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HistoryApr 02, 2012 - 12:00 a.m.

Cisco Security Advisory: Cisco IOS Software Network Address Translation Vulnerability

2012-04-0200:00:00
vulners.com
15

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Cisco Security Advisory: Cisco IOS Software Network Address Translation
Vulnerability

Advisory ID: 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 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

  • CSCti35326 ("Cisco IOS Software NAT SIP Memory Starvation Vulnerability")

CVSS Base Score - 7.8
Access Vector - Network
Access Complexity - Low
Authentication - None
Confidentiality Impact - None
Integrity Impact - None
Availability Impact - Complete

CVSS Temporal Score - 6.4
Exploitability - Functional
Remediation Level - Official-Fix
Report Confidence - 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 | Availability of Repaired Releases |
| Release | |
|----------±------------------------------------------------|
| Affected | |First Fixed Release for All |
|12.0-Based|First Fixed Release |Advisories in the March 2012|
| Releases | |Cisco IOS Software Security |
| | |Advisory Bundled Publication|
|------------------------------------------------------------|

There are no affected 12.0 based releases
Affected
12.2-Based
Releases
------------------------------------------------------------
There are no affected 12.2 based releases
------------------------------------------------------------
Affected
12.3-Based
Releases
------------------------------------------------------------
There are no affected 12.3 based releases
------------------------------------------------------------
Affected
12.4-Based
Releases
----------±-------------------±---------------------------
12.4
----------±-------------------±---------------------------
12.4GC
----------±-------------------±---------------------------
12.4JA
----------±-------------------±---------------------------
12.4JAX
----------±-------------------±---------------------------
12.4JDA
----------±-------------------±---------------------------
12.4JDC
----------±-------------------±---------------------------
12.4JDD
----------±-------------------±---------------------------
12.4JDE
----------±-------------------±---------------------------
12.4JHA
----------±-------------------±---------------------------
12.4JHB
----------±-------------------±---------------------------
12.4JHC
----------±-------------------±---------------------------
12.4JK
----------±-------------------±---------------------------
12.4JL
----------±-------------------±---------------------------
12.4JX
----------±-------------------±---------------------------
12.4JY
----------±-------------------±---------------------------
12.4JZ
----------±-------------------±---------------------------
12.4MD
----------±-------------------±---------------------------
12.4MDA
----------±-------------------±---------------------------
12.4MDB
----------±-------------------±---------------------------
12.4MDC
----------±-------------------±---------------------------
12.4MR
----------±-------------------±---------------------------
12.4MRA
----------±-------------------±---------------------------
12.4MRB
----------±-------------------±---------------------------
12.4SW
----------±-------------------±---------------------------
12.4T
----------±-------------------±---------------------------
12.4XA
----------±-------------------±---------------------------
12.4XB
----------±-------------------±---------------------------
12.4XC
----------±-------------------±---------------------------
12.4XD
----------±-------------------±---------------------------
12.4XE
----------±-------------------±---------------------------
12.4XF
----------±-------------------±---------------------------
12.4XG
----------±-------------------±---------------------------
12.4XJ
----------±-------------------±---------------------------
12.4XK
----------±-------------------±---------------------------
12.4XL
----------±-------------------±---------------------------
12.4XM
----------±-------------------±---------------------------
12.4XN
----------±-------------------±---------------------------
12.4XP
----------±-------------------±---------------------------
12.4XQ
----------±-------------------±---------------------------
12.4XR
----------±-------------------±---------------------------
12.4XT
----------±-------------------±---------------------------
12.4XV
----------±-------------------±---------------------------
12.4XW
----------±-------------------±---------------------------
12.4XY
----------±-------------------±---------------------------
12.4XZ
----------±-------------------±---------------------------
12.4YA
----------±-------------------±---------------------------
12.4YB
----------±-------------------±---------------------------
12.4YD
----------±-------------------±---------------------------
12.4YE
----------±-------------------±---------------------------
12.4YG
----------±-------------------±---------------------------
Affected
15.0-Based
Releases
----------±-------------------±---------------------------
15.0M
----------±-------------------±---------------------------
15.0MR
----------±-------------------±---------------------------
15.0MRA
----------±-------------------±---------------------------
15.0S
----------±-------------------±---------------------------
15.0SA
----------±-------------------±---------------------------
15.0SE
----------±-------------------±---------------------------
15.0SG
----------±-------------------±---------------------------
15.0SY
----------±-------------------±---------------------------
15.0XA
----------±-------------------±---------------------------
15.0XO
----------±-------------------±---------------------------
Affected
15.1-Based
Releases
----------±-------------------±---------------------------
15.1EY
----------±-------------------±---------------------------
15.1GC
----------±-------------------±---------------------------
15.1M
----------±-------------------±---------------------------
15.1MR
----------±-------------------±---------------------------
15.1S
----------±-------------------±---------------------------
15.1SG
----------±-------------------±---------------------------
15.1SNG
----------±-------------------±---------------------------
15.1SNH
----------±-------------------±---------------------------
15.1T
----------±-------------------±---------------------------
15.1XB
----------±-------------------±---------------------------
Affected
15.2-Based
Releases
------------------------------------------------------------
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 [email protected] or [email protected] 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: [email protected]

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:

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/en/US/products/products_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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