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Cisco Security Advisory

Multiple Vulnerabilities in Cisco Firewall Services Module

Advisory ID: cisco-sa-20121010-fwsm

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20121010-fwsm

Revision 1.0

For Public Release 2012 October 10 16:00  UTC (GMT)

Related Resources:

View related Security Advisory

Summary

The Cisco Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers is affected by the following vulnerabilities:

  • DCERPC Inspection Buffer Overflow Vulnerability
  • DCERPC Inspection Denial Of Service Vulnerabilities

These vulnerabilities are not interdependent; a release that is affected by one vulnerability is not necessarily affected by the other.

Exploitation of these vulnerabilities could allow an unauthenticated, remote attacker to trigger a reload of the affected device, or to execute arbitrary commands.  Repeated exploitation could result in a denial of service (DoS) condition.

Cisco has released free software updates that address these vulnerabilities. There are no workarounds that mitigate these vulnerabilities.

This advisory is available at the following link:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20121010-fwsm

Note: The Cisco Catalyst 6500 Series ASA Services Module, and the Cisco ASA 5500 Series Adaptive Security Appliance may also be affected by these vulnerabilities.

The vulnerabilities affecting the Cisco Catalyst 6500 Series ASA Services Module and Cisco ASA 5500 Series Adaptive Security Appliance have been disclosed in a separate Cisco Security Advisory. The Advisory is available at the following link:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20121010-asa

Affected Products

The Cisco FWSM for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers is affected by multiple vulnerabilities. The affected versions of the Cisco FWSM varies depending on the specific vulnerability.

Vulnerable Products

Consult the "Software Versions and Fixes" section of this security advisory for more information about the affected versions.

DCERPC Inspection Buffer Overflow Vulnerability

The Cisco FWSM is vulnerable when DCERPC inspection is enabled.  DCERPC inspection is not enabled by default.

DCERPC Inspection Denial Of Service Vulnerabilities

The Cisco FWSM is vulnerable when DCERPC inspection is enabled.  DCERPC inspection is not enabled by default. 

Checking Whether DCERPC Inspection Is Enabled


To determine if your FWSM configuration is affected by these vulnerabilities, issue the show service-policy | include dcerpc  command.

The following example indicates a Cisco FWSM with DCERPC inspection enabled:

fwsm# show  service-policy | include dcerpc
      Inspect: dcerpc, packet 0, drop 0, reset-drop 0


How to Determine the Running Software Version

To determine the version of the Cisco FWSM software that is running on a device, administrators can issue the show version command, as shown in the following example:

FWSM> show version

FWSM Firewall Version 4.0(16)
[...]

Customers who use the Cisco Adaptive Security Device Manager (ASDM) to manage their devices can find the version of the software displayed in the table in the login window or in the upper left corner of the Cisco ASDM window. The version notation is similar to the following example:

FWSM Version: 4.0(16)

Version information can also be obtained from the Cisco Catalyst 6500 Series Switch or the Cisco 7600 Series Router.  To determine the version of Cisco FWSM Software that is running on a device, issue the show module command from Cisco IOS Software or Cisco Catalyst Operating System Software to identify what modules and submodules are installed on the system.

The following example shows a system with a Cisco FWSM (WS-SVC-FWM-1) installed in slot 2:

switch>show module
Mod Ports Card Type                              Model              Serial No.
--- ----- -------------------------------------- ------------------ -----------
  1   16  SFM-capable 16 port 1000mb GBIC        WS-X6516-GBIC      SAL06334NS9
  2    6  Firewall Module                        WS-SVC-FWM-1       SAD10360485
  3    8  Intrusion Detection System             WS-SVC-IDSM-2      SAD0932089Z
  4    4  SLB Application Processor Complex      WS-X6066-SLB-APC   SAD093004BD
  5    2  Supervisor Engine 720 (Active)         WS-SUP720-3B       SAL0934888E

Mod MAC addresses                       Hw    Fw           Sw           Status
--- ---------------------------------- ------ ------------ ------------ -------
  1  0009.11e3.ade8 to 0009.11e3.adf7   5.1   6.3(1)       8.7(0.22)BUB Ok
  2  0018.ba41.5092 to 0018.ba41.5099   4.0   7.2(1)       4.0(16)      Ok
  3  0014.a90c.9956 to 0014.a90c.995d   5.0   7.2(1)       7.0(4)E4     Ok
  4  0014.a90c.66e6 to 0014.a90c.66ed   1.7   Unknown      Unknown      PwrDown
  5  0013.c42e.7fe0 to 0013.c42e.7fe3   4.4   8.1(3)       12.2(33)SXH8 Ok

[...]

After locating the correct slot, issue the show module <slot number> command to identify the software version that is running, as shown in the following example:

switch>show module 2
Mod Ports Card Type                              Model              Serial No.
--- ----- -------------------------------------- ------------------ -----------
  2    6  Firewall Module                        WS-SVC-FWM-1       SAD10360485

Mod MAC addresses                       Hw    Fw           Sw           Status
--- ---------------------------------- ------ ------------ ------------ -------
  2  0018.ba41.5092 to 0018.ba41.5099   4.0   7.2(1)       4.0(16)      Ok

[...]

The preceding example shows that the Cisco FWSM is running software version 4.0(16) as indicated by the Sw column.

If a Virtual Switching System (VSS) is used to allow two physical Cisco Catalyst 6500 Series switches to operate as a single logical virtual switch, the show module switch all command can display the software version of all FWSMs that belong to switch 1 and switch 2. The output from this command will be similar to the output from show module <slot number> but will include module information for the modules in each switch in the VSS.

Products Confirmed Not Vulnerable

With the exception of the Cisco Adaptive Security Appliance, and Cisco ASA Service Module, no other Cisco products are currently known to be affected by these vulnerabilities.

Details

The Cisco FWSM is a high-speed, integrated firewall module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers. The FWSM offers firewall services with stateful packet filtering and deep packet inspection.

The Cisco FWSM is affected by multiple vulnerabilities, which are described in the following sections:

DCERPC Inspection Buffer Overflow Vulnerability

DCERPC is a protocol widely used by Microsoft distributed client and server applications that allows software clients to execute programs on a server remotely.

A vulnerability exists in the code of the DCERPC inspection engine that would allow an unauthenticated, remote attacker to cause a reload of the affected system or to overflow the stack and possibly execute arbitrary commands. The vulnerability is due to insufficient validation of DCERPC packets within a valid DCERPC session. An attacker could exploit this vulnerability by sending a crafted DCERPC packet that will be inspected by the affected system.

Note: Only transit traffic can be used to exploit this vulnerability. This vulnerability affects both routed and transparent firewall mode in both single and multi-context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic.


This vulnerability is documented in Cisco bug ID CSCtr27522 (registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2012-4661.

DCERPC Inspection Denial Of Service Vulnerabilities

Two vulnerabilities exist in the DCERPC inspection engine that would allow an unauthenticated, remote attacker to cause a reload of the affected system. The vulnerabilities are due to insufficient validation of DCERPC packets within a valid DCERPC session. An attacker could exploit this vulnerability by sending a crafted DCERPC packet that will be inspected by the affected system.

Note: Only transit traffic can be used to exploit these vulnerabilities. These vulnerabilities affect both routed and transparent firewall mode in both single and multi-context mode. These vulnerabilities can be triggered by IPv4 and IPv6 traffic.

These vulnerabilities are documented in Cisco bug ID CSCtr27524 (registered customers only) and CSCtr27521 (registered customers only) and have been assigned CVE IDs CVE-2012-4662 and CVE-2012-4663, respectively.

Vulnerability Scoring Details

Cisco has scored the vulnerabilities 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

CSCtr27522 - DCERPC Inspection Buffer Overflow Vulnerability

Calculate the environmental score of CSCtr27522

CVSS Base Score - 9.0

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Medium

None

Complete

Partial

Complete

CVSS Temporal Score - 7.4

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed


CSCtr27524 - DCERPC Inspection Denial Of Service Vulnerability

Calculate the environmental score of CSCtr27524

CVSS Base Score - 7.1

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Medium

None

None

None

Complete

CVSS Temporal Score - 5.9

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed


CSCtr27521 - DCERPC Inspection Denial Of Service Vulnerability

Calculate the environmental score of CSCtr27521

CVSS Base Score - 7.1

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Medium

None

None

None

Complete

CVSS Temporal Score - 5.9

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed

Impact

Successful exploitation of either of the vulnerabilities could cause an affected device to reload. Repeated exploitation may result in a DoS condition.  Successful exploitation of the DCERPC Inspection Buffer Overflow Vulnerability may cause a stack overflow and permit the execution of arbitrary commands.

Software Versions and Fixes

When considering software upgrades, customers are advised to consult the Cisco Security Advisories and Responses 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.

DCERPC Inspection Buffer Overflow Vulnerability

Vulnerability Major Release
First Fixed Release
DCERPC Inspection Buffer Overflow Vulnerability - CSCtr27522
3.1 Not Vulnerable
3.2 Not Vulnerable
4.0 Not Vulnerable
4.1 4.1(9)

DCERPC Inspection Denial Of Service Vulnerabilities

Vulnerability Major Release
First Fixed Release
DCERPC Inspection Denial Of Service Vulnerabilities - CSCtr27524 and CSCtr27521
3.1 Not Vulnerable
3.2 Not Vulnerable
4.0 Not Vulnerable
4.1 4.1(7)

Recommended Releases

The following table lists all recommended releases. These recommended releases contain the fixes for all vulnerabilities in this advisory. Cisco recommends upgrading to a release that is equal to or later than these recommended releases.

Major Release

Recommended Release

3.1 Not Vulnerable
3.2 Not Vulnerable
4.0 Not Vulnerable
4.1 4.1(9)

Software Download

Cisco FWSM Software can be downloaded from the Software Center on Cisco.com by visiting http://www.cisco.com/cisco/software/navigator.html

For Cisco Catalyst 6500 Series ASA Services Module, navigate to Products > Cisco Interfaces and Modules > Cisco Services Modules >Cisco Catalyst 6500 Series Firewall  Services Module > ASA Services Module (FWSM) Software. Please note that some of these versions are interim versions and can be found by expanding the Interim tab on the download page.


Workarounds

Administrators can mitigate these vulnerabilities by disabling the DCERPC inspection if it is not required.

No other workarounds exist to mitigate these vulnerabilities.

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.

The vulnerabilities described in this security advisory were found during internal testing.

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-20121010-fwsm

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-October-10 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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