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Cisco Security Advisory

Multiple Cisco IOS Session Initiation Protocol Denial of Service Vulnerabilities

Advisory ID: cisco-sa-20080924-sip

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-sip

Revision 1.1

For Public Release 2008 September 24 16:00  UTC (GMT)


Summary

Multiple vulnerabilities exist in the Session Initiation Protocol (SIP) implementation in Cisco IOS that can be exploited remotely to trigger a memory leak or to cause a reload of the IOS device.

Cisco has released free software updates that address these vulnerabilities. Fixed Cisco IOS software listed in the Software Versions and Fixes section contains fixes for all vulnerabilities addressed in this advisory.

There are no workarounds available to mitigate the effects of any of the vulnerabilities apart from disabling the protocol or feature itself, if administrators do not require the Cisco IOS device to provide voice over IP services.

This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-sip.

Note: The September 24, 2008 IOS Advisory bundled publication includes twelve Security Advisories. Eleven of the advisories address vulnerabilities in Cisco's IOS software, and one advisory addresses vulnerabilities in Cisco Unified Communications Manager. Each Advisory lists the releases that correct the vulnerability described in the Advisory.

Individual publication links are listed below:

Affected Products

These vulnerabilities only affect devices running Cisco IOS that have SIP voice services enabled.

Vulnerable Products

Cisco devices running affected Cisco IOS versions and that may process SIP messages are affected. The only requirement for these vulnerabilities is that the Cisco IOS device processes SIP messages as part of configured voice over IP (VoIP) functionality (this does not apply to processing of SIP messages as part of the NAT and firewall feature sets.) Recent versions of Cisco IOS do not process SIP messages by default, but creating a "dial peer" via the command dial-peer voice will start the SIP processes and cause Cisco IOS to start processing SIP messages. An example of an affected configuration is as follows:

dial-peer voice <Voice dial-peer tag> voip
 ...
!

Note that older versions of Cisco IOS were affected by a bug that caused Cisco IOS to process SIP messages even without being configured for SIP operation. Please refer to http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070131-sip for additional information on Cisco bug ID CSCsb25337 ( registered customers only) .

In addition to inspecting the Cisco IOS device configuration for a dial-peer command that causes the device to process SIP messages, administrators can also use some show commands to determine if the Cisco IOS device is running processes that handle SIP messages, or if the device is listening on the SIP ports.

The command show processes | include SIP can be used to determine whether Cisco IOS is running the processes that handle SIP messages. In the following example, the presence of the processes CCSIP_UDP_SOCKET and CCSIP_TCP_SOCKET indicates that the Cisco IOS device is processing SIP messages:

Router#show processes | include SIP
 147 Mwe 40F46DF4           12          2    600023468/24000  0 CCSIP_SPI_CONTRO
 148 Mwe 40F21244            0          1       0 5524/6000   0 CCSIP_DNS       
 149 Mwe 40F48254            4          1    400023108/24000  0 CCSIP_UDP_SOCKET
 150 Mwe 40F48034            4          1    400023388/24000  0 CCSIP_TCP_SOCKET

Different versions of Cisco IOS have different ways of verifying whether the Cisco IOS device is listening for SIP messages. The show ip sockets, show udp, show tcp brief all, and show control-plane host open-ports commands can be used to determine this, although not all of these commands work on all IOS releases. Since it is not practical in this document to provide a list of commands corresponding to the various releases, users should try the aforementioned commands to determine which ones work for their device. The following is one example of one command that shows a router listening on port 5060 (the SIP port):

router#show control-plane host open-ports 
Active internet connections (servers and established)
Prot        Local Address      Foreign Address                  Service    State
<output removed for brevity>
 tcp               *:5060                  *:0                      SIP   LISTEN
<outoput removed for brevity>
 udp               *:5060                  *:0                      SIP   LISTEN

In order to determine the software that runs on a Cisco IOS product, log in to the device and issue the show version command to display the system banner. Cisco IOS software identifies itself as "Internetwork Operating System Software" or simply "IOS." On the next line of output, the image name displays between parentheses, followed by "Version" and the Cisco IOS release name. Other Cisco devices do not have the show version command or give different output.

The following example shows output from a device that runs an IOS image:

router>show version
Cisco IOS Software, 7200 Software (C7200-ADVSECURITYK9-M), Version 12.4(6)T2, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2006 by Cisco Systems, Inc.
Compiled Tue 16-May-06 16:09 by kellythw
<more output removed for brevity>

Additional information on the Cisco IOS release naming conventions can be found on the document entitled "White Paper: Cisco IOS Reference Guide", which is available at http://www.cisco.com/warp/public/620/1.html.

Cisco Unified Communications Manager is also affected by some of these vulnerabilities, although they are tracked by different Cisco bug IDs. A companion security advisory for Cisco Unified Communications Manager is available at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-cucm.

Products Confirmed Not Vulnerable

The SIP Application Layer Gateway (ALG), which is used by the IOS Network Address Translation (NAT) and firewall features of Cisco IOS, is not affected by these vulnerabilities.

Cisco devices that are running Cisco IOS XR are not affected.

With the exception of the Cisco Unified Communications Manager, no other Cisco products are currently known to be vulnerable to the issues described in this advisory.

Details

SIP is a popular signaling protocol used to manage voice and video calls across IP networks such as the Internet. SIP is responsible for handling all aspects of call setup and termination. Voice and video are the most popular types of sessions that SIP handles, but the protocol is flexible to accommodate for other applications that require call setup and termination. SIP call signaling can use UDP (port 5060), TCP (port 5060), or TLS (TCP port 5061) as the underlying transport protocol.

Multiple denial of service vulnerabilities exist in the SIP implementation in Cisco IOS. In all cases vulnerabilities can be triggered by processing valid SIP messages.

Memory Leak Vulnerability

CSCse56800 ( registered customers only) causes a memory leak in affected devices. The memory leak is caused by the processing of a specific type of valid SIP messages and may eventually disrupt the availability of all voice services, even if the Cisco IOS device is still running. This vulnerability has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2008-3799.

Device Reload Vulnerabilities

The following vulnerabilities can lead to a reload of the Cisco IOS device while processing some specific and valid SIP messages:

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.

CSCse56800

Calculate the environmental score of CSCse56800

CVSS Base Score - 7.8

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Low

None

None

None

Complete

CVSS Temporal Score - 6.4

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed

CSCsg91306 , CSCsk42759 , CSCsl62609

Calculate the environmental score of CSCsg91306/CSCsk42759/CSCsl62609

CVSS Base Score - 7.8

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Low

None

None

None

Complete

CVSS Temporal Score - 6.4

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed

Impact

Successful exploitation of the vulnerabilities described in this document may result in a reload of the device. The issue could be repeatedly exploited to result in an extended Denial Of Service (DoS) condition.

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.

Each row of the Cisco IOS software table (below) names a Cisco IOS 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

There are no affected 12.0 based releases

Affected 12.1-Based Releases

First Fixed Release

Recommended Release

There are no affected 12.1 based releases

Affected 12.2-Based Releases

First Fixed Release

Recommended Release

12.2

Not Vulnerable

12.2B

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2BC

Not Vulnerable

12.2BW

Not Vulnerable

12.2BX

Vulnerable; first fixed in 12.4

12.2(33)SB2; Available on 26-SEP-08

12.4(15)T7

12.4(18c)

12.2BY

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2BZ

Not Vulnerable

12.2CX

Not Vulnerable

12.2CY

Not Vulnerable

12.2CZ

Vulnerable; migrate to any release in 12.2S

12.2(33)SB2; Available on 26-SEP-08

12.2DA

Not Vulnerable

12.2DD

Not Vulnerable

12.2DX

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

12.2IRB

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

12.2IXG

Not Vulnerable

12.2JA

Not Vulnerable

12.2JK

Not Vulnerable

12.2MB

Not Vulnerable

12.2MC

Releases prior to 12.2(15)MC2c are vulnerable, release 12.2(15)MC2c and later are not vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

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

12.2SY

Not Vulnerable

12.2SZ

Not Vulnerable

12.2T

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2TPC

Vulnerable; contact TAC

 

12.2XA

Not Vulnerable

12.2XB

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2XC

Not Vulnerable

12.2XD

Not Vulnerable

12.2XE

Not Vulnerable

12.2XF

Not Vulnerable

12.2XG

Not Vulnerable

12.2XH

Not Vulnerable

12.2XI

Not Vulnerable

12.2XJ

Not Vulnerable

12.2XK

Not Vulnerable

12.2XL

Not Vulnerable

12.2XM

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2XN

Not Vulnerable

12.2XNA

Not Vulnerable

12.2XNB

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(15)T7

12.4(18c)

12.2XU

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2XV

Not Vulnerable

12.2XW

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2YA

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2YB

Vulnerable; contact TAC

 

12.2YC

Vulnerable; contact TAC

 

12.2YD

Vulnerable; contact TAC

 

12.2YE

Not Vulnerable

12.2YF

Vulnerable; contact TAC

 

12.2YG

Not Vulnerable

12.2YH

Vulnerable; contact TAC

 

12.2YJ

Vulnerable; contact TAC

 

12.2YK

Not Vulnerable

12.2YL

Vulnerable; contact TAC

 

12.2YM

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2YN

Vulnerable; contact TAC

 

12.2YO

Not Vulnerable

12.2YP

Not Vulnerable

12.2YQ

Not Vulnerable

12.2YR

Not Vulnerable

12.2YS

Not Vulnerable

12.2YT

Vulnerable; contact TAC

 

12.2YU

Vulnerable; contact TAC

 

12.2YV

Releases prior to 12.2(11)YV1 are vulnerable, release 12.2(11)YV1 and later are not vulnerable;

 

12.2YW

Vulnerable; contact TAC

 

12.2YX

Not Vulnerable

12.2YY

Vulnerable; contact TAC

 

12.2YZ

Not Vulnerable

12.2ZA

Not Vulnerable

12.2ZB

Vulnerable; contact TAC

 

12.2ZC

Vulnerable; contact TAC

 

12.2ZD

Vulnerable; contact TAC

 

12.2ZE

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2ZF

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2ZG

Not Vulnerable

12.2ZH

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.2ZJ

Vulnerable; contact TAC

 

12.2ZL

Vulnerable; contact TAC

 

12.2ZP

Vulnerable; contact TAC

 

12.2ZU

Not Vulnerable

12.2ZX

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(15)T7

12.4(18c)

12.3B

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3BC

Not Vulnerable

12.3BW

Not Vulnerable

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(15)T7

12.4(18c)

12.3TPC

Vulnerable; contact TAC

 

12.3VA

Vulnerable; contact TAC

 

12.3XA

Releases prior to 12.3(2)XA7 are vulnerable, release 12.3(2)XA7 and later are not vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XB

Vulnerable; contact TAC

 

12.3XC

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XD

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XE

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XF

Vulnerable; contact TAC

 

12.3XG

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XI

Vulnerable; migrate to any release in 12.2SB

12.2(33)SB2; Available on 26-SEP-08

12.3XJ

Vulnerable; first fixed in 12.3YX

12.3(14)YX13

12.4(15)T7

12.3XK

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XL

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XQ

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XR

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XS

Not Vulnerable

12.3XU

Vulnerable; first fixed in 12.4T

12.4(15)T7

12.3XW

Vulnerable; first fixed in 12.3YX

12.3(14)YX13

12.4(15)T7

12.3XX

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XY

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3XZ

Vulnerable; first fixed in 12.4

12.4(15)T7

12.4(18c)

12.3YA

Not Vulnerable

12.3YD

Not Vulnerable

12.3YF

Vulnerable; first fixed in 12.3YX

12.3(14)YX13

12.4(15)T7

12.3YG

12.3(8)YG7; Available on 01-OCT-08

12.4(15)T7

12.3YH

Not Vulnerable

12.3YI

Not Vulnerable

12.3YJ

Not Vulnerable

12.3YK

Releases prior to 12.3(11)YK3 are vulnerable, release 12.3(11)YK3 and later are not vulnerable; first fixed in 12.4T

12.4(15)T7

12.3YM

12.3(14)YM13; Available on 30-SEP-08

12.3(14)YM13; Available on 30-SEP-08

12.3YQ

Vulnerable; first fixed in 12.4T

12.4(15)T7

12.3YS

Vulnerable; first fixed in 12.4T

12.4(15)T7

12.3YT

Vulnerable; first fixed in 12.4T

12.4(15)T7

12.3YU

Vulnerable; first fixed in 12.4XB

12.4(2)XB10

12.4(9)XG3

12.4(15)T7

12.3YX

12.3(14)YX12

12.3(14)YX13

12.3YZ

12.3(11)YZ3

 

12.3ZA

Vulnerable; first fixed in 12.4T

12.4(15)T7

Affected 12.4-Based Releases

First Fixed Release

Recommended Release

12.4

12.4(13f)

12.4(17b)

12.4(18)

12.4(18c)

12.4JA

Not Vulnerable

12.4JK

Not Vulnerable

12.4JL

Not Vulnerable

12.4JMA

Not Vulnerable

12.4JMB

Not Vulnerable

12.4JMC

Not Vulnerable

12.4JX

Not Vulnerable

12.4MD

Not Vulnerable

12.4MR

12.4(19)MR

12.4(19)MR

12.4SW

Not Vulnerable

12.4T

12.4(15)T4

12.4(20)T

12.4(6)T11

12.4(15)T7

12.4XA

Vulnerable; first fixed in 12.4T

12.4(15)T7

12.4XB

12.4(2)XB10

12.4(2)XB10

12.4XC

Vulnerable; first fixed in 12.4T

12.4(15)T7

12.4XD

12.4(4)XD11; Available on 26-SEP-08

12.4(4)XD11; Available on 26-SEP-08

12.4XE

Vulnerable; first fixed in 12.4T

12.4(15)T7

12.4XF

Not Vulnerable

12.4XG

Not Vulnerable

12.4XJ

Vulnerable; first fixed in 12.4T

12.4(15)T7

12.4XK

Not Vulnerable

12.4XL

12.4(15)XL2

12.4(15)XL2

12.4XM

Not Vulnerable

12.4XN

Not Vulnerable

12.4XP

Vulnerable; contact TAC

 

12.4XQ

Not Vulnerable

12.4XR

Not Vulnerable

12.4XT

Vulnerable; first fixed in 12.4T

12.4(15)T7

12.4XV

Vulnerable; contact TAC

 

12.4XW

12.4(11)XW7

12.4(11)XW9

12.4XY

12.4(15)XY3

12.4(15)XY4

12.4XZ

Not Vulnerable

12.4YA

Not Vulnerable


Workarounds

If the affected Cisco IOS device needs to provide voice over IP services and therefore SIP cannot be disabled then none of the listed vulnerabilities have workarounds. Users are advised to apply mitigation techniques to limit exposure to the listed vulnerabilities. Mitigation consists of only allowing legitimate devices to connect to the routers. To increase effectiveness, the mitigation must be coupled with anti-spoofing measures on the network edge. This action is required because SIP can use UDP as the transport protocol.

Additional mitigations that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory, which is available at the following link: http://tools.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20080924-sip.

Disable SIP Listening Ports

For devices that do not require SIP to be enabled, the simplest and most effective workaround is to disable SIP processing on the device. Some versions of Cisco IOS allow administrators to accomplish this with the following commands:

sip-ua
 no transport udp
 no transport tcp

warning Warning:  When applying this workaround to devices processing MGCP or H.323 calls, the device will not allow you to stop SIP processing while active calls are being processed. Under these circumstances, this workaround should be implemented during a maintenance window when active calls can be briefly stopped.

It is recommended that after applying this workaround, the show commands discussed in the Vulnerable Products section be used to confirm that the Cisco IOS device is no longer processing SIP messages.

Control Plane Policing

For devices that need to offer SIP services it is possible to use Control Plane Policing (CoPP) to block SIP traffic to the device from untrusted sources. Cisco IOS software releases 12.0S, 12.2SX, 12.2S, 12.3T, 12.4, and 12.4T support the CoPP feature. CoPP may be configured on a device to protect the management and control planes to minimize the risk and effectiveness of direct infrastructure attacks by explicitly permitting only authorized traffic sent to infrastructure devices in accordance with existing security policies and configurations. The following example can be adapted to your network:


!-- The 192.168.1.0/24 network and the 172.16.1.1 host are trusted.
!-- Everything else is not trusted. The following access list is used
!-- to determine what traffic needs to be dropped by a control plane
!-- policy (the CoPP feature.) If the access list matches (permit)
!-- then traffic will be dropped and if the access list does not
!-- match (deny) then traffic will be processed by the router.

access-list 100 deny udp 192.168.1.0 0.0.0.255 any eq 5060
access-list 100 deny tcp 192.168.1.0 0.0.0.255 any eq 5060
access-list 100 deny tcp 192.168.1.0 0.0.0.255 any eq 5061
access-list 100 deny udp host 172.16.1.1 any eq 5060
access-list 100 deny tcp host 172.16.1.1 any eq 5060
access-list 100 deny tcp host 172.16.1.1 any eq 5061
access-list 100 permit udp any any eq 5060
access-list 100 permit tcp any any eq 5060
access-list 100 permit tcp any any eq 5061


!-- Permit (Police or Drop)/Deny (Allow) all other Layer3 and Layer4
!-- traffic in accordance with existing security policies and
!-- configurations for traffic that is authorized to be sent
!-- to infrastructure devices.



!-- Create a Class-Map for traffic to be policed by
!-- the CoPP feature.

class-map match-all drop-sip-class
  match access-group 100


!-- Create a Policy-Map that will be applied to the
!-- Control-Plane of the device.

policy-map drop-sip-traffic
 class drop-sip-class
  drop


!-- Apply the Policy-Map to the Control-Plane of the
!-- device.

control-plane
 service-policy input drop-sip-traffic

warning Warning:  Because SIP can utilize UDP as a transport protocol, it is possible to easily spoof the sender's IP address, which may defeat ACLs that permit communication to these ports from trusted IP addresses.

In the above CoPP example, the access control list entries (ACEs) that match the potential exploit packets with the "permit" action result in these packets being discarded by the policy-map "drop" function, while packets that match the "deny" action (not shown) are not affected by the policy-map drop function. Additional information on the configuration and use of the CoPP feature can be found at http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6586/ps6642/prod_white_paper0900aecd804fa16a.html and http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtrtlimt.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 any public announcements or malicious use of the vulnerability described in this advisory.

These vulnerabilities were discovered by Cisco internal testing and during handling of customer service requests.

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-20080924-sip

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-bulletins@lists.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 1.1

2009-April-16

Removed references to the combined software table, as it is now outdated

Revision 1.0

2008-September-24

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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