Cisco Security Advisory: Cisco IOS Software Crafted Encryption Packet Denial of Service Vulnerability

23 Sep 2009

Cisco IOS� Software contains a vulnerability that could allow an
attacker to cause a Cisco IOS device to reload by remotely sending a
crafted encryption packet.

Cisco has released free software updates that address this
vulnerability.

This advisory is posted at:

http://www.cisco.com/warp/public/707/cisco-sa-20090923-tls.shtml

Note: The September 23, 2009, Cisco IOS Security Advisory bundled
publication includes eleven Security Advisories. Ten of the
advisories address vulnerabilities in Cisco IOS Software, and one
advisory addresses a vulnerability in Cisco Unified Communications
Manager. Each advisory lists the releases that correct the
vulnerability or vulnerabilities detailed in the advisory. The
following table lists releases that correct all Cisco IOS Software
vulnerabilities that have been published on September 23, 2009, or
earlier.

http://www.cisco.com/warp/public/707/cisco-sa-20090923-bundle.shtml

Individual publication links are in "Cisco Event Response: Semiannual
Cisco IOS Software Advisory Bundled Publication" at the following
link:

http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep09.html

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

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

Devices running affected versions of Cisco IOS Software are
susceptible if configured with any of the following features:

  * Secure Socket Layer (SSL) Virtual Private Network (VPN)
  * Secure Shell (SSH)
  * Internet Key Exchange (IKE) Encrypted Nonces

Note: Other SSL/HTTPS related features than WebVPN and SSL VPN are
not affected by this vulnerability.

To determine whether SSLVPN is enabled on a device, log in to the
device and issue the command-line interface (CLI) command "show
running-config | include webvpn". If the device returns any output
then SSLVPN is configured and the device may be vulnerable.
Vulnerable configurations vary depending on whether the device is
supporting Cisco IOS WebVPN (introduced in Release 12.3(14)T) or
Cisco IOS SSLVPNs (introduced in Release 12.4(6)T). The following
methods describe how to confirm if the device is vulnerable:

If the output from "show running-config | include webvpn" contains
"webvpn enable" then the device is configured with the original Cisco
IOS WebVPN. The only way to determine whether the device is
vulnerable is to examine the output of "show running-config" to
confirm that webvpn is enabled via the command "webvpn enable" and
that a "ssl trustpoint" has been configured. The following example
shows a vulnerable device configured with Cisco IOS WebVPN:

    webvpn enable
    !
    webvpn
     ssl trustpoint TP-self-signed-29742012

If the output from "show running-config | include webvpn" contains
"webvpn gateway <word>" then the device is supporting the Cisco IOS
SSLVPN feature. A device is vulnerable if it has the "inservice"
command in at least one of the "webvpn gateway" sections. The
following example shows a vulnerable device configured with Cisco IOS
SSLVPN:

    Router# show running | section webvpn        
    webvpn gateway Gateway
     ip address 10.1.1.1 port 443  
     ssl trustpoint Gateway-TP
     inservice
     !
    Router#

A device that supports the Cisco IOS SSLVPN is not vulnerable if it
has no "webvpn gateways" configured or all the configured "webvpn
gateways" contain the "no inservice" webvpn gateway command.

To determine if SSH is enabled use the "show ip ssh" command, as shown
in the following example:

    Router#show ip ssh 
    SSH Enabled - version 1.99
    Authentication timeout: 120 secs; Authentication retries: 3
    Minimum expected Diffie Hellman key size : 1024 bits

To determine if the IKE encrypted nonces feature is enabled, use the 
"show running-config | include rsa-encr" command as follows:

    Router#show running-config | inc rsa-encr
     authentication rsa-encr

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 12.3(26) with an installed image name of
C2500-IS-L:

    Router#show version
    Cisco Internetwork Operating System Software
    IOS (tm) 2500 Software (C2500-IS-L), Version 12.3(26), RELEASE SOFTWARE (fc2)
    Technical Support: http://www.cisco.com/techsupport
    Copyright (c) 1986-2008 by cisco Systems, Inc.
    Compiled Mon 17-Mar-08 14:39 by dchih

    !--- output truncated

The following example identifies a Cisco product that is running
Cisco IOS Software Release 12.4(20)T with an installed image name of
C1841-ADVENTERPRISEK9-M:

    Router#show version
    Cisco IOS Software, 1841 Software (C1841-ADVENTERPRISEK9-M), Version 12.4(20)T, RELEASE SOFTWARE (fc3)
    Technical Support: http://www.cisco.com/techsupport
    Copyright (c) 1986-2008 by Cisco Systems, Inc.
    Compiled Thu 10-Jul-08 20:25 by prod_rel_team

    !--- output truncated

Additional information about Cisco IOS Software release naming
conventions is available in "White Paper: Cisco IOS Reference Guide"
at the following link:

http://www.cisco.com/warp/public/620/1.html

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

The Cisco ASA 5500 Series Adaptive Security Appliances are not
affected by this vulnerability.

Cisco IOS XR Software is not affected by this vulnerability.

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

Details
=======

A Cisco IOS device that is configured for SSLVPN or SSH may reload
when it receives a specially crafted TCP packet on TCP port 443
(SSLVPN) or TCP port 22 (SSH). Completion of the three-way handshake
to the associated TCP port number of these features is required for
the vulnerability to be successfully exploited; however,
authentication is not required. A Cisco IOS device that is configured
for IKE encrypted nonces may reload when it receives a specially
crafted UDP packet on port 500 or 4500 (if configured for NAT
Traversal (NAT-T)).

This vulnerability is documented in Cisco bug ID CSCsq24002 and has
been assigned the Common Vulnerabilities and Exposures (CVE) identifier
CVE-2009-2871.

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

Cisco has provided scores for the vulnerability 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

CSCsq24002 - Crafted Encrypted packet may cause device reload

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 vulnerability described in this
document may result in a reload of the device. The issue could be
repeatedly exploited to cause an extended 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.

Each row of the Cisco IOS software table (below) names a Cisco IOS
release train. If a given release train is vulnerable, then the
earliest possible releases that contain the fix (along with the
anticipated date of availability for each, if applicable) are listed
in the "First Fixed Release" column of the table. The "Recommended
Release" column indicates the releases which have fixes for all the
published vulnerabilities at the time of this Advisory. A device
running a release in the given train that is earlier than the release
in a specific column (less than the First Fixed Release) is known to
be vulnerable. Cisco recommends upgrading to a release equal to or
later than the release in the "Recommended Releases" column of the
table.

+-------------------------------------------------------------------+
|   Major    |          Availability of Repaired Releases           |
|  Release   |                                                      |
|------------+------------------------------------------------------|
|  Affected  |                                        | Recommended |
| 12.0-Based |          First Fixed Release           |   Release   |
|  Releases  |                                        |             |
|-------------------------------------------------------------------|
| There are no affected 12.0 based releases.                        |
|-------------------------------------------------------------------|
|  Affected  |                                        | Recommended |
| 12.1-Based |          First Fixed Release           |   Release   |
|  Releases  |                                        |             |
|-------------------------------------------------------------------|
| There are no affected 12.1 based releases.                        |
|-------------------------------------------------------------------|
|  Affected  |                                        | Recommended |
| 12.2-Based |          First Fixed Release           |   Release   |
|  Releases  |                                        |             |
|------------+----------------------------------------+-------------|
| 12.2       | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2B      | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2BC     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2BW     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2BX     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2BY     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2BZ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2CX     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2CY     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2CZ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2DA     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2DD     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2DX     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2EW     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2EWA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2EX     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2EY     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2EZ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2FX     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2FY     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2FZ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IRA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IRB    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IRC    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IXA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IXB    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IXC    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IXD    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IXE    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IXF    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IXG    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2IXH    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2JA     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2JK     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2MB     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2MC     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2S      | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SB     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SBC    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SCA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SCB    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SE     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SEA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SEB    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SEC    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SED    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SEE    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SEF    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SEG    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SG     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SGA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SL     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SM     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SO     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SQ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SRA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SRB    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SRC    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SRD    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2STE    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SU     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SV     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SVA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SVC    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SVD    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SVE    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SW     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SX     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SXA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SXB    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SXD    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SXE    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SXF    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SXH    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SXI    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SY     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2SZ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2T      | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2TPC    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XA     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XB     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XC     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XD     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XE     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XF     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XG     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XH     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XI     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XJ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XK     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XL     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XM     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XNA    | Please see Cisco IOS-XE Software       |             |
|            | Availability                           |             |
|------------+----------------------------------------+-------------|
| 12.2XNB    | Please see Cisco IOS-XE Software       |             |
|            | Availability                           |             |
|------------+----------------------------------------+-------------|
| 12.2XNC    | Please see Cisco IOS-XE Software       |             |
|            | Availability                           |             |
|------------+----------------------------------------+-------------|
| 12.2XND    | Please see Cisco IOS-XE Software       |             |
|            | Availability                           |             |
|------------+----------------------------------------+-------------|
| 12.2XO     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XQ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XR     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XS     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XT     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XU     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XV     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2XW     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YA     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YB     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YC     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YD     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YE     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YF     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YG     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YH     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YJ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YK     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YL     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YM     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YN     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YO     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YP     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YQ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YR     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YS     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YT     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YU     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YV     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YW     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YX     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YY     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2YZ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZA     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZB     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZC     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZD     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZE     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZF     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZG     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZH     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZJ     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZL     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZP     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZU     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZX     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZY     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.2ZYA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
|  Affected  |                                        | Recommended |
| 12.3-Based |          First Fixed Release           |   Release   |
|  Releases  |                                        |             |
|-------------------------------------------------------------------|
| There are no affected 12.3 based releases.                        |
|-------------------------------------------------------------------|
|  Affected  |                                        | Recommended |
| 12.4-Based |          First Fixed Release           |   Release   |
|  Releases  |                                        |             |
|------------+----------------------------------------+-------------|
| 12.4       | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4GC     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4JA     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4JDA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4JDC    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4JDD    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4JK     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4JL     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4JMA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4JMB    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4JX     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4MD     | 12.4(15)MD3                            | 12.4(15)MD3 |
|------------+----------------------------------------+-------------|
| 12.4MDA    | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4MR     | 12.4(19)MR3                            | 12.4(19)MR3 |
|------------+----------------------------------------+-------------|
|            |                                        | 12.4(15)T10 |
| 12.4SW     | Vulnerable; first fixed in 12.4T       |             |
|            |                                        | 12.4(20)T4  |
|------------+----------------------------------------+-------------|
|            | 12.4(22)T2                             |             |
|            |                                        | 12.4(15)T10 |
| 12.4T      | 12.4(20)T3                             |             |
|            |                                        | 12.4(20)T4  |
|            | 12.4(24)T                              |             |
|------------+----------------------------------------+-------------|
| 12.4XA     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4XB     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4XC     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4XD     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4XE     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
|            |                                        | 12.4(15)T10 |
| 12.4XF     | Vulnerable; first fixed in 12.4T       |             |
|            |                                        | 12.4(20)T4  |
|------------+----------------------------------------+-------------|
| 12.4XG     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
|            |                                        | 12.4(15)T10 |
| 12.4XJ     | Vulnerable; first fixed in 12.4T       |             |
|            |                                        | 12.4(20)T4  |
|------------+----------------------------------------+-------------|
|            |                                        | 12.4(15)T10 |
| 12.4XK     | Vulnerable; first fixed in 12.4T       |             |
|            |                                        | 12.4(20)T4  |
|------------+----------------------------------------+-------------|
| 12.4XL     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4XM     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4XN     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4XP     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4XQ     | 12.4(15)XQ3                            | 12.4(15)T10 |
|------------+----------------------------------------+-------------|
|            |                                        | 12.4(15)XR7 |
| 12.4XR     | 12.4(15)XR5                            |             |
|            |                                        | 12.4(22)XR  |
|------------+----------------------------------------+-------------|
| 12.4XT     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
|            | Vulnerable; Contact your support       |             |
| 12.4XV     | organization per the instructions in   |             |
|            | Obtaining Fixed Software section of    |             |
|            | this advisory                          |             |
|------------+----------------------------------------+-------------|
|            |                                        | 12.4(15)T10 |
| 12.4XW     | Vulnerable; first fixed in 12.4T       |             |
|            |                                        | 12.4(20)T4  |
|------------+----------------------------------------+-------------|
|            |                                        | 12.4(15)T10 |
| 12.4XY     | Vulnerable; first fixed in 12.4T       |             |
|            |                                        | 12.4(20)T4  |
|------------+----------------------------------------+-------------|
|            |                                        | 12.4(15)T10 |
| 12.4XZ     | Vulnerable; first fixed in 12.4T       |             |
|            |                                        | 12.4(20)T4  |
|------------+----------------------------------------+-------------|
|            |                                        | 12.4(15)T10 |
| 12.4YA     | Vulnerable; first fixed in 12.4T       |             |
|            |                                        | 12.4(20)T4  |
|------------+----------------------------------------+-------------|
| 12.4YB     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4YD     | Not Vulnerable                         |             |
|------------+----------------------------------------+-------------|
| 12.4YE     | Not Vulnerable                         |             |
+-------------------------------------------------------------------+

Note: No Cisco IOS Software Modularity releases are affected by this
vulnerability.

Cisco IOS XE Software

+-------------------------------------------------------------------+
|       IOS XE Release       |         First Fixed Release          |
|----------------------------+--------------------------------------|
| 2.1.x                      | Not Vulnerable                       |
|----------------------------+--------------------------------------|
| 2.2.x                      | Not Vulnerable                       |
|----------------------------+--------------------------------------|
| 2.3.x                      | 2.3.2                                |
|----------------------------+--------------------------------------|
| 2.4.x                      | Not Vulnerable                       |
+-------------------------------------------------------------------+

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

There are no available workarounds other than disabling the affected
features and protecting SSH access with the use of VTY access control
lists.

Use the "no webvpn enable" command to disable SSL VPN use.

For Cisco IOS the SSH server can be disabled by applying the command 
"crypto key zeroize rsa" while in configuration mode. The SSH server is
enabled automatically upon generating an RSA key pair. Zeroing the
RSA keys is the only way to completely disable the SSH server.

Access to the SSH server on Cisco IOS Software may also be disabled
by removing SSH as a valid transport protocol. This action can be
done by reapplying the transport input command with 'ssh' removed
from the list of permitted transports on vty lines while in
configuration mode. For example:

    line vty 0 4                                                                    
          transport input telnet                                                        
        end

If SSH server functionality is desired, access to the server can be
restricted to specific source IP addresses or blocked entirely
through the use of Access Control Lists (ACLs) on the vty lines as
shown in the following URL:

http://www.cisco.com/en/US/docs/switches/lan/catalyst2950/software/release/1...

More information on configuring ACLs can be found on Cisco's public
website:

http://www.cisco.com/en/US/products/sw/secursw/ps1018/products_tech_note0918...

The following is an example of a vty access-list:

    access-list 2 permit 10.1.1.0 0.0.0.255
    access-list 2 deny any

    line vty 0 4
     access-class 2 in

In the previous example, only the 10.1.1.0/24 network is allowed to
SSH to the Cisco IOS device.

To disable IKE encrypted nonces use the "no authentication rsa-encr"
command under an ISAKMP policy, as shown in the following example:

    crypto isakmp policy
     no authentication rsa-encr

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 vulnerability described in this advisory.

This vulnerability was 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's worldwide website at:

http://www.cisco.com/warp/public/707/cisco-sa-20090923-tls.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 |                   | Initial |
| 1.0      | 2009-September-23 | 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.h...

This includes instructions for press inquiries regarding Cisco security
notices. All Cisco security advisories are available at:

http://www.cisco.com/go/psirt
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Cisco Security Advisory: Cisco IOS Software Crafted Encryption Packet Denial of Service Vulnerability

Cisco Systems Product Security Incident Response Team