Fixed Release	Recommended Release
  12.4	12.4(18b) 12.4(19a) 12.4(19b) 12.4(21)	12.4(19a) 12.4(19b)
  12.4JA	Not Vulnerable
  12.4JK	Not Vulnerable
  12.4JMA	Not Vulnerable
  12.4JMB	Not Vulnerable
  12.4JMC	Not Vulnerable
  12.4JX	Not Vulnerable
  12.4MD	12.4(15)MD	12.4(15)MD
  12.4MR	12.4(19)MR	12.4(19)MR
  12.4SW	Vulnerable; contact TAC
  12.4T	12.4(15)T6 12.4(20)T; Available on 11-JUL-08	12.4(20)T; Available on 11-JUL-08
  12.4XA	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.4XB	12.4(2)XB10
  12.4XC	Vulnerable; contact TAC
  12.4XD	12.4(4)XD11; Available on 31-JUL-08	12.4(20)T; Available on 11-JUL-08
  12.4XE	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.4XF	Not Vulnerable
  12.4XG	Not Vulnerable
  12.4XJ	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08
  12.4XK	Not Vulnerable
  12.4XL	12.4(15)XL2	12.4(15)XL2
  12.4XM	12.4(15)XM1	12.4(15)XM1
  12.4XN	Vulnerable; contact TAC
  12.4XQ	Vulnerable; contact TAC
  12.4XT	Vulnerable; contact TAC
  12.4XV	Vulnerable; contact TAC
  12.4XW	12.4(11)XW8	12.4(11)XW6
  12.4XY	12.4(15)XY3
  12.4XZ	Vulnerable; first fixed in 12.4T	12.4(20)T; Available on 11-JUL-08

  Cisco Network Registrar

  Affected Release Train	First Fixed Release
  Pre-6.1.x	Software has reached End of Support status. Customers running pre-6.1.x versions are advised to upgrade to a newer version as soon as possible.
  6.1.x	Upgrade to 6.2.4.1; available now
  6.2.x	6.2.4.1; available now
  6.3.x	6.3.1.5; available now
  7.0.x	7.0.1; available late September 2008

  Cisco Network Registrar software is available for download at http://www.cisco.com/pcgi-bin/Software/Tablebuild/tablebuild.pl/nr-eval?psrtdcat20e2

  Cisco Application and Content Networking System

  This issue is fixed in version 5.5.11.2 of Cisco ACNS software, which is available now.

  Cisco ACNS 5.5 software is available for download at http://www.cisco.com/pcgi-bin/tablebuild.pl/acns55?psrtdcat20e2.

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of malicious use of the vulnerability described in this advisory. Full technical details about the nature of the vulnerability are publicly available and the Metasploit project has published two modules that can exploit this vulnerability.

  Although DNS cache poisoning attacks are not new, security researcher Dan Kaminsky of IOActive recently presented a technique that makes DNS cache poisoning attacks more likely to succeed. Cisco would like to thank Dan Kaminsky for notifying vendors about his findings.

  Note that vulnerability information for Cisco IOS Software is being provided in this advisory outside of the announced publication schedule for Cisco IOS Software described at http://www.cisco.com/go/psirt due to industry-wide disclosure of the vulnerability.

  The multi-vendor advisory published by US-CERT is available at http://www.kb.cert.org/vuls/id/800113 ("VU#800113 - Multiple DNS implementations vulnerable to cache poisoning").

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080708-dns

Revision History

• Revision 2.1	2008-September 09	Added Cisco bug IDs for the Cisco Application Control Engine (ACE) module and the Cisco ACE appliance to the "Port Address Translation Considerations" section since these devices may have a predictable source port allocation policy when doing PAT. Updated fixed software information and availability dates for Cisco Network Registrar and for Cisco Application and Content Networking System.
  Revision 2.0	2008-July-28	Added a "Port Address Translation Considerations" section to highlight the problems and risks when DNS servers are behind network devices performing PAT, and to provide information and Cisco bug IDs for Cisco products that can perform PAT and that use predictable source port allocation policies when performing the layer 4 rewrite needed for PAT operation. Updated fixed software availability dates for Cisco Network Registrar.
  Revision 1.2	2008-July-25	Updated the "Exploitation and Public Announcements" section to indicate that full technical details and exploit code are publicly available. Added link to US-CERT Vulnerability Note.
  Revision 1.1	2008-July-22	Fixed link to CVSS score calculator. Updated table of fixed software for Cisco Network Registrar. Mention that we are aware of public discussion of the details of the vulnerability. Updated availability information for ACNS software.
  Revision 1.0	2008-July-08	Initial public release.

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