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Cisco Security Advisory

Cisco IOS Software Zone-Based Firewall and Content Filtering Vulnerability

Advisory ID: cisco-sa-20130925-cce

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130925-cce

Revision 1.0

For Public Release 2013 September 25 16:00  UTC (GMT)

Related Resources:

View related IPS SignatureView related Event ResponseView related Alert

Summary

A vulnerability in the Zone-Based Firewall (ZBFW) component of Cisco IOS Software could allow an unauthenticated, remote attacker to cause an affected device to hang or reload.

The vulnerability is due to improper processing of specific HTTP packets when the device is configured for either Cisco IOS Content Filtering or HTTP application layer gateway (ALG) inspection. An attacker could exploit this vulnerability by sending specific HTTP packets through an affected device. An exploit could allow the attacker to cause an affected device to hang or reload.

Cisco has released free software updates that address this vulnerability.

Workarounds that mitigate this vulnerability are not available.

This advisory is available at the following link:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130925-cce

Note: The September 25, 2013, Cisco IOS Software Security Advisory bundled publication includes eight Cisco Security Advisories. All advisories address vulnerabilities in Cisco IOS Software. Each Cisco IOS Software Security 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 Cisco IOS Software vulnerabilities in the September 2013 bundled publication.

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_sep13.html

Affected Products

Vulnerable Products

Cisco devices that are running affected Cisco IOS Software versions are vulnerable when HTTP ALG inspection or Cisco IOS Content Filtering is configured under the ZBFW.

To verify whether the HTTP ALG inspection under the ZBFW is configured on a device use the show running-config command. If the service policy that is attached to any zone contains a policy map that contains the command service-policy http name then the device is configured for HTTP ALG. The following is the output from the show running-config command executed on a device running Cisco IOS Software that has the HTTP ALG inspection enabled under the ZBFW configuration:
ios-fw#show running-config

< output removed for brevity >

policy-map type inspect in->out
 class type inspect filtered-hosts
  inspect
  service-policy http http_bad
 class class-default
  drop
!
zone security inside
zone security outside
zone-pair security in-to-out source inside destination outside
 service-policy type inspect in->out
< output removed for brevity >
ios-fw#
To verify whether Cisco IOS Content Filtering under the ZBFW is configured on a device use the show policy-map type inspect zone-pair urlfilter | include URL Filtering privileged EXEC command and check for output.  A blank line indicates that the feature is not enabled.  Output with URL Filtering is in indicates the device is configured with Cisco IOS Content Filtering under ZBFW.  The following is the output from the show policy-map type inspect zone-pair urlfilter | include URL Filtering command executed on a device running Cisco IOS Software that has Cisco IOS Content Filtering enabled under the ZBFW configuration:
ios-fw#show policy-map type inspect zone-pair urlfilter | include URL Filtering
        URL Filtering is in
ios-fw#
Note: Cisco IOS Content Filtering using ip inspect and ip urlfilter commands are not affected.

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

Cisco IOS XR Software is not affected by this vulnerability.

Cisco IOS XE Software is not affected by this vulnerability.

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

Details

A vulnerability in the Zone-Based Firewall (ZFW) component of Cisco IOS Software could allow an unauthenticated, remote attacker to cause an affected device to hang or reload.

The vulnerability is due to improper processing of specific HTTP packets when the device is configured for content filtering or HTTP application layer gateway inspection. An attacker could exploit this vulnerability by sending specific HTTP packets through an affected device. An exploit could allow the attacker to cause an affected device to hang or reload.
Only transit traffic can trigger this vulnerability; HTTP traffic destined to a vulnerable device cannot trigger this vulnerability.

In devices that meet the vulnerable configuration criteria, valid HTTP packets could trigger this vulnerability.   This vulnerability can only be exploited with IPv4 traffic.  IPv6 traffic cannot be used to exploit this vulnerability.

This vulnerability has been documented in Cisco Bug ID CSCtx56174 (registered customers only) and has been assigned the Common Vulnerabilities and Exposures (CVE) ID CVE-2013-5476. 

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


CSCtx56174: Cisco IOS Software Zone-Based Firewall and Content Filtering Vulnerability

Calculate the environmental score of CSCtx56174

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 vulnerability may cause the affected device to crash or hang. If the device hangs, it must be power cycled to recover. If the device supports and is configured with scheduler isr-watchdog then the device will reset and reload if the vulnerability is exploited.

For more information on the scheduler isr-watchdog command consult the Cisco IOS Configuration Fundamentals Command Reference at the following link: http://www.cisco.com/en/US/docs/ios/fundamentals/command/reference/cf_r1.html#wp1079401

Software Versions and Fixes

When considering software upgrades, customers are advised to consult the Cisco Security Advisories, Responses, and Notices archive at http://www.cisco.com/go/psirt and review subsequent advisories to determine exposure and a complete upgrade solution.

In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.

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 September 2013 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 September 2013 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 September 2013 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 September 2013 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 September 2013 Cisco IOS Software Security Advisory Bundled Publication
There are no affected 12.4 based releases
Affected 15.0-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
There are no affected 15.0 based releases
Affected 15.1-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
15.1EY Not vulnerable
Vulnerable; First fixed in Release 15.2S
15.1GC Vulnerable; First fixed in Release 15.1M
Releases up to and including 15.1(2)GC2 are not vulnerable.
Vulnerable; First fixed in Release 15.1M
15.1M Releases including and prior to 15.1(4)M1 are not vulnerable. First fixed in 15.1(4)M6.
15.1(4)M7
15.1MR Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.1MRA Not vulnerable
15.1(3)MRA2
15.1S Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.1(3)S6
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
15.1(2)SG1
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
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.1SNI Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.1SVD Not vulnerable
Not vulnerable
15.1SVE Not vulnerable
Not vulnerable
15.1SVF Not vulnerable
Not vulnerable
15.1SY Not vulnerable
15.1(1)SY2; Available on 28-OCT-13
15.1(2)SY
15.1T Not vulnerable
Vulnerable; First fixed in Release 15.1M
15.1XO Not vulnerable
Not vulnerable
Affected 15.2-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
15.2E Not vulnerable
Not vulnerable
15.2GC 15.2(4)GC
Vulnerable; migrate to any release in 15.4T
15.2JA Not vulnerable
15.2(4)JA1
15.2JAX Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.2JB Not vulnerable
15.2(2)JB2
15.2JN Not vulnerable
Not vulnerable
15.2M Not vulnerable
15.2(4)M4
15.2S Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.2(4)S4
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.2SA Not vulnerable
15.2(2)SA
15.2SNG Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.2SNH Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.2SNI Not vulnerable
Vulnerable; First fixed in Release 15.3S
15.2T 15.2(1)T4
15.2(3)T4
15.2(3)T4
Affected 15.3-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
There are no affected 15.3 based releases

Cisco IOS XE Software

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

Cisco IOS XR Software

Cisco IOS XR Software is not affected by any of the vulnerabilities that are disclosed in the September 2013 Cisco IOS Software Security Advisory Bundled Publication.

Workarounds

Workarounds that mitigate this vulnerability are not available.

Obtaining Fixed Software

Cisco has released free software updates that address the vulnerability 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.

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 Navigator on Cisco.com at http://www.cisco.com/cisco/software/navigator.html.

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 discovered when handling 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 Security Intelligence Operations at the following link:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130925-cce

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 2013-September-25 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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