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Cisco Security Advisory: Multiple Vulnerabilities in Cisco PIX and Cisco ASA
From: Cisco Systems Product Security Incident Response Team <psirt () cisco com>
Date: Wed, 22 Oct 2008 11:45:17 -0400

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Cisco Security Advisory: Multiple Vulnerabilities in Cisco PIX and
Cisco ASA

Advisory ID: cisco-sa-20081022-asa

http://www.cisco.com/warp/public/707/cisco-sa-20081022-asa.shtml

Revision 1.0

For Public Release 2008 October 22 1600 UTC (GMT)

Summary
=======

Multiple vulnerabilities exist in the Cisco ASA 5500 Series Adaptive
Security Appliances and Cisco PIX Security Appliances. This security
advisory outlines details of these vulnerabilities:

  * Windows NT Domain Authentication Bypass Vulnerability
  * IPv6 Denial of Service Vulnerability
  * Crypto Accelerator Memory Leak Vulnerability

Note: These vulnerabilities are independent of each other. A device may
be affected by one vulnerability and not affected by another.

Cisco has released free software updates that address these
vulnerabilities. Workarounds that mitigate some of these
vulnerabilities are available.

This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20081022-asa.shtml.

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

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

The following are the details about each vulnerability described within
this advisory.

Windows NT Domain Authentication Bypass Vulnerability
+----------------------------------------------------

Because of a Microsoft Windows NT Domain authentication issue the Cisco
ASA and Cisco PIX devices may be susceptible to a VPN authentication
bypass vulnerability. Cisco ASA or Cisco PIX security appliances that
are configured for IPSec or SSL-based remote access VPN using Microsoft
Windows NT Domain authentication may be vulnerable. Devices that are
using any other type of external authentication (that is, LDAP, RADIUS,
TACACS+, SDI, or local database) are not affected by this vulnerability.

The following example demonstrates how Windows NT domain authentication
is configured using the command line interface (CLI) on the Cisco ASA:

    aaa-server NTAuth protocol nt
     aaa-server NTAuth (inside) host 10.1.1.4
     nt-auth-domain-controller primary1

Alternatively, to see if a device is configured for Windows NT Domain
authentication use the
"show running-config | include nt-auth-domain-controller"
command.

IPv6 Denial of Service Vulnerability
+-----------------------------------

Cisco ASA and Cisco PIX security appliances that are running software
version 7.2(4)9 or 7.2(4)10 and configured for IPv6 may be vulnerable.
This vulnerability does not affect devices configured only for IPv4.

Note: IPv6 functionality is turned off by default.

IPv6 is enabled on the Cisco ASA and Cisco PIX security appliance
using the "ipv6 address" interface command. To verify if a device
is configured for IPv6 use the "show running-config | include ipv6"
command.

Alternatively, you can display the status of interfaces configured for
IPv6 using the show ipv6 interface command in privileged EXEC mode, as
shown in the following example:

    hostname# show ipv6 interface brief
    outside [up/up]
        unassigned
    inside [up/up]
        fe80::20d:29ff:fe1d:69f0
        fec0::a:0:0:a0a:a70
    dmz [up/up]
        unassigned

In this example, the "outside" and "dmz" interfaces are not configured
for IPv6.

Crypto Accelerator Memory Leak Vulnerability
+-------------------------------------------

Cisco ASA security appliances may experience a memory leak that can be
triggered by a series of crafted packets. This memory leak occurs in the
initialization code for the hardware crypto accelerator. Devices that
are running software versions in the 8.0.x release are vulnerable.

Note: Cisco ASA appliances that are running software versions in the
7.0, 7.1, and 7.2 releases are not vulnerable. The Cisco PIX security
appliance is not affected by this vulnerability.

Determination of Software Versions
+---------------------------------

The "show version" command-line interface (CLI) command can be used to
determine whether a vulnerable version of the Cisco PIX or Cisco ASA
software is running. The following example shows a Cisco ASA Security
Appliance that runs software release 8.0(4):

        ASA# show version

        Cisco Adaptive Security Appliance Software Version 8.0(4)
        Device Manager Version 6.0(1)

        [...]

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 ASDM
window.

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

The Cisco Firewall Services Module (FWSM) is not affected by any of
these vulnerabilities. Cisco PIX security appliances running versions
6.x are not vulnerable. No other Cisco products are currently known to
be affected by these vulnerabilities.

Details
=======

This Security Advisory describes multiple distinct vulnerabilities.
These vulnerabilities are independent of each other.

Windows NT Domain Authentication Bypass Vulnerability
+----------------------------------------------------

Because of a Microsoft Windows NT Domain authentication issue the Cisco
ASA and Cisco PIX devices may be susceptible to a VPN authentication
bypass vulnerability. Cisco ASA or Cisco PIX security appliances
configured for IPSec or SSL-based remote access VPN may be vulnerable.

Note: Cisco ASA or Cisco PIX security appliances that are configured for
IPSec or SSL-based remote access VPN using any other type of external
authentication (that is, LDAP, RADIUS, TACACS+, SDI, or local database)
are not affected by this vulnerability.

The Cisco ASA security appliance supports Microsoft Windows server
operating systems that support NTLM version 1, collectively referred to
as "NT servers". NT Domain authentication is supported only for remote
access VPNs.

This vulnerability is documented in Cisco Bug ID CSCsu65735 and has
been assigned Common Vulnerabilities and Exposures (CVE) identifiers
CVE-2008-3815.

IPv6 Denial of Service Vulnerability
+-----------------------------------

A specially crafted IPv6 packet may cause the Cisco ASA and Cisco PIX
security appliances to reload. Devices that are running software version
7.2(4)9 or 7.2(4)10 and configured for IPv6 may be vulnerable. This
vulnerability does not affect devices that are configured only for IPv4.

Note: Devices that are running software versions in the 7.0, 7.1, 8.0,
and 8.1 releases are not vulnerable.

To configure IPv6 on a Cisco ASA or Cisco PIX security appliance, at a
minimum, each interface needs to be configured with an IPv6 link-local
address. Additionally, you can add a global address to the interface.

Note: Only packets that are destined to the device (not transiting the
device) may trigger the effects of this vulnerability. These packets
must be destined to an interface configured for IPv6.

This vulnerability is documented in Cisco Bug ID CSCsu11575 and has
been assigned Common Vulnerabilities and Exposures (CVE) identifier
CVE-2008-3816.

Crypto Accelerator Memory Leak Vulnerability
+-------------------------------------------

The Cisco ASA security appliances may experience a memory leak triggered
by a series of packets. This memory leak occurs in the initialization
code for the hardware crypto accelerator.

Note: Only packets destined to the device (not transiting the device)
may trigger this vulnerability.

The following Cisco ASA features use the services the crypto accelerator
provides, and therefore may be affected by this vulnerability:

  * Clientless WebVPN, SSL VPN Client, and AnyConnect Connections
  * ASDM (HTTPS) Management Sessions
  * Cut-Through Proxy for Network Access
  * TLS Proxy for Encrypted Voice Inspection
  * IP Security (IPsec) Remote Access and Site-to-site VPNs
  * Secure Shell (SSH) Access

This vulnerability is documented in Cisco Bug ID CSCsj25896 and has
been assigned the Common Vulnerabilities and Exposures (CVE) identifier
CVE-2008-3817.

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

* Windows NT Domain Authentication Bypass Vulnerability (CSCsu65735)

CVSS Base Score - 4.3
    Access Vector -            Network
    Access Complexity -        Medium
    Authentication -           None
    Confidentiality Impact -   Partial
    Integrity Impact -         None
    Availability Impact -      None

CVSS Temporal Score - 3.7
    Exploitability -           High
    Remediation Level -        Official-Fix
    Report Confidence -        Confirmed

* Cisco ASA may reload after receiving certain IPv6 packets (CSCsu11575)

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

* Crypto Accelerator Memory Leak (CSCsj25896)

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 the VPN Authentication Bypass Vulnerability
may allow an attacker to successfully connect to the Cisco ASA via
remote access IPSec or SSL-based VPN. The Denial of Service (DoS)
vulnerabilities may cause a reload of the affected device. Repeated
exploitation could result in a sustained DoS condition.

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.

The following list contains the first fixed software release of each
vulnerability:

+----------------------------------------+
|                | Affected | First      |
| Vulnerability  | Release  | Fixed      |
|                |          | Version    |
|----------------+----------+------------|
|                | 7.0      | 7.0(8)3    |
|                |----------+------------|
| Windows NT     | 7.1      | 7.1(2)78   |
|Domain          |----------+------------|
| Authentication | 7.2      | 7.2(4)16   |
|Bypass          |----------+------------|
| Vulnerability  | 8.0      | 8.0(4)6    |
|                |----------+------------|
|                | 8.1      | 8.1(1)13   |
|----------------+----------+------------|
|                | 7.0      | Not        |
|                |          | Vulnerable |
|                |----------+------------|
|                | 7.1      | Not        |
|                |          | Vulnerable |
|IPv6 Denial of  |----------+------------|
| Service        | 7.2      | 7.2(4)11   |
|Vulnerability   |----------+------------|
|                | 8.0      | Not        |
|                |          | Vulnerable |
|                |----------+------------|
|                | 8.1      | Not        |
|                |          | Vulnerable |
|----------------+----------+------------|
|                | 7.0      | Not        |
|                |          | Vulnerable |
|                |----------+------------|
|                | 7.1      | Not        |
| Crypto         |          | Vulnerable |
|Accelerator     |----------+------------|
| Memory Leak    | 7.2      | Not        |
| Vulnerability  |          | Vulnerable |
|                |----------+------------|
|                | 8.0      | 8.0(4)     |
|                |----------+------------|
|                | 8.1      | 8.1(2)     |
+----------------------------------------+

The following maintenance software releases are the first software
releases that contain the fixes for the vulnerabilities mentioned in
this Security Advisory:

Fixed PIX software can be downloaded from:

http://www.cisco.com/pcgi-bin/tablebuild.pl/pix?psrtdcat20e2

Fix ASA software can be downloaded from:

http://www.cisco.com/pcgi-bin/tablebuild.pl/asa?psrtdcat20e2

For the "Windows NT Domain Authentication Bypass Vulnerability", only
interim fixed software is currently available. Customers wishing to
upgrade to a fixed version instead of applying a workaround may download
PIX and ASA interim versions from:

http://www.cisco.com/pcgi-bin/tablebuild.pl/PIXPSIRT?psrtdcat20e2

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

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

Windows NT Domain Authentication Bypass Vulnerability
+----------------------------------------------------

LDAP authentication is not affected by this vulnerability. As a
workaround, you can enable a different type of external authentication
for Remote Access VPN instead of Windows NT Domain authentication.

Note: For more information about support for a specific AAA server
type, refer to the following link:
http://www.cisco.com/en/US/docs/security/asa/asa80/configuration/guide/aaa.html#wp1069492

IPv6 Denial of Service Vulnerability
+-----------------------------------

Customers that do not require IPv6 functionality on their devices can
use the "no ipv6 address" interface sub-command to disable processing of
IPv6 packets and eliminate their exposure

Crypto Accelerator Memory Leak Vulnerability
+-------------------------------------------

There are no workarounds for this vulnerability.

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/products/prod_warranties_item09186a008088e31f.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.

These vulnerabilities were found during internal testing and during the
resolution of a technical support 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-20081022-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  | 2008-October-22  | 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 2007-2008 Cisco Systems, Inc. All rights reserved.
+--------------------------------------------------------------------

Updated: Oct 22, 2008                             Document ID: 108009

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