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Cisco Security Advisory

Multiple Cisco Products Vulnerable to DNS Cache Poisoning Attacks

Advisory ID: cisco-sa-20080708-dns

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080708-dns

Revision 2.1

For Public Release 2008 July 8 18:00  UTC (GMT)

Related Resources:

View related IPS Signature

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 free software updates that address these vulnerabilities.

This advisory is posted at http://tools.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.

Vulnerability Scoring Details

Cisco has provided scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this Security Advisory is done in accordance with CVSS version 2.0.

CVSS is a standards-based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.

Cisco has provided a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

Cisco has provided an FAQ to answer additional questions regarding CVSS at

http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html.

Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at

http://intellishield.cisco.com/security/alertmanager/cvss.

CSCso81854, CSCsq01298, CSCsq21930

Calculate the environmental score of CSCso81854/CSCsq01298/CSCsq21930

CVSS Base Score - 6.4

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Low

None

None

Partial

Partial

CVSS Temporal Score - 5.3

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed

Impact

Successful exploitation of the vulnerability described in this document may result in invalid hostname-to-IP address mappings in the cache of an affected DNS server. This may lead users of this DNS server to contact the wrong provider of network services. The ultimate impact varies greatly, ranging from a simple denial of service (for example, making www.example.com resolve to 127.0.0.1) to phishing and financial fraud.

Software Versions and Fixes

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.


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.

Obtaining Fixed Software

Cisco has released free software updates that address these vulnerabilities. Prior to deploying software, customers should consult their maintenance provider or check the software for feature set compatibility and known issues specific to their environment.

Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades, customers agree to be bound by the terms of Cisco's software license terms found at http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html, or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

Do not contact psirt@cisco.com or security-alert@cisco.com for software upgrades.

Customers with Service Contracts

Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com.

Customers with Service Contracts

Customers Using Third-Party Support Organizations

Customers whose Cisco products are provided or maintained through prior or existing agreements with third-party support organizations, such as Cisco Partners, authorized resellers, or service providers should contact that support organization for guidance and assistance with the appropriate course of action in regards to this advisory.

The effectiveness of any workaround or fix is dependent on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied workaround or fix is the most appropriate for use in the intended network before it is deployed.

Customers Without Service Contracts

Customers who purchase direct from Cisco but do not hold a Cisco service contract, and customers who purchase through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should acquire upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC contacts are as follows.

  • +1 800 553 2447 (toll free from within North America)
  • +1 408 526 7209 (toll call from anywhere in the world)
  • e-mail: tac@cisco.com

Customers should have their product serial number available and be prepared to give the URL of this notice as evidence of entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.

Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including localized telephone numbers, and instructions and e-mail addresses for use in various languages.

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 leavingcisco.com ("VU#800113 - Multiple DNS implementations vulnerable to cache poisoning").

Status of This Notice: Final

THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.

A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.


Distribution

This advisory is posted on Cisco's worldwide website at

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080708-dns.

In addition to worldwide web posting, a text version of this notice is clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail and Usenet news recipients.

  • cust-security-announce@cisco.com
  • first-teams@first.org
  • bugtraq@securityfocus.com
  • vulnwatch@vulnwatch.org
  • cisco@spot.colorado.edu
  • cisco-nsp@puck.nether.net
  • full-disclosure@lists.grok.org.uk
  • comp.dcom.sys.cisco@newsgate.cisco.com

Future updates of this advisory, if any, will be placed on Cisco's worldwide website, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the above URL for any updates.


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.

Cisco Security Procedures

Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco's worldwide website at http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html. This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt.


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