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Cisco Security Advisory

Cisco IOS Software NAT Skinny Call Control Protocol Vulnerability

Advisory ID: cisco-sa-20100324-sccp

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20100324-sccp

Revision 1.1

Last Updated  2012 September 21 19:10  UTC (GMT)

For Public Release 2010 March 24 16:00  UTC (GMT)


Summary

Skinny Client Control Protocol (SCCP) crafted messages may cause a Cisco IOS device that is configured with the Network Address Translation (NAT) SCCP Fragmentation Support feature to reload.

Cisco has released free software updates that address this vulnerability. A workaround that mitigates this vulnerability is available.

This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20100324-sccp.

Note: The March 24, 2010, Cisco IOS Software Security Advisory bundled publication includes seven Security Advisories. All the advisories address vulnerabilities in Cisco IOS Software. Each advisory lists the releases that correct the vulnerability or vulnerabilities detailed in the advisory. The table at the following URL lists releases that correct all Cisco IOS Software vulnerabilities that have been published on March 24, 2010, or earlier:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20100324-bundle

Individual publication links are in "Cisco Event Response: Semiannual Cisco IOS Software Security Advisory Bundled Publication" at the following link:

http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_mar10.html

Affected Products

Vulnerable Products

This security advisory applies to all Cisco products that run Cisco IOS Software configured for Network Address Translation (NAT) and that support the NAT SCCP Fragmentation Support feature. This feature was first introduced in Cisco IOS Software Release 12.4(6)T.

To verify if NAT is enabled on a Cisco IOS device, log into the device and issue the command show ip nat statistics. The following example shows a device configured with NAT:

Router# show ip nat statistics
Total translations: 2 (0 static, 2 dynamic; 0 extended)
Outside interfaces: Serial0
Inside interfaces: Ethernet1
Hits: 135  Misses: 5
Expired translations: 2
Dynamic mappings:
-- Inside Source
access-list 1 pool mypool refcount 2
 pool mypool: netmask 255.255.255.0
        start 192.168.10.1 end 192.168.10.254
        type generic, total addresses 14, allocated 2 (14%), misses 0

You can also use the show running-config | include ip nat command to verify if NAT has been enabled on the device.

In NAT traditional configurations, the term "inside" refers to those networks that will be translated. Inside this domain, hosts will have addresses in one address space, while on the "outside", they will appear to have addresses in another address space when NAT is configured. The first address space is referred to as the local address space and the second is referred to as the global address space. The ip nat inside and ip nat outside interface commands must be present on the corresponding router interfaces in order for NAT to be enabled.

The NAT Virtual Interface (NVI) feature removes the requirement to configure an interface as either NAT inside or NAT outside. If the device is configured for NVI, you can use the show ip nat nvi statistics command in user EXEC or privileged EXEC mode, as shown in the following example.

Router# show ip nat nvi statistics

Total active translations: 0 (0 static, 0 dynamic; 0 extended) NAT Enabled interfaces:
Hits: 0  Misses: 0
CEF Translated packets: 0, CEF Punted packets: 0 Expired translations: 0 Dynamic mappings:
-- Inside Source
[Id: 1] access-list 1 pool pool1 refcount 1213 pool pool1: netmask 255.255.255.0
         start 192.168.1.10 end 192.168.1.253
         start 192.168.2.10 end 192.168.2.253
         start 192.168.3.10 end 192.168.3.253
         start 192.168.4.10 end 192.168.4.253
         type generic, total addresses 976, allocated 222 (22%), misses 0


!---output truncated

In order to determine the software that is running 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.

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

!---output truncated

Products Confirmed Not Vulnerable

Cisco IOS XR Software and IOS XE Software are not affected by this vulnerability.

Cisco IOS devices not explicitly configured for NAT are not vulnerable.

No other Cisco products are currently known to be affected by this vulnerability.

Details

The Skinny Client Control Protocol (SCCP) enables voice communication between an SCCP client and a Call Manager (CM). Typically, the CM provides service to the SCCP clients on TCP Port 2000 by default. Initially, an SCCP client connects to the CM by establishing a TCP connection; the client will also establish a TCP connection with a secondary CM, if available.

The NAT SCCP Fragmentation Support feature enables the Skinny Application Layer Gateway (ALG) to reassemble skinny control messages. Since this feature was introduced in Cisco IOS version 12.4(6)T, SCCP payloads requiring reassembly and NAT are no longer dropped.

A series of crafted SCCP packets may cause a Cisco IOS router that is running the NAT SCCP Fragmentation Support feature to reload.

This vulnerability is documented in Cisco Bug ID CSCsy09250 ( registered customers only) and has been assigned the CVE ID CVE-2010-0584.

Vulnerability Scoring Details

Cisco has provided scores for the vulnerability 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 .

CSCsy09250 -Bus error and crash when crafted packet is sent to device

Calculate the environmental score of CSCsy09250

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 this vulnerability may cause the affected device to reload. Repeated exploitation will result in a 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 "Bundle First Fixed Release" column indicates the earliest possible releases which have fixes for all the published vulnerabilities in this Cisco IOS Security Advisory bundled publication. Cisco recommends upgrading to the latest available release where possible.

Major Release

Availability of Repaired Releases

Affected 12.0-Based Releases

First Fixed Release for this Advisory

First Fixed Release for all Advisories in 24 March 2010 Bundle Publication

There are no affected 12.0 based releases

Affected 12.1-Based Releases

First Fixed Release for this Advisory

First Fixed Release for all Advisories in 24 March 2010 Bundle Publication

There are no affected 12.1 based releases

Affected 12.2-Based Releases

First Fixed Release for this Advisory

First Fixed Release for all Advisories in 24 March 2010 Bundle Publication

There are no affected 12.2 based releases

Affected 12.3-Based Releases

First Fixed Release for this Advisory

First Fixed Release for all Advisories in 24 March 2010 Bundle Publication

There are no affected 12.3 based releases

Affected 12.4-Based Releases

First Fixed Release for this Advisory

First Fixed Release for all Advisories in 24 March 2010 Bundle Publication

12.4

Not Vulnerable

12.4(25c)

15.0(1)M1

12.4GC

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4JA

Not Vulnerable

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4JDA

Not Vulnerable

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4JDC

Not Vulnerable

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4JDD

Not Vulnerable

12.4(10b)JDD1

12.4JHA

Not Vulnerable

Not Vulnerable

12.4JK

Not Vulnerable

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4JL

Not Vulnerable

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4JMA

Not Vulnerable

Releases prior to 12.4(3g)JMA2 are vulnerable, release 12.4(3g)JMA2 and later are not vulnerable

12.4JMB

Not Vulnerable

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4JX

Not Vulnerable

Vulnerable; first fixed in 12.4JA

12.4MD

12.4(11)MD10

12.4(24)MD

12.4MDA

12.4(22)MDA2

12.4(22)MDA2

12.4MR

Releases up to and including 12.4(4)MR1 are not vulnerable.

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4SW

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4T

12.4(20)T4

12.4(22)T3

12.4(15)T10

12.4(24)T2

12.4(15)T12

12.4(20)T5

12.4(24)T3; Available on 26-MAR-10

12.4(22)T4

12.4XA

Not Vulnerable

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XB

Not Vulnerable

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XC

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XD

Not Vulnerable

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XE

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XF

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XG

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XJ

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XK

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XL

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4XM

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XN

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4XP

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4XQ

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XR

12.4(22)XR3

12.4(22)XR3

12.4XT

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XV

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4XW

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XY

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4XZ

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4YA

Vulnerable; migrate to any release in 15.0M or a fixed 12.4T release.

Vulnerable; migrate to any release in 15.0M or a fixed 12.4 release.

12.4YB

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4YD

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

12.4YE

12.4(22)YE2

12.4(22)YE2

12.4(24)YE

12.4YG

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

Vulnerable; Contact your support organization per the instructions in Obtaining Fixed Software section of this advisory

Affected 15.0-Based Releases

First Fixed Release for this Advisory

First Fixed Release for all Advisories in 24 March 2010 Bundle Publication

There are no affected 15.0 based releases

Affected 15.1-Based Releases

First Fixed Release for this Advisory

First Fixed Release for all Advisories in 24 March 2010 Bundle Publication

There are no affected 15.1 based releases

Cisco IOS-XE Software

IOS-XE Release

First Fixed Release

2.1.x

Not Vulnerable

2.2.x

Not Vulnerable

2.3.x

Not Vulnerable

2.4.x

Not Vulnerable

2.5.x

Not Vulnerable

2.6.x

Not Vulnerable


Workarounds

As workaround, an administrator can disable SCCP NAT support using the no ip nat service skinny tcp port 2000 command, as shown in the following example:

Router(config)# no ip nat service skinny tcp port 2000

Note: If your Cisco CallManager is using a TCP port for skinny signaling different from the default port (2000), you need to adjust this command accordingly.

caution Caution: This workaround is only feasible on networks where SCCP traffic does not need to be processed by NAT. Please confirm before implementing this workaround.

Obtaining Fixed Software

Cisco has released free software updates that address this vulnerability. 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 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/en/US/support/tsd_cisco_worldwide_contacts.html 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. This vulnerability was found during the resolution 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-20100324-sccp

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 1.0

2010-March-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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