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Cisco Security Advisory

Cisco IOS Software Network Address Translation Vulnerability

Advisory ID: cisco-sa-20120328-nat

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120328-nat

Revision 1.0

For Public Release 2012 March 28 16:00  UTC (GMT)


Summary

The Cisco IOS Software Network Address Translation (NAT) feature contains a denial of service (DoS) vulnerability in the translation of Session Initiation Protocol (SIP) packets.

The vulnerability is caused when packets in transit on the vulnerable device require translation on the SIP payload.

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

This advisory is available at the following link:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120328-nat

Note: The March 28, 2012, Cisco IOS Software Security Advisory bundled publication includes nine Cisco Security Advisories. Each advisory lists the Cisco IOS Software releases that correct the vulnerability or vulnerabilities detailed in the advisory as well as the Cisco IOS Software releases that correct all vulnerabilities in the March 2012 bundled publication.

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

http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_mar12.html

Affected Products


Vulnerable Products

Cisco devices that are running Cisco IOS Software are vulnerable when they are configured for NAT and contain support for NAT for Session Initiation Protocol.

There are two methods to determine if a device is configured for NAT: 
  • Determine if NAT is active on a running device.
  • Determine if NAT commands are included in the device configuration.

Determine if NAT is Active on a Running Device

The preferred method to verify whether NAT is enabled on a Cisco IOS device is to log in to the device and issue the show ip nat statistics command. If NAT is active, the sections Outside interfaces and Inside interfaces will each include at least one interface. The following example shows a device on which the NAT feature is active:

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

Depending on the Cisco IOS Software release, the interface lists can be in the lines following the Outside interfaces and Inside interfaces. In releases that support the section filter on show commands, the administrator can determine whether NAT is active by using the show ip nat statistics | section interfaces command, as illustrated in the following example: 

Router> show ip nat statistics | section interfaces
Outside interfaces:
  GigabitEthernet0/0
Inside interfaces: 
  GigabitEthernet0/1
Router>

Determine if NAT Commands are Included in the Device Configuration

Alternatively, to determine whether NAT has been enabled in the Cisco IOS Software configuration, either the ip nat inside or ip nat outside commands must be present in different interfaces, or in the case of the NAT Virtual Interface, the ip nat enable interface command will be present.


Determine the Cisco IOS Software Release

To determine the Cisco IOS Software release that is running on a Cisco product, administrators can log in to the device and issue the show version command to display the system banner. The system banner confirms that the device is running Cisco IOS Software by displaying text similar to "Cisco Internetwork Operating System Software" or "Cisco IOS Software." The image name displays in parentheses, followed by "Version" and the Cisco IOS Software release name. Other Cisco devices do not have the show version command or may provide different output.

The following example identifies a Cisco product that is running Cisco IOS Software Release 15.0(1)M1 with an installed image name of C3900-UNIVERSALK9-M:

Router> show version 
Cisco IOS Software, C3900 Software (C3900-UNIVERSALK9-M), Version 15.0(1)M1, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Wed 02-Dec-09 17:17 by prod_rel_team
!--- output truncated 

Additional information about Cisco IOS Software release naming conventions is available in "White Paper: Cisco IOS and NX-OS Software Reference Guide" at http://www.cisco.com/web/about/security/intelligence/ios-ref.html.

Products Confirmed Not Vulnerable

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

Details

Cisco IOS Software NAT SIP Memory Starvation Vulnerability

 NAT SIP application level gateway (ALG)  translation of SIP packets could cause a memory resource exhaustion condition that can lead to a DoS condition, which could cause the reload of the vulnerable device.

NAT for SIP is performed on UDP port 5060 packets by default. The port is configurable using the ip nat service sip udp port  global configuration command.

 This vulnerability is documented in Cisco bug ID CSCti35326 (registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2012-0383.

Vulnerability Scoring Details

Cisco has scored the vulnerability in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this security advisory is in accordance with CVSS version 2.0.

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

Cisco has provided a base and temporal score. Customers can also compute environmental scores that help determine the impact of the vulnerability in their own networks.

Cisco has provided additional information regarding CVSS at the following link:

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

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

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


Cisco IOS Software NAT SIP Memory Starvation Vulnerability

Calculate the environmental score of CSCti35326

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 incrementing use of memory that will not be released until the device is reloaded. This memory consumption could lead to a DoS condition and cause the vulnerable device to become unresponsive or reload.

Software Versions and Fixes

Cisco IOS Software

Each row of the following Cisco IOS Software table corresponds to a Cisco IOS Software train. If a particular train is vulnerable, the earliest releases that contain the fix are listed in the First Fixed Release column. The First Fixed Release for All Advisories in the March 2012 Bundled Publication column lists the earliest possible releases that correct all the published vulnerabilities in the Cisco IOS Software Security Advisory bundled publication. Cisco recommends upgrading to the latest available release, where possible.

The Cisco IOS Software Checker allows customers to search for Cisco Security Advisories that address specific Cisco IOS Software releases. This tool is available on the Cisco Security Intelligence Operations (SIO) portal at http://tools.cisco.com/security/center/selectIOSVersion.x


Major Release      Availability of Repaired Releases
Affected 12.0-Based Releases First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
There are no affected 12.0 based releases
Affected 12.2-Based Releases First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
There are no affected 12.2 based releases
Affected 12.3-Based Releases First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
There are no affected 12.3 based releases
Affected 12.4-Based Releases First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
12.4 Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4GC Releases up to and including 12.4(24)GC3a are not vulnerable.
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4JA Not vulnerable
12.4(23c)JA4
12.4(25e)JA
12.4JAX Not vulnerable
Vulnerable; First fixed in Release 12.4JA
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
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4JDE Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4JHA Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4JHB Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4JHC Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
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.
12.4JX Not vulnerable
Vulnerable; First fixed in Release 12.4JA
12.4JY Not vulnerable
Vulnerable; First fixed in Release 12.4JA
12.4JZ Not vulnerable
Vulnerable; First fixed in Release 12.4JA
12.4MD Only releases 12.4(24)MD5 and 12.4(24)MD6 are vulnerable.
12.4(22)MD3; Available on 30-MAR-12
12.4MDA Releases 12.4(24)MDA5 and prior are not vulnerable; first fixed in 12.2(24)MDA11
12.4(24)MDA11
12.4MDB 12.4(24)MDB4
12.4(24)MDB5a
12.4MDC Not vulnerable
Not vulnerable
12.4MR Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4MRA Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4MRB Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4SW Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4T Only releases 12.4(24)T5 and 12.4(24)T6 are vulnerable.
12.4(15)T17
12.4(24)T7

12.4XA Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XB Not vulnerable
Vulnerable; First fixed in Release 12.4T
12.4XC Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XD Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XE Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XF Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XG Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XJ Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XK Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XL Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4XM Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XN Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4XP Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4XQ Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XR Not vulnerable
Vulnerable; First fixed in Release 12.4T
12.4XT Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XV Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4XW Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XY Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4XZ Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4YA Not vulnerable
Vulnerable; First fixed in Release 15.0M
12.4YB Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4YD Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.4YE Not vulnerable
12.4(24)YE3d
12.4YG Not vulnerable
12.4(24)YG4
Affected 15.0-Based Releases First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
15.0M Only releases 15.0(1)M4 and 15.0(1)M5 are vulnerable.
15.0(1)M8
15.0MR Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.0MRA Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.0S Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.0(1)S5
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.0SA Not vulnerable
Not vulnerable
15.0SE Not vulnerable
15.0(1)SE1
15.0SG Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.0(2)SG2
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.0SY Not vulnerable
15.0(1)SY1
15.0XA Not vulnerable
Vulnerable; First fixed in Release 15.1T
15.0XO Cisco IOS XE devices: Please see Cisco IOS-XE Software Availability
Cisco IOS XE devices: Please see Cisco IOS-XE Software Availability
Affected 15.1-Based Releases First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
15.1EY Not vulnerable
15.1(2)EY2
15.1GC Not vulnerable
15.1(2)GC2
15.1M Not vulnerable
15.1(4)M4; Available on 30-MAR-12
15.1MR Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.1S Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.1(3)S2
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.1SG Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.1SNG Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.1SNH Not vulnerable
Not vulnerable
15.1T 15.1(1)T4
15.1(2)T5; Available on 27-APR-12
15.1(3)T
15.1(3)T3
15.1XB Not vulnerable
Vulnerable; First fixed in Release 15.1T
Affected 15.2-Based Releases First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
There are no affected 15.2 based releases

Cisco IOS XE Software

Cisco IOS XE Software is not affected by the vulnerability that is disclosed in this document.

Cisco IOS XR Software

 Cisco IOS XR Software is not affected by any of the vulnerabilities disclosed in the March 2012 Cisco IOS Software Security Advisory bundled publication. 


Workarounds

NAT for SIP Resource Exhaustion Vulnerability

This vulnerability can be mitigated by disabling NAT SIP ALG over the UDP transport by using the no ip nat service sip udp port 5060 global configuration command. This command can only be configured in Cisco IOS images that include the NAT ALG SIP feature. Layer 3 NAT translation will continue to be performed on SIP packets but the SIP payload will not be translated.

Obtaining Fixed Software

Cisco has released free software updates that address the vulnerability|vulnerabilities described in this advisory. Prior to deploying software, customers are advised to consult their maintenance providers or check the software for feature set compatibility and known issues that are specific to their environments.

Customers may only install and expect support for feature sets they have purchased. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license at http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html, or as set forth 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, upgrades should be obtained through the Software Center on Cisco.com at http://www.cisco.com.

Customers Using Third-Party Support Organizations

Customers with Cisco products that 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 organization for assistance with the appropriate course of action.

The effectiveness of any workaround or fix depends on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Because of the variety of affected products and releases, customers should consult their service providers or support organizations to ensure that any applied workaround or fix is the most appropriate in the intended network before it is deployed.

Customers Without Service Contracts

Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco Technical Assistance Center (TAC):

  • +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 the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade. Customers without service contracts should request free upgrades through the TAC.

Refer to Cisco Worldwide Contacts at http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html for additional TAC contact information, including localized telephone numbers, instructions, and e-mail addresses for support in various languages.

Exploitation and Public Announcements

The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

This vulnerability was found during troubleshooting of TAC 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 Security Intelligence Operations at the following link:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120328-nat

Additionally, a text version of this advisory is clear signed with the Cisco PSIRT PGP key and circulated among the following e-mail addresses:

  • 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

Future updates of this advisory, if any, will reside on Cisco.com but may not be announced on mailing lists. Users can monitor this advisory's URL for any updates.


Revision History

Revision 1.0 2012-March-28 Initial public release.

Cisco Security Procedures

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


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