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Cisco Security Advisory: Multiple Vulnerabilities in Cisco ASA 5500 Series Adaptive Security Appliances and Cisco Catalyst 6500 Series ASA Services Module
From: Cisco Systems Product Security Incident Response Team <psirt () cisco com>
Date: Wed, 5 Oct 2011 11:45:10 -0400

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Cisco Security Advisory: Multiple Vulnerabilities in Cisco ASA 5500
Series Adaptive Security Appliances and Cisco Catalyst 6500 Series ASA
Services Module

Advisory ID: cisco-sa-20111005-asa

Revision 1.0

For Public Release 2011 October 05 1600 UTC (GMT)

+--------------------------------------------------------------------

Summary
=======

Cisco ASA 5500 Series Adaptive Security Appliances and Cisco Catalyst
6500 Series ASA Services Module are affected by multiple
vulnerabilities as follows:

  * MSN Instant Messenger (IM) Inspection Denial of Service
    vulnerability
  * TACACS+ Authentication Bypass vulnerability
  * Four SunRPC Inspection Denial of Service vulnerabilities
  * Internet Locator Service (ILS) Inspection Denial of Service
    vulnerability

These vulnerabilities are independent; a release that is affected by
one vulnerability may not necessarily be affected by the others.

Workarounds for some of the vulnerabilities are provided in this
advisory.

This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20111005-asa.shtml.

Note:  The Cisco Firewall Services Module (FWSM) is affected by the
TACACS+ authentication bypass vulnerability, SunRPC Inspection denial
of service (DoS) vulnerabilities and ILS inspection DoS
vulnerability. A separate Cisco Security Advisory has been published
to disclose the vulnerabilities that affect the FWSM. This advisory
is available at:

http://www.cisco.com/warp/public/707/cisco-sa-20110831-fwsm.shtml

Affected Products
=================

Cisco ASA 5500 Series Adaptive Security Appliances and Cisco Catalyst
6500 Series ASA Services Module are affected by multiple
vulnerabilities. Affected versions of Cisco ASA Software will vary
depending on the specific vulnerability.

Vulnerable Products
+------------------

For specific version information, refer to the Software Versions and
Fixes section of this advisory.

MSN IM Inspection Denial of Service Vulnerability
+------------------------------------------------

The MSN IM inspection feature of Cisco ASA 5500 Series Adaptive
Security Appliances is affected by a DoS vulnerability.

MSN IM inspection is not enabled by default.

Administrators can enable MSN IM inspection and specify actions when
a message violates a parameter, create an IM inspection policy map.
You can then apply the inspection policy map when you enable IM
inspection, as shown in the following example:

    policy-map type inspect im MY-MSN-INSPECT
     parameters
     match protocol msn-im 
      log
    !
    policy-map global_policy
      class inspection_default
        inspect im MY-MSN-INSPECT

TACACS+ Authentication Bypass Vulnerability
+------------------------------------------

An authentication bypass vulnerability affects the TACACS+
implementation of Cisco ASA 5500 Series Adaptive Security Appliances.

In order to enable TACACS+ for authentication, authorization, or
accounting (AAA), you must first create at least one AAA server group
per AAA protocol and add one or more servers to each group with the
"aaa-server" command. You identify AAA server groups by name. The
following example shows how a AAA server group is configured for TACACS+
authentication:

    aaa-server my-tacacs-sever protocol tacacs+
    aaa-server my-tacacs-server (inside) host 203.0.113.11 

SunRPC Inspection Denial of Service Vulnerabilities
+--------------------------------------------------

Four DoS vulnerabilities affect the SunRPC inspection feature of
Cisco ASA 5500 Series Adaptive Security Appliances.

SunRPC inspection is enabled by default.

To check if SunRPC inspection is enabled, issue the "show service-policy
| include sunrpc" command and confirm that output, such as what is
displayed in the following example, is returned.

    ciscoasa# show service-policy | include sunrpc
          Inspect: sunrpc, packet 0, drop 0, reset-drop 0

The following configuration commands are used to enable SunRPC
inspection in the Cisco ASA.

    class-map inspection_default
     match default-inspection-traffic
    !
    policy-map global_policy
     class inspection_default
      ...
      inspect sunrpc 
      ...
    !
    service-policy global_policy global

ILS Inspection Denial of Service Vulnerability
+---------------------------------------------

A DoS vulnerability affects the ILS inspection feature of Cisco ASA
5500 Series Adaptive Security Appliances.

ILS inspection is not enabled by default.

To check if ILS inspection is enabled, issue the "show service-policy |
include ils" command and confirm that output, such as what is displayed
in the following example, is returned.

    ciscoasa# show service-policy | include ils
          Inspect: ils, packet 0, drop 0, reset-drop 0

The following configuration commands are used to enable ILS
inspection in the Cisco ASA.

    class-map inspection_default
     match default-inspection-traffic
    !
    policy-map global_policy
     class inspection_default
      ...
      inspect ils
      ...
    !
    service-policy global_policy global

How to Determine the Running Software Version
+--------------------------------------------

To determine whether a vulnerable version of Cisco ASA Software is
running on an appliance, administrators can issue the "show version"
command. The following example shows a Cisco ASA 5500 Series Adaptive
Security Appliance that is running software version 8.4(1):

    ASA#show version | include Version
    Cisco Adaptive Security Appliance Software Version 8.4(1)
    Device Manager Version 6.4(1)

Customers who use Cisco ASDM to manage devices can locate the
software version in the table that is displayed in the login window
or upper-left corner of the Cisco ASDM window.

Products Confirmed Not Vulnerable
+--------------------------------

With the exception of the Cisco FWSM, no other Cisco products are
currently known to be affected by these vulnerabilities.

Details
=======

Cisco ASA 5500 Series Adaptive Security Appliances and Cisco Catalyst
6500 Series ASA Services Module are affected by the following
vulnerabilities:

MSN IM Inspection Denial of Service Vulnerability
+------------------------------------------------

The IM inspect engine lets you apply fine grained controls on the IM
application to control the network usage and stop leakage of
confidential data, propagation of worms, and other threats to the
corporate network.

A DoS vulnerability affects the MSN IM inspection feature of Cisco
ASA 5500 Series Adaptive Security Appliances. During successful
exploitation, an unauthenticated attacker could cause the affected
device to reload and may result in a sustained DoS condition.

Note: Only transit traffic can trigger this vulnerability; traffic that
is destined to the appliance will not trigger the vulnerability. MSN IM
inspection is not enabled by default.

This vulnerability is documented in Cisco bug ID CSCtl67486 and has been
assigned CVE ID CVE-2011-3304.

TACACS+ Authentication Bypass Vulnerability
+------------------------------------------

AAA enables the ASA to determine who the user is (authentication),
what the user can do (authorization), and what the user did
(accounting). The Cisco ASA supports TACACS+ authentication for VPN
users, firewall sessions, and administrative access to the device.

An authentication bypass vulnerability exists in the TACACS+
implementation of the Cisco ASA. Successful exploitation could allow
a remote attacker to bypass TACACS+ authentication of VPN users,
firewall sessions, or administrative access to the device. The
attacker needs to have access to the network between the ASA and the
TACACS+ server in order to successfully exploit this vulnerability.

This vulnerability is documented in Cisco bug ID CSCto40365 and has been
assigned CVE ID CVE-2011-3298.

SunRPC Inspection Denial of Service Vulnerabilities
+--------------------------------------------------

The Sun RPC inspection engine performs application inspection for the
Sun RPC protocol. Sun RPC is used by Network File System (NFS) and
Network Information Service (NIS). Sun RPC services can run on any
port. When a client attempts to access a Sun RPC service on a server,
it must learn the port that service is running on. The client does
this by querying the port mapper process, usually rpcbind, on the
well-known port of 111.

Four DoS vulnerabilities affect the SunRPC inspection feature of
Cisco ASA 5500 Series Adaptive Security Appliances, in which an
unauthenticated attacker may cause the affected device to reload.

Note:  Only transit traffic can trigger these vulnerabilities;
traffic that is destined to the appliance will not trigger the
vulnerabilities. These vulnerabilities can be triggered by using UDP
packets, not TCP. SunRPC inspection is enabled by default.

These vulnerabilities are documented in Cisco bug IDs CSCto92380,
CSCtq06065, CSCtq06062, CSCto92398; and have been assigned CVE IDs
CVE-2011-3299, CVE-2011-3300, CVE-2011-3301, and CVE-2010-3302,
respectively.

ILS Inspection Denial of Service Vulnerability
+---------------------------------------------

The ILS inspection engine provides NAT support for Microsoft
NetMeeting, SiteServer, and Active Directory products that use LDAP
to exchange directory information with an ILS server.

A DoS vulnerability affects the ILS inspection feature of Cisco ASA
5500 Series Adaptive Security Appliances. During successful
exploitation, an unauthenticated attacker could cause the affected
device to reload and may result in a sustained DoS condition.

Note:  Only transit traffic can trigger this vulnerability; traffic
that is destined to the appliance will not trigger the vulnerability.
ILS inspection is not enabled by default.

This vulnerability is documented in Cisco bug ID CSCtq57697 and has been
assigned CVE CVE-2011-3303.

Vulnerability Scoring Details
=============================

Cisco has provided scores for the vulnerabilities in this advisory
based on the Common Vulnerability Scoring System (CVSS). The CVSS
scoring in this Security Advisory is done in accordance with CVSS
version 2.0.

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

Cisco has provided a base and temporal score. Customers can then
compute environmental scores to assist in determining the impact of
the vulnerability in individual networks.

Cisco has provided an FAQ to answer additional questions regarding
CVSS at:

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

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

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

* CSCtl67486 ("MSN IM Inspection Denial of Service 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

* CSCto40365 ("TACACS+ Authentication Bypass Vulnerability")

CVSS Base Score - 7.9
    Access Vector -            Adjacent Network
    Access Complexity -        Medium
    Authentication -           None
    Confidentiality Impact -   Complete
    Integrity Impact -         Complete
    Availability Impact -      Complete

CVSS Temporal Score - 6.5
    Exploitability -           Functional
    Remediation Level -        Official-Fix
    Report Confidence -        Confirmed

* CSCto92380, CSCtq06065, CSCtq06062, CSCto92398 ("SunRPC Inspection
Denial of Service Vulnerabilities")

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

* CSCtq57697 ("ILS inspection crash on malformed ILS traffic")

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 all the DoS vulnerabilities could cause an
affected device to reload. Repeated exploitation could result in a
sustained DoS condition.

Successful exploitation of the TACACS+ authentication bypass
vulnerability could allow an attacker to bypass authentication of
VPN, firewall and/or administrative sessions.

Software Versions and Fixes
===========================

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.

+------------------------------------------------------------+
| Vulnerability                  | Major   | First Fixed     |
|                                | Release | Release         |
|--------------------------------+---------+-----------------|
|                                | 7.0     | Not vulnerable  |
|                                |---------+-----------------|
|                                | 7.1     | Not vulnerable  |
|                                |---------+-----------------|
|                                | 7.2     | 7.2(5.3)        |
|                                |---------+-----------------|
|                                | 8.0     | 8.0(5.25)       |
|MSN Instant Messeger (IM)       |---------+-----------------|
| Inspection Denial of Service   | 8.1     | 8.1(2.50)       |
|Vulnerability (CSCtl67486)      |---------+-----------------|
|                                | 8.2     | 8.2(5.9)        |
|                                |---------+-----------------|
|                                | 8.3     | 8.3(2.23)       |
|                                |---------+-----------------|
|                                | 8.4     | 8.4(2)          |
|                                |---------+-----------------|
|                                | 8.5     | 8.5(1.1)        |
|--------------------------------+---------+-----------------|
|                                | 7.0     | 7.0(8.13)       |
|                                |---------+-----------------|
|                                |         | Vulnerable;     |
|                                | 7.1     | migrate to 7.2  |
|                                |         | (5.4) or later  |
|                                |---------+-----------------|
|                                | 7.2     | 7.2(5.3)        |
|                                |---------+-----------------|
| TACACS+ Authentication Bypass  | 8.0     | 8.0(5.24)       |
|Vulnerability (CSCto40365)      |---------+-----------------|
|                                | 8.1     | 8.1(2.50)       |
|                                |---------+-----------------|
|                                | 8.2     | 8.2(5)          |
|                                |---------+-----------------|
|                                | 8.3     | 8.3(2.18)       |
|                                |---------+-----------------|
|                                | 8.4     | 8.4(1.10)       |
|                                |---------+-----------------|
|                                | 8.5     | 8.5(1.1)        |
|--------------------------------+---------+-----------------|
|                                | 7.0     | 7.0(8.13)       |
|                                |---------+-----------------|
|                                |         | Vulnerable;     |
|                                | 7.1     | migrate to 7.2  |
|                                |         | (5.4) or later  |
|                                |---------+-----------------|
|                                | 7.2     | 7.2(5.4)        |
|                                |---------+-----------------|
| SunRPC Inspection Denial of    | 8.0     | 8.0(5.25)       |
|Service Vulnerabilities         |---------+-----------------|
|                                |         | Vulnerable;     |
| (CSCto92380, CSCtq06065,       | 8.1     | migrate to 8.2  |
| CSCtq06062, CSCto92398)        |         | or later        |
|                                |---------+-----------------|
|                                | 8.2     | 8.2(5.9)        |
|                                |---------+-----------------|
|                                | 8.3     | 8.3(2.23)       |
|                                |---------+-----------------|
|                                | 8.4     | 8.4(2.6)        |
|                                |---------+-----------------|
|                                | 8.5     | 8.5(1.1)        |
|--------------------------------+---------+-----------------|
|                                | 7.0     | 7.0(8.13)       |
|                                |---------+-----------------|
|                                |         | Vulnerable;     |
|                                | 7.1     | migrate to 7.2  |
|                                |         | (5.4) or later  |
|                                |---------+-----------------|
|                                | 7.2     | 7.2(5.4)        |
|                                |---------+-----------------|
| ILS Inspection Denial of       | 8.0     | 8.0(5.25)       |
|Service Vulnerability           |---------+-----------------|
| (CSCtq57697.)                  | 8.1     | 8.1(2.50)       |
|                                |---------+-----------------|
|                                | 8.2     | 8.2(5.6)        |
|                                |---------+-----------------|
|                                | 8.3     | 8.3(2.23)       |
|                                |---------+-----------------|
|                                | 8.4     | 8.4(2.7)        |
|                                |---------+-----------------|
|                                | 8.5     | 8.5(1.1)        |
+------------------------------------------------------------+

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                        |
|---------------+--------------------------------------------|
| 7.0           | 7.0(8.13)                                  |
|---------------+--------------------------------------------|
| 7.1           | Vulnerable; migrate to 7.2(5.4) or later   |
|---------------+--------------------------------------------|
| 7.2           | 7.2(5.4)                                   |
|---------------+--------------------------------------------|
| 8.0           | 8.0(5.25)                                  |
|---------------+--------------------------------------------|
| 8.1           | Vulnerable; migrate to 8.2 or later        |
|---------------+--------------------------------------------|
| 8.2           | 8.2(5.11)                                  |
|---------------+--------------------------------------------|
| 8.3           | 8.3(2.24)                                  |
|---------------+--------------------------------------------|
| 8.4           | 8.4(2.7)                                   |
|---------------+--------------------------------------------|
| 8.5           | 8.5(1.1)                                   |
+------------------------------------------------------------+

Workarounds
===========

This Cisco Security Advisory describes multiple distinct
vulnerabilities. These vulnerabilities and their respective
workarounds are independent of each other.

MSN Instant Messeger (IM) Inspection DoS Vulnerability
+-----------------------------------------------------

Administrators can mitigate this vulnerability by disabling MSN IM
inspection if it is not required. Administrators can disable MSN IM
inspection by issuing the "no inspect im" command in class configuration
sub-mode in the policy map configuration. Disabling MSN IM inspection
may cause MSN IM traffic to stop through the security appliance.

TACACS+ Authentication Bypass Vulnerability
+------------------------------------------

There are no workarounds available for this vulnerability other than
using a different authentication protocol such as RADIUS, Active
Directory, etc.

SunRPC Inspection DoS Vulnerabilities
+------------------------------------

Administrators can mitigate this vulnerability by disabling SunRPC
inspection if it is not required. Administrators can disable SunRPC
inspection by issuing the "no inspect sunrpc" command in class
configuration sub-mode in the policy map configuration. Disabling
SunRPC inspection may cause SunRPC traffic to stop through the security
appliance.

ILS Inspection DoS Vulnerability
+-------------------------------

Administrators can mitigate this vulnerability by disabling ILS
inspection if it is not required. Administrators can disable
ILS inspection by issuing the "no inspect ils" command in class
configuration sub-mode in the policy map configuration. Disabling ILS
inspection may cause ILS traffic to stop through the security appliance.

Obtaining Fixed Software
========================

Cisco has released free software updates that address these
vulnerabilities. Prior to deploying software, customers should
consult their maintenance provider or check the software for feature
set compatibility and known issues specific to their environment.

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

Customers using Third Party Support Organizations
+------------------------------------------------

Customers whose Cisco products 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 support organization for guidance and assistance
with the appropriate course of action in regards to this advisory.

The effectiveness of any workaround or fix is dependent on specific
customer situations, such as product mix, network topology, traffic
behavior, and organizational mission. Due to the variety of affected
products and releases, customers should consult with their service
provider or support organization to ensure any applied workaround or
fix is the most appropriate for use in the intended network before it
is deployed.

Customers without Service Contracts
+----------------------------------

Customers who purchase direct from Cisco but do not hold a Cisco
service contract, and customers who purchase through third-party
vendors but are unsuccessful in obtaining fixed software through
their point of sale should acquire upgrades by contacting the Cisco
Technical Assistance Center (TAC). TAC contacts are as follows.

  * +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 their product serial number available and be
prepared to give the URL of this notice as evidence of entitlement to
a free upgrade. Free upgrades for non-contract customers must be
requested through the TAC.

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

Exploitation and Public Announcements
=====================================

The Cisco PSIRT is not aware of any public announcements or malicious
use of the vulnerabilities described in this advisory.

All the DoS vulnerabilities were discovered during internal testing.

The TACACS+ authentication vulnerability was found during the
troubleshooting of a customer service request.

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's worldwide website at:

http://www.cisco.com/warp/public/707/cisco-sa-20111005-asa.shtml

In addition to worldwide web posting, a text version of this notice
is clear-signed with the Cisco PSIRT PGP key and is posted to the
following e-mail and Usenet news recipients.

  * 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
  * comp.dcom.sys.cisco () newsgate cisco com

Future updates of this advisory, if any, will be placed on Cisco's
worldwide website, but may or may not be actively announced on
mailing lists or newsgroups. Users concerned about this problem are
encouraged to check the above URL for any updates.

Revision History
================

+------------------------------------------------------------+
| Revision 1.0 | 2011-October-05  | Initial public release.  |
+------------------------------------------------------------+

Cisco Security Procedures
=========================

Complete information on reporting security vulnerabilities
in Cisco products, obtaining assistance with security
incidents, and registering to receive security information
from Cisco, is available on Cisco's worldwide website at
http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html.
This includes instructions for press inquiries regarding
Cisco security notices. All Cisco security advisories are available at
http://www.cisco.com/go/psirt.

+--------------------------------------------------------------------
Copyright 2010-2011 Cisco Systems, Inc. All rights reserved.
+--------------------------------------------------------------------

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