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Cisco Security Advisory: Multiple Vulnerabilities Found by PROTOS IPSec Test
Suite
Advisory ID: 68158
http://www.cisco.com/warp/public/707/cisco-sa-20051114-ipsec.shtml
Revision 1.0
For Public Release 2005 November 14 1100 GMT (UTC)
- ---------------------------------------------------------------------------
Contents
========
Summary
Affected Products
Details
Impact
Software Versions and Fixes
Workarounds
Obtaining Fixed Software
Exploitation and Public Announcements
Status of This Notice: FINAL
Distribution
Revision History
Cisco Security Procedures
- ---------------------------------------------------------------------------
Summary
=======
Multiple Cisco products contain vulnerabilities in the processing of IPSec IKE
(Internet Key Exchange) messages. These vulnerabilities were identified by the
University of Oulu Secure Programming Group (OUSPG) "PROTOS" Test Suite for
IPSec and can be repeatedly exploited to produce a denial of service.
Cisco has made free software available to address this vulnerability for
affected customers. 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.
This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20051114-ipsec.shtml.
Affected Products
=================
Vulnerable Products
+------------------
Cisco devices running affected versions of software and configured for IKE are
vulnerable. This vulnerability is not dependent on a specific hardware
configuration. For example, the Cisco VPNSM or VPN SPA are not required for the
device to be vulnerable.
* Cisco IOS versions based on 12.2SXD, 12.3T, 12.4 and 12.4T
* Cisco PIX Firewall versions up to but not including 6.3(5)
* Cisco PIX Firewall/ASA versions up to but not including 7.0.1.4
* Cisco Firewall Services Module (FWSM) versions up to but not
including 2.3(3)
* Cisco VPN 3000 Series Concentrators versions up to but not including
4.1(7)H and 4.7(2)B
* Cisco MDS Series SanOS versions up to but not including 2.1(2)
To determine the software running on a Cisco IOS product, log in to the device
and issue the show version command to display the system banner. Cisco IOS
software will identify itself as "Internetwork Operating System Software" or
simply "IOS." On the next line of output, the image name will be displayed
between parentheses, followed by "Version" and the Cisco IOS release name.
Other Cisco devices will not have the show version command, or will give
different output.
The following example identifies a Cisco 7200 router running Cisco IOS release
12.3(10a) with an installed image name of C7200-JO3S-M.
Router# show version
Cisco Internetwork Operating System Software
IOS (tm) 7200 Software (C7200-JO3S-M), Version 12.3(10a), RELEASE SOFTWARE (fc2)
Copyright (c) 1986-2004 by cisco Systems, Inc.
Additional information about Cisco IOS release naming can be found at
http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_white_paper09186a008018305e.shtml.
Only Cisco IOS images that contain the Crypto Feature Set contain the
vulnerable IPSec code. Customers that are not running an IOS image with crypto
support are not exposed to this vulnerability.
Cisco IOS feature set naming indicates that IOS images with crypto support will
have 'K8' or 'K9' in the feature designator field.
For example, the image in the example above, C7200-JO3S-M, does not contain
'K8' or 'K9.' This indicates that this image does not support crypto, and is
therefore not vulnerable to the issues described in this Security Advisory.
The following output was taken from a device that is running an IOS image with
crypto support:
Cisco Internetwork Operating System Software
IOS (tm) c6sup2_rp Software (c6sup2_rp-PK9S-M), Version 12.2(18)SXD5, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by cisco Systems, Inc.
Compiled Fri 13-May-05 21:12 by ssearch
Since the feature set designator (PK9S) contains 'K9', we can quickly determine
that this feature set contains crypto support.
Products Confirmed Not Vulnerable
+--------------------------------
No other IOS trains are known to be affected.
Cisco IOS XR is not affected.
No other Cisco products are currently known to be affected by these
vulnerabilities.
Details
=======
IP Security, or IPSec, is a set of protocols standardized by the IETF to
support encrypted and/or authenticated transmission of IP packets. IPSec is a
protocol commonly used in Virtual Private Networks (VPNs).
The Internet Key Exchange (IKE) protocol is used to negotiate keying material
for IPSec Security Associations (SAs) and provides authentication of peers.
For more complete information on IPSec, consult IETF Request For Comments
(RFCs) 2401:
http://www.ietf.org/rfc/rfc2401.txt
For more complete information on IKE, consult IETF Request For Comments (RFCs)
2408 and 2409:
http://www.ietf.org/rfc/rfc2408.txt
http://www.ietf.org/rfc/rfc2409.txt
IPSec is used in two general cases.
The first case is LAN-to-LAN VPN operation in which two devices negotiate an
IPSec connection between them for the purposes of connecting two remote LANs
via an IPSec tunnel. In this case the devices negotiating the IPSec connection
generally have static IP addresses, and the IPSec tunnel is up as long as there
is traffic that needs to traverse the tunnel.
The second case is a Remote Access (RA) VPN which is typically used to allow
remote clients a connection to a secure network or service. A common example of
this is a user connecting to a corporate network while away from the office. In
this scenario, the remote user could be connecting from anywhere, and their IP
address is not static, but rather dynamically assigned via the transport
provider.
IKE is not a requirement for the establishment of IPSec connections. Depending
on your requirements and the devices involved, it may be possible to statically
configure the SA information and disable IKE. This type of configuration may
not be possible in the case of RA VPNs due to the user's IP address being
unknown prior to the establishment of the IPSec connection. See the Workarounds
Section for more information.
The PROTOS test suite for IPSec is designed to test the design limits of IPSec
implementations by sending malformed IKE messages to the target device.
When receiving certain malformed packets, vulnerable Cisco devices may reset,
causing a temporary Denial of Service (DoS).
The vulnerabilities identified can be easily and repeatedly reproduced with the
use of the OUSPG "PROTOS" Test Suite for IKE. This suite is designed to test
the design limits of implementations that process IKE messages.
Additional Details for Cisco IOS
+-------------------------------
The vulnerabilities addressed by this Advisory were introduced in IOS version
12.3(11)T and are present in versions of 12.3T, 12.4, 12.4T and 12.2SXD.
Prior to IOS version 12.3(8)T, IKE was enabled by default, with no crypto
configuration needed for the IOS device to process IKE messages.
As of IOS version 12.3(8)T (which includes all 12.4-based versions), crypto
configuration is required to enable IKE message processing.
In order for an IOS device to process IKE packets, a crypto map must be
configured and applied to an interface.
Additional Details for Cisco PIX
+-------------------------------
The Cisco PIX does not enable IKE processing by default in any versions of
software.
For Cisco PIX versions prior to 7.0, use the following to determine if IKE
message processing is enabled:
show isakmp enable
The following example shows the output when IKE is enabled on the outside
interface:
pixfirewall(config)# show isakmp enable
isakmp enable outside
The following example shows the output when IKE is not enabled on any
interface:
pixfirewall(config)# show isakmp
enable pixfirewall(config)#
For Cisco PIX/ASA versions 7.0 and later, IKE is enabled only if the following
command is in the device configuration:
isakmp enable
Cisco Bug IDs
+------------
Below are the Cisco bug IDs and their corresponding product(s):
* Cisco IOS versions based on 12.2SX, 12.3T, 12.4 and 12.4T - CSCed94829
* Cisco PIX Firewall versions up to but not including 6.3(5) - CSCei14171
* Cisco PIX Firewall/ASA versions up to but not including 7.0.1.4 -
CSCei15053
* Cisco Firewall Services Module (FWSM) versions up to but not including
2.3(3) - CSCei19275
* Cisco VPN 3000 Series Concentrators versions up to but not including
4.1(7)H and 4.7(2)B - CSCsb15296
* Cisco MDS Series SanOS versions up to but not including 2.1(2)
CSCei46258
Impact
======
Successful exploitation of the vulnerability on the Cisco MDS Series may result
in the restart of the IKE process. All other Cisco MDS device operations will
continue normally.
Successful exploitation of the vulnerabilities on all other Cisco devices may
result in the restart of the device. The device will return to normal operation
without any intervention required.
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.
Non-IOS Products
+---------------
+---------------------------------------------+
| Affected Product | Vulnerable | Fixed |
| | Version | Version |
|--------------------+--------------+---------|
| | Up to, but | 6.3(5) |
| Cisco PIX running | not | or |
| pre-7.0 code | including, | later |
| | 6.3(5) | |
|--------------------+--------------+---------|
| Cisco PIX/ASA | | |
| running 7.0 or | 7.0.1.4 | 7.0.1.4 |
| later code | | |
|--------------------+--------------+---------|
| Cisco FWSM for | Up to, but | 2.3(3) |
| Catalyst 6500 or | not | or |
| 7600 | including, | later |
| | 2.3(3) | |
|--------------------+--------------+---------|
| Cisco VPN3000 | | |
| Concentrators | 4.1(7)H | 4.1(7)H |
| running pre 4.7 | | |
| code | | |
|--------------------+--------------+---------|
| Cisco VPN3000 | Up to, but | 4.7(2)B |
| Concentrators | not | or |
| running 4.7 code | including, | later |
| | 4.7(2)B | |
|--------------------+--------------+---------|
| | Up to, but | 2.1(2) |
| Cisco MDS devices | not | or |
| | including, | later |
| | 2.1(2) | |
+---------------------------------------------+
Cisco IOS
+--------
Each row of the Cisco IOS software table (below) describes a release train and
the platforms or products for which it is intended. If a given release train is
vulnerable, then the earliest possible releases that contain the fix (the
"First Fixed Release") and the anticipated date of availability for each are
listed in the "Rebuild" and "Maintenance" columns. 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. The release should be
upgraded at least to the indicated release or a later version (greater than or
equal to the First Fixed Release label).
For further information on the terms "Rebuild" and "Maintenance, " please
consult the following URL: http://www.cisco.com/warp/public/620/1.html
For Cisco IOS, the vulnerabilities were introduced with 12.3(11)T and 12.2(18)
SXD. Previous versions of Cisco IOS are not affected.
+---------------------------------------------+
| Major | Availability of Repaired |
| Release | Releases |
|------------+--------------------------------|
| Affected | | |
| 12.2-Based | Rebuild | Maintenance |
| Release | | |
|------------+------------------+-------------|
| | 12.2(18)SXD7; | |
| | available End of | |
| 12.2SXD | Dec, 2005 | |
| |------------------+-------------|
| | | Migrate to |
| | | 12.2(18)SXE |
|------------+------------------+-------------|
| Affected | | |
| 12.3-Based | Rebuild | Maintenance |
| Release | | |
|------------+------------------+-------------|
| | 12.3(11)T9; | |
| | available | |
| 12.3T | 12-Dec-05 | |
| |------------------| |
| | 12.3(14)T5 | |
|------------+------------------+-------------|
| 12.3YF | Vulnerable; | |
| | contact TAC | |
|------------+------------------+-------------|
| | Vulnerable; | |
| 12.3YK | migrate to 12.4 | |
| | (4)T | |
|------------+------------------+-------------|
| 12.3YM | 12.3(14)YM4 | |
|------------+------------------+-------------|
| 12.3YQ | 12.3(14)YQ4; | |
| | available TBD | |
|------------+------------------+-------------|
| 12.3YS | Vulnerable; | |
| | contact TAC | |
|------------+------------------+-------------|
| | Vulnerable; | |
| 12.3YT | migrate to 12.4 | |
| | (4)T | |
|------------+------------------+-------------|
| 12.3YU | Vulnerable; | |
| | contact TAC | |
|------------+------------------+-------------|
| 12.3YX | Vulnerable; | |
| | contact TAC | |
|------------+------------------+-------------|
| Affected | | |
| 12.4-Based | Rebuild | Maintenance |
| Release | | |
|------------+------------------+-------------|
| | 12.4(1c); | |
| | available | |
| | 14-Nov-05 | |
|12.4 |------------------+-------------|
| | 12.4(3b); | |
| | available | 12.4(5) |
| | 15-Nov-05 | |
|------------+------------------+-------------|
| | 12.4(2)T2 | |
|12.4T |------------------+-------------|
| | | 12.4(4)T |
|------------+------------------+-------------|
| 12.4XA | Vulnerable; | |
| | contact TAC | |
|------------+------------------+-------------|
| | | 12.4(2)XB; |
| 12.4XB | | available |
| | | TBD |
+---------------------------------------------+
Workarounds
===========
The effectiveness of any workaround 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 is the most appropriate for use in the intended
network before it is deployed.
For customers that use IPSec, but do not require IKE for connection
establishment, IPSec connection information may be able to be entered manually,
and IKE can be disabled, eliminating the exposure.
Note: Due to the potential complexity of configuring IPSec information, this is
likely not a viable alternative for most customers, but is mentioned here for
completeness. Please consult your product documentation for further information
on static IPSec configuration.
Restricting IKE Messages
+-----------------------
It is possible to mitigate the effects of this vulnerability by restricting the
devices that can send IKE traffic to your IPSec devices. Due to the potential
for IKE traffic to come from a spoofed source address, a combination of Access
Control Lists (ACLs) and anti-spoofing mechanisms will be most effective.
Anti-spoofing
+------------
The Unicast Reverse Path Forwarding (Unicast RPF) feature helps to mitigate
problems that are caused by spoofed IP source addresses. It is available on
Cisco routers and firewalls. For further details, please refer to:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fsecur_c/fothersf/scfrpf.htm
By enabling Unicast Reverse Path Forwarding (uRPF), all spoofed packets will be
dropped at the first device. To enable uRPF, use the following commands.
router(config)# ip cef
router(config)# interface <interface #>
router(config-if)# ip verify unicast reverse-path
Infrastructure Access Control Lists
+----------------------------------
Although it is often difficult to block traffic transiting your network, it is
possible to identify traffic which should never be allowed to target your
infrastructure devices and block that traffic at the border of your network.
Infrastructure ACLs are considered a network security best practice and should
be considered as a long-term addition to good network security as well as a
workaround for this specific vulnerability. The white paper "Protecting Your
Core: Infrastructure Protection Access Control Lists" presents guidelines and
recommended deployment techniques for infrastructure protection ACLs:
http://www.cisco.com/warp/public/707/iacl.html.
Obtaining Fixed Software
========================
Cisco has made free software available to address this vulnerability for
affected customers. 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/public/sw-license-agreement.html,
or as otherwise set forth at Cisco.com Downloads at
http://www.cisco.com/public/sw-center/sw-usingswc.shtml.
Do not contact either "psirt@private" or "security-alert@private" 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 agreement 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 who do not hold a Cisco service
contract and customers who purchase through third-party vendors but are
unsuccessful at obtaining fixed software through their point of sale should get
their 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@private
Have your product serial number available and give the URL of this notice as
evidence of your entitlement to a free upgrade. Free upgrades for non-contract
customers must be requested through the TAC.
Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for
additional TAC contact information, including special localized telephone
numbers and instructions and e-mail addresses for use in various languages.
Exploitation and Public Announcements
=====================================
The OUSPG Test Suite for IPSec can be used to trigger these vulnerabilities.
These vulnerabilities were discovered in cooperation with CERT-FI and NISCC.
For their release information, please see
http://www.niscc.gov.uk/niscc/vulnAdv-en.html.
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-20051114-ipsec.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@private
* first-teams@private
* bugtraq@private
* vulnwatch@private
* cisco@private
* cisco-nsp@private
* full-disclosure@private
* comp.dcom.sys.cisco@private
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 | 14-November-2005 | 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.
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