Cisco IOS Software NAT Skinny Call Control Protocol Vulnerability

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 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.

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

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.

  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

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.

URL

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

Revision History

• Revision 1.0

  2010-March-24

  Initial public release

  Show Less