Cisco Security Advisory-
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 https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20051114-ipsec.
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This section provides details on 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.
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Cisco IOS versions based on 12.2SXD, 12.3T, 12.4 and
12.4T
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Cisco PIX Firewall versions up to but not including
6.3(5)
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Cisco PIX Firewall/ASA versions up to but not including
7.0.1.4
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Cisco Firewall Services Module (FWSM) versions up to but not
including 2.3(3)
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Cisco VPN 3000 Series Concentrators versions up to but not including
4.1(7)H and 4.7(2)B
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Cisco MDS Series SanOS versions up to but not including
2.1(2)
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Cisco Wireless LAN Controllers up to and including 3.2.78.0 with
Crypto Accelerator present.
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/warp/public/620/1.html.
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.
Cisco wireless LAN controllers without Crypto Accelerator present.
Cisco Catalyst 6500 Series Wireless Services Module.
Cisco Wireless LAN Controller Module for Integrated Services Routers.
No other Cisco products are currently known to be affected by these vulnerabilities.
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Cisco IOS versions based on 12.2SXD, 12.3T, 12.4 and
12.4T
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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(4)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.
12.2SXD versions of Cisco IOS have IKE enabled by default. To ensure that IKE processing is disabled, enter the global configuration command no crypto isakmp enable.
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 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
Additional Details for Cisco Wireless LAN controllers
The Cisco Wireless LAN controllers do not enable IKE message processing by default in any versions of software and requires a Crypto Accelerator card to be present in the controller to allow configuration of IPsec and IKE message processing.
To determine if IKE message processing is enabled from the CLI prompt issue the command:
show wlan <wlan identifier>
In a system where IKE message processing is enabled, IP Security field will be marked "Enabled" and IKE configuration information will be present in the show wlan <wlan ID> output.
The following example shows the output when IKE message processing is enabled on WLAN 1:
(WLC) >show wlan 1 WLAN Identifier.................................. 1 Network Name (SSID).............................. mobile Status........................................... Enabled MAC Filtering.................................... Disabled Broadcast SSID................................... Enabled AAA Policy Override.............................. Disabled Network Access Control........................... Disabled Number of Active Clients......................... 1 Exclusionlist Timeout............................ 60 seconds Session Timeout.................................. Infinity Interface........................................ management DHCP Server...................................... 10.1.1.3 DHCP Address Assignment Required................. Enabled Quality of Service............................... Silver (best effort) WMM.............................................. Disabled 802.11e.......................................... Disabled Dot11-Phone Mode (7920).......................... Disabled Wired Protocol................................... None IPv6 Support..................................... Disabled Radio Policy..................................... All Security 802.11 Authentication:........................ Open System Static WEP Keys............................... Disabled 802.1X........................................ Disabled Wi-Fi Protected Access (WPA1)................. Disabled Wi-Fi Protected Access v2 (WPA2).............. Disabled IP Security................................... Enabled Authentication:................................. HMAC-SHA-1 Encryption:..................................... 3DES AH:............................................. Disabled (not changeable) IKE Authentication:............................. Pre-Shared-Key Pre-Shared Key Length:..................... 8 bytes IKE Diffie Hellman Group:....................... DH Group 2 (1024 bits) IKE Phase 1 Mode:............................... Aggressive PFS Key Mode:................................... Disabled (not changeable) IKE Timeout:.................................... 57600 seconds IP Security Passthru.......................... Disabled L2TP.......................................... Disabled Web Based Authentication...................... Disabled Web-Passthrough............................... Disabled Auto Anchor................................... Disabled Cranite Passthru.............................. Disabled Fortress Passthru............................. DisabledIn a system where IKE message processing is not enabled, IP Security field will be marked "Disabled" and IKE configuration information will not be present in the show wlan <wlan ID> output.
The following example shows the output when IKE message processing is not enabled on any WLAN interface:
(WLC) >show wlan 1 WLAN Identifier.................................. 1 Network Name (SSID).............................. Airespace1 Status........................................... Disabled MAC Filtering.................................... Disabled Broadcast SSID................................... Enabled AAA Policy Override.............................. Disabled Network Access Control........................... Disabled Number of Active Clients......................... 0 Exclusionlist Timeout............................ 60 seconds Session Timeout.................................. 1800 seconds Interface........................................ management DHCP Server...................................... Default Quality of Service............................... Silver (best effort) WMM.............................................. Disabled 802.11e.......................................... Disabled Dot11-Phone Mode (7920).......................... Disabled Wired Protocol................................... None IPv6 Support..................................... Disabled Radio Policy..................................... All Security 802.11 Authentication:........................ Open System Static WEP Keys............................... Disabled 802.1X........................................ Enabled Encryption:..................................... 104-bit WEP Wi-Fi Protected Access (WPA1)................. Disabled Wi-Fi Protected Access v2 (WPA2).............. Disabled IP Security................................... Disabled IP Security Passthru.......................... Disabled L2TP.......................................... Disabled Web Based Authentication...................... Disabled Web-Passthrough............................... Disabled Auto Anchor................................... Disabled Cranite Passthru.............................. Disabled Fortress Passthru............................. DisabledCisco Bug IDs
Below are the Cisco bug IDs and their corresponding product(s):
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Cisco IOS versions based on 12.2SX, 12.3T, 12.4 and 12.4T -
CSCed94829
(
registered customers only)
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Cisco PIX Firewall versions up to but not including 6.3(5) -
CSCei14171
(
registered customers only)
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Cisco PIX Firewall/ASA versions up to but not including 7.0.1.4 -
CSCei15053
(
registered customers only)
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Cisco Firewall Services Module (FWSM) versions up to but not
including 2.3(3) -
CSCei19275
(
registered customers only)
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Cisco VPN 3000 Series Concentrators versions up to but not including
4.1(7)H and 4.7(2)B -
CSCsb15296
(
registered customers only)
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Cisco MDS Series SanOS versions up to but not including 2.1(2) -
CSCei46258
(
registered customers only)
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Cisco Wireless LAN controllers up to and including 3.2.78.0 -
CSCsc75655
(
registered customers only)
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Cisco IOS versions based on 12.2SX, 12.3T, 12.4 and 12.4T -
CSCed94829
(
registered customers only)
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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.
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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 Version
Fixed Version
Cisco PIX running pre-7.0 code
Up to, but not including, 6.3(5)
6.3(5) or later
Cisco PIX/ASA running 7.0 or later code
Up to, but not including 7.0.1.4
7.0.1.4 or later
Cisco FWSM for Catalyst 6500 or 7600
Up to, but not including, 2.3(3)
2.3(3) or later
Cisco VPN3000 Concentrators running pre 4.7 code
Up to, but not including, 4.1(7)H
4.1(7)H or later
Cisco VPN3000 Concentrators running 4.7 code
Up to, but not including, 4.7(2)B
4.7(2)B or later
Cisco MDS devices
Up to, but not including, 2.1(2)
2.1(2) or later
Cisco Wireless LAN controller
Up to, and including 3.2.78.0
Vulnerable, contact TAC
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(4)T and 12.2(18)SXD. Previous versions of Cisco IOS are not affected.
Major Release
Availability of Repaired Releases
Affected 12.2-Based Release
Rebuild
Maintenance
12.2SXD
12.2(18)SXD7; available 13-Dec-05
Affected 12.3-Based Release
Rebuild
Maintenance
12.3T
12.3(4)T12: Vulnerable; migrate to 12.4(5) or later
12.3(11)T9; available 27-Dec-05
12.3(14)T5
12.3TPC
Vulnerable; contact TAC
12.3XD
Vulnerable; migrate to 12.3(14)T5 or later
12.3XE
Vulnerable. For C820v and SOHO78, migrate to 12.4(5) or later. For all other platforms, contact TAC.
12.3XF
Vulnerable; migrate to 12.3(14)T5 or later
12.3XG
Vulnerable. For C828, C820v, and SOHO78, migrate to 12.4(5) or later. For all other platforms, contact TAC.
12.3XH
Vulnerable; contact TAC
12.3XI
Vulnerable; contact TAC
12.3XJ
Vulnerable: migrate to 12.3(14)YX; available 22-Dec-05
12.3XK
Vulnerable; contact TAC
12.3XM
Vulnerable; migrate to 12.3(14)T5 or later
12.3XQ
Vulnerable; migrate to 12.4(5) or later
12.3XR
Vulnerable. For C820v, C828, and SOHO78, migrate to 12.4(5) or later. For all other platforms, contact TAC.
12.3XS
Vulnerable; migrate to 12.4(5) or later
12.3XU
Vulnerable; migrate to 12.4(4)T or later
12.3XW
Vulnerable: migrate to 12.3(14)YX; available 22-Dec-05
12.3XX
Vulnerable; migrate to 12.4(5) or later
12.3YA
Vulnerable. For C828, migrate to 12.4(5) or later. For all other platforms, contact TAC.
12.3YD
Vulnerable; migrate to 12.4(4)T or later
12.3YF
Vulnerable: migrate to 12.3(14)YX; available 22-Dec-05
12.3YG
Vulnerable; contact TAC
12.3YH
Vulnerable; contact TAC
12.3YI
Vulnerable; contact TAC
12.3YJ
Vulnerable; migrates to 12.3(14)YQ4, available 1-Dec-05
12.3YK
Vulnerable; migrate to 12.4(4)T
12.3YM
12.3(14)YM4
12.3YQ
12.3(14)YQ4; available 01-Dec-05
12.3YS
Vulnerable; contact TAC
12.3YT
Vulnerable; migrate to 12.4(4)T
12.3YU
Vulnerable; contact TAC
12.3YX
Vulnerable; contact TAC
Affected 12.4-Based Release
Rebuild
Maintenance
12.4
12.4(1c); available 14-Nov-05
12.4(3b); available 12-Dec-05
12.4(5)
12.4T
12.4(2)T2
12.4(4)T
12.4XA
Vulnerable; contact TAC
12.4XB
12.4(2)XB; available TBD
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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.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show Less
Revision 1.9
12-January-2006
Updated the Vulnerable Products section. Updated the Products Confirmed Not Vulnerable section. Add the Additional Details for Cisco Wireless LAN controllers section. Updated the Cisco Bug IDs section. Updated the Software Versions and Fixes section Non-IOS products table.
Revision 1.8
11-January-2006
Removed "12.3(7)T13" and "12.3(8)T12" from the Cisco IOS table under Software Versions and Fixes.
Revision 1.7
15-December-2005
Updated Cisco IOS Products table and changed the availability date of 12.3(11)T9 to 27-Dec-05.
Revision 1.6
06-December-2005
Updated Additional Details for Cisco IOS section. Updated Cisco IOS section.
Revision 1.5
29-November-2005
Updated Cisco IOS Products table.
Revision 1.4
17-November-2005
Updated Cisco IOS Products table.
Revision 1.3
15-November-2005
Updated Non-IOS Products table.
Revision 1.2
15-November-2005
Updated Advisory Id.
Revision 1.1
14-November-2005
Updated Non-IOS Products table. Updated command output in the Additional Details for Cisco PIX section. Updated Additional Details for Cisco IOS section.
Revision 1.0
14-November-2005
Initial public release
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